Jostein Hallén

• Skattebo, Øyvind; Martin-Rincon, Marcos; Calbet, Jose Antonio Lopez; Hallén, Jostein & Holmberg, Hans-Christer (2026). A Review of Central and Peripheral Limitations to Endurance Exercise Performance on the Road to the Milano-Cortina 2026 Olympics. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 36(3). doi: 10.1111/sms.70266. Full text in Research Archive
• Skattebo, Øyvind; Martin-Rincon, Marcos; Rud, Bjarne; Nielsen, Joachim; Hegg, Lars Henrik N. & Kleive, Andreas Vileid [Show all 12 contributors for this article] (2025). Determinants of maximal oxygen uptake in highly trained females and males: a mechanistic study of sex differences using advanced invasive methods. Journal of Physiology. ISSN 0022-3751. doi: 10.1113/JP289218. Full text in Research Archive
• Grendstad, Halvard; Skarstad, Sigrun Ådnegard; Edvardsen, Thor & Hallén, Jostein (2025). A Prospective Study on Maximal Oxygen Uptake and Cardiovascular Functions in 12-Year-Old Endurance Athletes and Their Non-Endurance-Trained Peers. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 35(1). doi: 10.1111/sms.70016. Full text in Research Archive
• Johansen, Sara Hassing; Sæter, Mali; Sarvari, Sebastian; Reinertsen, Kristin Valborg; Edvardsen, Elisabeth & Wisløff, Torbjørn [Show all 18 contributors for this article] (2025). Effects of Aerobic Exercise on Cardiorespiratory Fitness and Cardiovascular Risk Factors in Long-Term Breast Cancer Survivors: A Randomized Controlled Trial. JACC: CardioOncology. 7(4), p. 414–426. doi: 10.1016/j.jaccao.2025.04.006. Full text in Research Archive
• Leahy, Michael G.; Thompson, Kyle M. A.; Skattebo, Øyvind; Paz, Jose A. de; Martin-Rincon, Marcos & Garcia-Gonzalez, Eduardo [Show all 11 contributors for this article] (2024). Assessing Leg Blood Flow and Cardiac Output During Running Using Thermodilution. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(8). doi: 10.1111/sms.14705. Full text in Research Archive Show summary

  Cardiac output (Q̇C) and leg blood flow (Q̇LEG) can be measured simultaneously with high accuracy using transpulmonary and femoral vein thermodilution with a single-bolus injection. The invasive measure has offered important insight into leg hemodynamics and blood flow distribution during exercise. Despite being the natural modality of exercise in humans, there has been no direct measure of Q̇LEG while running in humans. We sought to determine the feasibility of the thermodilution technique for measuring Q̇LEG and conductance during high-intensity running, in an exploratory case study. A trained runner (30 years male) completed two maximal incremental tests on a cycle ergometer and motorized treadmill. Q̇LEG and Q̇C were determined using the single-bolus thermodilution technique. Arterial and venous blood were sampled throughout exercise, with continuous monitoring of metabolism, intra-arterial and venous pressure, and temperature. The participant reached a greater peak oxygen uptake (V̇O2peak) during running relative to cycling (74 vs. 68 mL/kg/min) with comparable Q̇LEG (19.0 vs. 19.5 L/min) and Q̇C (27.4 vs. 26.2 L/min). Leg vascular conductance was greater during high-intensity running relative to cycling (82 vs. 70 mL/min/mmHg @ ~80% V̇O2peak). The “beat phenomenon” was apparent in femoral flow while running, producing large gradients in conductance (62–90 mL/min/mmHg @ 70% V̇O2peak). In summary, we present the first direct measure of Q̇LEG and conductance in a running human. Our findings corroborate several assumptions about Q̇LEG during running compared with cycling. Importantly, we demonstrate that using thermodilution in running exercise can be completed effectively and safely.

