Tron Krosshaug

Professor Department of Sports Medicine

Email: tronk@nih.no
Phone: +47 23 26 23 49

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Background and experience

Tron Krosshaug, PhD is an associate professor at the Oslo Sports Trauma Research Center and the Department of Sports Medicine at the Norwegian School of Sport Sciences. His main research area is sports injury prevention, with a primary focus on biomechanical analysis of serious knee injuries in various sports. He defended his PhD thesis on the topic "Video analysis of the mechanisms for ACL injuries" in August 2006. In the PhD work he developed a new method for extracting detailed joint motion from videos of real injury situations. The method is used by researchers world-wide to investigate e.g. ankle sprains and head impacts in various sports.

Krosshaug is also an entrepreneur, running the company Muscle Animations that is developing 3D animations of strength training exercises, including biomechanical analyses. For this work, he has won several prices. In October 2015, Muscle Animations launched a free app, in collaboration with the Norwegian Diabetes federation, sponsored by the Norwegian directorate of Health. The app includes state-of-the-art intuitive 3D animations of strength training exercises, illustrating how persons at any level can get effective workouts without external weights. The app is downloaded by more than 35.000 Norwegians.

Teaching

Strength/endurance/flexibility training, biomechanics, motion analysis and functional anatomy.

Research

Biomechanics, motion analysis, strength training technique, injury mechanisms and risk factors for ACL injuries, ankle injuries, head injuries in ball/team sports and alpine sports.

Projects

Andersen, Vidar; Petushek, Erich J.; Sæterbakken, Atle Hole; Paulsen, Gøran & Krosshaug, Tron (2026). Squat Performance in Elite Powerlifters: Biomechanical Analyses of Maximal and Near Maximal Lifts. Journal of Strength and Conditioning Research. ISSN 1064-8011. p. 1–9. doi: 10.1519/JSC.0000000000005532. Full text in Research Archive Show summary
The aim of this study was to investigate lifting technique and joint loading near maximal and maximal loads in elite powerlifters and to investigate their strategies to maximize performance. Eight elite national powerlifters volunteered to participate in the study. The subjects lifted single repetitions at 3 different loads (90, 95, and 100% of 1-RM). The ascending movement was divided into presticking, sticking, and poststicking regions and analyzed for hip torque, knee torque, and hip/knee torque ratio in addition to barbell displacement, barbell velocity, lifting time, and joint angles. The results indicated a significantly higher hip torque than knee torque across all phases, particularly during the sticking region, where a hip-to-knee torque ratio exceeding 3:1 was observed. This ratio indicates a much larger contribution from the hip extensors in powerlifters than what has previously been reported in recreational lifters. Based on ANOVA and equivalence testing (equivalence bounds: d = ±0.51), the increased barbell loading increased the knee joint torque in the presticking region (8% between 90 and 95% of 1-RM), increased the forward lean toward the end of the sticking region and reduced lifting velocity in the sticking and poststicking region. In conclusion, top-level powerlifters were able to maintain their load distribution across the knee and hip when increasing the loading in the barbell back squat, while increasing the initial thrust from the bottom position with higher knee torques during the heaviest lifts. The high proportion of the load distributed to the hip joint indicates that a powerlifting squat requires substantial hip extensor strength.
Mausehund, Lasse; Bieri, Laura & Krosshaug, Tron (2026). Fake-cut maneuvers: biomechanical determinants of performance and ACL injury risk. Frontiers in Sports and Active Living. 8. doi: 10.3389/fspor.2026.1856706. Full text in Research Archive Show summary
Change-of-direction maneuvers can be executed with deceptive intent (‘fake-cuts’), yet the biomechanical determinants of fake-cut performance and their trade-offs with anterior cruciate ligament (ACL) injury risk remain poorly understood. Therefore, we compared cutting biomechanics between skilled and less skilled fake-cut performers during sport-specific fake-cut maneuvers. Methods Ninety-six handball players performed fake-cuts while 3D kinematics and kinetics were recorded. Fake-cut performance was classified by each player's primary coach, and performance groups were compared using factorial ANOVA. Results Skilled fake-cut performers displayed shorter ground contact times, higher movement speeds throughout stance, a shallower cutting angle and greater cutting width compared with less skilled performers. They also showed greater and faster head movements against the intended cutting direction, suggesting upper-body-driven deception. No clear group differences were observed in ACL injury risk–related knee biomechanics within the first 100 ms after initial contact. However, skilled performers showed greater peak knee abduction moment across the stance phase. Also, several biomechanical characteristics associated with superior fake-cut performance have previously been linked to greater ACL injury–related knee loading. Conclusion Overall, effective fake-cut performance appears to rely on speed-oriented cutting mechanics and upper-body-driven deception. At the same time, the present findings may indicate a performance–injury conflict during fake-cut maneuvers. Cutting technique strategies that reduce ACL injury risk without impairing fake-cut performance warrant further investigation.
Mai, Patrick; Willwacher, Steffen; Rahlf, Lina; Hoenig, Tim; Braun, Luca & Diecken, Carlo von [Show all 12 contributors for this article] (2026). Situations Leading to Anterior Cruciate Ligament Injury in Sports: A Systematic Review with Meta-analysis. Sports Medicine. ISSN 0112-1642. doi: 10.1007/s40279-026-02436-1. Full text in Research Archive Show summary
Background Anterior cruciate ligament (ACL) injuries are common in many sports and impose substantial performance and long-term health burdens. A quantitative synthesis of real-world, video-identified game situations can inform sport-specific prevention methods. Objective The aim of the study was to identify game situations and movement patterns leading to ACL injury in different sports. Design Systematic review with meta-analysis. Data Sources PubMed, Google Scholar, Web of Science, and Scopus were searched for studies analyzing video recordings of ACL injuries sustained by athletes of any sex during training or competition. Random effects meta-analyses of prevalence and moderator analyses (sport as a factor) were performed. Results In total, 39 articles (1551 video-verified ACL injuries) of on-average moderate quality (Quality Appraisal for Sports Injury Video Analysis Studies [QA-SIVAS]) scale mean 66%) were included. Noncontact ( n = 745), indirect contact ( n = 533), and direct contact ( n = 273) mechanisms were reported, with notable sport-specific differences. Across all injuries, the most frequent contexts were ball action (45.7%), pressing/tackling (40.9%), and cutting (36.6%). Within noncontact cases, cutting (53.8%), pressing/tackling (50.2%), decelerating (38.9%), and landing (30.1%) were the most prevalent actions, whereas being tackled was most frequent in indirect contact cases (56.1%). For direct contact injuries, pooled action-specific estimates were available for being tackled (23.9%) and pressing/tackling (24.2%). Injuries typically occurred at high horizontal speed (53.8%; noncontact 70.7%), were more frequent during ball possession (67.5%) and offensive play (55.4%), and happened more early in time within the first 25% of the game in football (37.5%) and netball (37.8%). Conclusions The identified patterns support the use of mechanism-specific, sport-tailored prevention strategies (e.g., technique/strength, neurocognitive functioning for noncontact, perturbation-based drills for indirect contact, and rules/choice of equipment for knee-directed contact). Methodological improvements, such as harmonized and more detailed injury reporting, are needed to refine risk estimates.
Jarske, Heidi; Leppänen, Mari; Avela, Janne; Vasankari, Tommi; Krosshaug, Tron & Pasanen, Kati [Show all 7 contributors for this article] (2026). Effects of two pre-running training interventions on running kinematics and strength – A randomized controlled trial in novice recreational runners. Gait & Posture. ISSN 0966-6362. 128. doi: 10.1016/j.gaitpost.2026.110174. Full text in Research Archive
Leppänen, Mari; Jarske, Heidi; Krosshaug, Tron; Myklebust, Grethe; Vasankari, Tommi & Parkkari, Jari [Show all 7 contributors for this article] (2026). No Association Between Anatomic Factors and Non-Contact ACL Injury Risk in 217 Female Team Sport Players: A Prospective 4.5-Year Study. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 36(5). doi: 10.1111/sms.70290. Full text in Research Archive
Gronwald, Thomas; Finnern, Luca Sophie; Wilke, Jan; Willwacher, Steffen; Pasanen, Kati & Hollander, Karsten [Show all 11 contributors for this article] (2026). Infographic. Video analysis of muscle strains in sport: qualitative and quantitative situational characteristics across muscle groups. British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2026-111709. Full text in Research Archive
Finnern, Luca Sophie; Wilke, Jan; Willwacher, Steffen; Pasanen, Kati; Hollander, Karsten & Dalos, Dimitris [Show all 11 contributors for this article] (2026). Qualitative and quantitative situational characteristics of muscle strains in sports: a systematic review and meta-analysis. British Journal of Sports Medicine. ISSN 0306-3674. doi: 10.1136/bjsports-2025-110327. Full text in Research Archive
Müller-Kühnle, Julian; Bill, Kevin; Thun, Patrik; Mai, Patrick; Bagehorn, Timo & Kamatsuki, Yusuke [Show all 18 contributors for this article] (2025). A Novel Cutting Technique and Resistance Training Intervention to Improve Movement Patterns in Youth Female Handball Players. Journal of Orthopaedic & Sports Physical Therapy Open (JOSPT Open). 3(4), p. 473–482. doi: 10.2519/josptopen.2025.0144. Full text in Research Archive Show summary
OBJECTIVE: To assess whether a 9-week intervention combining cutting technique retraining and hip/calf resistance exercises reduced knee abduction moment (KAM) in young female handball players. STUDY DESIGN: Controlled laboratory study. METHODS: Forty female players (aged 15-18 years) were assigned to an intervention group (IG; n = 20) or control group (CG; n = 20). KAM during sidestep cutting and isometric strength were assessed preintervention and postintervention. The IG completed a twice-weekly program integrated into team practice. RESULTS: Group × time interaction was not significant for KAM ( P = .366) or foot strike angle (FSA; P = .171). Both groups reduced KAM ( P = .002; IG: 0.68 ± 0.16 to 0.59 ± 0.21 Nm/kg*m; CG: 0.68 ± 0.31 to 0.53 ± 0.22 Nm/kg*m) and increased FSA ( P = .040). Knee valgus angle showed no significant interaction ( P = .462) or main effects ( P = .148, P = .080). There was no interaction for hip external rotation, hip abduction, or ankle plantarflexion strength ( P≥.05). Hip abduction strength increased over time ( P = .046) without group differences. CONCLUSION: The intervention did not significantly improve KAM or strength versus standard training, though trends suggest possible effects on cutting mechanics. JOSPT Open 2025;3(4):473-482. Epub 20 August 2025. doi:10.2519/josptopen.2025.0144
Petushek, Erich; Breen, Sarah; Myer, Gregory D.; Dupuis, Beau P.; Dorgo, Sandor & Ebben, William [Show all 7 contributors for this article] (2025). Competency and Confidence in Qualitative Biomechanical Assessment of Exercise Technique Among Exercise Professionals. Journal of Strength and Conditioning Research. ISSN 1064-8011. 40(1), p. 16–23. doi: 10.1519/jsc.0000000000005249. Full text in Research Archive Show summary
Abstract Petushek, E, Breen, S, Myer, GD, Dupuis, BP, Dorgo, S, Ebben, W, and Krosshaug, T. Competency and confidence in qualitative biomechanical assessment of exercise technique among exercise professionals. J Strength Cond Res 40(1): 16–23, 2026—Understanding resistance exercise technique is critical for exercise professionals, but research on this as a specific competency is lacking. This study evaluated resistance exercise technique analysis competency, confidence, and perceived importance in a diverse set of exercise professionals. A 30-question true/false and multiple-choice instrument was developed that focused on application of biomechanical principles to resistance exercises. Subsequently, instrument data were collected from 310 exercise professionals (e.g., personal trainers, strength coaches, physical therapists), and overall percentage of correct answers was calculated across the 30 questions. Perceived importance and confidence in abilities were also assessed. Overall scores were compared across occupation and years of experience using 1-way ANOVA and follow-up t -tests correcting for multiple comparisons. Wilcoxon rank sum tests were used to compare confidence and importance data. Overall percentage of correct answers was 50%. There were no significant differences in scores among exercise professionals or years of experience ( p > 0.05). Subjects were most confident in choosing appropriate exercises to target specific muscles (72%) and identifying poor technique (70%) and least confident about optimizing exercises to maximize activation (45%). About 97% of professionals expressed a desire to learn more about assessing resistance exercises. Exercise professionals in this cohort lacked knowledge in biomechanics related to resistance exercise, exercise prescription, assessment, and modification. Most exercise professionals believed these skills were very important and desired to learn more.
