School of Health and Human Performance, Dublin City University, Glasnevin, Dublin 9, Ireland.
National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland.
Eur J Appl Physiol. 2022 Oct;122(10):2243-2257. doi: 10.1007/s00421-022-05000-7. Epub 2022 Jul 14.
To investigate the effects of rapid weight loss (RWL), incorporating comparison of hot water immersion (HWI) in fresh or salt water, on changes in body mass, blood markers, and indices of performance in mixed martial arts athletes.
In a crossover design comparing fresh water (FWB) to salt water (SWB; 5.0%wt/vol Epsom salt) bathing, 13 males performed 20 min of HWI (~ 40.3 °C) followed by 40 min wrapped in a heated blanket, twice in sequence (2 h total). Before bathing, ~ 26 to ~ 28 h of fluid and dietary restriction was undertaken, and ~ 24 to ~ 26 h of a high carbohydrate diet and rehydration was undertaken as recovery.
During the entire RWL process, participants lost ~ 5.3% body mass. Body mass lost during the 2 h hot bath protocol was 2.17 ± 0.81 kg (~ 2.7% body mass) and 2.24 ± 0.64 kg (~ 2.8% body mass) for FWB and SWB, respectively (P = 0.647 between trials). Blood urea nitrogen, creatinine, sodium, chloride, hemoglobin, and hematocrit were increased (all P < 0.05), and plasma volume was decreased (~ 14%; P < 0.01), but did not differ between FWB and SWB, and were similar to baseline values after recovery. No indices of performance (e.g., countermovement jump, isometric strength, and functional threshold power) were impacted when RWL was followed by the recovery process.
Under the conditions of this hot bath protocol, fluid loss was not augmented by the addition of ~ 5.0%wt/vol of Epsom salt during HWI, and RWL of ~ 5.3% body mass followed by > 24 h of recovery did not impact indices of performance.
研究快速减重（RWL）的影响，包括比较在淡水或盐水中进行热水浸泡（HWI）对混合武术运动员体重、血液标志物和表现指标的变化。
在一项比较淡水（FWB）和盐水（SWB；5.0%wt/vol 泻盐）沐浴的交叉设计中，13 名男性进行了 20 分钟的 HWI（~40.3°C），然后用加热毯包裹 40 分钟，连续进行两次（总共 2 小时）。在沐浴前，进行了约 26 至 28 小时的液体和饮食限制，以及约 24 至 26 小时的高碳水化合物饮食和再水化作为恢复。
在整个 RWL 过程中，参与者体重减轻了约 5.3%。在 2 小时热水浴方案中，体重减轻量为 2.17±0.81kg（2.7%体重）和 2.24±0.64kg（2.8%体重），分别用于 FWB 和 SWB（试验之间 P=0.647）。血尿素氮、肌酐、钠、氯、血红蛋白和血细胞比容增加（均 P<0.05），血浆容量减少（~14%；P<0.01），但 FWB 和 SWB 之间无差异，并且在恢复后与基线值相似。当 RWL 后进行恢复过程时，没有任何表现指标（例如，反跳跳、等长力量和功能阈值功率）受到影响。
在热水浴方案的条件下，在 HWI 期间添加约 5.0%wt/vol 的泻盐不会增加液体损失，而减轻约 5.3%体重的 RWL 后进行超过 24 小时的恢复不会影响表现指标。
