Activity modification in heat: critical assessment of guidelines across athletic, occupational, and military settings in the USA

Abstract

Exertional heat illness (EHI) risk is a serious concern among athletes, laborers, and warfighters. US Governing organizations have established various activity modification guidelines (AMGs) and other risk mitigation plans to help ensure the health and safety of their workers. The extent of metabolic heat production and heat gain that ensue from their work are the core reasons for EHI in the aforementioned population. Therefore, the major focus of AMGs in all settings is to modulate the work intensity and duration with additional modification in adjustable extrinsic risk factors (e.g., clothing, equipment) and intrinsic risk factors (e.g., heat acclimatization, fitness, hydration status). Future studies should continue to integrate more physiological (e.g., valid body fluid balance, internal body temperature) and biometeorological factors (e.g., cumulative heat stress) to the existing heat risk assessment models to reduce the assumptions and limitations in them. Future interagency collaboration to advance heat mitigation plans among physically active population is desired to maximize the existing resources and data to facilitate advancement in AMGs for environmental heat.

Keywords: Exertional heat illness; Health; Heat hazard; Policy and procedure; Safety.

Fig. 1

Cartesian coordinate graph displaying factors that influence body heat balance when performing physical activity in the heat. Horizontal axis weighs the degree to which the factor is modifiable (+) or non-modifiable (−). Vertical axis weighs whether the factor is influenced by extrinsic variable (+) or intrinsic variable (−) of the exercising individual

Fig. 2

A model illustrating different time scales of environmental observations and their relations to extreme heat management strategies