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Int J Sports Med
DOI: 10.1055/a-2647-2236
Training & Testing

Hypoxia Impairs Neuromuscular Function More Than Heat After Incremental Test to Exhaustion

Zhizhong Geng
1   Graduate school, Shanghai University of Sport School of Exercise and Health, Shanghai, China (Ringgold ID: RIN659907)
,
Jinhao Wang
2   Center for Competitive Sports Research, Shanghai Research Institute of Sports Science, Shanghai, China (Ringgold ID: RIN154545)
,
Guohuan Cao
2   Center for Competitive Sports Research, Shanghai Research Institute of Sports Science, Shanghai, China (Ringgold ID: RIN154545)
,
Chenhao Tan
2   Center for Competitive Sports Research, Shanghai Research Institute of Sports Science, Shanghai, China (Ringgold ID: RIN154545)
,
Longji Li
1   Graduate school, Shanghai University of Sport School of Exercise and Health, Shanghai, China (Ringgold ID: RIN659907)
,
Jun Qiu
2   Center for Competitive Sports Research, Shanghai Research Institute of Sports Science, Shanghai, China (Ringgold ID: RIN154545)
› Author Affiliations
Supported by: Science and Technology Innovation Plan Of Shanghai Science and Technology Commission 22dz1204601
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Abstract

Heat stress and hypoxia impair athletic performance through inflammation, muscle injury, and neuromuscular dysfunction. This study examined these effects in 15 endurance athletes (13 males and 2 females, VO2max=59.5±3.9 ml/min/kg) performing incremental load tests to exhaustion under normal (CON), hypoxic (HYP), and high-temperature and humidity (HOT) conditions. Pre- and postexercise assessments, including blood biomarkers, performance, and surface electromyography (sEMG) during the counter-movement jump (CMJ) and isometric mid-thigh pull (IMTP), were conducted under normal conditions. Compared to CON, time to exhaustion was significantly reduced in HYP and HOT (p<0.05). CMJ performance declined under CON and HYP (p<0.05). Force at 200 and 250 ms decreased under both CON and HYP during IMTP (p<0.05). The root mean square (RMS) and the median power frequency (MPF) were decreased under HYP during CMJ and IMTP (p<0.05). In contrast, no significant differences in sEMG and kinetic markers were observed in the HOT (p>0.05). No significant changes in creatine kinase and lactate dehydrogenase levels were observed (p>0.05). Postexercise, tumor necrosis factor-alpha was lower in HYP (p<0.05), while interleukin-6 increased in HOT (p<0.05). Hypoxia impairs neuromuscular function and suppresses inflammation, whereas heat stress induces inflammation without neuromuscular deficits.

Keywords

acute environmental stressors - inflammatory cytokines - neuromuscular fatigue - electromyographic analysis - biomechanical assessment


Publication History

Received: 14 November 2024

Accepted after revision: 01 July 2025

Accepted Manuscript online:
01 July 2025

Article published online:
05 September 2025

© 2025. Thieme. All rights reserved.

Georg Thieme Verlag KG
Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

 

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