Thermoregulatory Responses of Runners following a Warm-Weather Road Race

Purpose: To quantify the skin temperature changes following intense exercise in warm-weather. Methods: Anterior thermal images and gastrointestinal temperature (TGI) from 20 male runners (mean±SD; 73.5 ± 10.9 kg) participating in a 11.2 km road race were collected before and immediately after the race. Wet-bulb globe temperature (WBGT) and wind speed were recorded at the finish line. Infrared thermal images were divided into 11 distinct regions, superior torso (ST), inferior torso (IT), face (F), right forearm (RF), left forearm (LF), right upper arm (RUA), left upper arm (LUA), right thigh (RT), left thigh (LT), right lower leg (RLL) and left lower leg (LLL). Mean weighted anterior skin temperature (MWST) was calculated via approximation of body surface area. Paired samples t-tests were performed to compare pre- and post-race values. Correlation analysis was performed to evaluate the relationship between MWST and TGI. Results: Mean WBGT was 27.04 ± 1.20 °C. Mean wind speed was 1.38 ± 0.87 km/h. TGI significantly increased from pre- to post-race (pre: 37.18 ± 0.37 °C, post: 39.39 ± 0.73 °C, p\u3c0.001). MWST decreased, approaching significance (pre: 30.46 ± 1.77 °C, post: 29.48 ± 0.95 °C, p=0.059). Mean skin temperature for ST (p=0.001), IT (p\u3c0.001), RUA (p=0.015) and LUA (p=0.004) significantly decreased from pre-race values. There was no relationship between Post-TGI and Post-MWST (r=0.052, p=0.848). Conclusions: Despite a significant increase in TGI, skin temperature decreased compared to pre-race measures. ST, IT, RUA and LUA may represent the areas with the greatest potential for heat loss, given the air to skin temperature gradient