The Effect of Short-Term Heat Acclimation on the Ability of an Individual to Tolerate a Cold Environment

Abstract

Athletic and occupational demands often require individuals to complete their tasks under challenging environmental conditions. During these tasks individuals may neglect nutrition and well-being to prioritize task completion, which can lead to physiological strain (e.g., dehydration and impaired thermoregulation) or even injury. These physiological states can also result in decreased physical and cognitive performance, two key contributors to task completion. Environmental factors such as temperature and humidity impact hydration, energy expenditure, and thermoregulation, thus influencing performance. Heat acclimation (HA) strategies can be implemented to offset these negative environmental factors. Typically, HA adaptations are gained through lab-based protocols which typically require prolonged exposure to a thermally challenging environment across a consistent number of days (i.e., 8-15 days). More recently researchers have tried to optimize these HA strategies by attempting to derive adaptations in the shortest number of days. Short-term heat acclimation (STHA) of just five days is documented as an effective strategy to acquire physiological adaptations from heat exposure, thus improving exercise performance. However, no study has assessed whether the benefits of STHA impact the physiological responses and tolerability of cold environments. Therefore, this study seeks to investigate the effects of STHA on an individual’s ability to tolerate a cold environment. The proposed study will investigate the effects of STHA (5-days of 70-min of exercise in ~40° C and 60% relative humidity) or a control on pre- and post-STHA cold tolerance tests (at ~-1.1° C) to evaluate thermoregulation (core and skin temperature, shivering onset and shivering intensity, and manual dexterity) and perceptive measures of rating of perceived exertion (RPE) and thermal sensation (TSS). Results will contribute towards the understanding of adaptations from heat acclimation and their relation to cold tolerance.