Yamaguchi Keiichi, Kasai Nobukazu, Hayashi Nanako, Yatsutani Haruka, Girard Olivier, Goto Kazushige
Graduate School of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan.
Department of Sports Science, Japan Institute of Sports Sciences, Kita-ku, Japan.
Int J Sports Med. 2022 Jul;43(8):708-714. doi: 10.1055/a-1495-5612. Epub 2022 Jan 27.
The aim of the present study was to examine the effects of a combined hot and hypoxic environment on muscle oxygenation and performance during repeated cycling sprints. In a single-blind, counterbalanced, cross-over research design, 10 male athletes performed three sets of 3 × 10-s maximal pedaling interspersed with 40-s recovery between sprints under four different environments. Each condition consisted of a control (CON; 20°C, 20.9% FiO), normobaric hypoxia (HYP; 20°C, 14.5% FiO), hot (HOT; 35°C, 20.9% FiO), and combined hot and normobaric hypoxia (HH; 35°C, 14.5% FiO). Power output and muscle oxygenation were measured. Peak power output was significantly higher in HOT (892±27 W) and HH (887±24 W) than in CON (866±25 W) and HYP (859±25 W) during the first set (p<0.05). The increase in total hemoglobin during recovery periods was larger in HH than in HYP (p<0.05), while change in tissue saturation index was smaller in HYP than in CON and HOT (p<0.05). The findings suggest that the combination of hot and hypoxia during repeated cycling sprints presented different characteristics for muscle metabolism and power output compared to temperature or altitude stressor alone.
本研究的目的是检验热环境与低氧环境相结合对重复自行车冲刺运动期间肌肉氧合及运动表现的影响。在一项单盲、平衡、交叉研究设计中，10名男性运动员在四种不同环境下进行了三组3×10秒的最大蹬踏运动，每组冲刺之间穿插40秒的恢复时间。每种条件包括对照组（CON；20°C，吸入氧分数20.9%）、常压低氧组（HYP；20°C，吸入氧分数14.5%）、热环境组（HOT；35°C，吸入氧分数20.9%）以及热环境与常压低氧相结合组（HH；35°C，吸入氧分数14.5%）。测量了功率输出和肌肉氧合情况。在第一组运动期间，HOT组（892±27W）和HH组（887±24W）的峰值功率输出显著高于CON组（866±25W）和HYP组（859±25W）（p<0.05）。恢复期间总血红蛋白的增加量HH组大于HYP组（p<0.05），而组织饱和度指数的变化HYP组小于CON组和HOT组（p<0.05）。研究结果表明，与单独的温度或海拔应激源相比，重复自行车冲刺运动期间热环境与低氧环境相结合呈现出不同的肌肉代谢和功率输出特征。
