Effects of Repeated Contrast Therapy on Forearm Microcirculatory and Neuromechanical Recovery After Climbing-Specific Fatigue in Amateur Climbers: A Randomized Controlled Trial

Objective: To determine whether contrast therapy improves recovery after climbing-specific forearm fatigue in amateur climbers. Methods: In a randomized repeated-measures trial, 40 climbers were allocated to passive recovery (n = 20) or Game Ready contrast therapy (n = 20). Both groups completed a fixed-task intermittent fingerboard protocol on a 20 mm edge using a half-crimp grip, with 7 s of work and 3 s of rest for five sets; the load was not individualized to climbing-specific maximal finger-flexor force. The intervention group received bilateral forearm treatment consisting of alternating 1 min cold (3 °C) and heat (45 °C) phases combined with pneumatic compression ranging from 15 to 75 mmHg. Sessions lasted 20 min and were administered immediately after post-fatigue testing, at 24 h and 48 h, and then three times weekly on alternate days for 8 weeks, for a total of 27 sessions. Outcomes were assessed at baseline, immediately after fatigue, at 24 h and 48 h, and after 8 weeks. Outcomes included perfusion, reactive hyperemia, stiffness, pressure pain threshold, grip strength, perceived recovery, creatine kinase, and interleukin-6. Results: Immediate post-fatigue responses were comparable. Contrast therapy produced greater 24 h and 48 h resting perfusion responses (+7.28 percentage points, 95% CI 6.58 to 7.98; +7.62, 95% CI 6.94 to 8.31; both adjusted p < 0.001). At week 8, peak hyperemic perfusion improved more with contrast therapy (+6.21 PU, 95% CI 5.62 to 6.79; p < 0.001). Recovery favored contrast therapy for stiffness at 48 h (−71.7 N/m, 95% CI −75.6 to −67.8), pressure pain threshold at week 8 (+8.1 N/cm2, 95% CI 7.3 to 8.8), and grip strength at 48 h (+7.8 kgf, 95% CI 7.3 to 8.3; all p < 0.001). CK and IL-6 differences were transient, and no serious adverse events or intervention-related discontinuations were recorded. Conclusions: Contrast therapy was associated with more favorable cutaneous perfusion, post-occlusive reactive hyperemia-derived, and neuromechanical recovery outcomes, whereas biochemical differences were limited and time-dependent. The vascular findings do not establish improved endothelial function or nitric-oxide-mediated vasodilation because these mechanisms were not directly assessed. Trial registration: ISRCTN49499065 on 23 June 2025.