Gundersen, Andreas H.; Krosshaug, Tron; Mausehund, Lasse; Tillaar, Roland Johannes Wilhelmus van den & Larsen, Stian (2025). The impact of grip width on kinetics and kinematics in the shoulder press among resistance-trained men. Sports Biomechanics. ISSN 1476-3141. p. 1–15. doi: 10.1080/14763141.2025.2590028. Full text in Research Archive Show summary
This study investigated the impact of grip width on kinematics and kinetics in the seated barbell shoulder press among resistance-trained men. Eleven participants (age: 25.9 ± 3.1 years, height: 180.4 ± 5.4 cm, body mass: 87.0 ± 7.9 kg) performed eight repetitions to failure with a narrow, medium and wide grip width. Statistical parametric mapping was used to analyse kinematics and kinetics during the entire concentric phase of the last repetition. The main findings revealed that narrower grips increased both load lifted, and shoulder, and elbow range of motion. Moreover, grip width influenced horizontal barbell forces throughout 100% of the lift, and joint kinetics during the initial 64% of the lift. Wider grips increased lateral barbell forces and reduced elbow net joint moments (NJMs), while narrower grips increased medial forces and reduced shoulder NJMs. These findings suggest that grip width modulates joint kinematics, NJMs and lateral barbell forces during the shoulder press. Based on our findings, practitioners can make technical adjustments according to individual training goals, or tailor execution to minimise pain or injury risk. For example, by increasing or decreasing loading of a specific joint or altering joint ROM according to the athlete’s or patient’s needs.
Bill, Kevin; Bartsch, Julia; Willwacher, Steffen; Eriksrud, Ola; Mausehund, Lasse & Kersting, Uwe [Show all 8 contributors for this article] (2025). Same Same but Different: Why Both Sport-Specific Cutting Tasks and Generic Change-of-Direction Tasks Might Need to Be Considered to Prevent ACL Injury. Journal of Orthopaedic & Sports Physical Therapy Open (JOSPT Open). 3(2), p. 162–170. doi: 10.2519/josptopen.2024.0076. Full text in Research Archive Show summary
OBJECTIVES: To compare knee abduction moment (KAM) magnitudes between a generic 180° pivot turn (modified 505 change-of-direction test [m505]) and a handball-specific sidestep cut, to assess ranking consistency, and to examine the resultant ground reaction force (GRF) and its frontal plane moment arm to the knee to comprehend their contributions to KAM. STUDY DESIGN: Observational laboratory study. METHODS: High-level female handball players (n = 45) performed the m505 and the handball-specific sidestep cut. The resultant GRF and its frontal plane moment arm to the knee as well as KAM were obtained and subsequently compared between tasks. Rank correlation coefficients were employed to assess if the variables of both tasks were related. RESULTS: Peak KAM was similar for the m505 and the sidestep cut (median [range], 1.79 [0.95-3.53] Nm/kg vs 1.64 [0.34-3.60] Nm/kg; r b = .25; P = .14). The ranking of the players’ peak KAM differed substantially ( r s = .26; P = .084), suggesting that different tasks could classify the same player with different injury risk. The m505 generated lower resultant GRFs (24 ± 4 N/kg, 95% CI [23, 24] vs 33 ± 9 N/kg, 95% CI [31, 35]; d = 1.30; P<.001) but longer frontal plane moment arms (7.8 ± 1.8 cm, 95% CI [7.3, 8.4] vs 5.4 ± 1.5 cm, 95% CI [5.0, 5.8]; d = 1.36; P<.001) compared to those generated by the sidestep cut. CONCLUSION: A difference in individual anterior cruciate ligament injury risk assessment depending on movement type was revealed. While KAM magnitudes were similar across direction-change tasks, player rankings differed. The contributions of resultant GRF and frontal plane moment arms to peak KAM varied between tasks, underscoring the importance of task-specific and individualized injury prevention. JOSPT Open 2025;3(2):162-170. Epub 4 December 2024. doi:10.2519/josptopen.2024.0076
Bill, Kevin; Mai, Patrick; Kersting, Uwe G. & Krosshaug, Tron (2025). Is the knee joint more vulnerable to injury in unplanned cutting tasks? An EMG vector field analysis of high-level female athletes. Knee (Oxford). ISSN 0968-0160. 55, p. 62–69. doi: 10.1016/j.knee.2025.04.002. Full text in Research Archive
Mausehund, Lasse; Patron, Anri; Äyrämö, Sami & Krosshaug, Tron (2025). Cluster analysis of cutting technique—a valuable approach for assessing anterior cruciate ligament injury risk? Frontiers in Sports and Active Living. 7. doi: 10.3389/fspor.2025.1463272. Full text in Research Archive Show summary
Background: Despite extensive efforts to pinpoint singular biomechanical risk factors for anterior cruciate ligament (ACL) injuries, research findings are still inconclusive. By combining multiple biomechanical variables, cluster analyses could help us identify safe and risky cutting technique strategies. Purpose: To identify common movement strategies during cutting maneuvers and to assess their association with ACL injury risk. Methods: A total of 754 female elite handball and football players, including 59 with a history of ACL injury, performed a sport-specific cutting task while 3D biomechanics were recorded. Over an 8-year follow-up period, 43 of these players sustained a primary ACL injury and 13 players a secondary ACL injury. Cutting technique was described using 36 discrete kinematic variables. To identify different cutting techniques, we employed a K-means clustering algorithm on data subsets involving different numbers of kinematic variables (36, 13 and 5 variables) and different sports (handball, football, and both combined). To assess the impact of the identified cutting technique clusters on ACL injury risk, we compared the proportion of injured players between these clusters using the Fisher-Freeman-Halton Exact test and adjusted rand indices (ARI). Results: We identified two distinguishable cutting technique clusters in the subset involving both sports and five kinematics variables (average silhouette score, ASS = 0.35). However, these clusters were formed based on sport- or task-related differences (Fisher's p < 0.001, ARI = 0.83) rather than injury-related differences (Fisher's p = 0.417, ARI = 0.00). We also found two cutting technique clusters in the handball (ASS = 0.23) and football (ASS = 0.30) subsets with five kinematic variables. However, none of these clusters appeared to be associated with ACL injury risk (Fisher's p > 0.05, ARI = 0.00). Conclusion: No safe or risky cutting technique strategies could be discerned among female elite handball and football players. Cluster analysis of cutting technique, using a K-means algorithm, did not prove to be a valuable approach for assessing ACL injury risk in this dataset.
Leppänen, Mari; Parkkari, Jari; Krosshaug, Tron; Vasankari, Tommi; Kannus, Pekka & Pasanen, Kati (2025). Association Between Lower Extremity Muscle Strength and Knee Loading During 180° Pivot Turn in Female Players. International Journal of Athletic Therapy and Training. ISSN 2157-7277. doi: 10.1123/ijatt.2024-0049. Full text in Research Archive
Bill, Kevin; Krosshaug, Tron & Kersting, Uwe G. (2025). Foot strike angle as key predictor of multi-plane knee joint moments in sidestep cutting: implications for ACL injury prevention. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2025.2506552. Full text in Research Archive
Pasanen, Kati; Seppänen, Arttu; Leppänen, Mari; Tokola, Kari; Järvelä, Timo & Vasankari, Tommi [Show all 9 contributors for this article] (2025). Knee laxity, joint hypermobility, femoral anteversion, hamstring extensibility and navicular drop as risk factors for non-contact ACL injury in female athletes: A 4.5-year prospective cohort study. Knee Surgery, Sports Traumatology, Arthroscopy. ISSN 0942-2056. 33, p. 4120–4127. doi: 10.1002/ksa.12625. Full text in Research Archive Show summary
PurposeTo investigate whether six selected anatomical variables were associated with non-contact anterior cruciate ligament (ACL) injury in female team sport athletes.MethodsTwo hundred eighty-seven female athletes (age 13–38 at baseline) from basketball, floorball, ice hockey and volleyball completed a baseline physical examination, including measurements of anterior-posterior (AP) knee laxity, knee hyperextension, generalized joint hypermobility, femoral anteversion, hamstring extensibility and navicular drop. Athletes entered the study either in 2011, 2012 or 2013 and were followed up until the end of 2015. During the follow-up, all complete and magnetic resonance-verified ACL injuries were recorded.ResultsTwenty-three non-contact ACL injuries were recorded. There were no significant differences in baseline physical examination variables between athletes who sustained ACL injuries and those who did not. However, a side-to-side difference in AP knee laxity greater than 2 mm was observed in 20% of the ACL injury group compared to 12% of the non-injured group, although this difference was not statistically significant.ConclusionsIn this study, AP knee laxity, knee hyperextension, generalized joint hypermobility, femoral anteversion, hamstring extensibility and navicular drop were not associated with increased risk for non-contact ACL injury in female team sport athletes. This study was powered to detect moderate to strong risk associations; thus, smaller risk associations may not have been identified.
