Trine Stensrud

• Kojen, Aurora Jørnsdatter; Halvorsen, Thomas; Gjelstad, Astrid; Larsen, Stig; Lauritzen, Fredrik & Stensrud, Trine (2026). Reported use of anti-asthmatic medication in doping control forms from 2015 to 2019 – mapping retrospective data. Frontiers in Sports and Active Living. 8. doi: 10.3389/fspor.2026.1815697. Full text in Research Archive Show summary

  Objectives: Asthma and bronchial hyperresponsiveness is common in athletes, particularly in sports with high ventilatory demands or exposure to irritants such as cold, dry air, polluted air, or trichloramines. The mechanisms behind asthma in athletes remain unclear, but repeated high-volume ventilation and exposures to irritants, as well as airway inflammation and remodelling likely contribute. Symptoms resemble those of asthma, and airway hyperresponsiveness plays a key role, even in athletes with no other classic asthma features. Treatment of asthma in athletes follows the same approach as asthma in the general population. Use of asthma medication is commonly reported by athletes on doping control forms (DCFs). Thus, this study aimed to investigate the use of different anti-asthmatic medications among doping-controlled athletes. Methods: This was an observational cross-sectional study, evaluating retrospective data from athletes′ DCFs obtained during 2015–2019 as part of Anti-doping Norway′s national testing program in Norwegian sport, some of whom reappearing in the data set with multiple forms. Results: Of 10 418 DCFs, 1702 (16.3%) contained one or more anti-asthmatic medications. Bronchodilators were most frequently reported, with anticholinergics being most common. DCFs reported from females, national level athletes, and athletes with high risk of asthma contained significantly more anti-asthmatic medications compared to their counterparts (p< 0.01). Usage was highest among athletes aged 30–34, and in those in endurance sports. Conclusion: Despite the limitation of athletes’ reappearance in the dataset, this study provides insight into guideline adherence and asthma medication use among athletes in Norway. Further research is needed in this area.

• Kristiansen, Elsa; Stensrud, Trine & Holmeset, Vigdis (2026). Utvikling av robuste kvinnelige håndballspillere: Mestring av overgangen til elitenivå. In Sæther, Stig Arve & Høigaard, Rune (Ed.), Toppidrett i Skandinavia: En samfunnsvitenskapelig forskningsantologi om utviklings- og prestasjonsmiljø. Cappelen Damm Akademisk. ISSN 9788202916046. p. 315–337. doi: 10.23865/cdf.282.ch14. Full text in Research Archive Show summary

  This chapter focuses on how young handball players manage the transition from high school to elite league and national team play – in other words, the transition to the mastery phase as a ‘young adult.’ What does it take to succeed and remain in sport? Three athletes from Norway’s gold-winning team at the Paris 2024 Olympics were interviewed about how they learned to cope with the challenges associated with this phase. The three players made different choices in their careers, guided by what they wanted to challenge themselves with. Crucial to their decisions were also communication and trust from their coach – and the joy of playing handball confirmed that it was what they truly wanted. We also interviewed three coaches, who emphasized that there is no formula for success; instead, athletes need to make independent decisions based on their own abilities and development. Both players and coaches talked about stepwise progression in workload, but it is important to keep in mind that there is no one-size-fits-all approach to these steps. Combining studies with playing in the elite league can be challenging, and sufficient recovery is essential. Being physically and mentally robust is an advantage; however, robustness must be developed in athletes for them to reach their goals and establish themselves at their desired level. Finding a balance between challenge and security is crucial.

• Berge, Jarle; Nunavath, Vimala; Asbjørnsen, Rikke Aune; Borgeraas, Heidi; Hertel, Jens Kristoffer & Linge, Anita Dyb [Show all 15 contributors for this article] (2025). Machine learning for estimating cardiorespiratory fitness in patients with obesity: protocol for a retrospective and prospective multi - center cohort study (Preprint). JMIR Research Protocols. doi: 10.2196/preprints.85069. Full text in Research Archive Show summary

  BACKGROUND Cardiorespiratory fitness (VO2max) is a key predictor of cardiovascular and other health-related diseases and is often impaired in individuals with obesity due to functional and structural limitations. Improving cardiorespiratory fitness enhances overall health and reduces mortality, making it an important indicator for preventing and treating obesity. OBJECTIVE The primary aim of this study is to develop an obesity-specific machine learning (ML) model that can accurately estimate VO2max, a key indicator of cardiovascular fitness, and make it accessible through a web-based application. METHODS A ML model will be trained to estimate VO2max in individuals with obesity using retrospective data combining assessments of VO2max tests and clinical parameters from adult patients with severe obesity body mass index (BMI ≥40.0 kg/m2, or 35.0-39.9 kg/m2 with at least one obesity-related comorbidity) from Vestfold Hospital Trust, Muritunet Rehabilitation Institution and Norwegian School of Sport Sciences. The ML-based VO2max estimation model will be presented as a web application, allowing easy access and interaction. The model’s estimations will be compared against direct VO2max measurements obtained from medical equipment across institutions as part of a prospective validation. Ethical approval has been obtained for the use of two databases in the initial model development; approval for the remaining data and prospective phase is pending. RESULTS Vestfold Hospital Trust, the Norwegian School of Sport Medicine, and Muritunet Rehabilitation have from 2013 to 2025 conducted > 2623 VO2max test and clinical parameters from 1,279 adults with severe obesity, both before, during and after lifestyle interventions. This comprehensive data set serves as the foundation for developing the ML model, which is presented through a user-friendly web application. A web application has been developed and will be tested with patients and healthcare personnel. The first scientific publication of the ML model is expected to be published in 2026. The results of the overall project are expected to be completed in 2028. CONCLUSIONS This project aims to develop a machine learning model, which serves as a cost-effective tool for VO2max estimation in individuals with obesity, improving accessibility to this important health marker. This is the first known attempt in Norway to estimate VO2max in an obese population using machine learning, based on a unique clinical database. The project holds significant societal value with potential national and international relevance for healthcare and patient outcomes. CLINICALTRIAL ClinicalTrials.gov (Identifier: NCT07011108)

• Kennedy, M.D.; Parent, E.C.; Stang, Julie; Comeau, A.K. & Stensrud, Trine (2025). Influence of multiple cross-country ski races on respiratory function and symptoms in cross-country skiers. Science & sports. ISSN 0765-1597. 40, p. 147–158. doi: 10.1016/j.scispo.2024.08.002. Full text in Research Archive Show summary

  Objectives This study studied how multiple cross-country ski races affect respiratory function and symptoms in different age groups. Methods Eighteen ≥ 19 and 18 ≤ 18 years of age skiers performed morning spirometry, post-race/training spirometry and recorded respiratory symptoms daily over a National Championship (baseline day, 3 races and 2 training days). Results Races decreased resting spirometry and a rest day increased spirometry in both groups. Overall resting maximal mean decline was 4.6 ± 8.8%; 2.5 ± 8.2% for forced expiratory flow in 1 second (FEV1) and 6.3 ± 2.7%; 4.5 ± 2.7% forced vital capacity (FVC) in ≥ 19 and ≤ 18 aged skiers respectively. FEV1 decreased in 50% of skiers post-race, mean symptoms were 3.3 ± 0.5 (≤ 18 yrs); and 2.5 ± 0.5 (≥ 19 yrs). Post-race cough (86%) was most common symptom. Conclusions Multiple races reduced resting function, especially FVC in both age groups. Greater cough and decreased function in FEV1 pre-post-race in older skiers indicate potential age-related change. This study is the first to show how multiple ski races affect respiratory function and symptoms cumulatively.

• Kyte, Ferdinand Grov; Kyte, Karoline Holsen; Skinstad, Linn; Hisdal, Jonny & Stensrud, Trine (2025). Breathing Reserve and Lung Function in Female Elite Runners. Sports. 13(7). doi: 10.3390/sports13070231. Full text in Research Archive Show summary

  Breathing reserve (BR) is the remaining proportion of achievable minute ventilation that remains unutilized at total exhaustion during exercise. Previous studies have found a smaller BR in endurance-trained athletes compared to untrained controls. However, most of these studies have examined men. Given that women have a greater ventilatory limitation than stature-matched men, the present cross-sectional study aimed to investigate how this sex difference influences BR and lung function tests in endurance-trained females compared to matched, untrained females. To obtain further insight, we also aimed to investigate whether VO2max serves as a predictor of BR. We examined 15 female elite runners and 15 healthy, matched female controls aged 24–33 years with regard to pulmonary function, MVV, VEmax, BR, and VO2max. The elite runner group had a median BR of 5%, while that of the controls was 21%, representing a significant difference. Lung function tests showed no differences between the two groups. A moderate association was found between VO2max and BR. The female elite runners demonstrated a lower BR than the group of matched, untrained controls, which was lower than that found for male elite athletes in previous studies. This may indicate a greater ventilatory demand in female relative to male endurance athletes.

• Kristiansen, Elsa; Broch, Trygve B & Stensrud, Trine (2024). Chasing an Olympic dream: a holistic approach to how youth athletes narrate injuries, performance, and the value of being seen. Sports Coaching Review. ISSN 2164-0629. doi: 10.1080/21640629.2024.2343576. Full text in Research Archive Show summary

  This article explores how athletes experience injuries and performance pressures when striving for an “Olympic dream”, and focuses on how ten young women, aged 19–22, understand present and past experiences with injuries. Through a narrative analysis, we found that female players striving to become elite athletes often talk about injuries as something that made them feel invisible in a culture where visibility is key. “Being seen” emerged as a parallel narrative to that of injuries and the elite athlete as the players often looked back with regrets about how young and naïve they had been. This holistic take on injuries as a cultural construct is important for any coach to consider when working with young aspiring athletes. We conclude that this process is contingent on social processes and is a matter of when, how, and on what or whose terms young athletes are seen.

• Kolnes, Liv-Jorunn; Stensrud, Trine & Andersen, Oddbjørn Klomsten (2024). A multidimensional strategy to managing dysfunctional breathing and exercise-induced laryngeal obstruction in adolescent athletes. BMC sports science, medicine and rehabilitation. 16. doi: 10.1186/s13102-023-00804-2. Full text in Research Archive Show summary

  Background: Exercise induced laryngeal obstruction (EILO) causes inspiratory distress in the upper airway in many adolescent athletes. The nature of EILO is not fully understood, and effective management strategies are lacking. This study aimed to assess the effectiveness of a multidimensional individually tailored intervention, including Norwegian Psychomotor Physiotherapy (NPMP), elements of cognitive behavioural therapy and a rehabilitation plan, in reducing inspiratory distress and dysfunctional breathing in adolescent athletes with EILO. Methods: A mixed methods design, which combined qualitative and quantitative research, was used. Data, including subjective experiences of respiratory distress, findings from body examinations and objective measurements of lung function and aerobic capacity were gathered before and after a five month intervention involving 18 participants. Results: Following the intervention, the participants showed a reduction in respiratory distress and anxiousness associated with their breathing difficulties. Furthermore, the participants reported to be more in control of their breathing. The body assessments revealed a more functional breathing motion and improved posture, which imply that the breathing was less thoracic and more diaphragmatic in rest and exercise in all participants after the intervention. Conclusions: Our results suggest that a multidimensional individually tailored intervention, including NPMP based physiotherapy, cognitive behavioural therapy elements, and a rehabilitation plan may reduce inspiratory distress and dysfunctional breathing in athletes with EILO.

• Kyte, Karoline Holsen; Haakstad, Lene Annette Hagen; Hisdal, Jonny; Sunde, Andrine & Stensrud, Trine (2023). Bone health in Norwegian female elite runners: A cross-sectional, controlled study. BMJ Open sport & exercise medicine. 9(1). doi: 10.1136/bmjsem-2022-001472. Full text in Research Archive Show summary

  Objective: The primary objective was to compare bone mineral density (BMD) in Norwegian female elite long-distance runners with a control group of inactive females. Secondary objectives were to identify cases of low BMD, to compare the concentration of bone turnover markers, vitamin D and symptoms of low energy availability (LEA) between the groups, and to identify possible associations between BMD and selected variables. Methods: Fifteen runners and fifteen controls were included. Assessments included dual-energy X-ray absorptiometry measurement of BMD in the total body, lumbar spine and dual proximal femur. Blood samples included endocrine analyses and circulating bone turnover markers. The risk of LEA was assessed through a questionnaire. Results: Runners had higher Z-scores in the dual proximal femur (1.30 (0.20 to 1.80) vs 0.20 (−0.20 to 0.80), p<0.021) and total body (1.70 (1.20 to 2.30) vs 0.90 (0.80 to 1.00), p<0.001). The lumbar spine Z-score was similar between groups (0.10 (−0.70 to 0.60) vs −0.10(−0.50 to 0.50), p=0.983). Three runners had low BMD (Z-score <−1) in the lumbar spine. Vitamin D and bone turnover markers showed no differences between the groups. Forty-seven per cent of the runners were at risk of LEA. Dual proximal femur BMD showed a positive correlation to estradiol and a negative correlation to LEA symptoms in runners. Conclusion: Norwegian female elite runners had higher BMD Z-score in the dual proximal femur and total body compared with controls, while no difference was observed in the lumbar spine. The advantages of long-distance running on bone health seem to be site specific, and there is still a need for the prevention of LEA and menstrual disorders in this group.

• Riiser, Amund; Stensrud, Trine & Andersen, Lars Bo (2023). Glucocorticoids and physical performance: A systematic review with meta-analysis of randomized controlled trials. Frontiers in Sports and Active Living. 5. doi: 10.3389/fspor.2023.1108062. Full text in Research Archive Show summary

  Introduction: This systematic review with meta-analysis investigates the effect of glucocorticoids on maximal and submaximal performance in healthy subjects. Methods: We searched for randomised controlled trials investigating the effect of glucocorticoids on physical performance in Web of Science, Scopus, Medline, Embase and SportDiscus in March 2021. Risk of bias was assessed with the revised Cochrane Collaboration Risk of Bias Tool (RoB2). Data from random effect models are presented as standardized difference in mean (SDM) with 95% confidence interval. We included 15 studies comprising 175 subjects. Results: Two studies had high risk of bias. Glucocorticoids had a small positive effect on maximal physical performance compared to placebo (SDM 0.300, 95% CI 0.080 to 0.520) and the SDM for the 13 included comparisons was not heterogeneous (I2 = 35%, p = 0.099). Meta regression found no difference in the effect of acute treatment vs. prolonged treatment or oral ingestion vs. inhalation (p > 0.124). In stratified analysis prolonged treatment (SDM 0.428, 95% CI 0.148 to 0.709) and oral ingestion (SDM 0.361, 95% CI 0.124 to 0.598) improved physical performance. Glucocorticoids improved aerobic performance (SDM 0.371, 95% CI 0.173 to 0.569) but not anaerobic performance (p = 0.135). Glucocorticoids did not change energy expenditure during submaximal performance (SDM 0.0.225 95% CI −0.771 to 0.112). Discussion: This study indicates that glucocorticoids improves maximal performance and aerobic performance. Glucocorticoids did not affect the energy expenditure during submaximal performance. The conclusions are based on relatively few subjects leading to limited statistical power and uncertain estimates. Still, these results are consistent and should be of interest to WADA and anyone concerned about fair play.

• Bernhardsen, Guro Pauck; Stang, Julie; Halvorsen, Thomas & Stensrud, Trine (2022). Differences in lung function, bronchial hyperresponsiveness and respiratory health between elite athletes competing in different sports. European Journal of Sport Science (EJSS). ISSN 1746-1391. doi: 10.1080/17461391.2022.2113144. Full text in Research Archive Show summary

  The aim of this study was to examine lung function, bronchial hyperresponsiveness (BHR) and exercise-induced respiratory symptoms in elite athletes performing different sports. Norwegian national-team athletes (30 swimmers, 32 cross-country skiers, 16 speed-skaters, 11 rowers/paddlers, 17 handball players and 23 soccer players) completed a validated questionnaire, measured exhaled nitric oxide (FENO), spirometry, methacholine provocation (PD20met) and skin prick test. Three cut-off levels defined BHR; i.e. PD20met ≤2 µmol, ≤4 µmol and ≤8 µmol. Mean forced vital capacity (FVC) was highest in swimmers (Mean z-score[95%CI]  = 1.16 [0.80, 1.51]), and close to or higher than reference values according to the Global Lung Initiative equation, across all sports. Mean forced expiratory volume in 1 s (FEV1) was higher than reference values in swimmers (0.48 [0.13, 0.84]), and ball game athletes (0.69 [0.41, 0.97]). Mean forced expiratory flow between 25 and 75% of FVC (FEF25-75), and/or FEV1/FVC were lower than reference values in all endurance groups. BHR defined by ≤2 and ≤8 µmol methacholine was observed in respectively 50%–87% of swimmers, 25%–47% of cross-country skiers, 20%–53% of speed-skaters, 18%–36% of rowers/paddlers, and 0%–17% of the ball game athletes. Exercise-induced symptoms were common in all groups, most frequent in cross-country skiers (88%), swimmers (83%) and speed-skaters (81%).

