Otani Hidenori, Goto Takayuki, Kobayashi Yuki, Goto Heita, Shirato Minayuki, Hosokawa Yuri, Tokizawa Ken, Kaya Mitsuharu
Faculty of Health Care Sciences, Himeji Dokkyo University, Himeji, Japan.
National Institute of Technology, Akashi College, Akashi, Japan.
Front Sports Act Living. 2023 Feb 28;5:1147845. doi: 10.3389/fspor.2023.1147845. eCollection 2023.
There are no reports examining the time-of-day effect on team training sessions in the gym without airflow and air conditioning on thermal strain in the summer heat. We investigated this effect during badminton training sessions on a clear summer day.
Nine male high school badminton players (Mean ± SD; age 17.1 ± 0.6 y, height 171 ± 4 cm, body mass 59 ± 7 kg) completed two 2.5-h badminton training sessions in the gym without airflow and air conditioning. The training sessions were started at 0900 h (AM) and 1600 h (PM) on separate days in August. Skin temperatures (chest, triceps, thigh, calf), infrared tympanic temperature, heart rate, thermal sensation and rating of perceived exertion were recorded at rest and at regular intervals during the sessions.
Indoor and outdoor environmental heat stress progressively increased in AM and decreased in PM during the sessions. Ambient temperature (AM 30.1 ± 0.9°C; PM 33.2 ± 1.0°C: < 0.001) and wet-bulb globe temperature (AM 28.1 ± 0.5°C; PM 30.0 ± 0.9°C: = 0.001) during the sessions in the gym were higher in PM than AM. Mean skin temperature (AM 34.2 ± 1.0°C; PM 34.7 ± 0.7°C: < 0.001), infrared tympanic temperature (AM 37.8 ± 0.5°C; PM 38.1 ± 0.4°C: = 0.001) and thermal sensation (AM 2.7 ± 1.4; PM 3.3 ± 1.0: < 0.001) during the sessions were higher in PM than AM. Body heat storage (AM 159 ± 30 W·m; PM 193 ± 30 W·m: < 0.05) was greater in PM than AM. There were no time-of-day differences in the average heart rate (AM 75 ± 4% age-predicted maximal heart rate; PM 76 ± 5 age-predicted maximal heart rate: = 0.534), body mass loss (AM 0.6 ± 0.3 kg; PM 0.8 ± 0.2°C: = 0.079), the volume of water ingested (AM 1.5 ± 0.1 L; PM 1.6 ± 0.3 L: = 0.447) and rating of perceived exertion (AM 16 ± 2; PM 16 ± 3: = 0.281).
This study indicates greater thermal strain in PM trial than in AM trial during team training sessions in the gym without airflow and air conditioning on a clear summer day. Therefore, athletes and coaches of indoor sports should perceive that athletes may be exposed to a greater risk for thermal strain in the late afternoon from 1600 h than in the morning from 0900 h during the sessions in the gym under these conditions.
尚无研究探讨在夏季炎热天气下，没有通风和空调的体育馆内团队训练时段的时间效应与热应激之间的关系。我们在一个晴朗的夏日进行羽毛球训练时对此效应进行了调查。
九名高中男子羽毛球运动员（平均±标准差；年龄17.1±0.6岁，身高171±4厘米，体重59±7千克）在没有通风和空调的体育馆内完成了两次2.5小时的羽毛球训练。训练分别在8月的不同日期上午09:00和下午16:00开始。在休息时以及训练期间每隔一段时间记录皮肤温度（胸部、肱三头肌、大腿、小腿）、红外鼓膜温度、心率、热感觉和主观用力程度分级。
在训练过程中，室内和室外环境热应激在上午逐渐增加，在下午逐渐降低。体育馆内训练时段的环境温度（上午30.1±0.9°C；下午33.2±1.0°C：<0.001）和湿球黑球温度（上午28.1±0.5°C；下午30.0±0.9°C：=0.001）下午高于上午。训练期间的平均皮肤温度（上午34.2±1.0°C；下午34.7±0.7°C：<0.001）、红外鼓膜温度（上午37.8±0.5°C；下午38.1±0.4°C：=0.001）和热感觉（上午2.7±1.4；下午3.3±1.0：<0.001）下午高于上午。下午的身体热量储存（上午159±30W·m；下午193±30W·m：<0.05）大于上午。平均心率（上午75±4%年龄预测最大心率；下午76±5年龄预测最大心率：=0.534）、体重减轻（上午0.6±0.3千克；下午0.8±0.2°C：=0.079）、摄入水量（上午1.5±0.1升；下午1.6±0.3升：=0.447）和主观用力程度分级（上午16±2；下午16±3：=0.281）在一天中的不同时间没有差异。
本研究表明，在晴朗的夏日，没有通风和空调的体育馆内进行团队训练时，下午的热应激比上午更大。因此，室内运动的运动员和教练应该认识到，在这些条件下，下午16:00训练时运动员面临的热应激风险可能比上午09:00更大。
