Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Department of Physical Education, Faculty of Education, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
PLoS One. 2023 Aug 17;18(8):e0290081. doi: 10.1371/journal.pone.0290081. eCollection 2023.
Environmental heat stress impairs endurance performance by enhancing exercise-induced physiological and perceptual responses. However, the time course of these responses during self-paced running, particularly when comparing hot and temperate conditions, still needs further clarification. Moreover, monitoring fatigue induced by exercise is paramount to prescribing training and recovery adequately, but investigations on the effects of a hot environment on post-exercise neuromuscular fatigue are scarce. This study compared the time course of physiological and perceptual responses during a 10 km self-paced treadmill run (as fast as possible) between temperate (25°C) and hot (35°C) conditions. We also investigated the changes in countermovement jump (CMJ) performance following exercise in these two ambient temperatures. Thirteen recreational long-distance runners (11 men and 2 women), inhabitants of a tropical region, completed the two experimental trials in a randomized order. Compared to 25°C, participants had transiently higher body core temperature (TCORE) and consistently greater perceived exertion while running at 35°C (p < 0.05). These changes were associated with a slower pace, evidenced by an additional 14 ± 5 min (mean ± SD) to complete the 10 km at 35°C than at 25°C (p < 0.05). Before, immediately after, and 1 h after the self-paced run, the participants performed CMJs to evaluate lower limb neuromuscular fatigue. CMJ height was reduced by 7.0% (2.3 ± 2.4 cm) at 1 h after the race (p < 0.05) compared to pre-exercise values; environmental conditions did not influence this reduction. In conclusion, despite the reduced endurance performance, higher perceived exertion, and transiently augmented TCORE caused by environmental heat stress, post-exercise neuromuscular fatigue is similar between temperate and hot conditions. This finding suggests that the higher external load (faster speed) at 25°C compensates for the effects of more significant perceptual responses at 35°C in inducing neuromuscular fatigue.
环境热应激通过增强运动引起的生理和感知反应来损害耐力表现。然而，在自我调节的跑步过程中，这些反应的时间进程，特别是在比较热和温和条件时，仍需要进一步阐明。此外，监测运动引起的疲劳对于充分规定训练和恢复至关重要，但关于热环境对运动后神经肌肉疲劳的影响的研究很少。本研究比较了在温和（25°C）和热（35°C）条件下进行 10 公里自我调节跑步机跑步（尽可能快）时的生理和感知反应的时间进程。我们还研究了在这两种环境温度下运动后反跳式跳跃（CMJ）性能的变化。13 名来自热带地区的休闲长跑运动员（11 名男性和 2 名女性）以随机顺序完成了这两个实验试验。与 25°C 相比，参与者在 35°C 时跑步时核心体温（TCORE）暂时升高，且一直感到更用力（p<0.05）。这些变化与较慢的步伐有关，在 35°C 下完成 10 公里的时间比在 25°C 下多 14±5 分钟（平均值±标准差）（p<0.05）。在自我调节跑步之前、之后立即和之后 1 小时，参与者进行 CMJ 以评估下肢神经肌肉疲劳。与运动前值相比，比赛后 1 小时 CMJ 高度降低了 7.0%（2.3±2.4 厘米）（p<0.05）；环境条件不影响这种降低。总之，尽管环境热应激导致耐力表现下降、感知用力增加和核心体温暂时升高，但温和与热条件下运动后神经肌肉疲劳相似。这一发现表明，在 25°C 时更高的外部负荷（更快的速度）补偿了在 35°C 时更显著的感知反应对神经肌肉疲劳的影响。