Pasanen, Kati; Parkkari, Jari; Äyrämö, Sami; Vasankari, Tommi; Krosshaug, Tron & Leppänen, Mari (2025). No association between knee biomechanics during 90-degree cutting maneuver and future anterior cruciate ligament injury in female floorball players. Clinical Biomechanics. ISSN 0268-0033. 126. doi: 10.1016/j.clinbiomech.2025.106571. Full text in Research Archive Show summary
Background Young female floorball players are among the athletes at the highest risk of rupturing their anterior cruciate ligament in games and practices. Most anterior cruciate ligament injuries in female floorball occur in noncontact cutting situations. The primary aim of this study was to investigate association between knee biomechanics during a 90-degree cutting task and the risk for future non-contact anterior cruciate ligament injury in female floorball players. Methods Sixty-five female floorball players (median age 19.5 years; range 15–31) completed preseason testing and 2.5-year follow-up. The testing included marker-based three-dimensional motion analysis of a floorball-specific 90-degree cutting task. Players' movements were recorded by eight 300 Hz cameras, and ground reaction forces were captured by 1500 Hz force plates. Seven biomechanical variables were measured: knee valgus angle at initial contact, peak knee valgus angle, knee flexion angle at initial contact, peak knee flexion angle, peak knee abduction moment, peak knee flexion moment, and peak knee internal rotation moment. Anterior cruciate ligament injuries were recorded throughout the follow-up. Findings Ten ACL injuries occurred and were included in the analysis. No differences were observed in baseline biomechanical variables between players who sustained an ACL injury during follow-up and those who remained injury-free. Interpretation Knee valgus and flexion angles, and knee abduction, flexion, and internal rotation moments during the 90-degree cutting test were not associated with the risk of non-contact anterior cruciate ligament injury in female floorball players. The 90-degree cutting test developed for this study cannot predict ACL injuries in female floorball players.
Mørtvedt, Anne Inger; Krosshaug, Tron & Petushek, Erich J (2025). Perspectives on usability and adoption of a new ACL injury prevention programme for female handball players: A mixed methods approach. BMJ Open sport & exercise medicine. 11(1). doi: 10.1136/bmjsem-2024-001965. Full text in Research Archive Show summary
Effective injury prevention programmes (IPPs) hold promise for mitigating ACL injuries in female handball players, yet adherence remains a challenge. This mixed methods study explores the relationship between programme usability characteristics and the potential effectiveness of a newly developed ACL IPP through survey and interview data from 23 female handball players aged 15–18 and their four coaches. Players’ knee abduction moment (KAM) was measured during a cutting task and used to measure potential effectiveness. Findings reveal significant correlations between reductions in KAM and players’ perceived effectiveness of the programme in reducing ACL injury risk and their intention to use it (Spearman’s rho (rs) −0.52, 95% CI −0.78 to –0.1, p=0.02 and rs −0.46, 95% CI −0.75 to –0.03, p=0.04, respectively). Coaches and players identified efficiency and perceived effectiveness as key factors influencing programme adoption. Concerns regarding programme length and doubts about exercise efficacy and transferability emerged as barriers, while perceived effectiveness, efficiency and enjoyability were facilitators for programme use. Players’ suggestions for programme improvement included shortening the duration and incorporating playful elements. Design thinking sessions yielded strategies to optimise time efficiency and integrate IPPs into existing training routines. The study reaffirms the importance of balancing programme effectiveness with practicality and clear communication about its purpose and benefits to facilitate programme adoption. Enhancing programme usability and involving all end-users in the design process are crucial steps toward promoting the acceptance and adoption of IPPs among target populations.
Bill, Kevin; Mai, Patrick; Mausehund, Lasse; Solbakken, Sigurd; Krosshaug, Tron & Kersting, Uwe G. (2024). Individualized Technique Feedback for Instant Technique Improvements and Knee Abduction Moment Reductions – A New Approach for ‘Sidestepping’ ACL Injuries? International Journal of Sports Physical Therapy. 19(5), p. 535–547. doi: 10.26603/001c.116274. Full text in Research Archive Show summary
Background: Sidestep cutting technique is highly individual and has been shown to influence knee joint loading. However, studies assessing whether individualized technique feedback improves technique and ACL injury-relevant knee joint loads instantly in a sport-specific task are lacking. Purpose: To determine the instant effects of individualized augmented technique feedback and instructions on technique and the peak external knee abduction moment (pKAM) in a handball-specific sidestep cut. Additionally, to determine the effects of technique modifications on the resultant ground reaction force and its frontal plane moment arm to the knee joint center. Study Design: Controlled laboratory cohort study Methods: Three-dimensional biomechanics of 48 adolescent female handball players were recorded during a handball-specific sidestep cut. Following baseline cuts to each side, leg-specific visual and verbal technique feedback on foot strike angle, knee valgus motion, or vertical impact velocity using a hierarchically organized structure accounting for the variables’ association with performance was provided. Subsequently, sidestep cuts were performed again while verbal instructions were provided to guide technique modifications. Combined effects of feedback and instructions on technique and pKAM as well as on the resultant ground reaction force and its frontal plane moment arm to the knee joint center were assessed. Results: On average, each targeted technique variable improved following feedback and instructions, leading to instant reductions in pKAM of 13.4% to 17.1%. High inter-individual differences in response to feedback-instruction combinations were observed. These differences were evident in both the adherence to instructions and the impact on pKAM and its components. Conclusion: Most players were able to instantly adapt their technique and decrease ACL injury-relevant knee joint loads through individualized augmented technique feedback, thereby potentially reducing the risk of injury. More research is needed to assess the retention of these adaptations and move towards on-field technique assessments using low-cost equipment. Level of Evidence: Level 3
Bagehorn, Timo; Bill, Kevin; Mai, Patrick; Krosshaug, Tron & Kersting, Uwe G. (2024). A biomechanical report of an acute lateral ankle sprain during a handball-specific cutting movement. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2024.2319134. Full text in Research Archive Show summary
Biomechanical measurements of accidental ankle sprain injuries are rare but make important contributions to a more detailed understanding of the injury mechanism. In this case study, we present the kinematics and kinetics of a lateral ankle sprain of a female athlete performing handball-specific fake-and-cut manoeuvres. Three-dimensional kinematics and kinetics were recorded and six previously performed trials were used as reference. Plantarflexion, inversion, and internal rotation angles were substantially larger than the reference trials and peaked between 190 and 200 ms after initial ground contact. We observed a highly increased inversion and internal rotation moment. However, compared to the non-injury trials the data also revealed a reduction in the second dorsiflexion moment peak. Ground reaction forces were lower throughout the injury trial. Other parameters at initial ground contact including ankle and hip position, step length, and the traction coefficient indicate that a preparatory maladjustment occurred. This study adds valuable contributions to the understanding of lateral ankle sprains by building upon previously published reports and considering the shoe-surface interaction as an important factor for injury.
Kamatsuki, Yusuke; Qvale, Marie Synnøve; Steffen, Kathrin; Wangensteen, Arnlaug & Krosshaug, Tron (2024). Anatomic Risk Factors for Initial and Secondary Noncontact Anterior Cruciate Ligament Injury: A Prospective Cohort Study in 880 Female Elite Handball and Soccer Players. American Journal of Sports Medicine. ISSN 0363-5465. 53(1), p. 123–131. doi: 10.1177/03635465241292755. Full text in Research Archive Show summary
Background: Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes. It is important to identify risk factors because a better understanding of injury causation can help inform athletes about risk and increase their understanding of and motivation for injury prevention. Purpose: To investigate the relationship between anatomic factors and risk for future noncontact ACL injuries. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 870, excluding 9 players with a new contact ACL injury and a player with a new noncontact ACL injury just before the testing, female elite handball and soccer players—86 of whom had a history of ACL injury—underwent measurements of anthropometrics, alignment, joint laxity, and mobility, including leg length, knee alignment, knee anteroposterior laxity, generalized joint hypermobility, genu recurvatum, and hip anteversion. All ACL injuries among the tested players were recorded prospectively. Welch t tests and chi-square tests were used for comparison between the groups (new injury group, which sustained a new ACL injury in the follow-up period, and no new injury group). Results: An overall 64 new noncontact ACL injuries were registered. No differences were found between athletes with and without a new ACL injury among most of the measured variables. However, static knee valgus was significantly higher in the new injury group than in the no new injury group among all players (mean difference [MD], 0.9°; P = .007), and this tendency was greater in players with a previous ACL injury (MD, 2.1°; P = .002). Players with secondary injury also had a higher degree of knee hyperextension when compared with those previously injured who did not have a secondary injury (MD, 1.6°; P = .007). Conclusion: The anatomic factors that we investigated had a weak or no association with risk for an index noncontact ACL injury. Increased static knee valgus was associated with an increased risk for noncontact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was a risk factor for secondary ACL injury.