• Skattebo, Øyvind; Capelli, Carlo; Calbet, Jose Antonio Lopez & Hallén, Jostein (2024). Endurance Training Improves Leg Proton Release and Decreases Potassium Release During High-Intensity Exercise in Normoxia and Hypobaric Hypoxia. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(7). doi: 10.1111/sms.14688. Full text in Research Archive Show summary

  Aim: To assess the impact of endurance training on skeletal muscle release of H+ and K+. Methods: Nine participants performed one-legged knee extension endurance training at moderate and high intensities (70%–85% of Wpeak), three to four sessions·week−1 for 6 weeks. Post-training, the trained and untrained (control) leg performed two-legged knee extension at low, moderate, and high intensities (40%, 62%, and 83% of Wpeak) in normoxia and hypoxia (~4000 m). The legs were exercised simultaneously to ensure identical arterial inflow concentrations of ions and metabolites, and identical power output was controlled by visual feedback. Leg blood flow was measured (ultrasound Doppler), and acid–base variables, lactate- and K+ concentrations were assessed in arterial and femoral venous blood to study K+ and H+ release. Ion transporter abundances were assessed in muscle biopsies. Results: Lactate-dependent H+ release was similar in hypoxia to normoxia (p = 0.168) and was lower in the trained than the control leg at low–moderate intensities (p = 0.060–0.006) but similar during high-intensity exercise. Lactate-independent and total H+ releases were higher in hypoxia (p ＜ 0.05) and increased more with power output in the trained leg (leg-by-power output interactions: p = 0.02). K+ release was similar at low intensity but lower in the trained leg during high-intensity exercise in normoxia (p = 0.024) and hypoxia (p = 0.007). The trained leg had higher abundances of Na+/H+ exchanger 1 (p = 0.047) and Na+/K+ pump subunit α (p = 0.036). Conclusion: Moderate- to high-intensity endurance training increases lactate-independent H+ release and reduces K+ release during high-intensity exercise, coinciding with increased Na+/H+ exchanger 1 and Na+/K+ pump subunit α muscle abundances.

• Grendstad, Halvard & Hallén, Jostein (2023). Effects of adding high-intensity training during an 8-week period on maximal oxygen uptake in 12-year-old youth athletes. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. doi: 10.1111/sms.14489. Full text in Research Archive Show summary

  Purpose: Maximal oxygen uptake (V̇O2max) increases during adolescence parallel to the increase in fat-free mass (FFM). How much endurance training adds to this effect is still controversial. Our aim was to investigate if inclusion of high-intensity training (HIT) during an 8-week training period was superior to low-intensity strength and coordination training in 12-year-old youth athletes concerning the effect on V̇O2max. Methods: Thirty-five cross-country skiers were randomized into a HIT group (ET) and a strength and coordination group (SC), while 29 less active peers served as controls for growth and maturation (C). Anthropometrics and V̇O2max were assessed before and after the training period, and level of physical activity and training were monitored with accelerometers, training logs and a questionnaire. Results: The number of weekly training sessions were higher for ET (4.6 ± 1.2) and SC (4.1 ± 1.0) compared with C (1.8 ± 2.0) (p < 0.01), with only ET conducting HIT sessions (1.9 ± 0.2 per week). C spent more time sedentary and less time in moderate and vigorous activity compared with ET (p < 0.05). All groups had a similar %-change pre-post in absolute V̇O2max (mL min−1) of 6% ± 6% for ET (p < 0.01), 5% ± 7 for SC (p = 0.14), and 5% ± 13% for C (p = 0.03), with no significant differences between groups. V̇O2max relative to FFM did not change significantly for any groups. Conclusion: The change in V̇O2max paralleled the change in FFM for all groups, questioning the effect of HIT on V̇O2max over an 8-week period in youth athletes.

• Galvan-Alvarez, Victor; Martin-Rincon, Marcos; Gallego-Selles, Angel; Canton, Miriam Martínez; HamedChaman, NaDer & Gelabert-Rebato, Miriam [Show all 13 contributors for this article] (2023). Determinants of the maximal functional reserve during repeated supramaximal exercise by humans: The roles of Nrf2/Keap1, antioxidant proteins, muscle phenotype and oxygenation. Redox Biology. 66. doi: 10.1016/j.redox.2023.102859. Full text in Research Archive Show summary

