This study investigated the effects of weight increase of firefighters’ boots on physiological and psychological strain. Seven young males (70.9 ± 4.8 kg in body mass, BM) participated in the following four boot conditions while wearing standard firefighting personal protective equipment: 3.2, 3.9, 4.6, and 5.3 kg (4.5, 5.5, 6.5, and 7.5%BM). The results showed that the four boot conditions resulted in no differences in rectal temperature, mean skin temperature, energy expenditure and overall thermal comfort during walking, while increments in heart rate were greater for 5.3 kg than for other three conditions (P < 0.05). Subjects felt less warm and had less uncomfortable feet during exercise for the 3.2 kg condition compared to the three other heavier conditions (P < 0.05). These results indicate that psychological strain due to the load carried on the feet appeared earlier (between 4.5 to 5.5%BM) than physiological strain in terms of heart rate (between 6.5 to 7.5%BM). We finally suggest a 5% body mass upper limit for boot weight because subjective strain of the feet may be a valuable preliminary alarm for the physiological strain of firefighters wearing heavy boots.

中文翻译：

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穿着3.2至5.3公斤的消防靴时的生理和主观负担

这项研究调查了消防员的靴子增重对生理和心理压力的影响。七名年轻男性（体重70.9±4.8千克，BM）穿着以下标准的个人防护装备参加以下四个启动条件：3.2、3.9、4.6和5.3 kg（4.5、5.5、6.5和7.5％BM） 。结果表明，四种引导条件在行走过程中不会导致直肠温度，平均皮肤温度，能量消耗和整体热舒适度的差异，而5.3 kg的心率增量大于其他三种条件（P <0.05）。与其他三个较重的情况相比，在3.2公斤的情况下，受试者在运动过程中感觉较不温暖，脚部的不适感也较小（P <0.05）。这些结果表明，就心率而言（在6.5％至7.5％BM之间），由于脚上的负荷而引起的心理疲劳比生理性疲劳更早出现（在4.5％至5.5％BM之间）。我们最终建议将靴子的重量限制为5％的体重上限，因为脚的主观应变可能对于穿着厚底靴的消防员的生理应变可能是有价值的初步警报。