Jostein Hallén

• Forså, Marianne Inngjerdingen; Smedsrud, Marit Kristine; Haugaa, Kristina Ingrid Helena Hermann; Bjerring, Anders W.; Fruh, Andreas & Sarvari, Sebastian [Vis alle 9 forfattere av denne artikkelen] (2023). Distinguishing left ventricular hypertrophy from hypertrophic cardiomyopathy in adolescents: a longitudinal observation study. European Journal of Preventive Cardiology (EJPC). ISSN 2047-4873. 31(5), s. 591–598. doi: 10.1093/eurjpc/zwad361. Fulltekst i vitenarkiv
• Oberholzer, Laura; Montero, David; Robach, Paul; Siebenmann, Christoph; Ryrsøe, Camilla Koch & Bonne, Thomas C. [Vis alle 19 forfattere av denne artikkelen] (2023). Determinants and reference values for blood volume and total hemoglobin mass in women and men. American Journal of Hematology. ISSN 0361-8609. 99(1), s. 88–98. doi: 10.1002/ajh.27162. Fulltekst i vitenarkiv
• Oberholzer, Laura; Aamaas, Nikolai Søndersrød & Hallén, Jostein (2023). Changes in cycling economy and fractional utilization of V̇O2peak during a 40-min maximal effort exercise test with acute hypobaric hypoxia corresponding to 2800 m of altitude. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. doi: 10.1111/sms.14511. Vis sammendrag

  Introduction: Peak oxygen uptake (V̇O2peak) declines by ~7% per 1000 m of increasing altitude, whereas exercise performance seems reduced to a lesser extent. For example, 800–10 000 m track and field performances are decreased by 0.4%–2.4% above 1000 m as compared to below and some studies show similar drops in cycling performance. A greater decline in V̇O2peak than in endurance performance with altitude suggests a higher fractional utilization of V̇O2peak (%V̇O2peak). Therefore, we hypothesized that the %V̇O2peak is higher with acute hypoxic exposure than near sea level. Methods: Sixteen lowlanders (8 women, age: 31 ± 7 years [mean ± SD], body mass: 68 ± 8 kg, V̇O2peak: 60 ± 8 mL min−1 kg−1) underwent cycling testing in a hypobaric hypoxic chamber on 6 test days, three conducted at 300 m and three at 2800 m of acute altitude. At both altitudes, V̇O2peak was determined, and during a 40-min all out maximal effort time trial (TT), mean power output (MPO) and mean V̇O2 (%V̇O2peak) were assessed. Results: V̇O2peak decreased by 11.2 ± 3.0% (p < 0.001), while MPO during the TT declined by 10.7 ± 3.1% (p < 0.001) at 2800 m as compared to 300 m. During the TT, %V̇O2peak was higher at altitude, corresponding to 75.9 ± 4.5% at 300 m and 78.8 ± 4.2% at 2800 m (p = 0.011), and cycling economy (mL O2 kJ−1) was poorer (+3.4 ± 2.7%, p < 0.001). Conclusion: The %V̇O2peak was higher during a cycling TT at 2800 m of altitude than near sea level, while cycling economy was poorer. This resulted in a similar reduction in performance and V̇O2peak. Future studies should address the physiological mechanisms underlying the elevated %V̇O2peak.

• Galvan-Alvarez, Victor; Martin-Rincon, Marcos; Gallego-Selles, Angel; Martínez Canton, Miriam; HamedChaman, NaDer & Gelabert-Rebato, Miriam [Vis alle 13 forfattere av denne artikkelen] (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. ISSN 2213-2317. 66. doi: 10.1016/j.redox.2023.102859. Fulltekst i vitenarkiv Vis sammendrag

  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.

• 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. Vis sammendrag

  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.