  When high-intensity exercise is performed until exhaustion a “functional reserve” (FR) or capacity to produce power at the same level or higher than reached at exhaustion exists at task failure, which could be related to reactive oxygen and nitrogen species (RONS)-sensing and counteracting mechanisms. Nonetheless, the magnitude of this FR remains unknown. Repeated bouts of supramaximal exercise at 120% of VO2max interspaced with 20s recovery periods with full ischaemia were used to determine the maximal FR. Then, we determined which muscle phenotypic features could account for the variability in functional reserve in humans. Exercise performance, cardiorespiratory variables, oxygen deficit, and brain and muscle oxygenation (near-infrared spectroscopy) were measured, and resting muscle biopsies were obtained from 43 young healthy adults (30 males). Males and females had similar aerobic (VO2max per kg of lower extremities lean mass (LLM): 166.7 ± 17.1 and 166.1 ± 15.6 ml kg LLM−1.min−1, P = 0.84) and anaerobic fitness (similar performance in the Wingate test and maximal accumulated oxygen deficit when normalized to LLM). The maximal FR was similar in males and females when normalized to LLM (1.84 ± 0.50 and 2.05 ± 0.59 kJ kg LLM−1, in males and females, respectively, P = 0.218). This FR depends on an obligatory component relying on a reserve in glycolytic capacity and a putative component generated by oxidative phosphorylation. The aerobic component depends on brain oxygenation and phenotypic features of the skeletal muscles implicated in calcium handling (SERCA1 and 2 protein expression), oxygen transport and diffusion (myoglobin) and redox regulation (Keap1). The glycolytic component can be predicted by the protein expression levels of pSer40-Nrf2, the maximal accumulated oxygen deficit and the protein expression levels of SOD1. Thus, an increased capacity to modulate the expression of antioxidant proteins involved in RONS handling and calcium homeostasis may be critical for performance during high-intensity exercise in humans.

• Forså, Marianne Inngjerdingen; Bjerring, Anders W.; Haugaa, Kristina Ingrid Helena Hermann; Smedsrud, Marit Kristine; Sarvari, Sebastian & Landgraff, Hege Elisabeth W. [Show all 8 contributors for this article] (2023). Young athlete's growing heart: sex differences in cardiac adaptation to exercise training during adolescence. Open heart. 10(1). doi: 10.1136/openhrt-2022-002155. Full text in Research Archive Show summary

  Background: Athlete’s heart is a condition of exercise-induced cardiac remodelling. Adult male endurance athletes more often remodel beyond reference values. The impact of sex on remodelling through adolescence remains unclear. Paediatric reference values do not account for patient sex or exercise history. We aimed to study the effect of sex on cardiac remodelling throughout adolescence. Methods: We recruited 76 male (M) and female (F) 12-year-old cross-country skiers in a longitudinal cohort study. Echocardiography was performed and analysed according to guidelines at age 12 (48 M, 28 F), 15 (34 M, 14 F) and 18 (23 M, 11 F). Repeated echocardiographic measurements were analysed by linear mixed model regression. Results: Males displayed greater indexed left ventricular end-diastolic volumes (LV EDVi) from age 12 (M 81±7 vs F 76±7, mL/m², p≤0.01), and progressed further until follow-up at age 18 (M 2.3±9.7 vs F −3.9±4.5 ΔmL/m², p≤0.01). LV EDVi remained above adult upper reference values in both groups. Males increased LV Mass Index from age 12 to 18 (M 33±27 vs F 4±19, Δg/m², p≤0.01). Males displayed LV mass above paediatric reference values at ages 15 and 18. A subset of males (35%) and females (25%) displayed wall thickness above paediatric reference values at age 12. Cardiac function was normal. There was no sex difference in exercise hours. Conclusion: Sex-related differences in athlete’s heart were evident from age 12, and progressed throughout adolescence. Remodelling beyond reference values was more frequent than previously reported, particularly affecting males. Age, sex and exercise history may assist clinicians in distinguishing exercise-induced remodelling from pathology in adolescents.

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• Sperlich, Billy; Holmberg, Hans-Christer; Martin-Rincon, Marcos; Skattebo, Øyvind; Burr, Jamie F. & Hallén, Jostein [Show all 8 contributors for this article] (2024). Repeated Carbon Monoxide Inhalation in Sports: A New Frontier or a Dangerous Gamble? Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(12). doi: 10.1111/sms.70005. Full text in Research Archive

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