Short-Term Heat Acclimation and Precooling, Independently and Combined, Improve 5-km Time Trial Performance in the Heat

This study investigated the effect of short-term HA (STHA) combined with mixed methods PC, on endurance running performance and directly compared PC and HA. Nine amateur trained runners completed 5-km treadmill time trials (TTs) in the heat (32° C, 60% relative humidity) under 4 conditions; no intervention (CON), PC, short-term HA (5 days—HA) and STHA with PC (HA + PC). Mean (±SD) performance times were; CON 1,476 (173) seconds, PC 1,421 (146) seconds, HA 1,378 (116) seconds and HA + PC 1,373 (121) seconds. This equated to the following improvements versus CON; PC −3.7%, HA −6.6% and HA + PC −7.0%. Statistical differences were only observed between HA and CON (p = 0.004, d = 0.68, 95% CI [−0.27 to 1.63]) however, similar effect sizes were observed for HA + PC vs. CON (d = 0.70, 95% CI [−0.25 to 1.65]), with smaller effects between PC vs. CON (d = 0.34, 95% CI [−0.59 to 1.27]), HA vs. PC (d = 0.33, 95% CI [−0.60 to 1.26]) and HA + PC vs. PC (d = 0.36, 95% CI [−0.57 to 1.29]). Pilot testing revealed a TT typical error of 16 seconds (1.2%). Precooling offered no further benefit to performance in the acclimated individual, despite modest alleviation of physiological strain. Maintenance of running speed in HA + PC, despite reduced physiological strain, may indicate an inappropriate pacing strategy therefore, further familiarization is recommended to optimize a combined strategy. Finally, these data indicate HA, achieved through cycle training, yields a larger e...
Source: Journal of Strength and Conditioning Research - Category: Sports Medicine Tags: Original Research Source Type: research