Effect of hot water immersion at different temperatures during a transition period on vertical jump performance

Increased muscle temperature (Tm) enhances exercise performance but can decrease during the transition period between warm-up and competition. Although passive warming strategies can maintain Tm, the optimal heating temperatures and their effects on performance are unclear. Seventeen healthy males participated in this study with four experimental conditions: no intervention (CON), hot water immersion at 36°C (HWI36), 39°C (HWI39), and 42°C (HWI42) during a 20-min transition period. Vertical jump (VJ) performance, core temperature (Tc), heart rate (HR), and perceived thermal comfort were measured across eight VJ sets (VJ 1-8) performed over 1 h, and biomechanical analyses were conducted to understand the changes in jump performance. The improved VJ performance was primarily due to improved range of motion and concentric muscle contraction. These findings provide valuable insights for the optimization of passive warming strategies in competitive sports.肌肉温度（muscle temperature, Tm）升高可提升运动表现，但在热身与竞技赛事之间的过渡阶段，肌肉温度往往会出现下降。尽管被动热身策略可维持肌肉温度，但其最优加热温度及对运动表现的影响尚不明确。本研究招募17名健康男性受试者，设置四种实验干预条件：无干预组（CON）、36℃热水浸泡组（HWI36）、39℃热水浸泡组（HWI39）、42℃热水浸泡组（HWI42），所有干预均在20分钟的过渡阶段内实施。在持续1小时内完成的8组垂直跳（vertical jump，VJ 1至VJ8）测试中，研究者测定了受试者的垂直跳表现、核心温度（core temperature, Tc）、心率（heart rate, HR）以及主观热舒适度，并开展生物力学分析以探究跳高水平的变化机制。结果表明，垂直跳表现的提升主要源于关节活动范围的改善与向心肌肉收缩能力的增强。本研究结果可为竞技体育中被动热身策略的优化提供宝贵的参考依据。