Effect of a cooling strategy combining forearm water immersion and a low dose of ice slurry ingestion on physiological response and subsequent exercise performance in the heat.

Although numerous studies have shown the benefits of cooling strategies for reducing thermal strain and subsequent exercise performance in the heat, few studies have focused on a combination of external and internal cooling. Therefore, the purpose of the present study was to examine the impact of a cooling strategy combining forearm water immersion and a low dose of ice slurry ingestion on physiological response and subsequent exercise performance in the heat. Eight non-heat-acclimated males participated in this study. After reaching a rectal temperature of 38.5 °C through a bout of cycling exercise in the heat (35 °C, 60% relative humidity), the participants were subjected to one of the following four conditions for a 15-min period: W: forearm cooling; ICE: ice slurry (-1 °C) ingestion; MIX: both W and ICE, and CON: no cooling intervention. After the intervention, the participants performed time to exhaustion (TTE) cycling exercise at 75% V˙O2max. The rate of decrease in rectal temperature in the MIX group was significantly lower than that in the CON group from 6 min to the end of the cooling intervention period (P < 0.05). In addition, mean skin temperature, heart rate, physiological strain index, and perceptual strain were significantly reduced for MIX and W compared with ICE and CON. However, TTE was longer for ICE compared with the other interventions. These results suggest the effectiveness of the newly developed cooling strategy combining external and internal cooling for reducing thermal strain in a short-term recovery period during exercise in the heat.