• Forså, Marianne Inngjerdingen; Bjerring, Anders W.; Haugaa, Kristina Ingrid Helena Hermann; Smedsrud, Marit Kristine; Sarvari, Sebastian & Landgraff, Hege Elisabeth W. [Vis alle 8 forfattere av denne artikkelen] (2023). Young athlete's growing heart: sex differences in cardiac adaptation to exercise training during adolescence. Open heart. ISSN 2053-3624. 10(1). doi: 10.1136/openhrt-2022-002155. Fulltekst i vitenarkiv Vis sammendrag

  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.

• Gorski, Piotr Patryk; Raastad, Truls; Ullrich, Max; Turner, Daniel; Hallén, Jostein & Sarvari, Sebastian [Vis alle 8 forfattere av denne artikkelen] (2022). Aerobic Exercise Training Resets the Human Skeletal Muscle Methylome Ten Years after Breast Cancer Treatment and Survival. The FASEB Journal. ISSN 0892-6638. 37(1). doi: 10.1096/fj.202201510RR. Vis sammendrag

  Background: Cancer survivors suffer impairments in skeletal muscle in terms of reduced mass and function. Interestingly, human skeletal muscle possesses an epigenetic memory of earlier stimuli, such as exercise. Long-term retention of epigenetic changes in skeletal muscle following cancer survival and/or exercise training have not yet been studied. We therefore investigated genome-wide DNA methylation (methylome) in skeletal muscle following a 5-month, 3/week aerobic-training intervention in breast cancer survivors 10-14 years after diagnosis and treatment. These results were compared to breast cancer survivors who remained untrained and to age-matched controls with no history of cancer, who undertook the same training intervention. Methods: Skeletal muscle biopsies were obtained from 23 females before(pre) and after(post) the 5-month training period. InfiniumEPIC 850K DNA methylation arrays and RT-PCR for gene expression performed. Results: The breast cancer survivors displayed a significant retention of increased DNA methylation (i.e.,hypermethylation) at a larger number of differentially methylated positions (DMPs) compared with healthy age-matched controls pre-training. Training in cancer survivors led to an exaggerated number of DMPs with a hypermethylated signature occurring at non-regulatory regions compared with training in healthy age-matched controls. However, the opposite occurred in important gene regulatory regions, where training in cancer survivors elicited a considerable reduction in methylation (i.e.,hypomethylation) in 99% of the DMPs located in CpG islands within promoter regions. Importantly, training was able to reverse the hypermethylation identified in cancer survivors back towards a hypomethylated signature that was observed pre-training in healthy age-matched controls at 300 (out of 881) of these island/promoter associated CpGs. Pathway enrichment analysis identified training in cancer survivors evoked this predominantly hypomethylated signature in pathways associated with: Cell cycle, DNA replication/repair, transcription, translation, mTOR signalling and the proteosome. Differentially methylated region (DMR) analysis also identified genes: BAG1, BTG2, CHP1, KIFC1, MKL2, MTR, PEX11B, POLD2, S100A6, SNORD104 and SPG7 as hypermethylated in breast cancer survivors, with training reversing these CpG island/promoter associated DMRs towards a hypomethylated signature. Training also elicited a largely different epigenetic response in healthy individuals than that observed in cancer survivors, with very few overlapping changes. Only one gene, SIRT2, was identified as having altered methylation in cancer survivors at baseline and after training in both the cancer survivors and healthy controls. Conclusions: Human skeletal muscle muscle may retain a hypermethylated signature as long as 10-14 years after breast cancer treatment/survival. Five months of aerobic training reset the skeletal muscle methylome towards signatures identified in healthy age-matched individuals in gene regulatory regions.