• Tangen, Elene Mauseth; Gjestvang, Christina; Stensrud, Trine & Haakstad, Lene Annette Hagen (2022). Is there an association between total physical activity level and VO<inf>2max</inf> among fitness club members? A cross-sectional study. BMC sports science, medicine and rehabilitation. 14(1). doi: 10.1186/s13102-022-00503-4. Full text in Research Archive Show summary

  Background: Since cardiorespiratory fitness is an important predictor for all-cause mortality, it is of interest to know if meeting the physical activity (PA) recommendations is associated with higher levels of maximal oxygen uptake (VO2max). We aimed to investigate the association between total PA level given as counts per minute (cpm) and minutes in moderate-to-vigorous PA (MVPA), and VO2max in new fitness club members. Methods: A total of 62 men and 63 women (≥ 18 years), defined as healthy (no disease considered to hinder PA) participated in this study. VO2max (mL kg−1 min−1) was measured with a cardiopulmonary exercise (modified Balke protocol), and total PA level was measured with ActiGraph GT1M for seven consecutive days. All participants accumulating ≥ 10 h of activity recordings ≥ 4 days were included in the data analysis. To examine associations between PA level and VO2max, a Pearson correlation and a multiple linear regression analysis adjusted for covariates were used. Results: VO2max (mL kg−1 min−1) was 40.5 ± 7.2 in men and 35.1 ± 6.0 in women. Total PA level (cpm) and MVPA (min) were 352.4 ± 123.4 and 260.0 ± 132.6 in men and 361.4 ± 103.8 and 273.2 ± 137.0 in women. Total PA level (men: r = 0.346, p < 0.01, women: r = 0.267 p < 0.01) and MVPA (men: r = 0.359, p =  < 0.01, women: r = 0.236, p = 0.03) was associated with VO2max. When adjusting for age and body fat percentage, total PA level and MVPA were no longer associated with VO2max (men: p = 0.11 and p = 0.79, women: p = 0.40 and p = 0.61). In men, age (β = − 0.469 p < 0.01) and body fat percentage (β = − 0.483, p < 0.01) were the strongest predictor for VO2max. For women, body fat percentage was the strongest predictor for VO2max (β = − 0.483, p < 0.01). Conclusions: Total PA level and MVPA were associated with VO2max, but the association was low and diminished when adjusted for age and body fat percentage. Body fat percentage (men and women) and age (men) were more strongly associated with VO2max than total PA level and MVPA.

• Vollsæter, Maria; Stensrud, Trine; Maat, Robert; Halvorsen, Thomas; Røksund, Ola Drange & Sandnes, Astrid [Show all 7 contributors for this article] (2022). Exercise related respiratory problems in the young—Is it exercise-induced bronchoconstriction or laryngeal obstruction? Frontiers in Pediatrics. 9. doi: 10.3389/fped.2021.800073. Full text in Research Archive Show summary

  Complaints of breathlessness during heavy exercise is common in children and adolescents, and represent expressions of a subjective feeling that may be difficult to verify and to link with specific diagnoses through objective tests. Exercise-induced asthma and exercise-induced laryngeal obstruction are two common medical causes of breathing difficulities in children and adolescents that can be challenging to distinguish between, based only on the complaints presented by patients. However, by applying a systematic clinical approach that includes rational use of tests, both conditions can usually be diagnosed reliably. In this invited mini-review, we suggest an approach we find feasible in our everyday clinical work.

• Melsom, Helene Støle; Randa, Anders; Hisdal, Jonny; Stang, Julie & Stensrud, Trine (2022). Prevalence of asthma among Norwegian elite athletes. Translational Sports Medicine (TSM). 2022, p. 1–10. doi: 10.1155/2022/3887471. Full text in Research Archive Show summary

  Objective. Asthma is a common problem among elite athletes and represents a health risk interfering with the athlete’s performance status. This study aimed to evaluate the asthma prevalence among Norwegian summer and winter elite athletes and asthma prevalence across sport categories. We also aimed to examine whether bronchial hyperresponsiveness (BHR), lung function, fraction of exhaled nitric oxide (FENO), and allergy status differed between asthmatic and non-asthmatic elite athletes. Methods. Norwegian athletes qualifying for the Beijing Olympic Summer Games 2008 (n = 80) and the Vancouver Olympic Winter Games 2010 (n = 55) were included. The athletes underwent clinical respiratory examination including lung function measurement, methacholine bronchial challenge for assessment of BHR, FENO, and skin prick testing. Asthma was diagnosed based on respiratory symptoms and clinical examination including objective measurements. Results. Asthma was more prevalent among winter athletes (50%) than summer athletes (20%). Thirty-three (52%) endurance athletes, 3 (6%) team sport athletes, and 7 (33%) technical sport athletes had medically diagnosed asthma. Significantly lower lung function (p<0.001) and higher prevalence of severe BHR (p<0.001) were found in asthmatic athletes compared with non-asthmatic athletes. Conclusion. Asthma is common among Norwegian elite athletes, with winter and endurance athletes showing the highest prevalence. Asthmatic athletes were characterized by lower lung function and more severe BHR compared with non-asthmatic counterparts. The high prevalence among winter and endurance athletes demonstrates a need for increased attention to prevent and reduce the prevalence of asthma among those athletes.

• Kyte, Karoline Holsen; Stensrud, Trine; Berg, Tore Julsrud; Seljeflot, Ingebjørg & Hisdal, Jonny (2022). Vascular Function in Norwegian Female Elite Runners: A Cross-Sectional, Controlled Study. Sports. 10(3). doi: 10.3390/sports10030037. Full text in Research Archive Show summary

  In general, aerobic exercise has a positive impact on the vascular system, but the syndrome of relative energy-deficiency in sports (RED-S) makes this impact less clear for the athlete. The present cross-sectional controlled study aimed to investigate the vascular function in female elite long-distance runners, compared to inactive women. Sixteen female elite long-distance runners and seventeen healthy controls were recruited. Assessments of vascular function and morphology included endothelial function, evaluated by flow-mediated dilatation (FMD), vascular stiffness, evaluated with pulse wave velocity (PWV), carotid artery reactivity (CAR %), and carotid intima-media thickness (cIMT). Blood samples included hormone analyses, metabolic parameters, lipids, and biomarkers reflecting endothelial activation. RED-S risk was assessed through the low energy availability in female questionnaire (LEAF-Q), and body composition was measured by dual-energy X-ray absorptiometry (DXA). We found no significant differences in brachial FMD, PWV, CAR %, cIMT, or biomarkers reflecting endothelial activation between the two groups. Forty-four percent of the runners had a LEAF-Q score consistent with being at risk of RED-S. Runners showed significantly higher HDL-cholesterol and insulin sensitivity compared to controls. In conclusion, Norwegian female elite runners had an as good vascular function and morphology as inactive women of the same age.

• Haakstad, Lene Annette Hagen; Stensrud, Trine; Rugseth, Gro & Gjestvang, Christina (2022). Weight Cycling and Dieting Behavior in Fitness Club Members. Frontiers in Endocrinology. 13. doi: 10.3389/fendo.2022.851887. Full text in Research Archive Show summary

  Background: Along with the rising prevalence of high body-mass index (BMI), there is also increased emphasis on leanness and fitness. Both these trends suggest that many individuals are concerned about weight management and may try to lose weight. Using data from the research project “Fitness clubs - a venue for public health?”, we aimed to describe weight cycling and energy-restricted dieting in men and women at start-up of fitness club membership, and to investigate influencing factors [age, BMI, educational level, self-classified overweight/obesity, compliance with nutritional guidelines, unhealthy weight control strategies and self-perceived health (SPH)]. Methods: In a cross-sectional online survey, 250 men and women from 25 fitness clubs in Oslo, reported anthropometrics, self-classified weight group, weight cycling, weight loss/gain, eating habits/dieting, and background/health information. Enrollment was limited to adult (≥18 years) novice exercisers (exercising <60 min/week at a moderate or vigorous intensity or brisk walking <150 min/week, the past six months) with less than four weeks of membership. Factors associated with weight cycling were examined using simple and multiple logistic regression, separated for men and women. Results: In both sexes (mean age: 36.4 ± 11.3, range 18-71 years), a high number reported substantial weight fluctuation (+/-5 kg) the past 12 months (men: 50% and women: 62%, mean difference 12%, 95% CI -0.3 to 23.8, p=0.056) and unhealthy weight control strategies (men: 24.8% and women: 47.2%, mean difference 22.4%, 95% CI 10.5 to 33.4, p<0.001). Weight cyclers had a higher mean BMI compared with non-cyclers (mean difference -1.5, 95% CI -2.6 to - 0.4, p= 0.003). Further, the difference in body weight was 6.7 kg (95% CI 2.2 to 10.8, p=0.004) and 10.8 kg (95% CI 5.8 to 15.8, <0.001) in men and women, respectively. Besides BMI status, self-classified overweight/obesity was the strongest predictor of reporting weight cycling (men: OR 5.54, 95% CI 2.03 to 15.12, p<0.01 and women: OR 7.17, 95% CI 2.48 to 20.68, p<0.001). Conclusion: In novice exercisers, a large proportion reported weight cycling and unhealthy weight control strategies, and both were more prevalent in women than in men. Self-classified overweight was found to be the most important factor influencing weight cycling.

• Mikalsen, Ingvild Bruun; Halvorsen, Thomas; Juliusson, Pétur Benedikt; Magnus, Maria Christine; Nystad, Wenche & Stensrud, Trine [Show all 9 contributors for this article] (2021). Early life growth and associations with lung function and bronchial hyperresponsiveness at 11-years of age. Respiratory Medicine. ISSN 0954-6111. 177, p. 1–8. doi: 10.1016/j.rmed.2021.106305. Full text in Research Archive Show summary

  Low birthweight and being born small-for-gestational age (SGA) are linked to asthma and impaired lung function. Particularly, poor intrauterine growth followed by rapid catch-up growth during childhood may predispose for respiratory disease. Bronchial hyperresponsiveness (BHR) is an essential feature of asthma, but how foetal and early childhood growth are associated with BHR is less studied. Our hypothesis was that children born SGA or with accelerated early life growth have increased BHR and altered lung function at 11-years of age. We studied the associations between SGA and early childhood growth with lung function and BHR at 11-years of age in a subgroup of 468 children from the Norwegian Mother, Father and Child Cohort Study (MoBa), and included data from the Medical Birth Registry of Norway (MBRN). Weight at 6 months of age was positively associated with forced vital capacity (adjusted Beta: 0.121; 95% Confidence interval: 0.023, 0.219) and negatively associated with the ratio of forced expiratory flow in first second/forced vital capacity (−0.204; −0.317, −0.091) at 11-years of age. Similar patterns were found for weight at 36 months and for change in weight from birth to 6 months of age. SGA or other various variables of early childhood growth were not associated with BHR at 11-years of age. Early life growth was associated with an obstructive lung function pattern, but not with BHR in 11-year old children. Foetal growth restriction or weight gain during early childhood do not seem to be important risk factors for subsequent BHR in children.

• Gjestvang, Christina; Stensrud, Trine; Paulsen, Gøran & Haakstad, Lene Annette Hagen (2021). Stay true to your workout: Does repeated physical testing boost exercise attendance? A one-year follow-up study. Journal of Sports Science and Medicine (JSSM). ISSN 1303-2968. 20(1), p. 35–44. doi: 10.52082/jssm.2021.35. Full text in Research Archive Show summary

  No prospective studies have investigated if repeated testing of physical performance and body composition are associated with exercise attendance or patterns in fitness club members. This study aimed to investigate if repeated physical testing was associated with exercise attendance and patterns in gym members and to report prospective data on use of the fitness club’s facilities and products. Untrained new members were recruited and divided into a test group (n = 125) and as controls (n = 125). All participants answered a survey including exercise involvement, at onset, and after 3, 6, and 12 months follow-up. The test group also measured body composition, maximal oxygen uptake, and maximal muscle strength (onset, and after 3 and 12 months). In total 73.6% answered all surveys, and in the test group, 44.8% completed all physical tests. Regular exercise attendance was defined as ≥2 sessions/week. Repeated testing showed no association with long-term regular exercise attendance (test group: 19.6%, controls: 19.8%; p = 0.638). At 3 months, a lower proportion in the test group reported engagement in resistance exercise (35.3% and 60.2%; p = 0.003) and had lower exercise frequency (2.0 and 2.6 days/week; p = 0.008) than controls. The test group had higher participation in group exercise classes (28.0% and 13.6%; p = 0.040). Exercise frequency decreased from onset to 12 months (from 2.6 to 2.2 days/week; p = 0.025) At 3, 6, and 12 months, 51.8%, 37.6%, and 37.4% reported regular exercise attendance, and 16.9% at all follow-ups. At all time-points, most common workout mode was individual resistance exercise (43.8% to 46.3%). Few attended group exercise classes (7.5% to 13.8%) or used a personal trainer (22.5% to 27.5%). Repeated physical testing did not improve exercise attendance, and we found no changes in members` use of the fitness club’s facilities and products. Only 16.9% reported regular exercise attendance throughout the first year of membership.

• Haakstad, Lene Annette Hagen; Stensrud, Trine & Gjestvang, Christina (2021). Does Self-Perception Equal the Truth When Judging Own Body Weight and Height? International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(16). doi: 10.3390/ijerph18168502. Full text in Research Archive Show summary

  Background: Data from the research project “Fitness clubs—a venue for public health?” provided an opportunity to evaluate the accuracy of self-reported body weight and height, and subsequent Body Mass Index (BMI), as well as the “trueness” of novice exercisers perception of weight status category, which has not been examined in this population. The aims were to examine self-reported body weight, height, and calculated BMI data from an online survey compared with measured data at fitness club start-up, investigate how accurately novice exercisers place themselves within self-classified weight group (underweight, normal weight, overweight, and obese), and compare this with fitness club attendance at three months follow-up. Methods: Prior to anthropometric measurements, 62 men and 63 women responded to an online questionnaire, including body weight (kilogram, kg) and height (centimeters, cm), and self-classified weight group (“I think I am … underweight, normal weight, overweight, obese”). We used the following statistical analysis: Paired sample t-tests, a Bland–Altman plot kappa statistics, chi-squared tests, and a logistic regression. Results: Mean difference of BMI calculated from self-reported and measured data was 0.06 (95% CI −0.29 to 0.17, p = 0.593) in men, and 0.16 (95% CI −0.40 to 0.09, p = 0.224) in women, with four participants being outliers of the 95% limits of agreement (Bland-Altman plot). Allowing a difference of 0.5 kg between self-reported and measured weight, we found that 16% reported their weight correctly, 31.2% underreported (−1.89 ± 1.59 kg), and 52.8% overreported (1.85 ± 1.23 kg), with no sex differences (p = 0.870). Further, our results suggest that both sexes may have difficulty recognizing overweight/obesity in themselves, and particularly men are likely to underreport their perceived weight group compared with women. More than half (53.3%) of the overweight men perceived themselves to be normal weight (women: 14%), and only 33.3% of obese men and women correctly classified themselves as being obese. We did not find any difference between participants correctly or incorrectly classifying weight group and fitness club attendance (≥2 times a week) at three months follow-up. Conclusion: Both sexes reported body weight and height reasonably accurately, and BMI based on self-report appears to be valid measure. Still, a large proportion of novice exercisers do not recognise their own overweight or obesity status, which may in part explain why public health campaigns do not reach risk populations.

• Stadheim, Hans Kristian; Stensrud, Trine; Brage, Søren & Jensen, Jørgen (2021). Caffeine Increases Exercise Performance, Maximal Oxygen Uptake, and Oxygen Deficit in Elite Male Endurance Athletes. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 53(11), p. 2264–2273. doi: 10.1249/MSS.0000000000002704. Full text in Research Archive Show summary

  Caffeine increases endurance performance, but the physiological mechanisms improving high-intensity endurance capacity are not well characterized. Purpose: The aims of the present study were to test the hypothesis that caffeine increases maximal oxygen uptake (V˙O2max) and to characterize the physiological mechanisms underpinning improved high-intensity endurance capacity. Methods: Twenty-three elite endurance-trained male athletes were tested twice with and twice without caffeine (four tests) in a randomized, double-blinded, and placebo-controlled study with crossover design. Caffeine (4.5 mg·kg−1) or placebo was consumed 45 min before standardized warm-up. Time to exhaustion during an incremental test (running 10.5° incline, start speed 10.0 km·h−1, and 0.5 km·h−1 increase in speed every 30 s) determined performance. Oxygen uptake was measured continuously to determine V˙O2max and O2 deficit was calculated. Results: Caffeine increased time to exhaustion from 355 ± 41 to 375 ± 41 s (Δ19.4 ± 16.5 s; P < 0.001). Importantly, caffeine increased V˙O2max from 75.8 ± 5.6 to 76.7 ± 6.0 mL·kg−1·min−1 (Δ 0.9 ± 1.7 mL·kg−1·min−1; P < 0.003). Caffeine increased maximal heart rate (HRpeak) and ventilation (VEpeak). Caffeine increased O2 deficit from 63.1 ± 18.2 to 69.5 ± 17.5 mL·kg−1 (P < 0.02) and blood lactate compared with placebo. The increase in time to exhaustion after caffeine ingestion was reduced to 11.7 s after adjustment for the increase in V˙O2max. Caffeine did not significantly increase V˙O2max after adjustment for VEpeak and HRpeak. Adjustment for O2 deficit and lactate explained 6.2 s of the caffeine-induced increase in time to exhaustion. The increase in V˙O2max, VE, HR, O2 deficit, and lactate explained 63% of the increased performance after caffeine intake. Conclusion: Caffeine increased V˙O2max in elite athletes, which contributed to improvement in high-intensity endurance performance. Increases in O2 deficit and lactate also contributed to the caffeine-induced improvement in endurance performance.

• Gjestvang, Christina; Abrahamsen, Frank Eirik; Stensrud, Trine & Haakstad, Lene Annette Hagen (2021). What Makes Individuals Stick to Their Exercise Regime? A One-Year Follow-Up Study Among Novice Exercisers in a Fitness Club Setting. Frontiers in Psychology. 12. doi: 10.3389/fpsyg.2021.638928. Full text in Research Archive Show summary

  Objectives: A fitness club may be an important arena to promote regular exercise. However, authors have reported low attendance rates (10 to 37%) the first months after individuals sign up for membership. It is therefore important to understand the reasons for poor exercise adherence. In this project, we aimed to investigate different psychosocial factors that might increase the likelihood of reporting regular exercise the first year of a fitness club membership, including self-efficacy, motives, social support, life satisfaction, and customer satisfaction. Methods: New members (≤4 weeks membership, n = 250) classified as novice exercisers (exercise < 60 min/week the last 6 months) from 25 multipurpose gyms were followed for 1 year. Data were collected by an electronic survey including background and health factors, self-efficacy, social support, life satisfaction, motives, customer satisfaction, and exercise attendance, and was answered at start-up and after three (n = 224), six (n = 213), and 12 (n = 187) months. It is well established in the literature that ≥2 exercise sessions/week improve physical fitness in novice exercisers (if adhered to). Hence, we divided the participants into regular exercise attendance (≥2 sessions/week) and non-regular exercise attendance (≤1 session/week, exercise dropout, or membership dropout) in the analysis. Results: A mixed-effects logistic regression model revealed that the strongest predictor for reporting regular exercise attendance was higher levels of the motive “enjoyment” (OR = 1.84, p ≤ 0.001, 95% CI for OR = 1.35, 2.50), followed by self-efficacy “sticking to it” (OR = 1.73, p = 0.002, 95% CI for OR = 1.22, 2.46) and social support from friends and family (OR = 1.16, p ≤ 0.001, 95% CI for OR = 1.09, 1.23). Conclusion: In novice exercisers, regular exercise at three, six, and 12 months was associated with higher scores of the motive “enjoyment,” self-efficacy (“sticking to it”), and social support compared with non-regular exercise. Our results show that the majority of new fitness club members do not achieve regular exercise behavior.

