Foster Josh, Smallcombe James W, Hodder Simon G, Jay Ollie, Flouris Andreas D, Morris Nathan B, Nybo Lars, Havenith George
Environmental Ergonomics Research Centre, School of Design and Creative Arts, Loughborough University, UK.
The University of Sydney, Thermal Ergonomics Laboratory, Faculty of Medicine and Health, Australia.
J Sci Med Sport. 2021 Aug;24(8):824-830. doi: 10.1016/j.jsams.2021.05.002. Epub 2021 May 8.
To derive an empirical model for the impact of aerobic fitness (maximal oxygen consumption; V̇O in mL∙kg∙min) on physical work capacity (PWC) in the heat.
Prospective, repeated measures.
Total work completed during 1 h of treadmill walking at a fixed heart rate of 130 b∙min was assessed in 19 young adult males across a variety of warm and hot climate types, characterised by wet-bulb globe temperatures (WBGT) ranging from 12 to 40 °C. For data presentation and obtaining initial parameter estimates for modelling, participants were grouped into low (n = 6, 74 trials), moderate (n = 8, 76 trials), and high (n = 5, 29 trials) fitness, with group mean V̇O 42, 52, and 64 mL∙kg∙min respectively. For the heated conditions (WBGT 18 to 40 °C), we calculated PWC% by expressing total energy expenditure (kJ above resting) in each trial relative to that achieved in a cool reference condition (WBGT = 12 °C = 100% PWC).
The relative reduction in energy expenditure (PWC%) caused by heat was significantly smaller by up to 16% for the fit participants compared to those with lower aerobic capacity. V̇O also modulated the relationship between sweat rate and body temperature changes to increasing WBGT. Including individual V̇O data in the PWC prediction model increased the predicting power by 4%.
Incorporating individual V̇O improved the predictive power of the heat stress index WBGT for Physical Work Capacity in the heat. The largest impact of V̇O on PWC was observed at a WBGT between 25 and 35 °C.
建立一个关于有氧适能（最大摄氧量；以毫升·千克·分钟为单位的V̇O）对热环境下体力工作能力（PWC）影响的实证模型。
前瞻性重复测量研究。
对19名年轻成年男性进行评估，他们在固定心率130次·分钟的情况下，于跑步机上行走1小时，期间完成的总工作量在多种温暖和炎热气候类型中进行测定，这些气候类型的湿球黑球温度（WBGT）范围为12至40°C。为了呈现数据并获得建模的初始参数估计值，参与者被分为低适能组（n = 6，74次试验）、中适能组（n = 8，76次试验）和高适能组（n = 5，29次试验），各组的平均V̇O分别为42、52和64毫升·千克·分钟。对于热环境条件（WBGT 18至40°C），我们通过将每次试验中的总能量消耗（高于静息状态的千焦数）相对于凉爽参考条件（WBGT = 12°C = 100% PWC）下实现的能量消耗来计算PWC%。
与有氧能力较低的参与者相比，适能参与者因热导致的能量消耗相对减少（PWC%）显著小高达16%。V̇O还调节了出汗率与体温变化之间的关系，随着WBGT升高。将个体V̇O数据纳入PWC预测模型可使预测能力提高4%。
纳入个体V̇O可提高热应激指数WBGT对热环境下体力工作能力的预测能力。在WBGT为25至35°C之间观察到V̇O对PWC的最大影响。
