Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, Connecticut, USA.
J Strength Cond Res. 2009 Dec;23(9):2533-41. doi: 10.1519/JSC.0b013e3181b73c3f.
The purpose of this study was to determine the influence of hydration status on pacing of trail runners in the heat (wet bulb globe temperature = 26.2 +/- 1.8 degrees C). A randomized, crossover design was used and the participation occurred within a 2-week period. Seventeen competitive, well-trained distance runners (9 men, 8 women, age 27 +/- 7 years, height 171 +/- 9 cm, weight 64.2 +/- 9.0 kg, body fat 14.6 +/- 5.5%) completed the study. Subjects started maximum effort trials that were either hydrated (HYR) and dehydrated (DHR). Each trial subjects ran three 4-km loops with a 4-minute rest between loops. Significance was set at p < or = 0.05. The DHR had a significantly greater body mass loss at the pre- and posttrial time points (-2.05 +/- 1.25 and -4.3 +/- 1.25%, respectively) vs. HYR (-0.79 +/- 0.95 and -2.05 +/- 1.09%, respectively). Subjects ran the 12 km faster (p < 0.001) in HYR (3,191 +/- 366 seconds) vs. DHR (3,339 +/- 450 seconds). Differences between fastest and slowest loops during HYR (54 +/- 40 seconds) were significantly smaller than DHR (111 +/- 93 seconds; p = 0.041). Additionally, loop times were slower for loop 1 (HYR 1,039 +/- 116 seconds vs. DHR 1,071 +/- 123 seconds; p = 0.028), loop 2 (HYR 1,066 +/- 123 seconds vs. DHR 1,105 +/- 148 seconds; p = 0.01) and loop 3 (HYR 1,081 +/- 132 seconds vs. DHR 1,168 +/- 189 seconds; p = 0.003) when dehydrated. Percent of the race completed by loop as calculated by finishing time was significantly different at loop 2 between HYR (33.6 +/- 0.36%) and DHR (33.1 +/- 0.35%, p = 0.002) and loop 3 (33.8 +/- 0.75% vs. 34.9 +/- 1.35%, respectively, p = 0.01). Total variation from the mean pace for the duration of the HYR compared to the DHR approached significance (p = 0.064). Average percent of variance approached significance between trials (p = 0.057). Differences between the fastest and slowest loops between trials demonstrated an increased ability for hydrated individuals to evenly pace themselves. While total variation from the mean pace was not significantly different, it could have practical applicability. These findings reveal that dehydration is associated with decreases in a runners' ability to evenly pace themselves during a competitive situation.
本研究旨在确定水合状态对热环境下（湿球-黑球温度=26.2±1.8°C）越野跑者配速的影响。采用随机交叉设计，在两周内进行了研究。17 名竞技性、训练有素的长跑运动员（9 名男性，8 名女性，年龄 27±7 岁，身高 171±9cm，体重 64.2±9.0kg，体脂 14.6±5.5%）完成了本研究。受试者开始进行最大努力的试验，要么是水合（HYR），要么是脱水（DHR）。每个试验中，受试者跑三个 4 公里的环，每个环之间休息 4 分钟。设定显著性水平为 p≤0.05。DHR 在试验前和试验后时间点的体重损失明显更大（分别为-2.05±1.25%和-4.3±1.25%），而 HYR 分别为-0.79±0.95%和-2.05±1.09%。在 HYR（3191±366 秒）中，受试者以更快的速度跑完 12 公里（p<0.001），而在 DHR（3339±450 秒）中则较慢。HYR（54±40 秒）最快和最慢的环之间的差异明显小于 DHR（111±93 秒；p=0.041）。此外，脱水时，第 1 环的时间（HYR 1039±116 秒 vs. DHR 1071±123 秒；p=0.028）、第 2 环（HYR 1066±123 秒 vs. DHR 1105±148 秒；p=0.01）和第 3 环（HYR 1081±132 秒 vs. DHR 1168±189 秒；p=0.003）的时间较慢。根据完成时间计算的比赛完成百分比在 HYR（第 2 环 33.6±0.36%）和 DHR（第 2 环 33.1±0.35%，p=0.002）和第 3 环（33.8±0.75% vs. 34.9±1.35%，p=0.01）之间存在显著差异。与 DHR 相比，HYR 期间从平均速度的总变化接近显著性（p=0.064）。试验之间的平均方差接近显著性（p=0.057）。试验之间最快和最慢的环之间的差异表明，水合个体能够更均匀地调整自己的配速，能力有所提高。虽然从平均速度的总变化没有显著差异，但它可能具有实际应用价值。这些发现表明，脱水会导致跑步者在竞争环境中均匀配速的能力下降。
