METHODS: 16 men and 15 women of similar age (69 ± 5 years) were exposed to an air temperature of 39.1 ± 0.3 °C and a relative humidity (RH) of 25.1 ± 1.9%, during 20 min of seated rest and at least 40 min of low-intensity (10 W) cycling exercise. RH was gradually increased by 2% every 5 min starting at minute 30. We measured sweat rate, heart rate, thermal sensation, and the rise in gastrointestinal temperature (Tgi) and skin temperature (Tsk).
RESULTS: Tgi consistently increased from minute 30 to 60, with no significant difference between females and males (0.012 ± 0.004 °C/min vs. 0.011 ± 0.005 °C/min; p = 0.64). Similarly, Tsk increase did not differ between females and males (0.044 ± 0.007 °C/min vs. 0.038 ± 0.011 °C/min; p = 0.07). Females exhibited lower sweat rates than males (0.29 ± 0.06 vs. 0.45 ± 0.14 mg/m2/min; p < 0.001) in particular at relative humidities exceeding 30%. No sex differences in heart rate and thermal sensation were observed.
CONCLUSIONS: Elderly females exhibit significantly lower sweat rates than their male counterparts during low-intensity exercise at ambient temperatures of 39 °C when humidity exceeds 30%. However, both elderly males and females demonstrate a comparable rise in core temperature, skin temperature, and mean body temperature, indicating similar health-related risks associated with heat exposure.
方法:16名年龄相仿(69±5岁)的男性和15名女性暴露于39.1±0.3°C的空气温度和25.1±1.9%的相对湿度(RH),在20分钟的坐着休息和至少40分钟的低强度(10W)自行车运动。在第30分钟开始,RH每5分钟逐渐增加2%。我们测量了出汗率,心率,热感觉,以及胃肠道温度(Tgi)和皮肤温度(Tsk)的升高。
结果:Tgi从30分钟到60分钟持续增加,女性和男性之间没有显着差异(0.012±0.004°C/minvs.0.011±0.005°C/min;p=0.64)。同样,Tsk的增加在女性和男性之间没有差异(0.044±0.007°C/min与0.038±0.011°C/min;p=0.07)。女性的出汗率低于男性(0.29±0.06vs.0.45±0.14mg/m2/min;p<0.001),特别是在相对湿度超过30%时。没有观察到心率和热感觉的性别差异。
结论:当湿度超过30%时,在39°C的环境温度下进行低强度运动时,老年女性的出汗率明显低于男性。然而,老年男性和女性都表现出可比的核心温度上升,皮肤温度,和平均体温,表明与热暴露相关的类似健康风险。