No differential effects among cooling strategies on post-exercise core temperature recovery in male athletes

Personal cooling strategies are used to lower body core temperature. This controlled cross-over trial evaluates the efficacy of cooling strategies following exercise-induced heat exposure resulting in increased body temperature. Ten healthy active males (25 ± 3 years, 84.5 kg with interquartile range 81.4-89.4) were randomized to a mixed cooling protocol every week within a five-week period. After completing a 60-minute intervention to increase body core temperature, they participated in one of four cooling interventions in thermoneutral (~24°C, ~45% relative humidity) conditions: (1) cool vest (18°C), (2) damp neck towel (24°C) in combination with forearm water immersion (15°C), 3) a combination of all methods, or 4) no intervention. In addition, 500 mL ice-cold water (0°C) was consumed during each cooling intervention (except for no intervention). Time to reach pre-exercise baseline core temperature and physiological responses (gastrointestinal temp-, skin temp- and heart rate) were measured. No significant differences were found between cooling conditions for heart rate (p ≥ 0.15) and body core temperature (p ≥ 0.18). Median cooling rates ranged between 0.02°C/min and 0.04°C/min across the groups with no significant difference (p = 0.51). Additionally, cooling duration (time to reach pre-exercise core body temperature) was not different between the groups (p = 0.38). Skin temperature decrement between the groups was significantly different (p < 0.001), specifically, control vs. combination (p = 0.029). In conclusion, no significant differences in cooling rate were found between mixed cooling interventions, but in all conditions with an average body core temperature ≥38.3°C gastrointestinal temperature decreased to safe levels within 60 minutes after moving to a thermoneutral room.