热环境下越野跑中补水对生理机能和表现的影响。
Influence of hydration on physiological function and performance during trail running in the heat.
机构信息
Department of Kinesiology, University of Connecticut, Storrs, CT 06269-1110, USA.
出版信息
J Athl Train. 2010 Mar-Apr;45(2):147-56. doi: 10.4085/1062-6050-45.2.147.
CONTEXT
Authors of most field studies have not observed decrements in physiologic function and performance with increases in dehydration, although authors of well-controlled laboratory studies have consistently reported this relationship. Investigators in these field studies did not control exercise intensity, a known modulator of body core temperature.
OBJECTIVE
To directly examine the effect of moderate water deficit on the physiologic responses to various exercise intensities in a warm outdoor setting.
DESIGN
Semirandomized, crossover design.
SETTING
Field setting.
PATIENTS OR OTHER PARTICIPANTS
Seventeen distance runners (9 men, 8 women; age = 27 +/- 7 years, height = 171 +/- 9 cm, mass = 64.2 +/- 9.0 kg, body fat = 14.6% +/- 5.5%).
INTERVENTION(S): Participants completed four 12-km runs (consisting of three 4-km loops) in the heat (average wet bulb globe temperature = 26.5 degrees C): (1) a hydrated, race trial (HYR), (2) a dehydrated, race trial (DYR), (3) a hydrated, submaximal trial (HYS), and (4) a dehydrated, submaximal trial (DYS).
MAIN OUTCOME MEASURE(S): For DYR and DYS trials, dehydration was measured by body mass loss. In the submaximal trials, participants ran at a moderate pace that was matched by having them speed up or slow down based on pace feedback provided by researchers. Intestinal temperature was recorded using ingestible thermistors, and participants wore heart rate monitors to measure heart rate.
RESULTS
Body mass loss in relation to a 3-day baseline was greater for the DYR (-4.30% +/- 1.25%) and DYS trials (-4.59% +/- 1.32%) than for the HYR (-2.05% +/- 1.09%) and HYS (-2.0% +/- 1.24%) trials postrun (P < .001). Participants ran faster for the HYR (53.15 +/- 6.05 minutes) than for the DYR (55.7 +/- 7.45 minutes; P < .01), but speed was similar for HYS (59.57 +/- 5.31 minutes) and DYS (59.44 +/- 5.44 minutes; P > .05). Intestinal temperature immediately postrun was greater for DYR than for HYR (P < .05), the only significant difference. Intestinal temperature was greater for DYS than for HYS postloop 2, postrun, and at 10 and 20 minutes postrun (all: P < .001). Intestinal temperature and heart rate were 0.22 degrees C and 6 beats/min higher, respectively, for every additional 1% body mass loss during the DYS trial compared with the HYS trial.
CONCLUSIONS
A small decrement in hydration status impaired physiologic function and performance while trail running in the heat.
背景
大多数现场研究的作者并没有观察到随着脱水程度的增加而导致生理功能和表现下降，尽管精心控制的实验室研究的作者一致报告了这种关系。在这些现场研究中，研究人员没有控制运动强度，而运动强度是调节身体核心温度的已知调节剂。
目的
直接研究适度水缺失对各种运动强度下在温暖户外环境中的生理反应的影响。
设计
半随机交叉设计。
地点
现场。
患者或其他参与者
17 名长跑运动员（9 男，8 女；年龄=27±7 岁，身高=171±9cm，体重=64.2±9.0kg，体脂=14.6%±5.5%）。
干预
参与者在热环境中完成了四次 12 公里跑步（由三个 4 公里的环组成）：（1）水合的，比赛试验（HYR），（2）脱水的，比赛试验（DYR），（3）水合的，亚最大强度试验（HYS），（4）脱水的，亚最大强度试验（DYS）。
主要观察指标
对于 DYR 和 DYS 试验，通过体重损失来衡量脱水情况。在亚最大强度试验中，参与者以适中的速度跑步，根据研究人员提供的速度反馈来加快或减慢速度。通过可摄入的热敏电阻器记录肠道温度，参与者佩戴心率监测器来测量心率。
结果
与 3 天基线相比，DYR（-4.30%±1.25%）和 DYS 试验（-4.59%±1.32%）中的体重损失大于 HYR（-2.05%±1.09%）和 HYS 试验（-2.0%±1.24%）后跑步（P<.001）。参与者在 HYR（53.15±6.05 分钟）中的跑步速度快于 DYR（55.7±7.45 分钟；P<.01），但 HYS（59.57±5.31 分钟）和 DYS（59.44±5.44 分钟）的速度相似（P>.05）。与 HYR 相比，DYR 后肠道温度立即升高（P<.05），这是唯一的显著差异。与 HYS 相比，DYR 在第 2 圈后、跑步后以及跑步后 10 分钟和 20 分钟时肠道温度更高（均 P<.001）。与 HYS 试验相比，在 DYS 试验中每增加 1%的体重损失，肠道温度和心率分别升高 0.22°C 和 6 次/分钟。
结论
在热环境中进行越野跑时，轻微的水合状态下降会损害生理功能和表现。
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