Ice Slurry and Cold Drink Reduces Exercise Induced Physiological Strain in the Heat

Purpose: To determine the effects of an ice slurry beverage on heat strain and thermoregulatory responses during prolonged exercise in the heat. Methods: Twenty males consumed slurry (ICE, -1.4 ± 0.2 °C), cold drink (COLD, -0.7 ± 0.2 °C), or room temperature drink (RT, 21.5 ± 1.0 °C), while walking at 50% of VO2max for 90 minutes in the heat (43.3 °C and 40% humidity). Heart rate (HR), core temperature (Tc), skin temperature (Ts), physiological strain index (PSI), sweat rate, and ratings of perceived exertion (RPE) were recorded. Results: Tc was lower at minutes 30, 60, and 90 during ICE (37.8 ± 0.1 °C, 38.3 ± 0.1 °C, 38.5 ± 0.1 °C) and COLD (37.8 ± 0.1 °C, 38.3 ± 0.1 °C, 38.7 ± 0.1 °C) vs. RT (37.9 ± 0.1 °C, 38.6 ± 0.1 °C, 39.2 ± 0.1 °C). HR was lower during ICE (138 ± 3) vs. RT (145 ± 3). PSI was lower in ICE at minutes 30, 60, and 90 (8.0 ± 0.3, 9.2 ± 0.4, 10.0 ± 0.4) and minutes 60 and 90 (9.2 ± 0.5, 10.0 ± 0.7) for the COLD compared to RT (8.4 ± 0.3, 10.3 ± 0.4, 11.5 ± 0.5). Ts and RPE were lower in the COLD vs. RT during the latter portion of the exercise. Sweat rate was lower during the ICE (11.81 ± 0.48 g·m-2·min-1) compared to the COLD (12.16 ± 0.51 g·m-2·min-1) and RT (12.95 ± 0.56 g·m-2·min-1). Conclusion: Ice slurry or a cold drink, reduces physiological strain during exercise in the heat and may act to decrease the acute risk for heat related injury