Environmental Extremes Laboratory, Center for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, United Kingdom.
National Sports Institute, Kompleks Sukan Negara, Kuala Lumpur, Malaysia.
J Strength Cond Res. 2018 May;32(5):1366-1375. doi: 10.1519/JSC.0000000000001979.
James, CA, Richardson, AJ, Watt, PW, Willmott, AGB, Gibson, OR, and Maxwell, NS. Short-term heat acclimation and precooling, independently and combined, improve 5-km time trial performance in the heat. J Strength Cond Res 32(5): 1366-1375, 2018-Following heat acclimation (HA), endurance running performance remains impaired in hot vs. temperate conditions. Combining HA with precooling (PC) demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. 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 ergogenic effect than PC on 5-km running performance in the heat, although PC remains beneficial when HA is not possible.
詹姆斯、CA、理查德森、AJ、瓦特、PW、威尔莫特、AGB、吉布森和马克斯韦尔，NS。短期热适应和预冷，单独和联合使用，可提高热环境下的 5 公里计时赛表现。J 力量与调节研究 32（5）：1366-1375，2018-热适应（HA）后，在热环境下，耐力跑步表现仍然受损，而在温带条件下则不受影响。在间歇性冲刺或连续循环运动方案中，将 HA 与预冷（PC）结合使用并没有表现出额外的益处，与耐力跑步相比，这些运动方案中的热应激可能不太严重。本研究调查了短期 HA（STHA）与混合方法 PC 联合使用对耐力跑步表现的影响，并直接比较了 PC 和 HA。9 名业余训练跑步者在热环境（32°C，60%相对湿度）下进行 5 公里跑步机计时赛（TT），在 4 种条件下进行；无干预（CON）、PC、短期 HA（5 天-HA）和 STHA 与 PC（HA + PC）。平均（±SD）表现时间为；CON1,476（173）秒，PC1,421（146）秒，HA1,378（116）秒，HA + PC1,373（121）秒。这相当于与 CON 相比的以下改进；PC-3.7%，HA-6.6%和 HA + PC-7.0%。仅在 HA 与 CON 之间观察到统计学差异（p=0.004，d=0.68，95%CI[-0.27 至 1.63]），然而，HA + PC 与 CON 之间的效应大小相似（d=0.70，95%CI[-0.25 至 1.65]），PC 与 CON 之间的效应较小（d=0.34，95%CI[-0.59 至 1.27]），HA 与 PC 之间的效应（d=0.33，95%CI[-0.60 至 1.26]）和 HA + PC 与 PC 之间的效应（d=0.36，95%CI[-0.57 至 1.29]）。初步测试显示 TT 典型误差为 16 秒（1.2%）。尽管生理应激得到了适度缓解，但预冷对适应个体的表现没有进一步的益处。在 HA + PC 中保持跑步速度，尽管生理应激减轻，可能表明采用了不适当的配速策略，因此，建议进一步熟悉以优化联合策略。最后，这些数据表明，通过循环训练实现的热适应产生的运动表现增益大于预冷，尽管在无法进行热适应时预冷仍然有益。
