This study sought to (a) estimate how the duration of running influences sweat losses and contributes to the daily fluid requirement, and (b) empirically estimate the drinking rates required to prevent significant dehydration (≥2% body weight as body water). Individual sweating data and running duration were obtained from male (n = 83) and female (n = 36) runners (n = 146 total observations) performing under highly heterogeneous conditions and over a range of exercise durations (33–280 min). Running <60 min/day increased daily fluid needs by a factor of 1.3, whereas running >60 min/day increased the daily fluid need by a factor of 1.9–2.3. Running <60 min/day generally required no fluid intake to prevent significant dehydration before run completion (31/35 runners). In contrast, running >60 min/day required more than 50% replacement of sweating rates to prevent the same (65/111 runners). Overall sweat losses ranged from ∼0.2 to ∼5.0 L/day, whereas the drinking rates required to prevent significant dehydration ranged from 0 to 1.4 L/hr. The characterization of sweat losses, sweat rate, and required drinking among runners in this study indicate wide individual variability that warrants personalized hydration practices, particularly when running is prolonged (>60 min) and performance is important. This study may serve as a useful guidepost for sports dietitians when planning and communicating fluid needs to athletes, as well as complement guidance related to both personalized programmed and thirst-driven drinking strategies.

本研究旨在 (a) 估计跑步持续时间如何影响汗水流失和对每日液体需求的影响，以及 (b) 凭经验估计防止严重脱水所需的饮水率（≥2% 体重作为体水）。从男性 ( n  = 83) 和女性 ( n  = 36) 跑步者 ( n = 146 个总观察值）在高度异质的条件下和一系列运动持续时间（33-280 分钟）内进行。跑步 <60 分钟/天会使每日液体需求增加 1.3 倍，而跑步 >60 分钟/天会使每日液体需求增加 1.9-2.3 倍。跑步<60 分钟/天通常不需要摄入液体以防止在跑步完成前出现严重脱水（31/35 跑步者）。相比之下，跑步 > 60 分钟/天需要更换超过 50% 的出汗率来防止同样的情况（65/111 跑步者）。总体出汗量为 0.2 至 5.0 升/天，而防止严重脱水所需的饮水量为 0 至 1.4 升/小时。出汗量、出汗率、本研究中跑步者的饮酒要求表明个体差异很大，需要进行个性化的补水实践，特别是在跑步时间延长（>60 分钟）且表现很重要的情况下。在计划和向运动员传达液体需求时，这项研究可以作为运动营养师的有用指南，以及与个性化程序和口渴驱动的饮酒策略相关的补充指导。