Leppänen, Mari; Viiala, Janne; Kaikkonen, Piia; Tokola, Kari; Vasankari, Tommi & Nigg, Benno M. [Show all 10 contributors for this article] (2024). Hip and core exercise programme prevents running-related overuse injuries in adult novice recreational runners: A three-arm randomised controlled trial (Run RCT). British Journal of Sports Medicine. ISSN 0306-3674. 58(13), p. 722–732. doi: 10.1136/bjsports-2023-107926. Full text in Research Archive Show summary
Objective: This study aims to investigate the efficacy of two exercise interventions in reducing lower extremity (LE) injuries in novice recreational runners. Methods: Novice runners (245 female, 80 male) were randomised into hip and core (n=108), ankle and foot (n=111) or control (n=106) groups. Interventions were completed before running and included exercise programmes focusing on either (1) hip and core or (2) ankle and foot muscles. The control group performed static stretching exercises. All groups were supervised by a physiotherapist and performed the same running programme. Injuries and running exposure were registered using weekly questionnaires during the 24-week study. Primary outcome was running-related LE injury. Results: The incidence of LE injuries was lower in the hip and core group compared with the control group (HR 0.66; 95% CI 0.45 to 0.97). The average weekly prevalence of overuse injuries was 39% lower (prevalence rate ratio, PRR 0.61, 95% CI 0.39 to 0.96), and the prevalence of substantial overuse injuries was 52% lower (PRR 0.48, 95% CI 0.27 to 0.90) in the hip and core group compared with the control group. No significant difference was observed between the ankle and foot group and control group in the prevalence of overuse injuries. A higher incidence of acute injuries was observed in the ankle and foot group compared with the control group (HR 3.60, 95% CI 1.20 to 10.86). Conclusion: A physiotherapist-guided hip and core-focused exercise programme was effective in preventing LE injuries in novice recreational runners. The ankle and foot programme did not reduce LE injuries and did not protect against acute LE injuries when compared with static stretching.
Mørtvedt, Anne Inger; Krosshaug, Tron & Petushek, Erich (2024). Usability considerations for enhancing exercise-based injury prevention interventions. Proceedings of the International Symposium on Human Factors and Ergonomics in Health Care. ISSN 2327-8595. 13(1), p. 236–241. doi: 10.1177/2327857924131004. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2024). Knee Biomechanics During Cutting Maneuvers and Secondary ACL Injury Risk: A Prospective Cohort Study of Knee Biomechanics in 756 Female Elite Handball and Soccer Players. American Journal of Sports Medicine. ISSN 0363-5465. 52(5), p. 1209–1219. doi: 10.1177/03635465241234255. Full text in Research Archive
Hoenig, Tim; Rahlf, Lina; Wilke, Jan; Krauß, Inga; Dalos, Dimitris & Willwacher, Steffen [Show all 11 contributors for this article] (2023). Appraising the Methodological Quality of Sports Injury Video Analysis Studies: The QA-SIVAS Scale. Sports Medicine. ISSN 0112-1642. 54(1), p. 203–211. doi: 10.1007/s40279-023-01907-z. Full text in Research Archive Show summary
Background: Video analysis (VA) is commonly used in the assessment of sports injuries and has received considerable research interest. Until now, no tool has been available for the assessment of study quality. Therefore, the objective of this study was to develop and evaluate a valid instrument that reliably assesses the methodological quality of VA studies. Methods: The Quality Appraisal for Sports Injury Video Analysis Studies (QA-SIVAS) scale was developed using a modified Delphi approach including expert consensus and pilot testing. Reliability was examined through intraclass correlation coefficient (ICC3,1) and free-marginal kappa statistics by three independent raters. Construct validity was investigated by comparing QA-SIVAS with expert ratings by using Kendall’s tau analysis. Rating time was studied by applying the scale to 21 studies and computing the mean time for rating per study article. Results: The QA-SIVAS scale consists of an 18-item checklist addressing the study design, data source, conduct, report, and discussion of VA studies in sports injury research. Inter- and intra-rater reliability were excellent with ICCs > 0.97. Expert ratings revealed a high construct validity (0.71; p < 0.001). Mean rating time was 10 ± 2 min per article. Conclusion: QA-SIVAS is a reliable and valid instrument that can be easily applied to sports injury research. Future studies in the field of VA should adhere to standardized methodological criteria and strict quality guidelines.
Lysdal, Filip Gertz; Wang, Yuehang; Delahunt, Eamonn; Gehring, Dominic; Kosik, Kyle B. & Krosshaug, Tron [Show all 12 contributors for this article] (2022). What have we learnt from quantitative case reports of acute lateral ankle sprains injuries and episodes of ‘giving-way’ of the ankle joint, and what shall we further investigate? Sports Biomechanics. ISSN 1476-3141. 21(4), p. 359–379. doi: 10.1080/14763141.2022.2035801. Full text in Research Archive Show summary
Lateral ankle sprains are a commonly incurred injury in sports. They have a high recurrence rate and can lead to the development of persistent injury associated symptoms. We performed a quantitative synthesis of published case reports documenting the kinematics of acute lateral ankle sprains and episodes of ‘giving-way’ of the ankle joint to provide a comprehensive description of the mechanisms. A systematic literature search was conducted to screen records within MEDLINE® and EMBASE®. Additional strategies included manual search of specific journals, as well as contacting researchers in relevant communities to retrieve unpublished data. Twenty-four cases were included in the quantitative synthesis, 11 from individual case reports and 13 from four separate case series. Two authors independently reviewed all the articles and extracted ankle joint kinematic data. Excessive ankle inversion was the most pronounced kinematic pattern observed across all included cases, with a mean peak inversion angle of 67.5° (range 2.0 to 142) and a mean peak inversion velocity of 974°/s (range 468 to 1752). This was followed by internal rotation and plantar flexion, respectively. A homogeneous linear function revealed a mean inversion velocity across all cases of 337°/s (range 117 to 1400; R2 = 0.78; p < 0.0001).
Jauhiainen, Susanne; Kauppi, Jukka-Pekka; Krosshaug, Tron; Bahr, Roald; Bartsch, Julia & Äyrämö, Sami (2022). Predicting ACL Injury Using Machine Learning on Data From an Extensive Screening Test Battery of 880 Female Elite Athletes. American Journal of Sports Medicine. ISSN 0363-5465. 50(11), p. 2917–2924. doi: 10.1177/03635465221112095. Full text in Research Archive Show summary
Background: Injury risk prediction is an emerging field in which more research is needed to recognize the best practices for accurate injury risk assessment. Important issues related to predictive machine learning need to be considered, for example, to avoid overinterpreting the observed prediction performance. Purpose: To carefully investigate the predictive potential of multiple predictive machine learning methods on a large set of risk factor data for anterior cruciate ligament (ACL) injury; the proposed approach takes into account the effect of chance and random variations in prediction performance. Study Design: Case-control study; Level of evidence, 3. Methods: The authors used 3-dimensional motion analysis and physical data collected from 791 female elite handball and soccer players. Four common classifiers were used to predict ACL injuries (n = 60). Area under the receiver operating characteristic curve (AUC-ROC) averaged across 100 cross-validation runs (mean AUC-ROC) was used as a performance metric. Results were confirmed with repeated permutation tests (paired Wilcoxon signed-rank-test; P < .05). Additionally, the effect of the most common class imbalance handling techniques was evaluated. Results: For the best classifier (linear support vector machine), the mean AUC-ROC was 0.63. Regardless of the classifier, the results were significantly better than chance, confirming the predictive ability of the data and methods used. AUC-ROC values varied substantially across repetitions and methods (0.51-0.69). Class imbalance handling did not improve the results. Conclusion: The authors’ approach and data showed statistically significant predictive ability, indicating that there exists information in this prospective data set that may be valuable for understanding injury causation. However, the predictive ability remained low from the perspective of clinical assessment, suggesting that included variables cannot be used for ACL prediction in practice.
Mai, Patrick; Bill, Kevin; Glöckler, Katharina; Claramunt-Molet, Mireia; Bartsch, Julia & Eggerud, Mathias M. [Show all 14 contributors for this article] (2022). Unanticipated fake-and-cut maneuvers do not increase knee abduction moments in sport-specific tasks: Implication for ACL injury prevention and risk screening. Frontiers in Sports and Active Living. 4. doi: 10.3389/fspor.2022.983888. Full text in Research Archive Show summary
Non-contact anterior cruciate ligament injuries typically occur during cutting maneuvers and are associated with high peak knee abduction moments (KAM) within early stance. To screen athletes for injury risk or quantify the efficacy of prevention programs, it may be necessary to design tasks that mimic game situations. Thus, this study compared KAMs and ranking consistency of female handball players in three sport-specific fake-and-cut tasks of increasing complexity. The biomechanics of female handball players (n = 51, mean ± SD: 66.9 ± 7.8 kg, 1.74 ± 0.06 m, 19.2 ± 3.4 years) were recorded with a 3D motion capture system and force plates during three standardized fake-and-cut tasks. Task 1 was designed as a simple pre-planned cut, task 2 included catching a ball before a pre-planned cut in front of a static defender, and task 3 was designed as an unanticipated cut with three dynamic defenders involved. Inverse dynamics were used to calculate peak KAM within the first 100 ms of stance. KAM was decomposed into the frontal plane knee joint moment arm and resultant ground reaction force. RANOVAs (α ≤ 0.05) were used to reveal differences in the KAM magnitudes, moment arm, and resultant ground reaction force for the three tasks. Spearman's rank correlations were calculated to test the ranking consistency of the athletes' KAMs. There was a significant task main effect on KAM (p = 0.02; η2p = 0.13). The KAM in the two complex tasks was significantly higher (task 2: 1.73 Nm/kg; task 3: 1.64 Nm/kg) than the KAM in the simplest task (task 1: 1.52 Nm/kg). The ranking of the peak KAM was consistent regardless of the task complexity. Comparing tasks 1 and 2, an increase in KAM resulted from an increased frontal plane moment arm. Comparing tasks 1 and 3, higher KAM in task 3 resulted from an interplay between both moment arm and the resultant ground reaction force. In contrast to previous studies, unanticipated cutting maneuvers did not produce the highest KAMs. These findings indicate that the players have developed an automated sport-specific cutting technique that is utilized in both pre-planned and unanticipated fake-and-cut tasks.
