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.

Received: 14 November 2024

Accepted after revision: 01 July 2025

Accepted Manuscript online:
01 July 2025

Article published online:
05 September 2025

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