Rodrigues, PatrickLawley, JSZovilé, GCFJaén-Carrillo, D2026-10-302026-10-302025-09-16Rodrigues, P., Lawley, J. S., Zovilé, G. C. F., & Jaén-Carrillo, D. (2025). Hot-water immersion enhances vertical-jump performance, lower-limb power, and stretch-shortening cycle. International Journal of Sports Physiology and Performance, 20(11), 1564-1571. https://doi.org/10.1123/ijspp.2025-01971555-0265https://hdl.handle.net/10289/18728Purpose: This study aimed to (a) examine the effects of hot-water immersion (HWI) on vertical-jump performance, lower-limb power, and stretch-shortening cycle responses and (b) evaluate temperature-dependent responses by comparing 2 HWI conditions (40 °C vs 42 °C). Methods: Twenty healthy, physically active participants (12 male and 8 female; age 25.1 (2.7) y; body mass index 22.6 [1.1] kg/m²) completed countermovement-jump (CMJ) and drop-jump assessments before, after, and 15 minutes after a 45-minute water-immersion session at either 34 °C (control), 40 °C, or 42 °C in a randomized order. CMJ outcomes included jump height, peak force, and peak power, while drop-jump outcomes included jump height, reactive strength index, and vertical stiffness. Results: CMJ height increased following a 45-minute HWI session at both 40 °C and 42 °C (P < .001, d = 1.09; P < .001, d = 1.77), with no differences between the 2 conditions (P = .515). Similar improvements were found for peak power and force. At 15 minutes post–water immersion, all performance measures returned to baseline and did not differ from the control condition. For the drop-jump tests, a main effect of temperature was observed. HWI at 42 °C significantly increased drop-jump height (P = .004; d = 0.71), whereas 40 °C did not (P = .205). Reactive strength index increased following both 40 °C (P = .002; d = 0.74) and 42 °C (P < .001; d = 0.91) conditions. No significant changes were observed in vertical stiffness. Conclusion: Both HWI conditions, 40 °C and 42 °C, improved CMJ performance (height, force, and power) and reactive strength index, while only HWI at 42 °C enhanced drop-jump height. These effects were transient, returning to baseline within 15 minutes postimmersion.enThis is an author’s accepted version of an article published in International Journal of Sports Physiology and Performance. ©The authors 2025.explosive contractionpassive heatingexplosive contractionpassive heatingJournal Article10.1123/ijspp.2025-01971555-027342 Health Sciences4207 Sports Science and Exercise3202 Clinical sciences3208 Medical physiology4207 Sports science and exercise