Bill, Kevin; Mai, Patrick; Willwacher, Steffen; Krosshaug, Tron & Kersting, Uwe (2022). Athletes with high knee abduction moments show increased vertical center of mass excursions and knee valgus angles across sport-specific fake-and-cut tasks of different complexities. Frontiers in Sports and Active Living. 4, p. 1–13. doi: 10.3389/fspor.2022.983889. Full text in Research Archive Show summary
Young female handball players represent a high-risk population for anterior cruciate ligament (ACL) injuries. While the external knee abduction moment (KAM) is known to be a risk factor, it is unclear how cutting technique affects KAMs in sport-specific cutting maneuvers. Further, the effect of added game specificity (e.g., catching a ball or faking defenders) on KAMs and cutting technique remains unknown. Therefore, this study aimed: (i) to test if athletes grouped into different clusters of peak KAMs produced during three sport-specific fake-and-cut tasks of different complexities differ in cutting technique, and (ii) to test whether technique variables change with task complexity. Fifty-one female handball players (67.0 ± 7.7 kg, 1.70 ± 0.06 m, 19.2 ± 3.4 years) were recruited. Athletes performed at least five successful handball-specific sidestep cuts of three different complexities ranging from simple pre-planned fake-and-cut maneuvers to catching a ball and performing an unanticipated fake-and-cut maneuver with dynamic defenders. A k-means cluster algorithm with squared Euclidean distance metric was applied to the KAMs of all three tasks. The optimal cluster number of koptimal = 2 was calculated using the average silhouette width. Statistical differences in technique variables between the two clusters and the tasks were analyzed using repeated-measures ANOVAs (task complexity) with nested groupings (clusters). KAMs differed by 64.5%, on average, between clusters. When pooling all tasks, athletes with high KAMs showed 3.4° more knee valgus, 16.9% higher downward and 8.4% higher resultant velocity at initial ground contact, and 20.5% higher vertical ground reaction forces at peak KAM. Unlike most other variables, knee valgus angle was not affected by task complexity, likely due to it being part of inherent movement strategies and partly determined by anatomy. Since the high KAM cluster showed higher vertical center of mass excursions and knee valgus angles in all tasks, it is likely that this is part of an automated motor program developed over the players' careers. Based on these results, reducing knee valgus and downward velocity bears the potential to mitigate knee joint loading and therefore ACL injury risk.
Petushek, Erich; Nilstad, Agnethe; Bahr, Roald & Krosshaug, Tron (2021). Drop Jump? Single-Leg Squat? Not if You Aim to Predict Anterior Cruciate Ligament Injury From Real-Time Clinical Assessment: A Prospective Cohort Study Involving 880 Elite Female Athletes. Journal of Orthopaedic and Sports Physical Therapy. ISSN 0190-6011. 51(7), p. 372–378. doi: 10.2519/jospt.2021.10170. Full text in Research Archive Show summary
Objective: To determine whether visually assessed performances of the single-leg squat (SLS) and vertical drop jump (VDJ) were associated with future noncontact anterior cruciate ligament (ACL) injury. Design: Prognostic accuracy cohort study. Methods: Elite female handball and football (soccer) athletes (n = 880) were tested from 2007 to 2014 and tracked through 2015. Trained physical therapists visually rated each leg during a SLS and overall control during a VDJ. Receiver operating characteristic curve, Pearson chi-square, and logistic regression analyses were used to determine the prognostic accuracy of the 2 screening tests. Results: Sixty-five noncontact ACL injuries occurred during the follow-up period. Fourteen percent of athletes who sustained an ACL injury had poor SLS performance, compared to 17% of the noninjured athletes (P = .52 and .67 for hip and knee ratings, respectively). Side-to-side asymmetry in the SLS was not different between injured and noninjured athletes (P = .10 and .99 for hip and knee asymmetry, respectively). Twenty-one percent of athletes who sustained an ACL injury had a poor VDJ rating, compared to 27% of the noninjured athletes (P = .09). Furthermore, area under the curve values ranged from 0.43 to 0.54 for the SLS and VDJ, demonstrating no to poor prognostic accuracy. Conclusion: Neither SLS nor VDJ test performance distinguished between athletes who sustained a subsequent noncontact ACL injury and those who did not.
Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Kulmala, Juha-Pekka & Krosshaug, Tron [Show all 8 contributors for this article] (2021). Change of Direction Biomechanics in a 180-Degree Pivot Turn and the Risk for Noncontact Knee Injuries in Youth Basketball and Floorball Players. American Journal of Sports Medicine. ISSN 0363-5465. 49(10), p. 2651–2658. doi: 10.1177/03635465211026944. Full text in Research Archive Show summary
Background: Studies investigating biomechanical risk factors for knee injuries in sport-specific tasks are needed. Purpose: To investigate the association between change of direction (COD) biomechanics in a 180-degree pivot turn and knee injury risk among youth team sport players. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 258 female and male basketball and floorball players (age range, 12-21 years) participated in the baseline COD test and follow-up. Complete data were obtained from 489 player-legs. Injuries, practice, and game exposure were registered for 12 months. The COD test consisted of a quick ball pass before and after a high-speed 180-degree pivot turn on the force plates. The following variables were analyzed: peak vertical ground-reaction force (N/kg); peak trunk lateral flexion angle (degree); peak knee flexion angle (degree); peak knee valgus angle (degree); peak knee flexion moment (N·m/kg); peak knee abduction moment (N·m/kg); and peak knee internal and external rotation moments (N·m/kg). Legs were analyzed separately and the mean of 3 trials was used in the analysis. Main outcome measure was a new acute noncontact knee injury. Results: A total of 18 new noncontact knee injuries were registered (0.3 injuries/1000 hours of exposure). Female players sustained 14 knee injuries and male players 4. A higher rate of knee injuries was observed in female players compared with male players (incidence rate ratio, 6.2; 95% CI, 2.1-21.7). Of all knee injuries, 8 were anterior cruciate ligament (ACL) injuries, all in female players. Female players displayed significantly larger peak knee valgus angles compared with male players (mean for female and male players, respectively: 13.9°± 9.4° and 2.0°± 8.5°). No significant associations between biomechanical variables and knee injury risk were found. Conclusion: Female players were at increased risk of knee and ACL injury compared with male players. Female players performed the 180-degree pivot turn with significantly larger knee valgus compared with male players. However, none of the investigated variables was associated with knee injury risk in youth basketball and floorball players.
Álvarez-Zafra, Marta; Yanci, Javier; García-Tabar, Ibai; Bikandi, Eder; Etxaleku, Saioa & Izquierdo, Mikel [Show all 9 contributors for this article] (2021). Functional and Anthropometrical Screening Test among High Performance Female Football Players: A Descriptive Study with Injury Incidence Analysis, the Basque Female Football Cohort (BFFC) Study. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(20). doi: 10.3390/ijerph182010658. Full text in Research Archive Show summary
The main objectives of the present study were to describe the injury incidence and to analyze the anthropometric and physical characteristics of players from three high-level women’s football teams. The present study involved 54 female football players (21.9 ± 4.9 years old) from three different teams competing in the Spanish Reto Iberdrola-Segunda División PRO league. A battery of tests was carried out to determine the anthropometric and physical performance characteristics of the players along with an injury incidence record during a full competitive season. The obtained results showed that there was a high incidence of injury, as 38% of the players suffered some type of injury during the season (range 1–5; 1.75 ± 1.02 injuries per player). Injuries occurred in both matches and during training at a similar percentage (48.6 vs. 51.4%), and the majority of the registered episodes were graded as moderate or severe injury types (60%). Players suffering from an injury accumulated a total of 1587 chronological days off work due to injury during the season, with a recurrence rate of 55%. Considering the high incidence of injury, and the injury burden and the reinjure rate observed in this research, it seems necessary to apply the most efficient prevention and recovery measures possible in these female football teams. These descriptive data could serve athletic trainers and medical staff of female football teams to better understand their own screening procedure-derived data.
Nilstad, Agnethe; Petushek, Erich; Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2021). Kiss goodbye to the ‘kissing knees’: no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1903541. Full text in Research Archive Show summary
he aim of this study was to investigate if frontal plane knee and hip control in single-leg squats or vertical drop jumps with an overhead target were associated with future non-contact anterior cruciate ligament (ACL) injury in elite female athletes. Of the 429 handball and 451 football athletes (age 21.5 ± 4.0 years, height 169.6 ± 6.4 cm, body weight 67.1 ± 8.0 kg), 722 non-injured and 56 non-contact ACL injured participants were eligible for analysis. We calculated lateral pelvic tilt, frontal plane knee projection angle, medial knee position, and side-to-side asymmetry in these from 2D videos recorded at baseline, and recorded any new ACL injuries prospectively. None of the aforementioned variables in either screening task were different or could discriminate between injured and non-injured athletes (all p values >.05 and Cohen’s d values < .27). Two-dimensional video assessment of frontal plane knee and hip control during both a single-leg squat and vertical drop jump was unable to identify individuals at increased risk of non-contact ACL injury, thus should not be used for screening.
Richter, Chris; Petushek, Erich; Grindem, Hege; Franklyn-Miller, Andrew; Bahr, Roald & Krosshaug, Tron (2021). Cross-validation of a machine learning algorithm that determines anterior cruciate ligament rehabilitation status and evaluation of its ability to predict future injury. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1947358. Full text in Research Archive Show summary
Classification algorithms determine the similarity of an observation to defined classes, e.g., injured or healthy athletes, and can highlight treatment targets or assess progress of a treatment. The primary aim was to cross-validate a previously developed classification algorithm using a different sample, while a secondary aim was to examine its ability to predict future ACL injuries. The examined outcome measure was ‘healthy-limb’ class membership probability, which was compared between a cohort of athletes without previous or future (No Injury) previous (PACL) and future ACL injury (FACL). The No Injury group had significantly higher probabilities than the PACL (p < 0.001; medium effect) and FACL group (p ≤ 0.045; small effect). The ability to predict group membership was poor for the PACL (area under curve [AUC]; 0.61<AUC<0.62) and FACL group (0.57<AUC<0.59). The ACL injury incidence proportion was highest in athletes with probabilities below 0.20 (9.4%; +2.7% to baseline), while athletes with probabilities above 0.80 had an incidence proportion of 4.1% (−2.6%). While findings that a low probability might represent an increase in injury risk on a group level, it is not sensitive enough for injury screening to predict a future injury on the individual level.
Jauhiainen, Susanne; Krosshaug, Tron; Petushek, Erich; Kauppi, Jukka-Pekka & Äyrämö, Sami (2021). Information Extraction from Binary Skill Assessment Data with Machine Learning. International Journal of Learning Analytics and Artificial Intelligence for Education (IJAI). 3(1), p. 20–35. doi: 10.3991/ijai.v3i1.24295. Full text in Research Archive Show summary
Strength training exercises are essential for rehabilitation, improving our health as well as in sports. For optimal and safe training, educators and trainers in the industry should comprehend exercise form or technique. Currently, there is a lack of tools measuring in-depth skills of strength training experts. In this study, we investigate how data mining methods can be used to identify novel and useful skill patterns from a binary multiple choice questionnaire test designed to measure the knowledge level of strength training experts. A skill test assessing exercise technique expertise and comprehension was answered by 507 fitness professionals with varying backgrounds. A triangulated approach of clustering and non-negative matrix factorization (NMF) was used to discover skill patterns among participants and patterns in test questions. Four distinct participant subgroups were identified in data with clustering and further question patterns with NMF. The results can be used to, for example, identify missing skills and knowledge in participants and subgroups of participants and form general and personalized or background specific guidelines for future education. In addition, the test can be optimized based on, for example, if some questions can be answered correct even without the required skill or if they seem to be measuring overlapping skills. Finally, this approach can be utilized with other multiple choice test data in future educational research.