• Illidi, Camilla Rønn; Stang, Julie; Melau, Jørgen; Hisdal, Jonny & Stensrud, Trine (2021). Does Cold-Water Endurance Swimming Affect Pulmonary Function in Healthy Adults? Sports. 9(1), p. 1–12. doi: 10.3390/sports9010007. Full text in Research Archive Show summary

  The acute effects of cold-water endurance swimming on the respiratory system have received little attention. We investigated pulmonary responses to cold-water endurance swimming in healthy recreational triathletes. Pulmonary function, alveolar diffusing capacity (DLCO), fractional exhaled nitric oxide (FENO) and arterial oxygen saturation by pulse oximetry (SpO2) were assessed in 19 healthy adults one hour before and 2.5 h after a cold-water (mean ± SD, 10 ± 0.9 °C) swim trial (62 ± 27 min). In addition, 12 out of the 19 participants measured pulmonary function, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) 3, 10, 20 and 45 min post-swim by maximal expiratory flow volume loops and DLCO by the single breath technique. FVC and FEV1 were significantly reduced 3 min post-swim (p = 0.02) (p = 0.04), respectively, and five of 12 participants (42%) experienced exercise-induced bronchoconstriction (EIB), defined as a ≥ 10% drop in FEV1. No significant changes were observed in pulmonary function 2.5 h post-swim. However, mean FENO and DLCO were significantly reduced by 7.1% and 8.1% (p = 0.01) and (p < 0.001), respectively, 2.5 h post-swim, accompanied by a 2.5% drop (p < 0.001) in SpO2. The absolute change in DLCO correlated significantly with the absolute decline in core temperature (r = 0.52; p = 0.02). Conclusion: Cold-water endurance swimming may affect the lungs in healthy recreational triathletes lasting up to 2.5 h post-swim. Some individuals appear to be more susceptible to pulmonary impairments than others, although these mechanisms need to be studied further.

• Kristiansen, Elsa & Stensrud, Trine (2020). Talent development in a longitudinal perspective: Elite female handball players within a sport school system. Translational Sports Medicine (TSM). 3(4), p. 364–373. doi: 10.1002/tsm2.143. Full text in Research Archive Show summary

  The purpose of the present longitudinal study was to explore the psychological and physical transition into (and subsequent 3 years in) a Sport Academy High School of 10 young female handball players. Psychological (coping with stress) and physical data (injuries, body composition, training volume, and sleep time) were collected. Parents (n = 5), coaches (n = 3), and a sport school manager (n = 1) were also interviewed after the final high school year, and they elaborated upon the collected data and gave their perspective on different topics. Successful athletes had resourceful parents (with sport knowledge) who helped them cope with perceived challenges—and also intervened when they found it necessary. The three athletes that had dropped out of handball did not perceive to get the same amount of support, and difficulties and injuries become career endings rather than bumps in the road which elite athletes have to learn to cope with. We did not observe any differences in physical development or prevalence of injuries between athletes who were successful and continued with handball and those who quit. However, coordination and communication between stakeholders are essential for monitoring young athletes' overall workload. Lack thereof may affect both school motivation and degree and number of injuries.

• Stensrud, Trine; Rossvoll, Øyvind; Mathiassen, Maria; Melau, Jørgen; Illidi, Camilla Rønn & Østgaard, Hege Nymo [Show all 8 contributors for this article] (2020). Lung function and oxygen saturation after participation in Norseman Xtreme Triathlon. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(6), p. 1008–1016. doi: 10.1111/sms.13651. Full text in Research Archive Show summary

  Objectives: To examine evidence of exercise-induced bronchoconstriction (EIB) defined as ≥10% reduction in forced expiratory volume in one second (FEV1 ) and exercise-induced arterial hypoxemia (EIAH) defined as ≥4% reduction in oxygen saturation (SpO2 ) from before to after participation in the Norseman Xtreme Triathlon. Secondarily, to assess whether changes in FEV1 and SpO2 are related to respiratory symptoms, training volume, and race time. Methods: In this quasi-experimental non-controlled study, we included 63 triathletes (50♂/13♀) aged 40.3 (±9.0) years (mean ± SD). Fifty-seven (46♂/11♀) measured lung function and 54 (44♂/10♀) measured SpO2 before the race, 8-10 minutes after the race (post-test 1) and the day after the race (post-test 2). Respiratory symptoms and training volume were recorded with modified AQUA questionnaire. ANOVA for repeated measures was used to detect differences in lung function and SpO2 . Statistical significance was accepted at 0.05 level. Results: Twenty-six participants (46%) presented with EIB at post-test 1 and 16 (28%) at post-test 2. Lung function variables were significantly reduced from baseline to post-test 1 and 2. Thirty-five participants (65%) showed evidence of mild to moderate EIAH. No significant correlations were observed except a weak correlation between maximal reduction in FEV1 and respiratory symptoms (r = 0.35, P = .016). Conclusion: Our results demonstrated that 46% of the participants presented with EIB and 65% showed evidence of EIAH after the Norseman Xtreme Triathlon. Changes in FEV1 and SpO2 were not correlated to weekly training hours or race time. We observed a weak correlation between maximal reduction in FEV1 and respiratory symptoms.

• Engan, Mette; Jansrud, Ida; Stensrud, Trine; Gundersen, Hilde; Edvardsen, Elisabeth & Clemm, Hege Havstad (2020). Pust opp Stolzen. Norsk idrettsmedisin. ISSN 0806-9328. Full text in Research Archive
• Gjestvang, Christina; Abrahamsen, Frank Eirik; Stensrud, Trine & Haakstad, Lene Annette Hagen (2020). Motives and barriers to initiation and sustained exercise adherence in a fitness club setting—A one-year follow-up study. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(9), p. 1796–1805. doi: 10.1111/sms.13736. Full text in Research Archive Show summary

  No prospective studies have investigated motives and barriers to exercise in new untrained fitness club members. The aims of the present prospective longitudinal study were to 1) examine proportions reporting regular exercise, non‐regular exercise and exercise dropout, 2) identify motives and barriers to exercise, and 3) compare motives between regular and non‐regular exercisers the first year of fitness club membership. New members (n = 250) were followed for one year. A questionnaire including demographics, exercise frequency, motives (EMI‐2) and barriers (18 common reported barriers) was used, and 184 answered at four time‐points (onset, and after three, six and 12 months). Participants were categorized into: regular exercise: ≥two sessions/week or non‐regular exercise: ≤one session/week, exercise relapse or dropout. At three, six and 12 months, 63.4%, 59.6% and 57.2% exercised regularly, whereas 20.1%, 21.1% and 28.3%, dropped out, respectively. Throughout the follow‐up, 37% reported regular exercise. At all time‐points, motives regarding positive health and strength/endurance were rated highest on a six‐point scale. Exercise dropouts rated priority as the greatest barrier. Regular exercisers rated the motives enjoyment (such as “I enjoy the feeling of exerting myself” ) and challenge (such as “To give me goals to work towards” ) higher than non‐regular exercisers (p = ≤0.05). In conclusion, less than half exercised regularly, and most members were motivated by factors such as positive health and physical fitness the first year of fitness club membership. Higher levels of the motives enjoyment and challenge were associated with regular exercise.

• Andersen, Eivind; Bang-Kittilsen, Gry; Bigseth, Therese Torgersen; Egeland, Jens; Holmen, Tom Langerud & Martinsen, Egil Wilhelm [Show all 8 contributors for this article] (2020). Effect of high-intensity interval training on cardiorespiratory fitness, physical activity and body composition in people with schizophrenia: a randomized controlled trial. BMC Psychiatry. 20, p. 1–12. doi: 10.1186/s12888-020-02827-2. Full text in Research Archive Show summary

  Background Exercise may improve cardiorespiratory fitness in people with schizophrenia, however, possible condition-specific cardiorespiratory disadvantages, a scarcity of methodologically sound studies, and conflicting results raise questions about the effect of exercise on maximal oxygen uptake (VO2max) in this group. The primary aim of this study, therefore, was to investigate the effect of high-intensity interval training on VO2max in people with schizophrenia. Second, we sought to determine whether the intervention would have an effect on general physical activity (PA) level and body composition. Methods Eighty-two patients with schizophrenia were randomly assigned to supervised high-intensity interval training or computer gaming skills training, performed twice a week for 12 weeks. Oxygen uptake was measured directly, during a maximum exercise session on a treadmill. PA level were assessed using ActiGraph accelerometer, and body composition was assessed by bioelectrical impedance. Differences between groups were assessed by analysis of variance using a univariate general linear model. Results There were no significant differences between the groups on any of the cardiorespiratory variables neither at baseline nor after the program. There were also no significant within-group differences in any of the cardiorespiratory fitness variables between the baseline and post-program time points, despite that 61% of the participants performing high-intensity interval training showed a significant increase in workload on the treadmill. However, 47% of the participants in the high-intensity interval training group had a ≥ 5% increase in VO2max. Participants supervised by mental health care providers with PA competence (e.g. rehabilitation center staff, sport scientist, physical trainer) had a much larger increase in VO2max compared to participants supervised by mental health workers without such competence, and when adding PA competence to the model, the intervention group increased VO2max significantly compared to the comparison group. The intervention had no significant effect on PA level or body composition. Conclusions The intervention did not improve VO2max, PA level or body composition but succeeded in increasing workload on the treadmill. With regard to VO2max, approximately half of the patients may be considered responders.

• Brynjulfsen, Trine; Demmelmaier, Ingrid; Berntsen, Sveinung; Foyn, Tonje Hellum; Andersen, Oddbjørn Klomsten & Stang, Julie [Show all 11 contributors for this article] (2020). Motivation for physical activity in adolescents with asthma. Journal of Asthma. ISSN 0277-0903. doi: 10.1080/02770903.2020.1778025. Full text in Research Archive Show summary

  Objective: We explored motivation for physical activity (PA) and exercise in adolescents with asthma who entered and continued a 10-week play-based exercise intervention. Methods: Eighteen adolescents with asthma, aged 13–17 years, participated in a 10-week play- and interval-based indoor exercise intervention during winter and autumn months. Semi-structured focus group interviews were conducted in weeks 2 and 8, focusing on motivation for PA and exercise, as well as field observations of exercise sessions in weeks 2, 6, and 8. The first interview was analyzed separately from the second one and descriptive observational data were obtained using thematic analysis and self-determination theory as a framework. Results: In the first round of focus group interviews, participants (n = 18) described amotivation and motivation for PA within the following five themes: “teachers’ lack of asthma knowledge”, “embarrassment over asthma symptoms”, “not being able to keep pace with peers”, “seasonal challenges”, and “mastering fun physical activities”. Based on the second interview (n = 14) and descriptive observational data (n = 18), participants reported and revealed amotivation and motivation for PA within the following four themes: “understanding and relatedness”, “social support”, “competition”, and “mastering fun activities”. Conclusion: We conclude that play-based exercises designed for groups of adolescents with asthma can support motivation for PA and exercise and reduce social and asthma-specific barriers.

• Riiser, Amund; Stensrud, Trine; Stang, Julie & Andersen, Lars Bo (2020). Can β2-agonists have an ergogenic effect on strength, sprint or power performance? Systematic review and meta-analysis of RCTs. British Journal of Sports Medicine. ISSN 0306-3674. 54(22), p. 1351–1359. doi: 10.1136/bjsports-2019-100708. Full text in Research Archive Show summary

  Objectives: We aimed to examine the effect of β2-agonists on anaerobic performance in healthy non-asthmatic subjects. Design: Systematic review and meta-analysis. Eligibility criteria: We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials, published until December 2019, examining the effect of β2-agonists on maximal physical performance lasting 1 min or shorter. Data are presented as standardised difference in mean (SDM) with 95% confidence intervals (95% CI). Results: 34 studies were included in the present meta-analysis. The studies include 44 different randomised and placebo-controlled comparisons with β2-agonists comprising 323 participants in crossover trials, and 149 participants in parallel trials. In the overall analyses, β2-agonists improved anaerobic performance by 5% (SDM 0.29, 95% CI 0.16 to 0.42), but the effect was related to dose and administration route. In a stratified analysis, the SDM was 0.14 (95% CI 0.00 to 0.28) for approved β2-agonists and 0.46 (95% CI 0.24 to 0.68) for prohibited β2-agonists, respectively. Furthermore, SDM was 0.16 (95% CI 0.02 to 0.30) for inhaled administration and 0.51 (95% CI 0.25 to 0.77) for oral administration, respectively, and 0.20 (95% CI 0.07 to 0.33) for acute treatment and 0.50 (95% CI 0.20 to 0.80) for treatment for multiple weeks. Analyses stratified for the type of performance showed that strength (0.35, 95% CI 0.15 to 0.55) and sprint (0.17, 95% CI 0.06 to 0.29) performance were improved by β2-agonists. Conclusion/implication: Our study shows that non-asthmatic subjects can improve sprint and strength performance by using β2-agonists. It is uncertain, however, whether World Anti-Doping Agency (WADA)-approved doses of β2-agonists improve performance. Our results support that the use of β2-agonists should be controlled and restricted to athletes with documented asthma.

• Riiser, Amund; Stensrud, Trine; Stang, Julie & Andersen, Lars Bo (2020). Aerobic performance among healthy (non-asthmatic) adults using beta2-agonists: a systematic review and meta-analysis of randomised controlled trials. British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2019-100984. Full text in Research Archive Show summary

  Objective: To examine the effect of beta2-agonists on aerobic performance in healthy, non-asthmatic study participants. Design: Systematic review and meta-analysis. Eligibility criteria: We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomised controlled trials published until December 2019. Studies examining the effect of beta2-agonists on maximal physical performance lasting longer than 1 min were included in the meta-analysis. Data are presented as standardised difference in mean (SDM) with 95% CI. Results: The present meta-analysis includes 47 studies. The studies comprise 607 participants in cross-over trials, including 99 participants in three-way cross-over trials and 27 participants in a four-way cross-over trial. Seventy-three participants were included in parallel trials. Beta2-agonists did not affect aerobic performance compared with placebo (SDM 0.051, 95% CI −0.020 to 0.122). The SDM for the included studies was not heterogeneous (I2=0%, p=0.893), and the effect was not related to type of beta2-agonist, dose, administration route, duration of treatment or performance level of participants. Beta2-agonists had no effect on time trial performance, time to exhaustion or maximal oxygen consumption (p<0.218). Conclusion/implication: The present study shows that beta2-agonists do not affect aerobic performance in non-asthmatic subjects regardless of type, dose, administration route, duration of treatment or performance level of participants. The results of the present study should be of interest to WADA and to anyone who is interested in equal opportunities in competitive sports.

• Bernhardsen, Guro Pauck; Stensrud, Trine; Nystad, Wenche & Ekelund, Ulf (2020). Pre- and post-natal factors and physical activity in childhood: The Norwegian Mother, Father and Child Cohort study. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(11), p. 2264–2274. doi: 10.1111/sms.13781. Full text in Research Archive Show summary

  Few studies have examined the possibility that pre‐ and post‐natal factors may be non‐linearly associated with later physical activity. We used data from the Norwegian Mother, Father and Child Cohort study (MoBa) and the Medical Birth Registry of Norway (MBRN), including 48 672 children with available data on leisure time physical activity (LTPA) at child's age 7 years. Restricted cubic and linear splines or linear regression was used to examine the associations between maternal pre‐pregnancy BMI, birth weight for gestational age, and infant weight gain from birth to 1 year with LTPA (frequency/wk) in 7‐year‐old children. The results suggest no associations between maternal pre‐pregnancy BMI, birth weight, and infant weight gain on subsequent LTPA in girls. Maternal pre‐pregnancy BMI and birth weight may be non‐linearly associated with LTPA in 7‐year‐old boys. Infant weight gain (change in weight z‐score from birth to 1 year) may be weakly linearly associated with LTPA in boys. Pre‐ and post‐natal factors may therefore influence LTPA in childhood differently in boys and girls. Maternal pre‐pregnancy BMI and birth weight are positively associated with LTPA at the lower ends of the maternal pre‐pregnancy BMI and birth weight continuums in boys. The negative associations at the higher ends of the continuums and the positive association between infant weight gain and LTPA in boys may not be important and needs further replication.

