Purpose: This study aimed to evaluate the effect of sustained neck cooling during time trial running in a hot environment.
Methods: Seven nonacclimated, familiarized males completed three experimental 90-min preloaded time trials in the heat (30.4°C ± 0.1°C and 53% ± 2% relative humidity). During one of the trials, the, participants wore a cooling collar from the start (CC); in another, they wore a collar from the start which was replaced at 30-min intervals (CCreplaced); and in the last trial, they wore no collar (NC). Participants ran for 75 min at 60% V˙O2max and then performed a 15-min time trial blinded from the distance ran. Distance ran, rectal temperature, neck skin temperature, HR, fluid loss and consumption, peripheral lactate, glucose, dopamine, serotonin and cortisol, RPE, thermal sensation, and feeling scales were recorded. Significance was set a priori at the P < 0.05 level.
Results: Participants ran further in CC (2779 ± 299 m) compared with NC (2597 ± 291 m, P = 0.007; d = 0.67) and in CCreplaced (2776 ± 331 m) compared with NC (P = 0.008; d = 0.62). There was no difference in the distance covered in CC compared with that in CCreplaced (P = 0.998). The collar lowered neck temperature (P < 0.001) and the thermal sensation of the neck region (P < 0.001) but had no effect on any of the other physiological, endocrinological, or perceptual variables.
Conclusions: Cooling the surface of the neck improves time trial performance in a hot environment without altering physiological or neuroendocrinological responses. Maintenance of a lower neck temperature via the replacement of a CC has no additional benefit to an acute cooling intervention.