Journal: Journal of Science and Medicine in Sport

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Elsevier

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ISSN

1440-2440

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2013 - 201952020 - 20234
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Publications1 - 9 of 9
  • High prevalence of false-positive plateau phenomena during VO2max testing in adolescents
    Item type: Journal Article
    Beltrami, Fernando G.; Wong, Del P.; Noakes, Timothy D. (2014)
    Journal of Science and Medicine in Sport
  • A physical fitness intervention during basic military training improves health behavior in civil life afterwards
    Item type: Other Journal Item
    Roos, Lilian; Beeler, Nadja; Wyss, Thomas (2017)
    Journal of Science and Medicine in Sport
  • Acute exercise-induced glycocalyx shedding does not differ between exercise modalities, but is associated with total antioxidative capacity
    Item type: Journal Article
    Kröpfl, Julia M.A.; Beltrami, Fernando G.; Rehm, Markus; et al. (2021)
    Journal of Science and Medicine in Sport
    Objectives Regular physical exercise is known to protect endothelial integrity. It has been proposed that acute exercise-induced changes of the (anti-)oxidative system influence early (glycocalyx shedding) and sustained endothelial activation (shedding of endothelial cells, ECs) as well as endothelial-cell repair by circulating hematopoietic stem and progenitor cells (HPCs). However, results are not conclusive and data in trained participants performing different exercise modalities is lacking. Design Eighteen healthy, well-trained participants (9 runners, 9 cyclists; age: 29.7 ± 4.2 yrs) performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with decreasing power profile and 3-min low-intensity in-between. Methods Average power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and shortly after exercise, total oxidative and antioxidative capacities (TAC), shedding of syndecan-1, heparan sulfate, hyaluronan, ECs, and circulating HPCs were investigated. Results TAC decreased from 1.81 ± 0.42 nmol/L to 1.47 ± 0.23 nmol/L post-exercise (p = 0.010) only in runners. Exercise-induced early and sustained endothelial activation were enhanced post-exercise- syndecan-1: 103.2 ± 63.3 ng/mL to 111.3 ± 71.3 ng/mL, heparan sulfate: from 2637.9 ± 800.1 ng/mL to 3197.1 ± 1416.3 ng/mL, both p < 0.05; hyaluronan: 84.3 ± 21.8 ng/mL to 121.4 ± 29.4 ng/mL, ECs: from 6.6 ± 4.5 cells/μL to 9.5 ± 6.2 cells/μL, both p < 0.01; results were not different between exercise modalities and negatively related to TAC concentrations post-exercise. HPC proportions and self-renewal ability were negatively, while EC concentrations were positively associated with circulating hyaluronan concentrations. Conclusions These results highlight the importance of the antioxidative system to prevent the endothelium from acute exercise-induced vascular injury – independent of exercise modality – in well-trained participants. Endothelial-cell repair is associated with hyluronan signaling, possibly a similar mechanism as in wound repair.
  • Thigh muscle activation patterns and dynamic knee valgus at peak ground reaction force during drop jump landings: Reliability, youth competitive alpine skiing-specific reference values and relation to knee overuse complaints
    Item type: Journal Article
    Ellenberger, Lynn; Casutt, Selina; Fröhlich, Stefan; et al. (2021)
    Journal of Science and Medicine in Sport
    Objectives (1) To evaluate the reliability of quantifying thigh muscle activation patterns and dynamic knee valgus during drop jump landings, (2) to provide reference values for female and male youth alpine skiers, and (3) to study their associations with age, anthropometrics, biological maturation and knee overuse complaints. Design Cross-sectional biomechanical experiment including questionnaires. Methods One hundred fourteen skiers of the under 16 category (main experiment) and twelve healthy participants (reliability experiment) volunteered. Quadriceps-to-hamstring-activation ratio and medial knee displacementat peak ground reaction force during drop jump landings were measured using marker-based motion analysis, force plates and electromyography. Additionally, age, anthropometrics, biological maturation and knee overuse complaints were assessed. Results There were good test–retest reliabilities and moderate standardized typical errors for both quadriceps-to-hamstring-activation ratio (intraclass correlation coefficient(3,1) = 0.84 [95% confidence interval: 0.69, 0.94]; standardized typical errors = 0.43 [0.35, 0.56]) and medial knee displacement (intraclass correlation coefficient(3,1) = 0.87 [0.74, 0.95]; standardized typical errors = 0.39 [0.32, 0.50]). Male skiers had a significantly higher quadriceps-to-hamstring-activation ratio (3.9 ± 2.0 vs. 2.9 ± 1.4, p = 0.011), whilst medial knee displacement was comparable to females (12 mm ± 11 mm vs. 13 mm ± 9 mm; p = 0.419). In male skiers, medial knee displacement correlated with anthropometrics and maturity offset; in female skiers, quadriceps-to-hamstring-activation ratio and medial knee displacement were associated with knee overuse complaints (p < 0.05). Conclusions Female and male youth skiers use different thigh muscle activation strategies, but show comparable dynamic knee valgus motions during drop jump landings. In females, a combination of increased relative quadriceps activity and medial knee displacement may favour knee overuse complaints.