Mausehund, Lasse & Krosshaug, Tron (2021). Understanding Bench Press Biomechanics — Training Expertise and Sex Affect Lifting Technique and Net Joint Moments. Journal of Strength and Conditioning Research. ISSN 1064-8011. doi: 10.1519/JSC.0000000000004191. Full text in Research Archive Show summary
The purpose of this study was to compare normalized net joint moments (NJMs), moment arms, and muscle activity in the bench press exercise between powerlifters and recreationally strength-trained lifters and between women and men. Thirty-four healthy adults, including 12 powerlifters (6 women and 6 men) and 22 recreational lifters (9 women and 13 men), performed a 6–8 repetition maximum set of the bench press, while elbow and shoulder NJMs and moment arms and electromyographic (EMG) activity of 6 upper extremity muscles were recorded. The results showed that training expertise and sex affected bench press technique substantially. Powerlifters applied a different bar path which impacted joint kinematics to a greater extent and joint kinetics to a lesser extent. Specifically, powerlifters had lower normalized peak elbow NJMs and shorter joint ROMs than recreational lifters (p ≤ 0.05), yet no differences in normalized shoulder NJMs and muscle activity were observed. Women showed lower normalized mean shoulder NJMs, higher normalized peak elbow NJMs, and higher mean elbow to shoulder NJM ratios than men (p ≤ 0.05). The muscle activity of the long head of the triceps brachii and the elbow to shoulder EMG ratio were higher, yet muscle activity of the sternocostal and abdominal head of the pectoralis major was lower for female than for male subjects (p ≤ 0.05). In conclusion, powerlifters and men are more shoulder dominant when performing the bench press than recreational lifters and women, respectively. These findings will have implications for resistance training program design, expected training adaptations and bench press performance.
Mausehund, Lasse; Werkhausen, Amelie; Bartsch, Julia & Krosshaug, Tron (2021). Understanding Bench Press Biomechanics-The Necessity of Measuring Lateral Barbell Forces. Journal of Strength and Conditioning Research. ISSN 1064-8011. 36(10), p. 2685–2695. doi: 10.1519/JSC.0000000000003948. Full text in Research Archive Show summary
The purpose of this study was to advance the expertise of the bench press exercise by complementing electromyographic (EMG) with net joint moment (NJM) and strength normalized NJM (nNJM) measurements, thus establishing the magnitude of the elbow and shoulder muscular loads and efforts. Normalized NJMs were determined as the ratio of the bench press NJMs to the maximum NJMs produced during maximum voluntary isokinetic contractions. Furthermore, we wanted to assess how changes in grip width and elbow positioning affected elbow and shoulder NJMs and nNJMs, and muscle activity of the primary movers. Thirty-five strength-trained adults performed a 6–8 repetition maximum set of each bench press variation, while elbow and shoulder NJMs and EMG activity of 7 upper extremity muscles were recorded. The results show that all bench press variations achieved high elbow and shoulder muscular efforts. A decrease in grip width induced larger elbow NJMs, and larger EMG activity of the lateral head of the triceps brachii, anterior deltoid, and clavicular head of the pectoralis major (p ≤ 0.05). An increase in grip width elicited larger shoulder NJMs and nNJMs, and larger EMG activity of the abdominal head of the pectoralis major (p ≤ 0.05). In conclusion, all bench press variations may stimulate strength gains and hypertrophy of the elbow extensors and shoulder flexors and horizontal adductors. However, greater adaptations of the elbow extensors and shoulder flexors may be expected when selecting narrower grip widths, whereas wider grip widths may induce greater adaptations of the shoulder horizontal adductors.
Patton, Declan A.; McIntosh, Andrew S.; Hagel, Brent & Krosshaug, Tron (2020). A Review of Head Injury and Impact Biomechanics in Recreational Skiing and Snowboarding. Muscles, Ligaments and Tendons Journal (MLTJ). 10(2), p. 211–232. doi: 10.32098/mltj.02.2020.07. Full text in Research Archive Show summary
Background: Skiing and snowboarding are popular competitive and recreational sports with associated head injury risks from impact hazards. Understanding head injury hazards and risks in snow sports can inform injury prevention measures, such as helmets, education and environment design of runs and terrain park features, to manage injury risk. Aim: To identify and discuss (a) the proportion and incidence of head injuries and effectiveness of helmets, (b) circumstances, situational events and characteristics of head injuries and (c) head impact biomechanics in recreational skiing and snowboarding. Methods: A narrative literature review was performed. Results: Head injuries comprise up to 38% and 29% of all injuries in skiing and snowboarding, respectively. Skull fractures were found to comprise nearly half of all moderate to severe head injuries in alpine sports across all studies. The most common intracranial injury in skiing and snowboarding was cerebral contusion and subdural haematoma, respectively. Fatal head injuries in skiing are rare with an incidence of approximately one death per one million skier-visits and less than 1% of all skiing head injuries resulted in death. The majority of head injuries were sustained by novice and intermediate level skiers and snowboarders during falls on mild or moderate gradient slopes. Head injury cases occurred in terrain parks were more common in snowboarders than skiers. Fall-related head injuries to skiers are typically in the forward direction with an impact to the front of the head, whereas snowboarders fall rearward and impact the occipital region. Helmet use has increased in recent years, but recent studies have observed an unexpected reduction of the protective effect of helmets in skiing and snowboarding. Alpine sports helmet standards require linear drops onto rigid anvils, but the correlation with snow surfaces is unknown and no helmet standard requires an oblique impact test. Significant protective effects of helmets have been found for collisions and falls onto hard snow. Conclusions: Alpine sport helmet performance standards should more closely reflect the boundary conditions of impacts to skiers and snowboarders associated with head injury. Administrative and engineering controls may also reduce the risk of head injury in skiing and snowboarding.
Räisänen, Anu; Kulmala, Tanja; Parkkari, Jari; Vasankari, Tommi; Kannus, Pekka & Krosshaug, Tron [Show all 10 contributors for this article] (2020). There Is No Relationship Between Lower Extremity Alignment During Unilateral and Bilateral Drop Jumps and the Risk of Knee or Ankle Injury: A Prospective Study. Journal of Orthopaedic and Sports Physical Therapy. ISSN 0190-6011. 50(5), p. 267–274. doi: 10.2519/jospt.2020.9247. Full text in Research Archive Show summary
Objective: To investigate the association between lower extremity alignment during unilateral and bilateral drop jump tests and the risk of acute noncontact knee or ankle injuries in young team sport athletes. Design: Prospective cohort study. Methods: A 2-dimensional video analysis was used to measure the frontal plane knee projection angle in the single-leg vertical drop jump (VDJ) and the bilateral VDJ in young team sport athletes. Out of the 364 athletes (187 male, 177 female), 189 played basketball and 175 played floorball. Results: Six male athletes sustained knee injuries and 23 sustained ankle injuries. Frontal plane knee projection angle in the single-leg VDJ or the bilateral VDJ was not associated with ankle injuries among male athletes. No statistical analysis was performed for the knee injuries. Among female athletes, 28 sustained knee and 41 sustained ankle injuries. Frontal plane knee projection angle during the single-leg VDJ or the bilateral VDJ was not a risk factor for knee or ankle injuries. Conclusion: Lower extremity alignment during unilateral and bilateral drop jump tests was not associated with future noncontact knee or ankle injuries among young team sport athletes. The findings should be interpreted cautiously due to the small number of injuries.
Leppänen, Mari; Rossi, Marco T.; Parkkari, Jari; Heinonen, Ari; Äyrämö, Sami & Krosshaug, Tron [Show all 9 contributors for this article] (2020). Altered hip control during a standing knee‐lift test is associated with increased risk of knee injuries. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(5), p. 922–931. doi: 10.1111/sms.13626. Full text in Research Archive Show summary
A few prospective studies have investigated hip and pelvic control as a risk factor for lower extremity (LE) injuries. The purpose of this study was to investigate whether deficits in hip and lumbopelvic control during standing knee‐lift test are associated with increased risk of acute knee and LE injuries in youth team sports. At baseline, 258 basketball and floorball players (aged 12‐21 years) participated in a standing knee‐lift test using 3‐dimensional motion analysis. Two trials per leg were recorded from each participant. Peak sagittal plane pelvic tilt and frontal plane pelvic drop/hike were measured. Both continuous and categorical variables were analyzed. New non‐contact LE injuries, and match and training exposure, were recorded for 12 months. Seventy acute LE injuries were registered. Of these, 17 were knee injuries (eight ACL ruptures) and 35 ankle injuries. Risk factor analyses showed that increased contralateral pelvic hike was significantly associated with knee injury risk when using categorical variable (HR for high vs low group 4.07; 95% CI 1.32‐12.6). Furthermore, significant association was found between high lateral pelvic hike angles and ACL injury risk in female players (HR for high vs low group 9.10; 95% CI 1.10‐75.2). Poor combined sensitivity and specificity of the test was observed. In conclusion, increased contralateral pelvic hike is associated with non‐contact knee injury risk among young team sport players and non‐contact ACL injuries among female players. More research to determine the role of pelvic control as a risk factor for knee injuries is needed.
Mørtvedt, Anne Inger; Krosshaug, Tron; Bahr, Roald & Petushek, Erich (2019). I spy with my little eye … a knee about to go ‘pop’? Can coaches and sports medicine professionals predict who is at greater risk of ACL rupture? British Journal of Sports Medicine. ISSN 0306-3674. 54(3). doi: 10.1136/bjsports-2019-100602. Full text in Research Archive Show summary
Background: The vertical drop jump (VDJ) test is widely used for clinical assessment of ACL injury risk, but it is not clear whether such assessments are valid. Aim: To examine if sports medicine professionals and coaches are able to identify players at risk of sustaining an ACL injury by visually assessing player performance during a VDJ test. Methods: 102 video clips of elite female handball and football players performing a baseline VDJ test were randomly extracted from a 738-person prospective cohort study that tracked ACL injuries. Of the sample, 20 of 102 went on to suffer an ACL injury. These 102 videos were uploaded to an online survey. Sports medicine professionals and coaches were invited to assess athlete performance and rate each clip with a number between 1 and 10 (1 representing low risk of sustaining an ACL injury and 10 representing high risk). Receiver operating characteristic analyses were used to assess classification accuracy and between-group differences were analysed using one-way analysis of variance. Results: 237 assessors completed the survey. Area under the curve values ranged from 0.36 to 0.60, with a mean score of 0.47, which is similar to random guessing. There were no significant differences in classification accuracy between groups (physicians, coaches, certified athletic trainers, researchers or physical therapists). Conclusion: Assessors have poor predictive ability (no better than chance), indicating that visual assessment of a VDJ test is a poor test for assessing ACL injury risk in elite female handball and football players.