• Bernhardsen, Guro Pauck; Stensrud, Trine; Hansen, Bjørge Hermann; Steene-Johannessen, Jostein; Kolle, Elin & Nystad, Wenche [Show all 17 contributors for this article] (2020). Birth weight, cardiometabolic risk factors and effect modification of physical activity in children and adolescents: pooled data from 12 international studies. International Journal of Obesity. ISSN 0307-0565. 44(10), p. 2052–2063. doi: 10.1038/s41366-020-0612-9. Full text in Research Archive Show summary

  Objectives: Low and high birth weight is associated with higher levels of cardiometabolic risk factors and adiposity in children and adolescents, and increases the risk of cardiovascular diseases, obesity, and early mortality later in life. Moderate-to-vigorous physical activity (MVPA) is associated with lower cardiometabolic risk factors and may mitigate the detrimental consequences of high or low birth weight. Thus, we examined whether MVPA modified the associations between birth weight and cardiometabolic risk factors in children and adolescents. Methods: We used pooled individual data from 12 cohort- or cross-sectional studies including 9,100 children and adolescents. Birth weight was measured at birth or maternally reported retrospectively. Device-measured physical activity (PA) and cardiometabolic risk factors were measured in childhood or adolescence. We tested for associations between birth weight, MVPA, and cardiometabolic risk factors using multilevel linear regression, including study as a random factor. We tested for interaction between birth weight and MVPA by introducing the interaction term in the models (birth weight x MVPA). Results: Most of the associations between birth weight (kg) and cardiometabolic risk factors were not modified by MVPA (min/day), except between birth weight and waist circumference (cm) in children (p = 0.005) and HDL-cholesterol (mmol/l) in adolescents (p = 0.040). Sensitivity analyses suggested that some of the associations were modified by VPA, i.e., the associations between birth weight and diastolic blood pressure (mmHg) in children (p = 0.009) and LDL- cholesterol (mmol/l) (p = 0.009) and triglycerides (mmol/l) in adolescents (p = 0.028). Conclusion: MVPA appears not to consistently modify the associations between low birth weight and cardiometabolic risk. In contrast, MVPA may mitigate the association between higher birth weight and higher waist circumference in children. MVPA is consistently associated with a lower cardiometabolic risk across the birth weight spectrum. Optimal prenatal growth and subsequent PA are both important in relation to cardiometabolic health in children and adolescents.

• Litleskare, Sigbjørn; Enoksen, Eystein; Sandvei, Marit; Støen, Line; Stensrud, Trine & Johansen, Egil Ivar [Show all 7 contributors for this article] (2020). Sprint interval running and continuous running produce training specific adaptations, despite a similar improvement of aerobic endurance capacity—a randomized trial of healthy adults. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 17(11). doi: 10.3390/ijerph17113865. Full text in Research Archive Show summary

  The purpose of the present study was to investigate training-specific adaptations to eight weeks of moderate intensity continuous training (CT) and sprint interval training (SIT). Young healthy subjects (n = 25; 9 males and 16 females) performed either continuous training (30–60 min, 70–80% peak heart rate) or sprint interval training (5–10 near maximal 30 s sprints, 3 min recovery) three times per week for eight weeks. Maximal oxygen consumption, 20 m shuttle run test and 5·60 m sprint test were performed before and after the intervention. Furthermore, heart rate, oxygen pulse, respiratory exchange ratio, lactate and running economy were assessed at five submaximal intensities, before and after the training interventions. Maximal oxygen uptake increased after CT (before: 47.9 ± 1.5; after: 49.7 ± 1.5 mL·kg−1·min−1, p < 0.05) and SIT (before: 50.5 ± 1.6; after: 53.3 ± 1.5 mL·kg−1·min−1, p < 0.01), with no statistically significant differences between groups. Both groups increased 20 m shuttle run performance and 60 m sprint performance, but SIT performed better than CT at the 4th and 5th 60 m sprint after the intervention (p < 0.05). At submaximal intensities, CT, but not SIT, reduced heart rate (p < 0.05), whereas lactate decreased in both groups. In conclusion, both groups demonstrated similar improvements of several performance measures including VO2max, but sprint performance was better after SIT, and CT caused training-specific adaptations at submaximal intensities.

• Engan, Mette; Jansrud, Ida; Stensrud, Trine; Gundersen, Hilde; Edvardsen, Elisabeth & Clemm, Hege Havstad (2020). Changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running. BMJ Open sport & exercise medicine. 6(1), p. 1–6. doi: 10.1136/bmjsem-2020-000815. Full text in Research Archive Show summary

  Objective: To evaluate changes in pulmonary function and feasibility of portable continuous laryngoscopy during maximal uphill running. Methods: Healthy volunteers participated in an uphill race. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were obtained before and 5 and 10 min after finishing the race. Capillary blood lactate concentration ([BLa-]) and Borg score for perceived exertion were registered immediately after the race. One participant wore a portable video-laryngoscope during the race, and the video was assessed for technical performance. Results: Twenty adult subjects participated with a mean (SD) age of 40.2 (9.7) years. Mean (SD) race duration and post-exercise [BLa-] was 13.9 (2.3) min and 10.7 (2.1) mmol/L, respectively, and the median (range) Borg score for perceived exertion was 9 (5–10). Mean percentage change (95% CI) 5 and 10 min post-exercise in FEV1 were 6.9 (3.7 to 10.2) % and 5.9 (2.7 to 9.0) %, respectively, and in FVC 5.2 (2.3 to 8.1) % and 4.7 (1.6 to 7.9) %, respectively. The recorded video of the larynx was of good quality. Conclusions: Maximal aerobic field exercise induced bronchodilatation in the majority of the healthy non-asthmatic participants. It is feasible to perform continuous video-laryngoscopy during heavy uphill exercise.

• Gjestvang, Christina; Stensrud, Trine; Hansen, Bjørge Hermann; Kolle, Elin & Haakstad, Lene Annette Hagen (2019). Are fitness club members likely to meet the current physical activity recommendations? Translational Sports Medicine (TSM). 3(2), p. 75–83. doi: 10.1002/tsm2.120. Full text in Research Archive
• Melau, Jørgen; Mathiassen, Maria; Stensrud, Trine; Tipton, Mike & Hisdal, Jonny (2019). Core temperature in triathletes during swimming with wetsuit in 10^◦c cold water. Sports. 7(6). doi: 10.3390/sports7060130. Full text in Research Archive Show summary

  Low water temperature (<15 °C) has been faced by many organizers of triathlons and swim-runs in the northern part of Europe during recent years. More knowledge about how cold water affects athletes swimming in wetsuits in cold water is warranted. The aim of the present study was therefore to investigate the physiological response when swimming a full Ironman distance (3800 m) in a wetsuit in 10 °C water. Twenty triathletes, 37.6 ± 9 years (12 males and 8 females) were recruited to perform open water swimming in 10 °C seawater; while rectal temperature (Tre) and skin temperature (Tskin) were recorded. The results showed that for all participants, Tre was maintained for the first 10–15 min of the swim; and no participants dropped more than 2 °C in Tre during the first 30 min of swimming in 10 °C water. However; according to extrapolations of the results, during a swim time above 135 min; 47% (8/17) of the participants in the present study would fall more than 2 °C in Tre during the swim. The results show that the temperature response to swimming in a wetsuit in 10 °C water is highly individual. However, no participant in the present study dropped more than 2 °C in Tre during the first 30 min of the swim in 10 °C water.

• Gjestvang, Christina; Stensrud, Trine & Haakstad, Lene Annette Hagen (2019). Are changes in physical fitness, body composition and weight associated with exercise attendance and dropout among fitness club members? Longitudinal prospective study. BMJ Open. 9(4). doi: 10.1136/bmjopen-2018-027987. Full text in Research Archive Show summary

  Objectives The primary aim of the present study was to investigate if changes in physical fitness, body composition and weight are associated with exercise attendance and dropout among fitness club members. Secondary, we wanted to identify motives for fitness club membership and exercise. Setting New members at 25 fitness clubs in Oslo, Norway. Participants In total, 125 new fitness club members were recruited. Eligible criteria were <4 weeks of membership, untrained (exercising <60min once a week) and ≥18 years. At inclusion, and after 3 (n=87) and 12 months (n=64), participants answered a questionnaire (including motives for membership and exercise, and attendance) and performed measurements of maximum oxygen uptake (VO2max), one repetition maximum (bench press and leg press), body composition and weight. In total, 56 participants underwent measurements at all time points. Based on self-reported attendance, participants were divided into three groups: regular attendance (≥2 sessions per week), low attendance (<2 sessions per week) and exercise dropout (no sessions the last month). Results At 3months, regular attendees had significantly higher VO2max than dropout (6.54mL/min/kg, 95%CI 2.00 to 11.07, p=0.003). At 12 months, a difference in VO2max of 5.32mL/min/kg (95%CI −0.08 to 10.72, p=0.054) was found between regular attendees and dropout, and between regular and low exercise attendance (6.17mL/ min/kg, 95%CI 0.19 to 12.15, p=0.042). VO2max was the only factor showing an association with attendance. No differences or associations were observed in maximal muscle strength or body composition between the three groups. Primary motive for fitness club membership and exercise was increase in physical fitness (92.8%). Conclusions VO2max was the only factor associated with exercise attendance at two time points. Increased physical fitness was primary motive for fitness club membership and exercise.

• Kolnes, Liv-Jorunn; Vollsæter, Maria; Røksund, Ola Drange & Stensrud, Trine (2019). Physiotherapy improves symptoms of exercise-induced laryngeal obstruction in young elite athletes: A case series. BMJ Open sport & exercise medicine. 5:e000487(1). doi: 10.1136/bmjsem-2018-000487. Full text in Research Archive Show summary

  Objective: A constricted, upper chest breathing pattern and postural dealignments habitually accompany exercise-induced laryngeal obstruction (EILO), but there are few effective treatments for athletes presenting with EILO. This case series was conducted to examine whether physiotherapy based on principles from the Norwegian psychomotor physiotherapy (NPMP) combined with elements of cognitive behavioural therapy can reduce laryngeal distress in athletes with EILO. Methods: Respiratory distress in four subjects was examined by interview prior to a physiotherapeutic body examination. Inappropriate laryngeal movements during exercise were measured by the continuous laryngoscopy exercise test, lung function was measured by flow-volume curves, and non-specific bronchial hyper-responsiveness was measured by a methacholine provocation test. History of asthma, allergy and respiratory symptoms was recorded in a modified AQUA2008 questionnaire. Parasympathetic activity was assessed by pupillometry. All data were gathered before and after 5 months of intervention. Results: Physiotherapy based on the principles from NPMP improved breathing problems in athletes with EILO. All athletes had less respiratory distress, improved lung function at rest and reduced inappropriate laryngeal movements during maximal exercise. Conclusion: A diaphragmatic breathing pattern, a more balanced tension in respiratory muscles, and sound cervical alignment and stability may help to reduce adverse stress on the respiratory system and optimise the function of the larynx during high-intensity exercise. Our results suggest that understanding and management of EILO need to extend beyond structures located in the anterior neck and include factors influencing the whole respiratory system.

• Bernhardsen, Guro Pauck; Stensrud, Trine; Nystad, Wenche; Dalene, Knut Eirik; Kolle, Elin & Ekelund, Ulf (2019). Early life risk factors for childhood obesity—Does physical activity modify the associations? The MoBa cohort study. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 29(10), p. 1636–1646. doi: 10.1111/sms.13504. Full text in Research Archive Show summary

  Objectives: High maternal pre‐pregnancy body mass index (BMI), high birth weight, and rapid infant weight gain are associated with increased risk of childhood obesity. We examined whether moderate‐to‐vigorous physical activity (MVPA) or vigorous physical activity (VPA) in 9‐ to 12‐year‐olds modified the associations between these early life risk factors and subsequent body composition and BMI. Methods: We used data from a sub‐cohort of the Norwegian Mother and Child Cohort Study (MoBa), including 445 children with available data on accelerometer assessed physical activity (PA). All participants had data on BMI, 186 of them provided data on body composition (dual energy X‐ray absorptiometry (DXA)). We used multiple regression analyses to examine the modifying effect of PA by including interaction terms. Results: Maternal pre‐pregnancy BMI and infant weight gain were more strongly related to childhood body composition in boys than in girls. Higher VPA attenuated the association between maternal pre‐pregnancy BMI and BMI in boys (low VPA: B = 0.32, 95% CI = 0.22, 0.41; high VPA B = 0.22, 95% CI = 0.12, 0.31). Birth weight was unrelated to childhood body composition, and there was no effect modification by PA. PA attenuated the associations between infant weight gain and childhood fat mass (low MVPA: B = 2.32, 95% CI = 0.48, 4.17; high MVPA: B = 1.00, 95% CI = 0.10, 1.90) and percent fat (low MVPA: B = 3.35, 95% CI = 0.56, 6.14; high MVPA: B = 1.41, 95% CI = −0.06, 2.87) in boys, but not girls. Conclusion: Findings from this study suggest that MVPA and VPA may attenuate the increased risk of an unfavorable body composition and BMI due to high maternal pre‐pregnancy BMI and rapid infant weight gain in boys, but not in girls.

• Mathisen, Therese Fostervold; Rosenvinge, Jan H; Friborg, Oddgeir; Pettersen, Gunn; Stensrud, Trine & Hansen, Bjørge Hermann [Show all 12 contributors for this article] (2018). Body composition and physical fitness in women with bulimia nervosa or binge-eating disorder. International Journal of Eating Disorders. ISSN 0276-3478. 51(4), p. 331–342. doi: 10.1002/eat.22841. Full text in Research Archive Show summary

  Objective:Knowledge about physical fitness in women with bulimia nervosa (BN) or binge-eatingdisorder (BED) is sparse. Previous studies have measured physical activity largely through self-report, and physical fitness variables are mainly restricted to body mass index (BMI) and bone min-eral density. We expanded the current knowledge in these groups by including a wider range ofphysical fitness indicators and objective measures of physical activity, assessed the influence of ahistory of anorexia nervosa (AN), and evaluated predictive variables for physical fitness.Method:Physical activity, blood pressure, cardiorespiratory fitness (CRF), muscle strength, bodycomposition, and bone mineral density were measured in 156 women with BN or BED, with mean(SD) age 28.4 years (5.7) and BMI 25.3 (4.8) kg m22.Results:Level of physical activity was higher than normative levels, still<50% met the officialphysical activity recommendation. Fitness in women with BN were on an average comparable withrecommendations or normative levels, while women with BED had lower CRF and higher BMI,VAT, and body fat percentage. We found 10–12% with masked obesity. A history of AN did notpredict current physical fitness, still values for current body composition were lower when compar-ing those with history of AN to those with no such history.Discussion:Overall, participants with BN or BED displayed adequate physical fitness; however, ahigh number had unfavorable CRF and body composition. This finding calls for inclusion of physicalfitness in routine clinical examinations and guided physical activity and dietary recommendationsin the treatment of BN and BED.

• Andersen, Oddbjørn Klomsten; Clarsen, Benjamin; Garthe, Ina; Mørland, Morten & Stensrud, Trine (2018). Bone health in elite Norwegian endurance cyclists and runners: a cross-sectional study. BMJ Open sport & exercise medicine. doi: 10.1136/bmjsem-2018-000449. Full text in Research Archive
• Kolnes, Liv-Jorunn & Stensrud, Trine (2018). Exercise-induced laryngeal obstruction in athletes: Contributory factors and treatment implications. Physiotherapy Theory and Practice. ISSN 0959-3985. 35(12), p. 1170–1181. doi: 10.1080/09593985.2018.1474306. Full text in Research Archive Show summary

  Otherwise healthy adolescent athletes presenting with respiratory symptoms consistent with exercise-induced laryngeal obstruction (EILO) are frequently encountered in clinical practice. The symptoms are often incorrectly considered to result from exercise-induced asthma, and may be wrongly treated as such. Given the potential implications for health and performance if EILO is left untreated, a more comprehensive understanding of contributory mechanisms is essential in order to create appropriate treatment procedures. Informed by knowledge from physical therapy, as well as the fields of voice rehabilitation and vocal pedagogy, this theoretical article presents a novel way of understanding and managing EILO by exploring bodily mechanisms and structures that may disturb laryngeal function during strenuous exercise. Firstly, the status quo of the EILO diagnosis, its aetiology and treatment options are reviewed. Secondly, considerations associated with laryngeal structures and mechanisms, and their potential influence on laryngeal movement and sensitivity are examined. Thirdly, the manner in which postural de-alignment and breathing pattern may interfere with laryngeal functioning will be discussed. Finally, interventions for voice disorders and singing and the relevance of these for EILO are evaluated. It is argued that clients with EILO should undergo a thorough physical examination to identify constrictions in the body as a whole – such as postural de-alignments and a dysfunctional breathing pattern – as these are hypothesized as playing a critical role in laryngeal tightness during exercise. Physical therapists possess particular skills and competence with regard to examining breathing patterns and postural de-alignments, and should be included in the treatment process of EILO.

• Stang, Julie; Sikkeland, Liv Ingunn Bjoner; Tufvesson, Ellen; Holm, Are Martin; Stensrud, Trine & Carlsen, Kai-Håkon (2018). The Role of Airway Inflammation and Bronchial Hyperresponsiveness in Athlete's Asthma. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 50(4), p. 659–666. doi: 10.1249/MSS.0000000000001478. Full text in Research Archive
• Andersen, Oddbjørn Klomsten; Clarsen, Benjamin; Garthe, Ina; Mørland, Morten & Stensrud, Trine (2018). Bone health in elite Norwegian endurance cyclists and runners: a cross-sectional study. BMJ Open sport & exercise medicine. 4(1). doi: 10.1136/bmjsem-2018-000449. Full text in Research Archive Show summary

  Background: Athletes who compete in non-weight-bearing activities such as swimming and cycling are at risk of developing low bone mineral density (BMD). Athletes in long-distance running are at risk of low BMD. Objective: (1) To evaluate the bone health in Norwegian male and female national elite road cyclists and middle-distance and long-distance runners, and to identify cases of low BMD. (2) To identify possible risk factors associated with low BMD. Methods: Twenty-one runners (11 females and 10 males) and 19 road cyclists (7 females and 12 males) were enrolled in this cross-sectional study. Dual-energy X-ray absorptiometry measurement of BMD in total body, femoral neck and lumbar spine was measured. Participants completed a questionnaire regarding training, injuries, calcium intake and health variables. Results: The cyclists had lower BMD for all measured sites compared with the runners (p≤0.05). Ten of 19 cyclists were classified as having low BMD according to American College of Sports Medicine criteria (Z-score ≤−1), despite reporting to train heavy resistance training on the lower extremities. Low BMD was site specific having occurred in the lumbar spine and the femoral neck and was not confined to females. Type of sport was the only factor significantly associated with low BMD. Conclusion: National elite Norwegian road cyclists had lower BMD compared with runners, and a large proportion was classified as having low BMD, despite having performed heavy resistance training. Interventions to increase BMD in this population should be considered.

