Passe Dennis, Horn Mary, Stofan John, Horswill Craig, Murray Robert
Gatorade Sports Science Institute, Barrington, IL 60010, USA.
Int J Sport Nutr Exerc Metab. 2007 Jun;17(3):284-95. doi: 10.1123/ijsnem.17.3.284.
This study investigated the relationship between runners' perceptions of fluid needs and drinking behavior under conditions of compensable heat stress (ambient temperature = 20.5 +/- 0.7 degrees C, 68.9 degrees F; relative humidity = 76.6%). Eighteen experienced runners (15 men, 40.5 +/- 2.5 y, and 3 women, 42 +/- 2.3 y) were given ad libitum access to a sports drink (6% carbohydrate-electrolyte solution) at Miles 2, 4, 6, and 8. After the run (75.5 +/- 8.0 min), subjects completed questionnaires that required them to estimate their individual fluid intake and sweat loss. Dehydration averaged 1.9% +/- 0.8% of initial body weight (a mean sweat loss of 21.6 +/- 5.1 mL.kg-1.h-1). Subjects replaced only 30.5% +/- 18.1% of sweat loss and underestimated their sweat loss by 42.5% +/- 36.6% (P <or= 0.001). Subjects' self-estimations of fluid intake (5.2 +/- 3.2 mL.kg-1.h-1) were not significantly different from actual fluid intake (6.1 +/- 3.4 mL.kg-1.h-1) and were significantly correlated (r = 0.63, P = 0.005). The data indicate that even under favorable conditions, experienced runners voluntarily dehydrate (P <or= 0.001), possibly because they are unable to accurately estimate sweat loss and consequently cannot subjectively judge how much fluid to ingest to prevent dehydration. This conclusion suggests that runners should not depend on self-assessment to maintain adequate hydration, underscores the need for runners to enhance their ability to self-assess sweat losses, and suggests that a predetermined regimen of fluid ingestion might be necessary if they wish to maintain more optimal hydration.
本研究调查了在可补偿热应激条件下（环境温度 = 20.5±0.7摄氏度，68.9华氏度；相对湿度 = 76.6%）跑步者对液体需求的感知与饮水行为之间的关系。18名有经验的跑步者（15名男性，40.5±2.5岁，3名女性，42±2.3岁）在第2英里、第4英里、第6英里和第8英里处可随意饮用运动饮料（6%碳水化合物 - 电解质溶液）。跑步结束后（75.5±8.0分钟），受试者完成问卷，要求他们估计自己的液体摄入量和出汗量。脱水平均为初始体重的1.9%±0.8%（平均出汗量为21.6±5.1毫升·千克⁻¹·小时⁻¹）。受试者仅补充了出汗量的30.5%±18.1%，且对出汗量的低估了42.5%±36.6%（P≤0.001）。受试者对液体摄入量的自我估计（5.2±3.2毫升·千克⁻¹·小时⁻¹）与实际液体摄入量（6.1±3.4毫升·千克⁻¹·小时⁻¹）无显著差异，且显著相关（r = 0.63，P = 0.005）。数据表明，即使在有利条件下，有经验的跑步者也会主动脱水（P≤0.001），可能是因为他们无法准确估计出汗量，因此无法主观判断应摄入多少液体以防止脱水。这一结论表明，跑步者不应依赖自我评估来维持充足的水合作用，强调了跑步者提高自我评估出汗量能力的必要性，并表明如果他们希望维持更理想的水合状态，可能需要预先设定液体摄入方案。