Mausehund, Lasse; Skard, Audun Eithun & Krosshaug, Tron (2019). Muscle Activation in Unilateral Barbell Exercises: Implications for Strength Training and Rehabilitation. Journal of Strength and Conditioning Research. ISSN 1064-8011. 33(7S), p. S85–S94. doi: 10.1519/JSC.0000000000002617. Full text in Research Archive Show summary
The purpose of the present investigation was to assess lower-body muscle activity and hamstrings-to-quadriceps (HQ) activation ratios during performance of the split squat (SS), single-leg squat (SLS), and rear foot elevated split squat (RFESS), while using the same relative load and performing the exercises to muscular failure. Eleven healthy, moderately strength-trained subjects performed a 6–8 repetition maximum set of each exercise while electromyographic (EMG) activity of the vastus lateralis, biceps femoris, gluteus maximus, and gluteus medius was recorded. The results show that there were no significant differences in EMG peak activity of the gluteus maximus and vastus lateralis between any of the exercises. Gluteus medius activation was significantly (p # 0.05) higher during the SLS (81.9% maximum voluntary isometric contraction [MVIC]), compared with the RFESS (54.9% MVIC) and SS (46.2% MVIC). The RFESS elicited higher (p # 0.05) biceps femoris activity (76.1% MVIC) than the SS (62.3% MVIC), as well as higher (p # 0.05) HQ activation ratios (0.83) than the SS (0.69) and SLS (0.63). During the SLS and the SS, HQ activation ratios increased significantly in the course of the repetition maximum set. In conclusion, although absolute loading differs between exercises, similar training stimuli of the gluteus maximus and quadriceps femoris can be expected for all exercises. The SLS is likely to induce the greatest improvements in gluteus medius strength, whereas the RFESS should be preferred if high hamstring coactivation is desired. To improve validity in EMG studies, strength training exercises should be performed close to failure while using the same relative loading.

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Mausehund, Lasse & Krosshaug, Tron (2026). Immediate effects of individualized cutting-technique feedback. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2026). Females unload the knee more than males after ACL injury during sport-specific cutting maneuvers. Full text in Research Archive
Krosshaug, Tron (2026). Biomechanics of alpine ski. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2026). Fake-cut performance and ACL injury risk. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2025). Knee Biomechanics During Cutting Maneuvers and Secondary ACL Injury Risk: Response. American Journal of Sports Medicine. ISSN 0363-5465. 53(1). doi: 10.1177/03635465241294193. Full text in Research Archive
Krosshaug, Tron (2025). Screening for ACL injury – how far away are we? Full text in Research Archive
Mausehund, Lasse; Schild, Simon; Carlsen, Emil; Wiedemann, Lea; Sollman, Britt & Fischbacher, Linda [Show all 10 contributors for this article] (2025). Sex differences in cutting biomechanics among handball players with and without previous ACL injury. Full text in Research Archive
Butler, Brendan; Kotsifaki, Roula; Myklebust, Grethe; King, Enda; Whiteley, Rod & Marques, Joao [Show all 8 contributors for this article] (2025). Do running biomechanics return to ‘normal’ after ACL reconstruction at the time of return to sport? Insights across running types, from acceleration to high-speed running. Full text in Research Archive
Bespomoshchnov, Vladislav; Jordet, Geir; Bahr, Roald; Nordstrøm, Anine & Krosshaug, Tron (2025). Did you see the hit coming? Examining the relationship between scanning, protective actions and concussion in elite ice hockey. Abstract book 25 years of protecting athlete health - forward together. Full text in Research Archive
Krosshaug, Tron & Zebis, Mette (2024). Translating biomechanics theory to practice - understand the exercises so you can design the best resistance training programs. Full text in Research Archive
Bencke, Jesper; Krosshaug, Tron & Nedergaard, Niels J (2024). Does your exercise target the muscles you think you’re targetting? (workshop). Full text in Research Archive
Krosshaug, Tron (2024). Using motion analysis to understand injury mechanisms and biomechanical risk factors for ACL Injury. A travel from year 2000 into the future (keynote lecture). Full text in Research Archive
Müller-Kühnle, Julian; Thun, Patrik; Solbakken, Sigurd; Singh, Manpreet; Mihailo, Petrovic & Bagehorn, Timo [Show all 15 contributors for this article] (2024). Impact of a nine-week training intervention on knee abduction moments and technique in female youth handball players. Full text in Research Archive
Krosshaug, Tron (2024). ACL rehabilitation – biomechanics and kinematics. Full text in Research Archive
Bill, Kevin; Mai, Patrick; Krosshaug, Tron & Kersting, Uwe G. (2024). The foot strike angle predicts three-dimensional knee joint moments in preplanned and unplanned sidestep cuts. Full text in Research Archive
Mørtvedt, Anne Inger; Krosshaug, Tron & Petushek, Erich (2024). Usability considerations for enhancing exercise-based injury prevention interventions. Full text in Research Archive
Krosshaug, Tron (2024). Strength training biomechanics. Full text in Research Archive
Krosshaug, Tron (2024). Strength training biomechanics (workshop). Full text in Research Archive
Bagehorn, Timo; Bill, Kevin; Mai, Patrick; Krosshaug, Tron & Kersting, Uwe G. (2024). Impact of footwear bending stiffness and torsional stiffness on ankle biomechanics during handball specific fake-and-cut manoeuvres. Full text in Research Archive
Bill, Kevin; Mai, Patrick; Krosshaug, Tron & Kersting, Uwe G. (2024). Thigh muscle activity in experienced female handball players during preplanned and unplanned sidestep cuts. Full text in Research Archive
Vleuten, Reid Vander; Wannop, John; Berg, Carla Van den; Critchley, Meghan; Jordan, Matthew & Krosshaug, Tron [Show all 7 contributors for this article] (2024). Knee Kinematics and Kinetics During Sport-Specific Cutting and Landing Maneuvers in Female University Soccer Players: Implications for ACL Injury Prevention. Full text in Research Archive
Eriksrud, Ola; Krosshaug, Tron; Mai, Patrick; Glørsen, Øyvind & Westheim, Frederic (2024). Deceleration demands in change of direction tests: insights from measurements using a motorized resistance device. Full text in Research Archive
Mausehund, Lasse; Patron, Anri; Äyrämö, Sami & Krosshaug, Tron (2024). Cluster analysis of cutting technique: A valuable approach for assessing anterior cruciate ligament injury risk? Full text in Research Archive
Krosshaug, Tron (2024). Immediate feedback on technique and loading parameters to make cutting movements safer. Full text in Research Archive
Bill, Kevin; Mai, Patrick; Krosshaug, Tron; Mausehund, Lasse & Kersting, Uwe (2024). Individualized Sidestep Cutting Technique Feedback in Handball Under Consideration of Performance - Best of Both Worlds for ACL Injury Prevention? Full text in Research Archive
Mai, Patrick; Bill, Kevin; Kersting, Uwe; Willwacher, Steffen; Eriksrud, Ola & Krosshaug, Tron (2024). A nine-week ACL injury prevention program for female handball players: Effect on knee joint loading and cutting technique during a handball-specific fake-cut. Full text in Research Archive
Kamatsuki, Yusuke; Qvale, Marie Synnøve; Wangensteen, Arnlaug; Steffen, Kathrin & Krosshaug, Tron (2024). Anatomical risk factors for primary and secondary non-contact ACL injury – a prospective cohort study in 880 female elite players. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2023). Cluster analysis of cutting technique - A valuable approach for assessing ACL injury risk? Full text in Research Archive
Krosshaug, Tron (2023). Cluster analysis of cutting technique - A valuable approach for assessing ACL injury risk? Full text in Research Archive
Krosshaug, Tron (2023). Does your exercise target the muscles you think you’re targetting? Full text in Research Archive
Krosshaug, Tron (2023). Translating biomechanics theory to practice: understand the exercises so you can design the best resistance training programs. Full text in Research Archive
Gjestvang, Christina; Krosshaug, Tron & Haakstad, Lene (2023). Hvorfor vil staten gjøre det dyrere å trene? Full text in Research Archive
Bill, Kevin; Mai, Patrick; Robertz, Leon; Glöckler, Katharina; Claramunt-Molet, Mireia & Bartsch, Julia [Show all 14 contributors for this article] (2022). Knee kinematics and kinetics of sport-specific fake-and-cut maneuvers of varying complexity in female handball players. Full text in Research Archive
Mai, Patrick; Bill, Kevin; Robertz, Leon; Glöckler, Katharina; Claramunt-Molet, Mireia & Bartsch, Julia [Show all 15 contributors for this article] (2022). Can a simplified knee abduction moment estimation be used for athlete screening? Implications for ACL injury prevention. Full text in Research Archive
Mausehund, Lasse & Krosshaug, Tron (2022). Why are players with a previous ACL injury at elevated risk of sustaining a new secondary ACL injury? Full text in Research Archive
Mai, Patrick; Bill, Kevin; Bartsch, Julia; Willwacher, Steffen; Kersting, Uwe & Krosshaug, Tron (2022). Screening athletes for ACL injury risk - effects of game specificity on knee abduction moment. Full text in Research Archive
Krosshaug, Tron (2022). ACL injury mechanisms and biomechanical risk factors. Full text in Research Archive
Krosshaug, Tron (2022). ACL injury mechanisms and biomechanical risk factors. Full text in Research Archive
Krosshaug, Tron (2022). Hva har vi lært av 20 års forskning på ACL-skader? Et dypdykk i skademekanismer og risikofaktorer med hovedfokus på biomekanikk/bevegelsesanalyse. Full text in Research Archive
Solstad, Tom Erik Jorung; Krosshaug, Tron; Mausehund, Lasse; Tillaar, Roland Johannes Wilhelmus van den; Larsen, Stian & Samnøy, Lars Edvin [Show all 7 contributors for this article] (2021). Episode 50 - Rundbordsprat om øvelsen benkpress. [Internet]. Idrettsforskning . Full text in Research Archive
Nilstad, Agnethe; Petushek, Erich; Mok, Kam-Ming; Bahr, Roald & Krosshaug, Tron (2021). Response to letter to the editor about ‘kiss goodbye to the “kissing knees”: no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes’. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1983637. Full text in Research Archive
Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Krosshaug, Tron & Kannus, Pekka [Show all 7 contributors for this article] (2021). Change of direction biomechanics and the risk for non-contact knee injuries in youth basketball and floorball players. British Journal of Sports Medicine. ISSN 0306-3674. 55, p. A17–A18. doi: 10.1136/bjsports-2021-IOC.40. Full text in Research Archive