• Mathisen, Therese Fostervold; Rosenvinge, Jan H; Pettersen, Gunn; Friborg, Oddgeir; Vrabel, Kari-Anne & Bratland-Sanda, Solfrid [Show all 11 contributors for this article] (2017). The PED-t trial protocol: The effect of physical exercise –and dietary therapy compared with cognitive behavior therapy in treatment of bulimia nervosa and binge eating disorder. Study protocol of a randomized controlled trial. BMC Psychiatry. 17:180, p. 1–11. doi: 10.1186/s12888-017-1312-4. Full text in Research Archive Show summary

  Background: <br> Sufferers from bulimia nervosa (BN) and binge eating disorder (BED) underestimate the severity risk of their illness and, therefore, postpone seeking professional help for years. Moreover, less than one in five actually seek professional help and only 50% respond to current treatments, such as cognitive behavioral therapy (CBT). The impetus for the present trial is to explore a novel combination treatment approach adapted from physical exercise- and dietary therapy (PED-t). The therapeutic underpinnings of these separate treatment components are well-known, but their combination to treat BN and BED have never been previously tested. The purpose of this paper is to provide the rationale for this new treatment approach and to outline the specific methods and procedures. <br> Methods: <br> The PED-t trial uses a prospective randomized controlled design. It allocates women between 18 and 40 years (BMI range 17.5–35.0) to groups consisting of 5–8 members who receive either CBT or PED-t for 16 weeks. Excess participants are allocated to a waiting list control group condition. All participants are assessed at baseline, post-treatment, 6, 12 and 24 months’ post-follow-up, respectively, and monitored for changes in biological, psychological and therapy process variables. The primary outcome relates to the ED symptom severity, while secondary outcomes relates to treatment effects on physical health, treatment satisfaction, therapeutic alliance, and cost-effectiveness. We aim to disseminate the results in high-impact journals, preferable open access, and at international conferences. <br> Discussion: <br> We expect that the new treatment will perform equal to CBT in terms of behavioral and psychological symptoms, but better in terms of reducing somatic symptoms and complications. We also expect that the new treatment will improve physical fitness and thereby, quality of life. Hence, the new treatment will add to the portfolio of evidence-based therapies and thereby provide a good treatment alternative for females with BN and BED. Trial registration: Prospectively registered in REC the 16th of December 2013 with the identifier number 2013/1871, and in Clinical Trials the 17th of February 2014 with the identifier number NCT02079935.

• Kristiansen, Elsa & Stensrud, Trine (2017). Young female handball players and sport specialisation: how do they cope with the transition from primary school into a secondary sport school? British Journal of Sports Medicine. ISSN 0306-3674. 51(1), p. 58–63. doi: 10.1136/bjsports-2016-096435. Full text in Research Archive Show summary

  Objective: The aim of the present study was to examine how six young female handball players (aged 13–14 years) perceived the transition from primary school to a sport-specialised secondary school. Methods: Physical and physiological data as well as data from questionnaires were collected at baseline and after the first year at the sport school, and qualitative interviews were performed retrospectively after the first year at school. Results: Evidence of competition-related stressors, organisational stressors (sport and school balance) and personal stressors (social life and sport balance, lack of sleep and severe injuries) was found. Three girls developed long-lasting musculoskeletal injuries (>3 months out of ordinary training) and one experienced repeated short periods (≤2 weeks out of ordinary training) of injuries during the first year. Onset of menarche and a length growth between 6 and 8 cm during the first year were characteristic traits of the four injured girls. Conclusions: From our small study, it appears that young athletes attending a specialised secondary sport school experienced many stressors due to a significant increase in training volume, reduction in sleeping time and development of severe and long-lasting injuries. Hence, trainers at sport schools, club trainers and parents need to communicate and support them in order to prevent this.

• Gjestvang, Christina; Stensrud, Trine & Haakstad, Lene Annette Hagen (2017). How is rating of perceived capacity related to VO2max and what is VO2max at onset of training? BMJ Open sport & exercise medicine. 3(1). doi: 10.1136/bmjsem-2017-000232. Full text in Research Archive Show summary

  Objective: To evaluate how rating of perceived capacity (RPC) is related to maximal oxygen uptake (VO2max) and examine VO2max at onset of training in healthy adults. Methods: In total, 125 newly registered fitness centre members, equally men and women, answered the RPC scale and performed a treadmill test for measurement of VO2max. Eligible criteria were <4 weeks of fitness centre membership, physically inactive, ≥18 years and not pregnant. The RPC is a one-page scale (1–20) based on metabolic equivalent tasks, where the individual chooses the most strenuous activity that can be sustained for at least 30 min. Results: The Bland-Altman plot demonstrated a tendency of overestimation, meaning that the participants ranked their own aerobic capacity 17.5% higher than objectively measured values of VO2max. The mean difference between the two methods were +4.92±1.96 and +6.35±1.96 mL/min/kg VO2 in men and women, respectively. The Pearson correlation coefficient was moderate, with r=0.426 (p<0.01). A linear regression analysis showed that both age and VO2max were significant predictors of RPC (p<0.01). Measured VO2max at onset of fitness centre membership was in men aged 38.7±11.7 and women aged 34.7±9.9, 40.5±7.2 and 35.0±6.0 mL/min/kg, respectively. Estimated VO2max from the RPC scale was 45.7±9.8 and 41.4±10.1 mL/min/kg in men and women, respectively. Conclusions: The RPC seems less accurate at the individual level and may overestimate VO2max. Still, it may be considered useful in large-scale studies.

• Mathisen, Therese Fostervold; Engen, Kethe Marie Elgesem; Sundgot-Borgen, Jorunn & Stensrud, Trine (2017). Evaluation of a short protocol for indirect calorimetry in females with eating disorders and healthy controls. Clinical Nutrition ESPEN. ISSN 2405-4577. 22, p. 28–35. doi: 10.1016/j.clnesp.2017.09.003. Full text in Research Archive Show summary

  Background and aims: To enable clinicians to identify the clinical picture and treatment progress and to adjust eating plans according to personal energy needs, it is important to know the patient's correct resting metabolic rate (RMR). Indirect calorimetry (IC) is the preferred method for assessment of RMR, but long duration of measurement increases the load on the patients, and reduces the effectiveness in clinical and scientific settings. Further; not all patients reach a valid RMR according to the suggested best practice protocol, with 5 min of steady state (SS) where respiratory gas volume exchange varies less than 10%. The aim of this study was to evaluate the possibility for an abbreviated RMR protocol and SS criterion. Methods: Forty two women diagnosed with bulimia nervosa or binge eating disorder (eating disorder group, ED), originally recruited for an outpatient treatment study, and 26 age and gender matched healthy controls (HC) were studied during a single, prolonged IC measurement. Participants rested for 10 min in supine position wearing a two-way breathing facemask, before a continuous measurement period of 20 min. Results from a standard 5 min SS criterion was compared to an abbreviated 3 min SS criterion. Both SS-criteria were evaluated through three different SS protocols (<10% variation in respiratory gas exchange), being: 1) measurement during the first 3 or 5 min, 2) measurement after discarding the first 5 min, and 3) the lowest identified RMR during the 20 min of measurement. Results: About 50% of the participants reached an early SS in both the defined SS minute criteria. Participants reaching a valid SS throughout the 20 min of measurement increased from ∼90% to 100% with an abbreviated 3 min SS. With a 5 min SS criterion, the median (range) RMR for the 3 protocols were 1639.9 (1239.2), 1508.8 (1457.6) and 1500.6 (1328.8) respectively for the ED group, and 1702.2 (1239.4), 1608.4 (1076.4) and 1594.8 (1029.2) respectively for the HC group, (p > 0.05 for all between-group analysis). With a 3 min SS criterion, the median (range) RMR were 1533.6 (1298.2), 1461.2 (1406.1), and 1395.8 (1447.3) respectively for the ED group and 1681.7 (1332.4), 1613.7 (1266.0) and 1523.1 (1050.3), respectively for the HC group, (p > 0.05 for all between-group analysis). Lowest measured RMR was different compared to the other two SS protocols in both the ED- and the HC group, and for both the 5 min- and the 3 min SS criteria, respectively (p < 0.04). Furthermore, a SS of 3 min resulted in lower RMR compared to 5 min SS (p < 0.00) and an increased number of participants classified as hypo-metabolic (RMRmeasured/RMRcalculated < 0.9). Conclusions: An abbreviated measurement protocol to identify the lowest RMR using IC was not successful. Abbreviating the SS criteria from 5 to 3 min, resulted in a lower RMR, hence encouraging further examination of the validity of shorter SS criterion than practiced today.

• Vik, Lene Carine; Lannem, Anne M.; Rak, Britt Marie & Stensrud, Trine (2017). Health status of regularly physically active persons with spinal cord injury. Spinal Cord Series and Cases. 3(1), p. 1–10. doi: 10.1038/s41394-017-0033-8. Full text in Research Archive Show summary

  Abstract Study design A non-controlled cross-sectional study. Objectives To make a descriptive examination of health status in persons with paraplegia and tetraplegia who exercise regularly according to Canadian guidelines. Settings Sunnaas Rehabilitation Hospital and the Norwegian School of Sport Sciences. Methods Eighteen persons (men/women = 9/9), aged 41‒72 years with spinal cord injury (SCI), who exercise regularly were included. Post-injury years ranged from 4 to 48 years. Clinical examination of body composition, bone mineral density (BMD), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), diffusion capacity (DLCO), cardiorespiratory fitness (VO2max), and self-reported quality of life (QOL) obtained by questionnaire was performed. Lung function results are presented as % predicted and VO2max as absolute values relative to body weight. All results are given as median and range. Results Persons with paraplegia (n = 13) were defined as overweight with fat mass 42% (25‒51). BMD 1.047 g cm−2 (0.885‒1.312) was within normal range. FVC 95% predicted (60‒131), FEV1 90% predicted (61‒119), DLCO 77% predicted (56‒103), and VO2max 16.66 ml kg−1 min−1 (12.15‒25.28) defined good aerobic capacity according to age controlled reference values (18). Persons with tetraplegia (n = 5) were slightly overweight with fat mass 35% (26‒47). BMD 1.122 g cm−2 (1.095‒1.299) was within normal range. FVC 72% predicted (46‒91), FEV1 75% predicted (43‒83), DLCO 67% predicted (56‒84), and VO2max 16.70 ml kg−1 min−1 (9.91‒21.01) defined excellent aerobic capacity according to reference values (18). QOL was ranked as median 7.5 (0‒10 scale). Conclusions Persons with SCI who exercise regularly following the Canadian guidelines responded with rather positive associations for health outcomes. Additional research is needed to strengthen our findings.

• Berntsen, Sveinung; Berntsen, Solvor; Mowinckel, Petter; Nystad, Wenche & Stensrud, Trine (2016). Lung function monitoring; a randomized agreement study. The Open Respiratory Medicine Journal. 10, p. 51–57. doi: 10.2174/1874306401610010051. Full text in Research Archive
• Stensrud, Trine; Stang, Julie; Thorsen, Einar & Bråten, Veslemøy (2016). Exhaled nitric oxide concentration in the period of 60 min after submaximal exercise in the cold. Clinical Physiology and Functional Imaging. ISSN 1475-0961. 36(2), p. 85–91. doi: 10.1111/cpf.12196. Full text in Research Archive Show summary

  Background Fractional expired nitric oxide (FENO) is decreased after exercise. The effect of exercise in the cold upon FENO is unknown. Purpose To examine changes in FENO after a short, high intensive exercise test in a cold and in a temperate environment. Methods Twenty healthy well-trained subjects (eight females) aged 18–28 years performed an 8-min exercise test at 18°C (SD = 1.0) and −10°C (SD = 1.2) ambient temperature. The tests were performed in a climate chamber in random order. The workload corresponded to 90–95% of peak heart rate (HRpeak) during the last 4 min. FENO was measured offline. Exhaled gas was sampled in Mylar® bags using a collector kit with a flow restrictor and analysed within 2 h. FENO was measured before exercise and repeatedly during the first hour after. ANOVA for repeated measures was used to compare differences in FENO after exercise between environments. Results There was no difference in baseline FENO. A significant difference in FENO between environments was found after warm-up and from 20 to 30 min after exercise, with FENO being lower after exercise in the cold (P<0.05). The maximal reduction in FENO was seen 5 min after exercise and was not different between environments. Conclusion Recovery of FENO was slower after exercising in −10°C compared with 18°C.

• Stang, Julie; Stensrud, Trine; Mowinckel, Petter & Carlsen, Kai-Håkon (2016). Parasympathetic activity and bronchial hyperresponsiveness in athletes. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 48(11), p. 2100–2107. doi: 10.1249/MSS.0000000000001008. Full text in Research Archive Show summary

  PURPOSE: A high prevalence of asthma and bronchial hyperresponsiveness (BHR) is reported in swimmers and cross-country skiers. It has been suggested that increased parasympathetic nervous activity is involved in asthma development in endurance athletes. We aimed to assess the associations of BHR to parasympathetic activity in healthy and asthmatic swimmers and cross-country skiers and healthy nonathletes. METHODS: Parasympathetic activity was measured by pupillometry and heart rate variability at the onset of exercise with the cardiac vagal index calculated in 28 cross-country skiers (♂18/♀10), 29 swimmers (♂17/♀12), and 30 healthy nonathlete controls (♂14/♀16) on two different days. All subjects performed a methacholine bronchial challenge with the provocation dose causing 20% decrease in the forced expiratory volume in 1 s calculated (PD20met). Data were analyzed by robust regression analysis and presented as β coefficients with 95% confidence intervals (CI). RESULTS: PD20met was negatively associated with cardiac vagal index (-13.9, 95% CI = -26.8 to -1.0) in all subjects. When adjusted to the type of sport, this association was stronger in swimmers (-8.3, 95% CI = -13.0 to -3.6) as compared with controls and nonsignificant in cross-country skiers. Percent pupil constriction was significantly associated with PD20met in swimmers (-9.4, 95% CI = -15.4 to -3.4) only after adjusting for the type of sport. Fourteen swimmers (48%) and 16 cross-country skiers (57%) had doctor-diagnosed asthma in combination with current BHR and/or current use of asthma drugs. Seventy-two percent swimmers, 44% cross-country skiers, and 39% controls had a PD20met ≤8 μmol (P = 0.015). Fourteen swimmers had a PD20met ≤2 μmol as compared with one cross-country skier (P < 0.001). CONCLUSION: Parasympathetic activity measured in the heart is more closely related to BHR as compared with parasympathetic activity measured in the pupils. The type of sport influences BHR severity and its relationship to parasympathetic activity.

• Stang, Julie; Couto, Mariana; Stensrud, Trine; Mowinckel, Petter; Moreira, André & Carlsen, Kai-Håkon (2016). Assessment of parasympathetic activity in athletes: Comparing two different methods. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 48(2), p. 316–322. doi: 10.1249/MSS.0000000000000769. Full text in Research Archive Show summary

  Introduction: A variety of methods are used to assess parasympathetic activity in athletes targeting different organs; however the reliability of or interchangeability between measurement procedures is not clear. Objective: To identify the repeatability of two parasympathetic activity measurement procedures; heart rate variability (HRV) during a four second exercise test (4sET) and the contractile properties of the pupil (pupillometry), and to assess their agreement. Secondarily, to assess their relationship with the bronchodilating effect of inhaled ipratropium bromide (iIB), blocking parasympathetic signals to the lungs. Methods: Forty athletic subjects were enrolled in a cross sectional study. After 15 minutes resting in semi-darkness subjects underwent pupillometry (PLR-200(TM), NeurOptics Inc, CA, USA), followed by 4sET on a cycle ergometer. HRV was assessed by Polar Electro(R) heart rate monitor (RS-800CX/G3 - OY, Kempele, Finland). Both protocols were repeated after 5 minutes. Statistical analysis was performed according to Bland and Altman, and by Pearson's correlation coefficient and intra-class correlation (ICC). Lung function measurements by flow volume curves were performed before and 45 minutes after iIB. Results: Mean of differences was 1.21% ([limits of agreement] -3.59, 6.02) for pupil constriction and 0.05 mm (-0.28, 0.39) for pupil amplitude. The mean of differences for 4sET was 0.005 (-0.31, 0.32). A very weak ICC (r=-.01, p=.58) showed no agreement between the methods. No correlation was observed between pupillometry variables or 4sET with the change in lung function after iIB. Conclusion: Pupillometry showed better repeatability compared with the 4sET. There is poor agreement between parasympathetic activity levels measured in three different target organs of athletic subjects; the heart, the pupil and the lung. Thus, methods assessing parasympathetic activity in different target organs cannot be used interchangeably.

• Stang, Julie; Bråten, Veslemøy; Caspersen, Cecilie; Thorsen, Einar & Stensrud, Trine (2015). Exhaled nitric oxide after high-intensity exercise at 2800 m altitude. Clinical Physiology and Functional Imaging. ISSN 1475-0961. 35(5), p. 338–343. doi: 10.1111/cpf.12131. Full text in Research Archive Show summary

  Background: Nitric oxide (NO) concentration in exhaled gas is a marker of some inflammatory processes in the lung, and endogenous NO plays a role in the physiological responses to exercise and altitude. The aim of this study was to compare changes in exhaled NO concentration 5–60 mins after high-intensity exercise at 2800 m and at 180 m altitude. Methods: Twenty trained healthy volunteers (12 men), aged 19–28 years, were included in this open, crossover study. Subjects performed two exercise tests at different altitudes, 2800 m and 180 m, in a randomized order. The fraction of NO in exhaled gas (FENO) was measured 5 mins before and 5–60 mins after 8 mins of running on a treadmill at a heart rate (HR) of 90% of peak HR. Peak HR was assessed during a pretest at 180 m. Ambient temperature was 20·1°C (SD = 1·2) and relative humidity 40·2% (SD = 3·2). FENO measurements were corrected for altitude gas density effects and converted to partial pressure of NO (PENOcorr). Results: PENOcorr was reduced from 1·47 (1·21, 1·73) millipascal (mPa) at baseline to 1·11 (0·87, 1·34) mPa 5 mins after exercise at 2800 m and from 1·54 (1·24, 1·84) to 1·04 (0·87, 1·22) mPa 5 mins after exercise at 180 m. There was no difference in PENOcorr between exercise at 2800 m and 180 m, and PENOcorr was normalized within 20 mins. Conclusions: Exercise at 2800 m induces a similar acute reduction in exhaled nitric oxide concentration as compared with 180 m in healthy subjects.

