Faculty of Physical Activity Sciences, University of Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
Research Center on Aging, University of Sherbrooke, Sherbrooke, QC J1H 4C4, Canada.
Nutrients. 2021 Dec 29;14(1):141. doi: 10.3390/nu14010141.
We compared the effect of programmed (PFI) and thirst-driven (TDFI) fluid intake on prolonged cycling performance and exercise associated muscle cramps (EAMC). Eight male endurance athletes (26 ± 6 years) completed two trials consisting of 5 h of cycling at 61% V˙O2peak followed by a 20 km time-trial (TT) in a randomized crossover sequence at 30 °C, 35% relative humidity. EAMC was assessed after the TT with maximal voluntary isometric contractions of the shortened right plantar flexors. Water intake was either programmed to limit body mass loss to 1% (PFI) or consumed based on perceived thirst (TDFI). Body mass loss reached 1.5 ± 1.0% for PFI and 2.5 ± 0.9% for TDFI ( = 0.10). Power output during the 20 km TT was higher ( < 0.05) for PFI (278 ± 41 W) than TDFI (263 ± 39 W), but the total performance time, including the breaks to urinate, was similar ( = 0.48) between conditions. The prevalence of EAMC of the plantar flexors was similar between the drinking conditions. Cyclists competing in the heat for over 5 h may benefit from PFI aiming to limit body mass loss to <2% when a high intensity effort is required in the later phase of the race and when time lost for urination is not a consideration.
我们比较了程序化（PFI）和口渴驱动（TDFI）液体摄入对长时间骑行表现和运动相关肌肉痉挛（EAMC）的影响。8 名男性耐力运动员（26 ± 6 岁）在 30°C、35%相对湿度下，以 61%的峰值摄氧量进行 5 小时的自行车骑行，随后进行 20 公里计时赛（TT），采用随机交叉序列完成两次试验。在 TT 后，通过缩短的右侧跖屈肌的最大自主等长收缩评估 EAMC。水的摄入量要么按照计划限制体重损失到 1%（PFI），要么根据口渴感（TDFI）摄入。PFI 组的体重损失达到 1.5 ± 1.0%，而 TDFI 组达到 2.5 ± 0.9%（= 0.10）。20 公里 TT 期间的功率输出，PFI（278 ± 41 W）高于 TDFI（263 ± 39 W）（<0.05），但包括排尿休息在内的总表现时间在两种条件下相似（= 0.48）。跖屈肌 EAMC 的发生率在两种饮水条件下相似。在炎热天气中骑行超过 5 小时的自行车运动员，如果在比赛后期需要高强度的努力，并且考虑到因排尿而损失的时间不是问题，那么 PFI 可以限制体重损失<2%，从而从中受益。
