Post-exercise home-based hot-bathing with/without light exercise: effects on physiological adaptations to short-term high-intensity resistance training in healthy young men.

BACKGROUND

High-intensity resistance training (RT) improves strength via neuromuscular adaptations but also heightens fatigue, potentially limiting gains. Whether post-exercise, home-based hot-bathing, with or without light-exercise, reduces these limitations and enhances neuromuscular adaptations remains unknown. The aims were: 1) to investigate whether home-based hot-bathing improves muscle strength gain and peripheral/central conditions in response to short-term high-intensity RT, and 2) assess whether combining hot-bathing with light exercise augments these benefits, both in healthy young men.

METHODS

Across two experiments and one supplementary group comparison, 43 young men were assigned to shower (no hot-bathing; n = 10), hot-bathing (40℃, n = 10), hot-bathing + light-exercise (n = 11), or shower + light-exercise (n = 12). Participants completed five sessions of isometric knee-extension training at 75% maximal voluntary contraction (MVC) over two weeks. MVC of the knee extensor, electrically evoked knee extension torque, and voluntary activation (VA) as indices of peripheral and central conditions were measured pre- and post-intervention.

RESULTS

Compared with shower, hot-bathing produced larger MVC gains (p = 0.027; d = 0.92 vs 0.36) and mitigated declines in tetanus torque assessed via electrical stimulation after RT (p < 0.05). VA did not change significantly in any group. Adding light-exercise to hot-bathing did not further improve strength or peripheral/central conditions. However, light-exercise without hot-bathing decreased VA (p = 0.021).

CONCLUSION

Post-exercise, home-based hot-bathing effectively enhanced muscle strength gains and mitigated peripheral fatigue following high-intensity RT. Additional light-exercise conferred no further benefit and might actually increase central fatigue if not combined with hot-bathing. Hot-bathing may serve as a practical recovery strategy to optimize adaptations following intensive RT in healthy young men.