• Couto, Mariana; Stang, Julie; Horta, Luis; Stensrud, Trine; Severo, Milton & Mowinckel, Petter [Show all 10 contributors for this article] (2015). Two distinct phenotypes of asthma in elite athletes identified by latent class analysis. Journal of Asthma. ISSN 0277-0903. 52(9), p. 897–904. doi: 10.3109/02770903.2015.1067321. Full text in Research Archive Show summary

  Introduction: Clusters of asthma in athletes have been insufficiently studied. Therefore, the present study aimed to characterize asthma phenotypes in elite athletes using latent class analysis (LCA) and to evaluate its association with the type of sport practiced. Methods: In the present cross-sectional study, an analysis of athletes’ records was carried out in databases of the Portuguese National Anti-Doping Committee and the Norwegian School of Sport Sciences. Athletes with asthma, diagnosed according to criteria given by the International Olympic Committee, were included for LCA. Sports practiced were categorized into water, winter and other sports. Results: Of 324 files screened, 150 files belonged to asthmatic athletes (91 Portuguese; 59 Norwegian). LCA retrieved two clusters: “atopic asthma” defined by allergic sensitization, rhinitis and allergic co-morbidities and increased exhaled nitric oxide levels; and “sports asthma”, defined by exercise-induced respiratory symptoms and airway hyperesponsiveness without allergic features. The risk of developing the phenotype “sports asthma” was significantly increased in athletes practicing water (OR = 2.87; 95%CI [1.82–4.51]) and winter (OR = 8.65; 95%CI [2.67–28.03]) sports, when compared with other athletes. Conclusion: Two asthma phenotypes were identified in elite athletes: “atopic asthma” and “sports asthma”. The type of sport practiced was associated with different phenotypes: water and winter sport athletes had three- and ninefold increased risk of “sports asthma”. Recognizing different phenotypes is clinically relevant as it would lead to distinct targeted treatments.

• Stang, Julie; Couto, Mariana; Carlsen, Kai-Håkon & Stensrud, Trine (2015). Increased bronchial parasympathetic tone in elite cross-country and biathlon skiers: a randomised crossover study. British Journal of Sports Medicine. ISSN 0306-3674. 49(1), p. 56–61. doi: 10.1136/bjsports-2014-094053. Full text in Research Archive Show summary

  Background: Increased parasympathetic activity in endurance-trained athletes has been reported by heart rate variability and pupillometry. Our primary objective was to assess parasympathetic activity and tone in the lower respiratory tract by investigating the effect of cholinergic antagonism by inhaled ipratropium bromide compared to the β2-receptor stimulating effect of inhaled salbutamol in elite cross-country and biathlon skiers. We also examined the medications’ relationship to cholinergic sensitivity as measured by bronchial responsiveness to methacholine (PD20met). Methods: In a randomised crossover study, 20 cross-country and two biathlon skiers (14♂/8♀) aged 20–37 years from the Norwegian national teams measured reversibility to inhaled ipratropium bromide and inhaled salbutamol and PD20met on three separate days. A positive reversibility test was defined as an increase in forced expiratory volume in 1 s (FEV1) of ≥12%. Spirometry was performed before and 45 and 15 min after inhaled ipratropium bromide and inhaled salbutamol, respectively. Bronchodilating medication was withheld according to the European Respiratory Society (ERS) guidelines. Correlations were assessed by Pearson's correlation coefficient (r). Results: Five athletes had significant reversibility after inhaled ipratropium bromide, and none after inhaled salbutamol. Twelve athletes (54.5%) had PD20met <8 μmol (1.57 mg). PD20met correlated negatively with ▵FEV1 after inhaled ipratropium bromide (r=−0.85, p<0.0001), but not after inhaled salbutamol (r=−0.308, p=0.16). Conclusions: In elite skiers, cholinergic sensitivity (PD20met) had a highly significant inverse correlation to the cholinergic antagonism of inhaled ipratropium bromide, but not at all to the bronchodilating inhaled salbutamol. This markedly increased bronchial parasympathetic tone may represent an important cholinergic role in the development of skier's asthma.

• Burns, Jacob; Mason, Catherine; Mueller, Natalie; Ohlander, Johan; Zock, Jan-Paul & Drobnic, Franchek [Show all 12 contributors for this article] (2015). Asthma prevalence in Olympic summer athletes and the general population: An analysis of three European countries. Respiratory Medicine. ISSN 0954-6111. 109(7), p. 813–820. doi: 10.1016/j.rmed.2015.05.002. Full text in Research Archive Show summary

  Background: Some studies have shown a higher prevalence of asthma in elite athletes as compared to the general population. It is inconclusive to what extent certain sport categories are especially affected. The present study offered a unique opportunity to assess these differences in asthma prevalence in the general population and elite summer athletes from a wide range of sport disciplines across various geographical areas. Methods: Cross-sectional data for 1568 general population participants from the European Community Respiratory Health Survey II and 546 elite athletes from the Global Allergy and Asthma European Network Olympic study from three European countries were analyzed. Using logistic regression, the asthma risks associated with athlete sport practice, endurance level and aquatic sport practice, respectively, were investigated. Results: Athletes in the highest endurance category had increased risk of doctor-diagnosed asthma (OR 3.5; 95% CI 1.7–7.5), asthma symptoms (OR 3.0; CI 1.5–6.0) and asthma symptoms or medication use (OR 3.5; CI 1.8–6.7) compared to the general population. Aquatic athletes were at increased risk of doctor-diagnosed asthma (OR 2.0; CI 1.1–3.9), asthma symptoms (OR 2.6; CI 1.3–5.0) and asthma symptoms or medication use (OR 2.3; CI 1.2–4.4) when compared to individuals not involved in aquatic sports. Regarding the entire athlete population, no increase in asthma was found when compared to the general population. Conclusions: Practice of very high endurance and aquatic sports may be associated with increased asthma risks. Athlete participation as such showed no association with asthma risk.

• Øglund, Guro Pauck; Stensrud, Trine & Ekelund, Ulf (2014). Early life determinants of physical activity and sedentary time: Current knowledge and future research. Norsk Epidemiologi. ISSN 0803-2491. 24(1-2), p. 177–186. doi: 10.5324/nje.v24i1-2.1820. Full text in Research Archive Show summary

  Previous findings of the association between low birth weight and subsequent health outcomes have led to the “developmental origins of health and disease hypothesis”. Furthermore, modifiable and partly modifiable early life factors may also influence behaviors such as physical activity and sedentary behavior. The aim of the present review was to summarize the existing knowledge on early life determinants (birth weight, rapid infant weight gain, motor development and infant temperament) of childhood physical activity and sedentary time, and suggest opportunities for future research based on the Mother and Child Cohort Study (MoBa). Inconsistent results have been observed when relating birth weight to later physical activity, likely explained by differences in methodology when assessing physical activity between studies. There is limited data on whether rapid weight gain in early life predicts later physical activity and few studies have examined the association between birth weight and infant weight gain with subsequent sedentary time. Motor development may be a predictor for childhood physical activity, however methodological limitations preclude firm conclusions. The association between motor development and sedentary time has rarely been examined. Conflicting results have been reported for the association between infant temperament and subsequent physical activity and sedentary time in toddlers. Finally, it is unknown whether physical activity modifies the association between birth weight, postnatal weight gain, and later health outcomes in youth. Additional research in well-characterized birth cohorts can be used to generate new knowledge on possible early life determinants of children’s and youth’s physical activity and sedentary time which may inform evidence-based public health interventions.

• Angell, Maj Røsvik; Augestad, Liv Berit; Haugen, Torbjørn S; Frostad, Anne; Grønnerød, Thor Arne & Stensrud, Trine (2014). Exercise-Induced Bronhoconstriction Diagnostics: Impact of a Repeated Exercise Challenge Test. Open Journal of Respiratory Diseases. ISSN 2163-940X. 4, p. 55–63. doi: 10.4236/ojrd.2014.42009. Full text in Research Archive
• Caspersen, Cecilie; Stensrud, Trine; Storebø, Michael Langballe & Thorsen, Einar (2013). Exhaled nitric oxide and lung function after moderate normobaric hyperoxic exposure. Undersea & Hyperbaric Medicine. ISSN 1066-2936. 40(1), p. 7–13. Full text in Research Archive
• Caspersen, Cecilie; Stang, Julie; Thorsen, Einar & Stensrud, Trine (2013). Exhaled nitric oxide concentration upon acute exposure to moderate altitude. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 23(2), p. e102–e107. doi: 10.1111/sms.12018. Full text in Research Archive Show summary

  The purpose of this study was to assess immediate changes in the partial pressure of nitric oxide (NO) in exhaled gas (PENO) in healthy trained subjects who were acutely exposed to moderate altitude. One group of nine and another group of 20 healthy subjects were exposed to an ambient pressure of 728 hPa (546 mmHg) corresponding to an altitude of 2800 m for 5 and 90 min, respectively, in an altitude chamber. PENO was measured offline by sampling exhaled gas in tight metal foil bags at 5, 30, 60, and 90 min. A correction for increased expiratory flow rate due to gas density effects at altitude was performed (PENOcorr). PENO was significantly decreased by 13–16%, while the fraction of NO in exhaled gas (FENO) was increased by 16–19% compared to sea level. There was no significant change in PENOcorr after exposure to altitude for 5, 30, 60, and 90 min. We conclude that there was no change in PENO upon arrival at altitude after correcting for gas density effects on expiratory flow rate. Corrections for altitude effects must be done before comparing measurements performed at different altitudes when using measurements of FENO to monitor athletes who have asthma during training at altitude.

• Kristiansen, Elsa; Abrahamsen, Frank Eirik & Stensrud, Trine (2012). Stress-Related Breathing Problems: An Issue for Elite Swimmers. Journal of Swimming Research. ISSN 0747-5993. 19(2). Full text in Research Archive Show summary

  The purpose of this preliminary study was to test if there are any links between breathing problems, and physiological and psychological recovery (or perceived lack thereof) in elite swimmers. In order to do so, twenty-four elite competitive swimmers (range 15-25 years, Mage = 18.25 years, SD = 1.60), from two swimming clubs in Norway both performed three physiological tests for bronchial hyperresponsiveness (BHR) and also completed a series of psychological questionnaires. The results are important for coaches, as it was revealed an alarmingly high prevalence of BHR. Possible links between physiological and psychological stress markers in athletes are explained by the use of Cognitive Activation Theory of Stress (CATS). Correlations revealed an association between one perfectionism factor (concern over mistakes) and the recovery scale (balance between training and recovery), practically meaning there might be a relationship between breathing problems and reduced recovery. However, a mastery climate may protect the swimmers against both perfectionism and burnout, helping their recovery in the long run. In conclusion, there is evidence that we need more research about this possible (breathing) stress-recovery imbalance in order to identify under recovery and avoid more severe negative consequences for elite swimmers.

• Sandvei, Marit; Jeppesen, Per Bendix; Støen, Line; Litleskare, Sigbjørn; Johansen, Egil Ivar & Stensrud, Trine [Show all 12 contributors for this article] (2012). Sprint interval running increases insulin sensitivity in young healthy subjects. Archives of Physiology and Biochemistry. ISSN 1381-3455. 118(3), p. 139–147. doi: 10.3109/13813455.2012.677454. Full text in Research Archive Show summary

  High intensity cycling training increases oxidative capacity in skeletal muscles and improves insulin sensitivity. The present study compared the effect of eight weeks of sprint interval running (SIT) and continuous running at moderate intensity (CT) on insulin sensitivity and cholesterol profile in young healthy subjects (age 25.2 ± 0.7; VO2max 49.3 ± 1.2 ml·kg−1·min−1). SIT and CT increased maximal oxygen uptake by 5.3 ± 1.8 and 3.8 ± 1.6%, respectively (p < 0.05 for both). Oral glucose tolerance test (OGTT) was performed before and 60 h after the last training session. SIT, but not CT, reduced glucose area under curve and improved HOMA β-cell index (p < 0.05). Insulin area under curve did not decrease significantly in any group. SIT, but not CT, reduced LDL and total cholesterol. In conclusion, sprint interval running improves insulin sensitivity and cholesterol profile in healthy subjects, and sprint interval running may be more effective to improve insulin sensitivity than continuous running at moderate intensity.

• Carlsen, Kai-Håkon; Hem, Erlend Jan & Stensrud, Trine (2011). Asthma in adolescent athletes. British Journal of Sports Medicine. ISSN 0306-3674. 45(16), p. 1266–1271. doi: 10.1136/bjsports-2011-090591. Full text in Research Archive Show summary

  Athletes active in endurance sports are at an increased risk of acquiring asthma through their sports activities, especially so for cross-country skiers, biathlon skiers, swimmers and athletes of other endurance sports. Asthma may be present from early childhood or develop while in active sports. This article focuses on the physical activity and sports activities in children and adolescents. Exercise-induced asthma (EIA) is found in 8–10% of a normal child population of school age and in about 35% of children with current asthma. EIA is caused by the markedly increased ventilation during exercise, with increased heat and water loss through respiration, leading to bronchial constriction. The risk of developing asthma in the young athlete is related to the repeated daily training activity with increased epithelial damage of the airways, delayed repair due to the daily repetition of the training and increased airway mucosal inflammation. The increased environmental exposure through the sports activity to environmental agents, such as cold, dry air in skiers and chlorine compounds in swimmers, increases symptoms and signs of asthma and bronchial hyper-responsiveness, either worsening an existing asthma or leading to a novel disease in a previously healthy athlete. Several specific aspects of daily training life, environmental exposure, diagnostic procedures and aspects of treatment related to the regulations of medication use in sports need particular attention when addressing the adolescent athlete with respiratory symptoms.

• Caspersen, Cecilie; Stensrud, Trine & Thorsen, Einar (2011). Bronchial Nitric Oxide Flux and Alveolar Nitric Oxide Concentration After Exposure to Hyperoxia. Aviation, Space and Environmental Medicine. ISSN 0095-6562. 82(10), p. 946–950. doi: 10.3357/ASEM.2995.2011. Full text in Research Archive Show summary

  Background: The fraction of nitric oxide in exhaled gas (FENO) is reduced by 30-70% after exposure to partial pressures of oxygen (Po2) of 200-240 kPa for 90 min. The purpose of this study was to partition FENO into its flow-independent alveolar and bronchial components. A reduced bronchial NO flux (JawNO) is associated with induced bronchoconstriction, while increased alveolar NO concentration (CANO) is associated with increased alveolar dead space. Methods: There were 12 patients undergoing hyperbaric oxygen (HBO) therapy for 90 min at a Po2 of 240 kPa and 20 healthy subjects exposed to normobaric hyperoxia (NBO) breathing 100% oxygen for 90 min who were compared to a control group of 6 subjects breathing ambient air. FENO was measured at flow rates from 30 to 250 ml · s−1 before and after the exposures and the Högman Märilainen algorithm was used to calculate JawNO and CANO. Results: FENO at an expiratory flow rate of 50 ml · s−1 was reduced from 17.6 ± 8.3 to 12.3 ± 6.3 ppb after HBO exposure and from 17.8 ± 6.2 to 13.3 ± 5.2 ppb after NBO exposure. There was a significant reduction in JawNO, but unchanged CANO. There were no changes in the control experiment. Discussion: The reduction in FENO after exposure to normobaric and hyperbaric hyperoxia appears to be predominantly an airway effect. An unchanged and low CANO indicate preserved integrity of the gas exchange units without increased alveolar dead space at rest.

• Stadelmann, Katrin; Stensrud, Trine & Carlsen, Kai-Håkon (2011). Respiratory Symptoms and Bronchial Responsiveness in Competitive Swimmers. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 43(3), p. 375–381. doi: 10.1249/MSS.0b013e3181f1c0b1. Full text in Research Archive Show summary

  AB Purpose: A high prevalence of bronchial hyperresponsiveness (BHR) and respiratory symptoms has been reported among competitive swimmers. From the 2002 Winter Olympics, BHR measurements or bronchodilator reversibility have been required for approved use of [beta]2-agonists in sports. The first aim of this study was to evaluate the relationship among respiratory symptoms in young elite swimmers, eucapnic voluntary hyperpnea (EVH), and the inhaled dose of methacholine, causing a 20% decrease in forced expiratory volume in 1 s (FEV1; PD20 methacholine). The second aim of this study was to assess the repeatability of the EVH test. Methods: For this study, 15 male and 9 female adolescent elite swimmers, aged 15 to 25 yr, performed one PD20 methacholine test and two EVH tests in a randomized order. Dry air containing 5% CO2 was inhaled for 6 min with a target ventilation of >=85% of maximum voluntary ventilation (minimum = 65%). PD20 methacholine <=2 [mu]mol and EVH with FEV1 reduction >=10% were considered positive. Respiratory symptoms and medication were reported in the modified AQUA2008 questionnaire. Results: Twenty swimmers (83%) reported respiratory symptoms, 13 (65%) of them had a positive provocation test. Fourteen (58%) had at least one positive test to either EVH or PD20 methacholine; three had only one positive EVH test. One athlete had BHR without symptoms. The sensitivity of PD20 methacholine <=2 [mu]mol for respiratory symptoms was 50% versus 60% and 47.37% for the two EVH tests, respectively, and 75% for PD20 methacholine <=4 [mu]mol. The Bland-Altman plot of the two EVH tests showed a consistent distribution, with only one subject outside the limits of agreement. Conclusions: BHR was frequently found among adolescent competitive swimmers. PD20 methacholine <=2 [mu]mol and EVH >= 10% compared well, but PD20 methacholine <=4 [mu]mol had the highest sensitivity for respiratory symptoms. The EVH test has high repeatability but is very expensive and uncomfortable to perform.

