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To test whether a pneumatic cold-compression system (CC) improves recovery of maximal voluntary contraction (MVC) at 48 h (T4) versus Sham after a standardized hamstring fatigue protocol. Secondary aims were to compare muscle stiffness, microvascular perfusion, pressure pain threshold (PPT), blood lactate, perceived recovery (TQR), and harms across subgroups. This multicenter, randomized, participant- and assessor-blinded, sham-controlled, two-period crossover trial enrolled 80 participants. After fatigue testing, participants received CC (3 °C, 75 mmHg, 10 min twice daily for 3 days) or Sham (15 °C, 15 mmHg). Outcomes were assessed at baseline (T0), post-fatigue (T1), immediately post-first intervention (T2), 24 h (T3), and 48 h (T4). Continuous outcomes were analyzed using mixed-way ANOVA with Population as the between-subject factor and Condition and Time as within-subject factors, followed by Bonferroni-adjusted pairwise comparisons. Paired Cohen’s dz was reported for key within-participant contrasts. TQR was analyzed using rank-based factorial ANOVA, and Borg CR10 scores using ordinal logistic regression. Across populations, MVC was higher under CC than Sham from T2 to T4, with the largest between-condition difference at T4 (all p < .001). Muscle stiffness was lower under CC from T2 to T4 (all p < .001). Microvascular perfusion and pressure pain threshold were higher under CC at T2 - T4 overall (all p < .001), with earlier between-condition differences in MMA athletes and young adults and delayed differences in older adults. Blood lactate was lower under CC only immediately after the first intervention session (T2; p < .001). TQR was higher under CC at T2 - T4 in MMA athletes, at T2 - T3 in older adults, and at T3 only in young adults. No adverse events were reported. CC accelerated recovery after hamstring fatigue, improving strength, stiffness, perfusion, pain thresholds, lactate, and perceived recovery across populations, with earlier benefits in athletes and young adults and delayed but comparable improvements in older adults. Registration: ISRCTN49499065. |
