Practical neck cooling and time-trial running performance in a hot environment.

The aim of this two-part experiment was to investigate the effect of cooling the neck on time-trial performance in hot conditions (~30°C; 50% RH). In Study A, nine participants completed a 75-min submaximal (~60% V(O₂(max)) pre-load phase followed by a 15-min self-paced time-trial (TT) on three occasions: one with a cooling collar (CC(90)), one without a collar (NC(90)) and one with the collar uncooled (C(90)). In Study B, eight participants completed a 15-min TT twice: once with (CC(15)) and once without (NC(15)) a cooling collar. Time-trial performance was significantly improved in Study A in CC(90) (3,030 ± 485 m) compared to C(90) (2,741 ± 537 m; P = 0.008) and NC(90) (2,884 ± 571 m; P = 0.041). Fifteen-minute TT performance was unaffected by the collar in Study B (CC(15) = 3,239 ± 267 m; NC(15) = 3,180 ± 271 m; P = 0.351). The collar had no effect on rectal temperature, heart rate or RPE. There was no effect of cooling the neck on S100β, cortisol, prolactin, adrenaline, noradrenaline or dopamine concentrations in Study A. Cooling the neck via a cooling collar can improve exercise performance in a hot environment but it appears that there may be a thermal strain threshold which must be breached to gain a performance benefit from the collar.