View all works in NVA

• Berge, Jarle; Nunavath, Vimala; Asbjørnsen, Rikke Aune; Borgeraas, Heidi; Hertel, Jens Kristoffer & Linge, Anita Dyb [Show all 15 contributors for this article] (2026). Machine Learning for Estimating Cardiorespiratory Fitness in Patients With Obesity: Protocol for a Retrospective and Prospective Multicenter Cohort Study. doi: 10.2196/85069. Full text in Research Archive Show summary

  Abstract Background Cardiorespiratory fitness (CRF) is a key predictor of cardiovascular and other health-related diseases in individuals with obesity. CRF is most accurately assessed through maximal exercise testing with advanced gas-analysis equipment (maximum volume of oxygen [VO 2max ]); however, this approach is time-consuming, costly, and requires specialized expertise. Therefore, submaximal tests and self-reported physical activity levels have been used to develop predictive algorithms to estimate CRF, yet they often performed poorly in individuals with low CRF levels, such as patients with obesity, because they are predominantly developed using data from healthy populations. Studies using machine learning (ML) models based on VO 2max data from patients with obesity appear to be lacking in the literature. ML models based on routinely collected clinical measures may offer a more practical and potentially accurate way to estimate CRF, reducing time, costs, and clinical burden. Objective The primary aim of this study is to use multicenter, longitudinal, real-world clinical data from a uniquely characterized population with obesity to develop and validate a clinically relevant ML model for estimating CRF and to compare its performance with the gold standard of VO 2max testing. Methods A retrospective data set combining assessments of VO 2max tests and clinical parameters from adult patients with severe obesity BMI (≥40.0 kg/m 2 or 35.0‐39.9 kg/m 2 with at least 1 obesity-related comorbidity) from Vestfold Hospital Trust, Muritunet Rehabilitation Institution, and Norwegian School of Sport Sciences will be the foundation for developing the ML model. The clinically relevant ML model for estimating CRF will be presented as a web application, allowing easy access and interaction. The model’s estimations will be compared against direct VO 2max measurements obtained from medical equipment across institutions as part of a prospective validation. Ethical approval has been obtained for the use of 2 databases in the initial model development; approval for the remaining data and prospective phase is pending. Results Vestfold Hospital Trust, the Norwegian School of Sport Medicine, and Muritunet Rehabilitation Institution conducted more than 2623 VO ₂max tests and collected clinical parameters from 1279 adults with severe obesity during 2013-2025, both before, during, and after lifestyle interventions. The first scientific publication of the clinically relevant ML model is expected to be published in 2026. The results of the overall project are expected to be completed in 2028. The project was awarded salary funding in two rounds from Vestfold Hospital (October and December 2023) and salary funding from the Research Council of Norway (October 2024). In addition, the project received allocated supervision hours from InnoMed Norway (April 2024). Conclusions This project aims to develop a clinically relevant ML model, which serves as a cost-effective tool for CRF estimation in individuals with obesity, improving accessibility to this important health marker. To our knowledge, this is the first initiative in Norway to estimate CRF in individuals with obesity using ML, based on a unique clinical database. The project carries substantial societal value and holds national and international relevance for health care practice and patient outcomes.

• Stensrud, Trine; Melau, Jørgen & Renberg, Julie (2025). FAM100 Exercise. Full text in Research Archive
• Stensrud, Trine (2025). Uncovering the gaps - blind spots in respiratory health in athletes. Full text in Research Archive
• Nagy, Cecilie Margrethe; Holmsve, Monica & Stensrud, Trine (2025). Changes in prevalence of asthma and respiratory symptoms among Norwegian adolescent handball players over two years. Full text in Research Archive
• Nagy, Cecilie Margrethe; Myklebust, Grethe & Stensrud, Trine (2025). Prevalence of severe knee injuries among Norwegian youth handball players – a three-year follow-up study. Full text in Research Archive
• Holmsve, Monica; Clemm, Hege Synnøve Havstad; Halvorsen, Thomas & Stensrud, Trine (2025). From peak performance to post-retirement: Pulmonary changes in elite athletes. Full text in Research Archive
• Kristiansen, Elsa; Holmeset, Vigdis & Stensrud, Trine (2025). Pathway to the elite: Key qualities and support mechanisms for female handball players transitioning to elite and national team levels. Full text in Research Archive
• Stensrud, Trine; Alonso, Maria Justo & Thaulow, Kristin (2024). Disse forskningsprosjektene fikk støtte. [Internet]. AstmaAllergi. Full text in Research Archive
• Kristiansen, Elsa & Stensrud, Trine (2023). Sports schools and the creation of champions: Following 10 female handballers for a decade. Full text in Research Archive
• Lie, Hanne Cathrine; Anderssen, Sigmund Alfred; Rueegg, Corina Silvia; Raastad, Truls; Grydeland, May & Thorsen, Lene [Show all 21 contributors for this article] (2022). The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) Study: Protocol for an International Mixed Methods Study. JMIR Research Protocols. 11(3). doi: 10.2196/35838. Full text in Research Archive Show summary

  Methods Results Discussion References Abbreviations Copyright Abstract Background: Survivors of childhood cancer represent a growing population with a long life expectancy but high risks of treatment-induced morbidity and premature mortality. Regular physical activity (PA) may improve their long-term health; however, high-quality empirical knowledge is sparse. Objective: The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) study comprises 4 work packages (WPs) aiming for the objective determination of PA and self-reported health behavior, fatigue, and quality of life (WP 1); physical fitness determination (WP 2); the evaluation of barriers to and facilitators of PA (WP 1 and 3); and the feasibility testing of an intervention to increase PA and physical fitness (WP 4). Methods: The PACCS study will use a mixed methods design, combining patient-reported outcome measures and objective clinical and physiological assessments with qualitative data gathering methods. A total of 500 survivors of childhood cancer aged 9 to 18 years with ≥1 year after treatment completion will be recruited in follow-up care clinics in Norway, Denmark, Finland, Germany, and Switzerland. All participants will participate in WP 1, of which approximately 150, 40, and 30 will be recruited to WP 2, WP3, and WP 4, respectively. The reference material for WP 1 is available from existing studies, whereas WP 2 will recruit healthy controls. PA levels will be measured using ActiGraph accelerometers and self-reports. Validated questionnaires will be used to assess health behaviors, fatigue, and quality of life. Physical fitness will be measured by a cardiopulmonary exercise test, isometric muscle strength tests, and muscle power and endurance tests. Limiting factors will be identified via neurological, pulmonary, and cardiac evaluations and the assessment of body composition and muscle size. Semistructured, qualitative interviews, analyzed using systematic text condensation, will identify the perceived barriers to and facilitators of PA for survivors of childhood cancer. In WP 4, we will evaluate the feasibility of a 6-month personalized PA intervention with the involvement of local structures. Results: Ethical approvals have been secured at all participating sites (Norwegian Regional Committee for Medical Research Ethics [2016/953 and 2018/739]; the Oslo University Hospital Data Protection Officer; equivalent institutions in Finland, Denmark [file H-19032270], Germany, and Switzerland [Ethics Committee of Northwestern and Central Switzerland, project ID: 2019-00410]). Data collection for WP 1 to 3 is complete. This will be completed by July 2022 for WP 4. Several publications are already in preparation, and 2 have been published. Conclusions: The PACCS study will generate high-quality knowledge that will contribute to the development of an evidence-based PA intervention for young survivors of childhood cancer to improve their long-term care and health. We will identify physiological, psychological, and social barriers to PA that can be targeted in interventions with immediate benefits for young survivors of childhood cancer in need of rehabilitation.

• Melsom, Helene Støle; Randa, Anders; Hisdal, Jonny; Stang, Julie & Stensrud, Trine (2022). Prevalence of asthma among Norwegian elite athletes. Full text in Research Archive
• Rasmussen, Søren Malte; Hansen, Erik Søren Halvard; Stensrud, Trine; Radon, Katja; Wolfarth, Bernd & Kurowski, Marcin [Show all 18 contributors for this article] (2022). Asthma endotypes in elite athletes: A cross-sectional study of European athletes participating in the Olympic Games. Allergy. European Journal of Allergy and Clinical Immunology. ISSN 0105-4538. 77(7), p. 2250–2253. doi: 10.1111/all.15313. Full text in Research Archive
• Westergren, Thomas; Stang, Julie; Stensrud, Trine; Andersen, Oddbjørn Klomsten; Sigdestad, Joakim Bordvik & Brynjulfsen, Trine [Show all 10 contributors for this article] (2019). Exercise adherence and psychological needs satisfaction in the PhysicaL activity and Asthma in Youth (PLAY) intervention. Full text in Research Archive
• Mathisen, Therese Fostervold; Bratland-Sanda, Solfrid; Rosenvinge, Jan H; Pettersen, Gunn; Stensrud, Trine & Hansen, Bjørge Hermann [Show all 12 contributors for this article] (2019). Fysisk helse og risikoprofil for ikke-smittsomme sykdommer hos kvinner med bulimia nervosa eller overspisingslidelse. Full text in Research Archive
• Myklebust, Grethe & Stensrud, Trine (2019). Helseproblemer blant junior elite håndballspillere ved Norges Toppidrettsgymnas og offentlig videregående skole. Full text in Research Archive
• Andersen, Oddbjørn Klomsten; Clarsen, Benjamin; Garthe, Ina; Mørland, Morten & Stensrud, Trine (2017). Beinhelse hos norske elitesyklister og elite mellom- og langdistanseløpere. Full text in Research Archive
• Sagelv, Edvard Hamnvik; Ekelund, Ulf & Stensrud, Trine (2016). A comparison between two different conditions of breaking up sedentary behaviour on glucose metabolism. Full text in Research Archive Show summary

  Conclusion: There is no effect of either breaking up sedentary behaviour each hour or performing 30 minutes of vigorous physical activity in one bout compared with prolonged sitting for six hours on glucose metabolism.

• Stang, Julie; Hem, Erlend Jan; Carlsen, Kai-Håkon; Couto, Mariana & Stensrud, Trine (2013). Increased Parasympathetic Tone and Bronchial Hyperresponsiveness In Elite Winter Sport Athletes. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 45(5), p. 330–330. Full text in Research Archive
• Thorsen, Einar; Caspersen, Cecilie & Stensrud, Trine (2012). Application of Exhaled Nitric Oxide in Pulmonary Oxygen Toxicity Response. Aviation, Space and Environmental Medicine. ISSN 0095-6562. 83(5), p. 531–532. Full text in Research Archive
• Stang, Julie; Hem, Erlend Jan; Carlsen, Kai-Håkon & Stensrud, Trine (2012). Er astma hos toppidrettsutøvere assosiert med økt parasympatisk aktivitet? Norsk idrettsmedisin. ISSN 0806-9328. 27(3), p. 23–23. Full text in Research Archive
• Stang, Julie; Hem, Erlend Jan; Carlsen, Kai-Håkon & Stensrud, Trine (2012). Er astma hos toppidrettsutøvere assosiert med økt parasympatisk aktivitet. Full text in Research Archive
• Stensrud, Trine & Johnsen, Elise (2022). Skadeprevalens, fysisk form og treningsvolum blant unge håndballspillere: En prospektiv kohortstudie. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Håndball er en kompleks idrett som stiller høye krav til flere fysiske og psykiske egenskaper (Michalsik & Aagaard, 2015, s. 879). Blant unge håndballspillere har det vist seg å være en sammenheng mellom fysisk form og håndballprestasjon (Matthys et al., 2013; Moss et al., 2015). Det kreves mange timer med målrettet trening for å nå verdenstoppen, og derfor er det stadig flere unge håndballspillere som begynner på spesialisert idrettsgymnas. Dette fører til at mange unge utøvere deltar i intensive treningsregimer, hvor treningsbelastningen er ekstremt høy. Imidlertid er det vist at høy belastning over tid gir økt risiko for skader, og i kombinasjon med for lite hvile kan det føre til overtrente utøvere (Windt et al., 2017; Møller et al., 2017; Meeusen et al., 2013). Videre er det vist at håndball er en av de olympiske idrettene med høyest insidens av skader (Engebretsen et al., 2013; Soligard et al., 2017). Til tross for dette er det få studier som har undersøkt om fysisk form og treningsvolum er assosiert med skader blant unge håndballspillere. Videre er det lite undersøkt i hvilken grad overgangen fra ungdomsskole til Norges Toppidrettsgymnas (NTG) påvirker fysisk form, treningsvolum og skadeprevalens blant spillerne. Hensikt: Undersøke om fysisk form og treningsvolum er assosiert med skader blant unge håndballspillere i første klasse på videregående skole (VGS). En sekundær hensikt var å undersøke om det er forskjell i fysisk form, treningsvolum og skadeprevalens mellom unge håndballspillere i første klasse på NTG og offentlig videregående skole (OVGS). Metode: Prospektiv kohortstudie av fire årskull (2002, 2003, 2004 og 2005) unge håndballspillere (n= 164) i første klasse på NTG (n= 84) eller OVGS (n= 80). Det ble innhentet informasjon om spillernes høyde, vekt og kroppssammensetning. Videre ble det benyttet et testbatteri for å måle fysisk form; maksimal hopphøyde, hurtighet, agility, utholdenhet og maksimal styrke. Data på treningsvolum (antall treningstimer/uke) ble innhentet via et spørreskjema som omhandler spillernes bakgrunn som utøver, tilsendt ved inklusjon. Skader ble registrert hver 14. dag i totalt 16 uker via et digitalt spørreskjema (Clarsen et al., 2014). Resultat: Det var ingen signifikant assosiasjon mellom fysisk form og skader, eller treningsvolum og skader. Totalt 82,9 % av alle spillerne rapporterte én eller flere skader i løpet av perioden med skaderegistrering. Det var ingen signifikant forskjell i antall skadede spillere mellom NTG og OVGS. Total gjennomsnittlig skadeprevalens per registrering var 37,2 %. Gjennomsnittlig skadeprevalens for spillerne på NTG var 42,7 %, og 31,6 % for spillerne på OVGS. Denne forskjellen var signifikant (p = 0,03). Det var ingen signifikant forskjell i fysisk form mellom spillerne på NTG og OVGS, bortsett fra at spillerne på OVGS hoppet signifikant høyere enn spillerne på NTG (p = 0,05). Videre var det signifikant flere spillere fra NTG som trente 16-20 timer/uke sammenlignet med OVGS (p < 0,01), og det var signifikat flere spillere fra OVGS som trente 6-10 timer/uke sammenlignet med NTG (p < 0,01). Konklusjon: Det var ingen signifikant assosiasjon mellom fysisk form og skader, eller treningsvolum og skader. En høy andel av alle spillerne (82,9 %) rapporterte én eller flere skader i løpet av skaderegistreringsperioden, og gjennomsnittlig skadeprevalens per registrering var 37,2 %. Spillerne på NTG hadde en signifikant høyere gjennomsnittlig skadeprevalens sammenlignet med OVGS. Det var ingen signifikant forskjell i fysisk form mellom spillerne på NTG og OVGS, bortsett fra at spillerne på OVGS hoppet signifikant høyere enn spillerne på NTG. Videre hadde spillerne på NTG et signifikant høyere treningsvolum i snitt sammenlignet med spillerne på OVGS. Det må imidlertid nevnes at deler av datamaterialet ble innhentet under Covid-19 pandemien, som kan ha påvirket resultatene. Videre var utvalget relativt lite og begrenset. Flere studier er nødvendig for å bekrefte og generalisere resultatene.

• Stensrud, Trine & Kvisler, Sarah Marlén Svastuen (2022). Søvn, kosthold og skader hos unge håndballspillere på juniornivå: En prospektiv kohortstudie. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Håndball er en av idrettene med høyest skadeforekomst både på junior- og seniornivå (Engebretsen et al., 2013; Junge et al., 2009; Junge et al., 2006; Olsen et al., 2006; Soligard et al., 2017), og en skade kan medføre en rekke konsekvenser for utøveren (Giroto et al., 2017, s. 195; Raya-González et al., 2020, s. 1). I Norge er det en stadig økning i antall unge som begynner på toppidrettsgymnas, hvor de kan spesialisere seg i sin idrett (Norges Toppidrettsgymnas, u.å-e). Gode søvn- og kostholdsvaner er viktig i forbindelse med restitusjon hos idrettsutøvere (Helle & Garthe, 2011, s. 9; Leeder et al., 2012, s. 541), men i hvilken grad søvn- og kostholdsvaner påvirker skadeforekomsten hos juniorspillere i håndball er enda uklar. Det er heller ikke kjent om spillere på Norges Toppidrettsgymnas (NTG) har andre søvn- og kostvaner enn spillere på offentlig videregående skole (OVGS). Hensikt: Hensikten med denne oppgaven var å undersøke om søvn- og kostholdsvaner er assosiert med skader hos håndballspillere på juniornivå som går 1.året på videregående skole (VGS). I tillegg til å undersøke om det var forskjell i søvn- og kostholdsvaner og skadeforekomst mellom håndballspillere på juniornivå som går 1.året på NTG og spillere som går på OVGS. Metode: Dette er en prospektiv kohortstudie med 164 håndballspillere som gikk 1. året på NTG (n= 84) eller OVGS (n=80). Data ble innsamlet fra fire årskull, henholdsvis 2002, 2003, 2004 og 2005. Sykdom og skader ble registrert hver 14. dag i totalt 16 uker via et digitalt spørreskjema (Clarsen et al., 2014). The Bergen Insomnia scale ble benyttet for å innhente søvnvolum ved baseline og hver 14.dag gjennom 16 uker (Pallesen et al., 2008). For å innhente informasjon om ernæring ble et matvarefrekvensspørreskjema som er basert på og utviklet av Martinsen (2015) benyttet. Logistisk regresjon ble benyttet for å undersøke om det var noen assosiasjoner mellom søvnvaner og skader samt kostholdsvaner og skader. Resultat: Det ble funnet en signifikant assosiasjon mellom anbefalt inntak av frukt og grønt (≥ 5 porsjoner daglig) og skader (OR: 0,35, 95% KI=0,13-0,95) og inntak av mellommåltider (≥ 3 totalt i uken) og skader (OR: 2,93, 95% KI=1,11-7,73) for hele gruppen samlet. De samme signifikante assosiasjonene ble også funnet hos spillerne på NTG, henholdsvis mellom inntak av frukt og grønt (≥ 5 porsjoner daglig) og skader (OR: 0,12, 95% KI=0,03-0,45) samt inntak av mellommåltider (≥ 3 totalt i uken) og skader (OR: 5,50, 95% KI=1,06-28,67). Videre var det en signifikant sammenheng mellom søvn (≥ 8 timer) og skader (OR: 3,21, 95% KI=1,03-10,03) på registrering 4 for hele gruppen samlet. Spillerne på NTG hadde en signifikant høyere gjennomsnittlig skadeforekomst per skaderegistrering (p=0,03), en signifikant større andel som innfridde søvnanbefalingene i ukedagene ved baseline (p=0,01) og signifikant flere som spiste ≥ 3 mellommåltider i uka (p=0,02) sammenlignet med spillerne på OVGS. Videre var det signifikant flere som oppfylte anbefalingene for søvn i helgene sammenlignet med ukedagene ved baseline for hele gruppen samlet (p=0,01). Konklusjon: For hele utvalget samlet, og for spillere på NTG, ble det funnet en signifikant assosiasjon mellom anbefalt inntak av frukt og grønt og skader, og mellom inntak av ≥ 3 mellommåltider i uken og skader. Deltagerne som oppnådde anbefalingene for frukt og grønt hadde signifikant lavere odds for å skade seg, mens de som spiste ≥ 3 mellommåltider i uken hadde signifikant høyere odds for å skade seg. For hele utvalget samlet ble det også funnet en signifikant assosiasjon mellom søvn og skader på skaderegistrering 4. Spillerne fra NTG hadde en signifikant høyere gjennomsnittlig skadeforekomst, det var en signifikant høyere andel som innfridde søvnanbefalingene i ukedagene og signifikant flere som spiste ≥ 3 mellommåltider i uken sammenlignet med OVGS. For hele utvalget samlet var det signifikant flere av deltagerne som oppfylte anbefalingene for søvn i helgene sammenlignet med ukedagen. Flere studier med god metodisk kvalitet er nødvendig for å bekrefte resultatene.