  • Sex differences in quadriceps and inspiratory muscle fatigability following high-intensity cycling
    Item type: Journal Article
    Beltrami, Fernando G.; Schaer, Corina E.; Spengler, Christina M. (2023)
    Journal of Science and Medicine in Sport
    Objectives As females have been hypothesized to have more fatigue resistant inspiratory muscles, this study aimed to compare the development of inspiratory and leg muscle fatigue between males and females following high-intensity cycling. Design Cross-sectional comparison. Methods 17 healthy young males (27 ± 6 years, V̇O2peak 55 ± 10 ml･min−1･kg−1) and females (25 ± 4 years, V̇O2peak 45 ± 7 ml･min−1･kg−1) cycled until exhaustion at 90% of the peak power output achieved during an incremental test. Changes in quadriceps and inspiratory muscle function were assessed via maximal voluntary contractions (MVC) and assessments of contractility via electrical stimulation of the femoral nerve and cervical magnetic stimulation of the phrenic nerves. Results Time to exhaustion was similar between sexes (p = 0.270, 95% CI − 2.4 – 0.7 min). MVC of the quadriceps was lower after cycling for males (83.9 ± 11.5% vs. 94.0 ± 12.0% of baseline for females, p = 0.018). Reductions in twitch forces were not different between sexes for the quadriceps (p = 0.314, 95% CI − 5.5 – 16.6 percent-points) or inspiratory muscles (p = 0.312, 95% CI − 4.0 – 2.3 percent-points). Changes in inspiratory muscle twitches were unrelated to the different measures of quadriceps fatigue. Conclusion Females incur similar peripheral fatigue in the quadriceps and inspiratory muscles compared with men following high-intensity cycling, despite smaller reduction in voluntary force. This small difference alone does not seem sufficient to warrant different training strategies to be recommended for women.
  • The FADIR test accuracy for screening cam and pincer morphology in youth ice hockey players
    Item type: Journal Article
    Casartelli, Nicola C.; Brunner, Romana; Maffiuletti, Nicola A.; et al. (2018)
    Journal of Science and Medicine in Sport
  • The comfort, acceptability and accuracy of energy expenditure estimation from wearable ambulatory physical activity monitoring systems in soldiers
    Item type: Other Journal Item
    Wyss, Thomas; Roos, Lilian; Beeler, Nadja; et al. (2017)
    Journal of Science and Medicine in Sport
  • Validation of the GT3X ActiGraph in children and comparison with the GT1M ActiGraph
    Item type: Journal Article
    Hanggi, Johanna M.; Phillips, Lisa R. S.; Rowlands, Alex V. (2013)
    Journal of Science and Medicine in Sport
  • Effects of the Elevation Training Mask® 2.0 on dyspnea and respiratory muscle mechanics, electromyography, and fatigue during exhaustive cycling in healthy humans
    Item type: Journal Article
    Boyle, Kyle G.; Napoleone, Gabby; Ramsook, Andrew H.; et al. (2022)
    Journal of Science and Medicine in Sport
    Objectives Examine the effects of the Elevation Training Mask® 2.0 (ETM) on dyspnea, and respiratory muscle function and fatigue during exercise. Design Randomized crossover. Methods 10 healthy participants completed 2 time-to-exhaustion (TTE) cycling tests while wearing the ETM or under a sham control condition. During the sham, participants were told they were breathing air equivalent to “9000 ft” (matched to the selected resistance valves on the ETM according to the manufacturer), but they were breathing room air. Dyspnea and leg discomfort were assessed using the modified 0–10 category-ratio Borg scale. Qualitative dyspnea descriptors at peak exercise were selected from a list of 15. Crural diaphragmatic electromyography (EMGdi) and transdiaphragmatic pressure (Pdi) were measured via a multipair esophageal electrode balloon catheter. Participants performed maximal respiratory maneuvers before and after exercise to estimate the degree of respiratory muscle fatigue. Results Exercise with the ETM resulted in a significant decrease in TTE (p = 0.015), as well as increased dyspnea at baseline (p = 0.032) and during the highest equivalent submaximal exercise time (p = 0.0001). The increase in dyspnea with the ETM was significantly correlated with the decrease in exercise time (r = 0.73, p = 0.020). EMGdi and Pdi were significantly increased with the ETM at all time points (all p < 0.05). There was a significant increase in the selection frequency of “my breath does not go in all the way” at peak exercise with the ETM (p = 0.02). The ETM did not induce respiratory muscle fatigue. Conclusions Exercising with the ETM appears to decrease exercise performance, in part, by increasing the sensation of dyspnea.
Publications1 - 9 of 9