The Physiological and Perceptual Responses During Acute Heat Stress Following Alcohol Consumption

Abstract

Introduction: Alcohol consumption has been suggested to increase the risk of heat-related injury during heat waves, however, current evidence remains inconclusive on the underlying mechanisms. The purpose of the proposed study was to investigate whether alcohol consumption would alter physiological and perceptual responses during heat stress relative to a volume matched placebo. Methods: 5 participants (2 females 25.2±7.8 y; 77.9±23.1 kg; 1.7±0.2 m) have completed two experimental trials presented in random order on separate days. Participants voided their bladder upon arrival to the lab, were instrumented and entered a climate room maintained at 40°C & 25%RH, completed a 20 minute baseline to equilibrate with the environment, and then consumed either i) an alcoholic beverage (ALC, orange juice and 80-proof gin) suffcient to target a blood alcohol concentration of 0.08 mg/ml, or ii) a volume matched placebo (PLA, orange juice and tonic) over 30 minutes, and rested for an additional 120 minutes in the heat. Blood alcohol concentration, core and mean skin temperature, heart rate, blood pressure, thermal comfort, and thermal sensation were assessed before beverage consumption, and every 30 minutes thereafter. Urine production was calculated as the sum of all micturition during and immediately following the heat exposure. Whole-body sweat loss was calculated as the net difference in mass following the 120-min heat exposure accounting for urine output. Results: No differences were observed at baseline for core temperature (PLA: 37.0±0.3°C, ALC: 36.9±0.2°C, P=0.12), heart rate (PLA: 82±10 BPM, ALC: 81±12 BPM, P=0.89), mean arterial pressure (PLA: 95±5 mmHg, ALC: 97±9 mmHg, P=0.61), and thermal comfort (P=0.21) and sensation (P>0.55). Blood alcohol concentration was 0.10±0.02 mg/ml at 30 minutes following alcohol consumption, and remained elevated at 120-min (0.09±0.01 mg/ml). Throughout heat exposure, core (P>0.49) and mean skin (P>0.61) temperature were not different between PLA and ALC. Thermal comfort was not different between PLA and ALC throughout heat exposure (P≥0.16), however a reduced thermal sensation was observed with ALC compared to PLA at 120-min (P=0.02). Heart rate was higher with ALC compared to PLA at 60-min (ALC: 94±12 BPM, PLA: 88±10 BPM, p<0.02), and remained higher with ALC compared to PLA throughout the remaining heat exposure (p<0.001). Mean arterial pressure was lower at 30-min with ALC (86±10 mmHg) compared to PLA (98±5 mmHg, p<0.001), and remained lower with ALC throughout heat exposure (p<0.001). Urine production was not different between PLA (559±254 ml) and ALC (681±101 ml, P=0.32). Whole-body sweat losses were not different between PLA (398±161 g) and ALC (477±242 g, P =0.52). Conclusion: Preliminary results suggest that the consumption of alcohol does not alter whole-body sweating, core and skin temperature, thermal comfort, and urine production during acute heat stress. However, relative to placebo, alcohol consumption increased heart rate and reduced mean arterial pressure during acute heat stress, and reduced thermal sensation. This research was supported by Dr. Ravanelli’s Lakehead University Research Funding and the Natural Sciences and Engineering Research Council of Canada Discovery Grant (PIN#2022-05096). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.