Krosshaug, Tron (2021). Introduction. Full text in Research Archive
Krosshaug, Tron (2021). Taking it to the next level. Sophisticated 3D animations for injury prevention delivery. Full text in Research Archive
Krosshaug, Tron (2021). Taking knee and hip biomechanics measurements from the lab to the field: Is it possible? Full text in Research Archive
Mai, Patrick; Bill, Kevin; Gloeckler, Katharina & Krosshaug, Tron (2021). Mimicking game scenarios in a laboratory-based environment - the effects on knee abduction moment when facing varied task demands. Full text in Research Archive
Bill, Kevin; Mai, Patrick; Molet, Claramunt & Krosshaug, Tron (2021). The effect of cutting task complexity on technique variables associated with increased risk of ACL injuries in female handball players. Full text in Research Archive
Krosshaug, Tron (2021). Biomechanics of cutting and landing – injury mechanisms and risk factors for ACL injury. Full text in Research Archive
Leppänen, Mari; Parkkari, Jari; Vasankari, Tommi; Äyrämö, Sami; Krosshaug, Tron & Kannus, Pekka [Show all 7 contributors for this article] (2021). Change of direction biomechanics and the risk for non contact knee injuries in youth basketball and floorball players. Full text in Research Archive
Krosshaug, Tron (2021). Animasjonsbasert undervisning i styrketrening og biomekanikk. Full text in Research Archive
Bahr, Roald & Krosshaug, Tron (2020). The Oslo Sports Trauma Research Center (OSTRC). Full text in Research Archive
Krosshaug, Tron (2020). Prospective ACL risk factor studies of landing and cutting biomechanics – what have we learnt after 15 years of research. Full text in Research Archive
Krosshaug, Tron (2020). Is cutting technique a risk factor for ACL injury? Full text in Research Archive
Strand, Jørn Erik; Nilstad, Agnethe & Krosshaug, Tron (2019). Knekontroll i frontalplanet under en ett-bens knebøy er ikke assosiert med økt risiko for fremre korsbåndskade. Full text in Research Archive
Krosshaug, Tron & Bartsch, Julia (2022). Comparing Knee Loading in Anticipated and Unanticipated Handball Specific Cutting Tasks and Generic 180-Degree-Change-of-Direction Master Thesis. University of Konstanz. Full text in Research Archive
Krosshaug, Tron & Eggerud, Mathias Midthjell (2022). Muscle activation of thigh muscles in predetermined and randomized cutting directions during side-cut faking tasks among female handball athletes: A cross-sectional study. Norges idrettshøgskole. Full text in Research Archive Show summary
Purpose: Muscle activity is an important factor contributing to knee joint stability during side-cut faking maneuvers. The side-cut faking maneuver is one of the most common non-contact anterior cruciate ligament (ACL) injury situations in female handball. Being a highly dynamic maneuver, the timeframe to plan an appropriate muscle activation strategy might decrease when faced with randomized events, putting the ACL at risk. However, research on muscle activation during side-cutting maneuvers has failed to recreate a realistic side-cut faking maneuver mimicking in-game scenarios. The purpose of this study was to investigate the effect of anticipation on muscle activity in female handball athletes under game-like scenarios during side-cut faking maneuvers. Methods: Fifty-one female handball players from the Norwegian Premier, 1st, 2nd and 3rd divisions were recruited to the study. The muscle activity of biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL), and vastus medialis (VM) was measured 50 milliseconds (ms) before and after initial contact (IC) by electromyography (EMG) during three side-cut faking maneuvers. For Task 1 the athletes did a side-cut in a predetermined direction. For Task 2 the athletes received a pass prior to executing a side-cut in a predetermined direction to fake a static defender. In Task 3 the athletes received a pass. When the ball was caught, two out of three defenders approached the athlete. The athlete would then be forced to cut away from the approaching defenders, resulting in a randomized cutting direction. Results: In ST and VM there was a statistically significantly higher average muscle activation in Task 2 compared to Task 1, 50 ms before IC. In VL there was statistically significantly lower average muscle activation in Task 3 compared to Task 2, 50 ms before IC. No significant differences were detected 50 ms after IC. Conclusion: No differences were detected between the simplest tasks with a predetermined cutting direction compared to the randomized cutting direction. The only exception was a reduced VL pre-activity between Task 2 and Task 3. Implying that the pre-activity, which is crucial to knee stability is not affected by the task complexity. Significant, yet small differences were detected within the predetermined side-cuts. Therefore, a simple task seems to be sufficient for EMG-screening when simulating ingame scenarios. There were no indications towards muscle activation patterns associated with increased ACL injury risk across tasks.
Krosshaug, Tron & Flathus, Mona Holtan (2022). Fordeling av leddmomenter mellom albue- og skulderledd ved seks ulike varianter av push-ups med ulike hånd- og albueposisjoner. Norges idrettshøgskole. Full text in Research Archive Show summary
Hensikt: Det er mangel på studier vedrørende kinetikk-basert kvantifikasjon av push-ups øvelser (Dhahbi, et al., 2022). Siden bruk av øvelsen er utbredt og blir benyttet i mange ulike sammenhenger, er vi avhengig av en grunnleggende biomekanisk forståelse av den. Hensikten med studien var derfor å undersøke leddmomentfordeling mellom skulder- og albueledd ved seks ulike varianter av styrketreningsøvelsen push-ups. Dette for å få en bredere forståelse av hvordan en endring i hånd- og albueposisjonering kan påvirke leddmomentene. Metode: Tjue friske voksne kvinner (n=10) og menn (n=10), utførte fem repetisjoner av hver av de seks push-ups variantene i randomisert rekkefølge. Under utførelsen benyttet vi markørbasert bevegelsesanalyse og kraftplattformer for å synkront samle inn kinetisk og kinematisk data. Dette datamaterialet ble så benyttet til å regne ut skulder- og albueleddmomenter. Resultater: Vi fant statistisk signifikant forskjell i leddmomentfordeling mellom de ulike øvelsesvariasjonene (p<0.001, ηₚ² = 0.92-0.93). Bred, Middels, Smal-nøytral og Smal-lav håndposisjonering hadde et høyere relativt skulderleddmoment enn albueleddmoment. Diamant hadde ca. like stort relativt albueleddmoment som skulderleddmoment, og Smal-høy hadde høyere relativt albueleddmoment enn skulderleddmoment. Bred hadde statistisk signifikant høyere absolutt skulderleddmoment enn de resterende variantene, og Diamant og Smal-høy hadde statistisk signifikant høyere absolutt albueleddmoment enn de fire andre variantene. Konklusjon: Vi fant at Smal-lav, Bred og Middels var forskjellig fra Smal-nøytral, Diamant og Smal-høy ved relativt skuldeleddmoment, der Smal-lav, Bred og Middels hadde høyere relativt skulderleddmoment enn Smal-nøytral ved maks. moment (11.2%, 10.9% og 10.2%) og ved laveste punkt (18.3%, 17.0% og 18.7%). Vi fant en forskjell i relativt skulderleddmoment mellom Smal-nøytral og Diamant, der Smal-nøytral hadde høyere relativt skulderleddmoment enn Diamant ved maks. moment (24.0%) og laveste punkt (28.3%). Vi fant også en forskjell i relativt skulderleddmoment mellom Diamant og Smal-høy, der Diamant hadde høyere relativt skuldeleddmoment enn Smal-høy ved maks. moment (17.0%) og laveste punkt (25.8%). Vi fant derimot ingen forskjell i relativt skuldeleddmoment mellom Smal-lav, Bred og Middels.
Krosshaug, Tron & Mo, Helena Cecilie (2022). Biomechanical analysis of groin related strength training exercises for injury prevention. Universitetet i Bergen. Full text in Research Archive Show summary
Purpose: Groin injuries in soccer are a widespread problem in sports medicine. One certain strength exercise, the Copenhagen adductor exercise, has shown an injury-preventing effect. But there are still many groin injuries, and better preventive measures are needed. The aim of this study was to investigate the load on groin structures during the performance of the Copenhagen adductor and three other exercises designed with a hypothesis of having a greater load. All are one-foot dynamic plank exercises. The Copenhagen adductor exercise is conducted by hip adduction, while the others had hip adduction, hip flexion, and a combination of both to resemble a soccer pass. More specific, muscle activation of the adductor longus muscle and the rectus femoris muscle were examined as well as torque exerted on the hip joint. Methods: 18 footballers (10 men and 8 women) at varying playing levels in the Oslo region performed the four plank exercises, while electromyography activity, motion capture and forces were recorded. Muscle activations were found from the electromyography data and normalized to a player’s maximum activation for the given muscle. By motion capture, the position of hip joints and force direction were determined. Together with measured forces, this was used to calculate torque and further normalised to the player’s weight. Both average mean values and peak values were calculated and used for comparison by Results: With a p-value set to 0.05, all exercises with hip adduction achieved significantly higher muscular activation of adductor longus than the exercise without. Exercise including only flexion of the leg showed significantly higher activation of rectus femoris than exercises including only adduction and both adduction and flexion. The muscle activation seemed to be higher during concentric muscle work rather than eccentric muscle work. None significantly differences were found in torque between the exercises, but it showed that torque was greatest early in the concentric phase for all exercises. Conclusion: Four exercises were investigated, and trend was shown of greater total load on one exercise intending to resemble a soccer pass compared to the Copenhagen adductor exercise. It should be investigated further whether this more sport-specific exercise has greater preventive potential. To ensure high activation on both adductor longus and rectus femoris, one single exercise does not seem to be sufficient, a combination of several exercises should be performed.

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Published Oct. 17, 2023 1:13 PM - Last modified Dec. 13, 2023 2:35 PM