• Myklebust, Håvard; Losnegard, Thomas Johansen & Hallén, Jostein (2022). Kinematic differences between uphill roller skiing and on-snow skiing using the V2 skating technique. European Journal of Applied Physiology. ISSN 1439-6319. 122(11), s. 2355–2365. doi: 10.1007/s00421-022-05007-0. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: Roller skiing is the primary sport-specific training and testing mode during pre-competition periods for cross-country skiers, biathletes, and Nordic combined athletes. The present study aimed to compare the kinematics between uphill roller skiing and on-snow skiing using the V2 sub-technique. Methods: In a cross-over design, nine well-trained male skiers performed short trials (< 40 s) at constant inclination (8.0°), speed (3.0 m‧s−1), and controlled rolling/gliding friction on asphalt (in the fall), on the treadmill (in the fall and winter), and during on-snow skiing (in the winter). Kinematic data were collected using a validated inertial measurement unit system. Results: Repeated-measures ANOVAs revealed no differences between treadmill and asphalt roller skiing. Further, including on-snow skiing showed moderate to good reliability (ICC ≥ 0.63, p ≤ 0.001) for ground-contact temporal variables. However, on-snow skiing moderately increased hip range of motion around the longitudinal axis (22.2 ± 7.7° vs. 14.1 ± 4.7°), lateral hip displacement (44.1 ± 7.1 cm vs. 37.2 ± 6.6 cm) and pole push times (422 ± 41 ms vs. 386 ± 31 ms), and on-snow skiing was characterized by altered hip rotational patterns compared to roller skiing. Conclusion: V2 roller ski skating simulates on-snow ski skating to a large extent, but the mechanical properties of the skis and/or surface hardness systematically alter skiers’ hip movements and pole push times. This implies a potential for equipment optimization to increase training specificity during pre-competition periods and highlights a need for future studies to examine the kinematic effects of snow hardness on all sub-techniques.

• Skattebo, Øyvind & Hallén, Jostein (2022). Individual variations in pre-altitude hemoglobin mass influence hemoglobin mass responses to repeated altitude sojourns. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 32(10), s. 1493–1501. doi: 10.1111/sms.14218. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: Previous studies have shown variable within-subject hemoglobin mass (Hbmass) responses to altitude training. We investigated whether Hbmass responses depend on individual variations in pre-altitude Hbmass during repeated altitude sojourns. Methods: Nine elite endurance athletes carried out 3–5 altitude sojourns over 17 ± 10 months (mean ± 95% confidence interval), at an altitude of 1976 ± 62 m, for 21 ± 1 days, and a total hypoxic dose of 989 ± 46 km·h, with Hbmass assessed before and after each sojourn (carbon monoxide rebreathing). The individual mean baseline was calculated as the mean of all pre-altitude Hbmass values for an athlete, and it was investigated whether the percent deviation from the individual mean baseline affected the altitude-induced Hbmass response. Results: On average, Hbmass increased by 3.4 ± 1.1% (p < 0.001) from pre- to post-altitude. The intra-individual changes in Hbmass were highly inconsistent (coefficient of variation, CV: 88%), and we found no relationship between Hbmass changes in successive altitude sojourns (r = 0.01; p = 0.735). However, the percent increase in Hbmass was highly correlated with the pre-altitude Hbmass, expressed as the percent deviation from the individual mean baseline (y = −0.7x + 3.4; r = 0.75; p < 0.001). Linear mixed-model analysis confirmed a −0.6 ± 0.2% smaller increase in Hbmass for each 1% higher pre-altitude Hbmass than the individual mean baseline (p < 0.001) after adjusting for the covariates hypoxic dose (p = 0.032) and the relative Hbmass (g·kg−1 body weight; p = 0.031). Conclusion: Individual variations in pre-altitude Hbmass significantly influence the athletes' Hbmass responses to repeated altitude sojourns, with a potentiated response after traveling to altitude with a low pre-altitude Hbmass.

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• Nilsen, Tormod Skogstad; Sæter, Mali; Sarvari, Sebastian; Reinertsen, Kristin Valborg; Johansen, Sara Hassing & Edvardsen, Elisabeth Rustad [Vis alle 17 forfattere av denne artikkelen] (2023). Effects of Aerobic Exercise on Cardiorespiratory Fitness, Cardiovascular Risk Factors, and Patient-Reported Outcomes in Long-Term Breast Cancer Survivors: Protocol for a Randomized Controlled Trial. JMIR Research Protocols. ISSN 1929-0748. 12. doi: 10.2196/45244. Fulltekst i vitenarkiv

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