• Stensrud, Trine; Luteberget, Live & Gøransson, Martine (2021). Fysiske karakteristika, fysisk form og skadeforekomst blant unge håndballspillere: Utviklingen fra første til andre klasse på Norges toppidrettsgymnas og offentlig videregående skole. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Håndball er en fysisk krevende kontaktidrett, og håndballprestasjon er dermed assosiert med fysiske karakteristika og fysisk form. Det er også vist at det er en høy forekomst av skader i håndball. Vi vet lite om hvordan unge håndballspillere utvikler fysiske karakteristika og fysisk form gjennom videregående skole, og det finnes heller ikke mye data på skadeforekomst. I tillegg er det stadig flere som søker seg til toppidrettsgymnas (som for eksempel Norges toppidrettsgymnas; NTG) for å kombinere videregående skolegang med satsing mot en toppidrettskarriere. Hvordan håndballspillere ved NTG og offentlig videregående skole (OVS) differensierer med hensyn til utvikling av fysiske karakteristika, fysisk form og endring i skadeforekomst gjennom videregående skole finnes det lite informasjon om. Hensikt: Hensikten med denne masteroppgaven var å undersøke utviklingen i fysiske karakteristika og fysisk form samt endringen i skadeforekomst blant unge håndballspillere fra første til andre klasse på videregående skole. En sekundær hensikt var å undersøke om denne utviklingen var ulik mellom håndballspillerne fra NTG og OVS. Metode: Denne studien var en prospektiv kohortstudie av unge håndballspillere i første til andre klasse på videregående skole. Mål for fysiske karakteristika bestod av høyde, kroppsvekt, kroppsmasseindeks (KMI), fettmasse, fettprosent og muskelmasse. Mål for fysisk form var Yo-Yo IR1, 10 og 20 meter sprint, agility, counter movement jump (CMJ), 1RM knebøy og 1RM benkpress. Skadeforekomst ble registrert via et nettbasert spørreskjema som ble sendt ut til deltakerne hver annen uke gjennom 24 uker av sesongen. Resultat: Samlet ble utvalget signifikant høyere (0,5 ± 0,5 %), tyngre (4,3 ± 4,9 %), økte i KMI (3,7 ± 5,1 %), økte fettmasse (16,0 ± 30,0 %) og økte muskelmasse (3,6 ± 4,0 %) fra første til andre klasse. Utvalget samlet forbedret resultatene signifikant i Yo-Yo IR1 (23,6 % ± 45,8 %), 10 meter sprint (-1,3 % ± 3,0 %), counter movement jump (CMJ) (11,6 % ± 18,7 %), knebøy (25,2 % ± 17,4 %) og benkpress (18,3 % ± 18,3 %). Det var en signifikant forskjell mellom utøverne fra NTG og OVS i utviklingen av fysiske karakteristika og fysisk form. Utøverne fra NTG økte mest i muskelmasse, mens utøverne fra OVS økte mest i fettmasse og fettprosent. Utøverne fra NTG gjorde det signifikant bedre i CMJ samt 10 og 20 meter sprint. Konklusjon: Fra første til andre klasse ble deltakerne i denne studien samlet høyere, tyngre, økte i KMI samt andelen fettmasse og muskelmasse. De forbedret resultatene på Yo-Yo IR1, 10 meter sprint, CMJ samt 1RM knebøy og benkpress. Det var ingen signifikant endring i skadeforekomst fra første til andre klasse. Det ble videre funnet en signifikant forskjell i utviklingen av fysiske karakteristika og fysisk form mellom utøverne fra NTG og OVS. Økningen i muskelmasse var størst for utøverne fra NTG, mens økningen i fettmasse og fettprosent var størst for utøverne fra OVS. Det var en signifikant forskjell mellom utøverne fra NTG og OVS i utvikling på 10 og 20 meter sprint samt CMJ i favør av utøverne fra NTG. Det ble ikke registrert noen forskjell mellom utøverne ved NTG og OVS med hensyn til endring i skadeforekomst fra første til andre klasse. Resultatene bør tolkes med forsiktighet da få deltakere er inkludert og nedstengingen i forbindelse med covid 19 pandemien kan hatt innvirkning på resultatene.

• Stensrud, Trine & Pettersen, Camilla Sahlin (2021). Kan jaget etter det perfekte føre til økt risiko for idrettsskader?: En prospektiv kohortstudie av tre årskull unge elitehåndballspillere første år på Videregående skole. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Perfeksjonisme defineres som en kombinasjon av overdrevne høye personlige standarder og usunn kritisk selvevaluering (Frost, Marten, Lahart & Rosenblate, 1990). Perfeksjonisme er et personlighetstrekk som er vanlig blant idrettsutøvere (Rees et al., 2016). Flere studier de siste ti år som omhandler perfeksjonisme og idrett konkluderer med at perfeksjonisme kan medføre en rekke negative konsekvenser som angst, depresjon, utbrenthet, overtrening og spiseforstyrrelser (Gaudreau & Verner-Filion, 2012; Hall & Hill, 2012; Hill, 2013; Mallinson-Howard, Hill & Hall, 2019). Kun en tidligere publisert artikkel har sett på sammenhengen mellom perfeksjonisme og skader blant unge idrettsutøvere (Madigan, Stoeber, Forsdyke, Dayson & Passfield, 2018). Her konkluderes det med at utøvere som skårer høyt på perfeksjonistisk bekymring (PC) har økt sannsynlighet for å bli skadet, sammenlignet med utøvere med en personlighetsprofil uten høy grad av perfeksjonistisk bekymring (PC). Formål: Undersøke 1) sammenhengen mellom perfeksjonisme og skader blant unge håndballspillere, 2) om det er forskjeller på grad av perfeksjonisme og skadeprevalens blant unge håndballspillere fra Norges Toppidrettsgymnas (NTG) og spillere fra offentlig videregående skole (Off.VGS). 3) Da data for en tredjedel av utvalget ble innsamlet under covid-19 pandemien (spillere født i 2004), var det tredje formålet med studien å undersøke forskjeller mellom spillere født i 2002/2003 hvor data ble innsamlet før pandemien sammenlignet med spillere født i 2004 med hensyn til perfeksjonismeskår og skadeprevalens. Metode: Prospektiv kohortstudie. Data er innsamlet fra 139 (62 gutter, 77 jenter) unge håndballspillere fra NTG (n= 63) og Off. VGS (n= 76) i løpet av første året på VGS. Tre årskull er representert (født 2002, 2003, 2004). Perfeksjonisme ble målt med Frost Multidimensional Perfectionism Scale (FMPS) (Frost et al., 1990). Skader ble registrert i sesong ved hjelp av OSTRC sykdoms og skaderegistrering (Clarsen et al., 2014) hver 14. dag i totalt 18. uker. Resultat: Det var en signifikant sammenheng mellom perfeksjonistisk bestrebelse og skader (OR 1,08, 95% KI = 1,00 - 1,18), og mellom perfeksjonistisk bekymring og skader (OR 1,06, 95% KI = 1,00 – 1,13) for hele gruppen samlet. Spillere som ble definert som skadet hadde en signifikant høyere gjennomsnittsskår på både perfeksjonistisk bestrebelse (Δ Gj.sn 2,2 (95% KI=0,04-4,4)) og perfeksjonistisk bekymring (Δ Gj.sn 3,9 (95% KI=0,3-7,5)) sammenlignet med spillerne som ikke ble definert som skadet. Spillerne fra NTG skåret både signifikant høyere på perfeksjonistisk bestrebelse (Δ Gj.sn 3,5 (95% KI=1,9-5,1)), samt hadde en signifikant høyere gjennomsnittlig skadeprevalens per registrering (X2 (1, N = 139) = 4,9, p = 0.03) sammenlignet med spillere fra Off. VGS. Resultatene viste en signifikant sammenheng mellom perfeksjonistisk bekymring og skader for spillere født 2004 (OR 1,1, 95% KI = 1,01 – 1,23) hvor data ble innsamlet under covid-19 pandemien. Konklusjon: Studien viser en svak, men signifikant sammenheng mellom perfeksjonisme og skader for hele utvalget samlet. Skadede spillere hadde signifikant høyere gjennomsnittsskår på både perfeksjonistisk bestrebelse og perfeksjonistisk bekymring sammenlignet med de ikke skadede spillerne. Det var forskjeller med hensyn til perfeksjonisme og skadeprevalens mellom spillere fra NTG og Off.VGS, hvor NTG spillere hadde en signifikant høyere gjennomsnittsskår på perfeksjonistisk bestrebelse og signifikant høyere gjennomsnittlig skadeprevalens per registrering sammenlignet med spillerne fra off.VGS. For spillere født i 2004 hvor data ble innsamlet under Covid – 19 pandemien viste resultatene en signifikant sammenheng mellom perfeksjonistisk bekymring og skader. Utvalget i studien var relativt lite og begrenset, og det er behov for flere studier for at resultatene skal kunne generaliseres og bekreftes.

• Granlund, Thea & Stensrud, Trine (2020). Fysisk form og skadeforekomst blant junior elite håndballspillere: En prospektiv kohortstudie. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Skader er en stor utfordring for håndballspillere, også for utøvere i ungdomsalder. Stadig flere unge talenter velger å begynne på et av de mange toppidrettsgymnasene vi har her i landet, hvor de får tilrettelagt for skole og mer trening i idretten sin. Vi vet enda ikke nok om hvordan disse skolene og den økte treningsmengden påvirker de unge håndballspillernes fysiske form og skadeforekomst. Formål: Hensikten med denne studien er å sammenligne fysisk form og utviklingen av skadeforekomst gjennom 24 uker hos junior elitehåndballspillere ved Norges Toppidrettsgymnas (NTG) med håndballspillere på samme nivå (kontroller) som går på offentlig videregående skole (VGS). Metode: Studien er en prospektiv kohortstudie med 114 utøvere (65 NTG og 49 kontroller) fordelt på 1., 2., og 3. klasse som har gjennomgått måling av kroppssammensetning med bioelektrisk motstandsanalyse (InBody 720, Seoul, Korea) samt gjennomført en rekke fysiske tester (Yo-Yo, 10m og 20m sprint, agility T-test, CMJ spenst-test på bærbar plattform (FP4, HUR Labs, Finland), og 1RM knebøy og benkpress i Smith-maskin) ved skole- og sesongstart. De har også rapportert inn skader og helseproblemer hver 14. dag gjennom 24 uker av sesongen via applikasjonen Briteback. Beregning av forekomst av skader hos utøverne samt analyse av eventuelle forskjeller i fysiske karakteristika, fysisk form og skadeforekomst hos elever på NTG og offentlig VGS er utført i SPSS versjon 24. Antall nye skader per deltaker, skadeforekomst per 1000 kamptime, skadelokalisasjon og total alvorlighets-skår ble også undersøkt og sammenlignet for gruppene. Resultat: Guttene på NTG hadde høyere midje-hofte-ratio (p<0,05), mens jentene hadde høyere vekt (p<0,01) og muskelmasse (p<0,001) enn kontrollene. Guttene på NTG løp lenger på yo-yo IR1 testen (p<0,05), men hoppet lavere på CMJ (p<0,01) og var tregere på 20m sprint (p<0,01) enn kontrollene. Jentene på NTG var raskere enn kontrollene på 10m sprint (p<0,05), 20m sprint (p<0,01) og agility (p<0,001). Guttene på NTG hadde signifikant lavere gjennomsnittlig forekomst av skader (p<0,05), mens jentene på NTG hadde høyere (p<0,001). Det ble derimot ikke funnet en signifikant forskjell mellom gruppene for antall nye skader per spiller gjennom sesongen, antall skader per 1000 kamptime eller total alvorlighets-skår. Når det gjelder skadelokalisasjon hadde jentene på NTG høyere forekomst av ryggskader (p<0,01) og kneskader (p<0,01), mens guttene på NTG hadde høyere forekomst av ryggskader (p<0,001) og skader i albue/hånd/finger (p<0,05) sammenlignet med kontrollene. Guttene på offentlig VGS hadde høyere forekomst av kneskader (p<0,001) og ankelskader (p<0,05). Konklusjon: Det var ingen forskjell i fysiske karakteristika mellom håndballspillerne på NTG og offentlig VGS, med unntak av at guttene på NTG hadde større midje-hofte-ratio og jentene på NTG hadde større total kroppsmasse og muskelmasse enn kontrollene. Guttene på NTG hadde bedre aerob kapasitet, men dårligere spenst med svikt og hurtighet på 20m sprint enn kontrollene, mens jentene på NTG var raskere enn kontrollene både på 10 og 20m sprint og agility. Jentene på NTG hadde høyere gjennomsnittlig forekomst av skader enn jenten i kontrollgruppa, mens guttene på NTG hadde lavere gjennomsnittlig skadeforekomst sammenlignet med kontrollene. Det var ingen forskjell mellom spillerne fra NTG og offentlig VGS i antall nye skader per utøver, antall skader per 1000 kamptime eller alvorlighets-skår. Resultatene må imidlertid tolkes med forsiktighet da utvalgsstørrelsen, spesielt for de mannlige kontrollene er svært liten.

• Evensen, Anne Karin; Stensrud, Trine & Myklebust, Grethe (2019). Helseproblemer blant junior elite håndballspillere ved Norges Toppidrettsgymnas og offentlig videregående skole: En prospektiv kohortstudie. Norges idrettshøgskole. Full text in Research Archive Show summary

  Bakgrunn: Hvert år velger flere unge lovende idretts talenter å begynne på et toppidrettsgymnas på veien til en eventuell toppidrettskarriere. Her får de unge tilrettelagt skolegang kombinert med spesialisering innenfor sin idrett. Vi vet lite om omfanget av helseproblemer blant junior elite håndballspillere. Formålet: Målet med oppgaven var å kartlegge helseproblemer blant junior elite håndballspillere som er elever ved Norges toppidretts gymnas Bærum (heretter vil jeg bruke forkortelsen NTG), og sammenligne de med junior elite håndballspillere som er elever ved offentlig videregående skole. Metode: En prospektiv kohortstudie over 12 uker. Ved hjelp av en applikasjon for smarttelefon ble det registrert akutte skader, belastningsskader og sykdom hos unge elite håndballspillere (alder 16-18 år) som er elever ved NTG Bærum og ved offentlig videregående skoler. Omfanget av skader og sykdom blant junior elite håndballspillere ved NTG Bærum ble registrert, og sammenlignet med håndballspillere på samme nivå ved offentlige videregående skoler uten toppidrett. Det ble beregnet prevalens og sett på byrden av helseproblemer, som skader og sykdom. De antatte risikofaktorene søvn og ernæring, ble belyst. Resultat: Gjennomsnittlig ukentlig prevalens av alle helseproblemer ble beregnet til 42 %, gjennomsnittlig ukentlig prevalens av alvorlige helseproblemer var 30 %. Det var høyere gjennomsnittlig ukentlig prevalens av belastningsskader (18 %) enn akutte skader (10 %) og sykdom (15 %). Utøverne fra Norges Toppidrettsgymnas hadde en høyere gjennomsnittlig ukentlig prevalens av belastningsskader (11 %) enn utøverne fra offentlig videregående skole (7 %). Spillerne fra offentlig videregående skole hadde en høyere gjennomsnittlig ukentlig prevalens av akutte skader enn NTG, 6 % mot 3 %. Konklusjon: Forekomsten av helseproblemer er høy blant junior elite håndballspillere på Norges Toppidrettsgymnas og offentlig videregående skole. Særlig belastningsskader reduserer deltakelse, treningsmengde og prestasjon i en kritisk periode av livet til utøvere i puberteten.

• Stensrud, Trine (2008). Asthma and exercise : climatic effects upon exersice-induced bronchoconstriction and exercise capacity in asthmatic subjects. Norges idrettshøgskole. ISSN 9788250204119. Full text in Research Archive Show summary

  Paper II: Berntsen S., Stensrud T., Ingjer F., Vilberg A., Carlsen K-H. Asthma in medium altitude - exercise-induced bronchoconstriction in hypobaric environment in subjects with asthma. Allergy 2005 Oct; 60(10):1308-11.

View all works in NVA