Vibration-Based Recovery Interventions Improve Perceived Fatigue, Blood Lactate Clearance, and Isokinetic Muscle Function Following Exercise-Induced Fatigue in Amateur Swimmers

High-intensity or repetitive exercise induces metabolic stress and neuromuscular fatigue in skeletal muscle. Using a within-subjects repeated-measures crossover design, eight male amateur swimmers completed five experimental sessions at one-week intervals. Following an isokinetic fatigue protocol, five recovery interventions were applied in a randomized order: control (NT), foam roller (FR), vibration foam roller (VFR), and whole-body vibration at 12 Hz (WBV-12) and 20 Hz (WBV-20). The isokinetic fatigue protocol produced a significant reduction in bilateral extensor peak torque (229.2 ± 37.8%BW to 189.8 ± 27.5%BW; t(7) = 4.19, p = 0.004, d = 1.48), confirming successful fatigue induction. Outcome measures included visual analog scale (VAS) scores, blood lactate concentration, and knee extensor/flexor peak torque (%BW) assessed at three time points. A two-way repeated-measures ANOVA (intervention × time) revealed significant main effects of recovery methods at the post-recovery time point for VAS scores (F(4,28) = 5.98, p = 0.001, η2g = 0.248), blood lactate (F(4,28) = 5.12, p = 0.003, η2g = 0.226), and isokinetic peak torque (F(4,28) = 10.75, p < 0.001, η2g = 0.226). Post hoc Bonferroni analysis indicated that VFR and WBV-20 produced significantly higher lactate recovery rates than NT. Active recovery interventions produced lower perceived fatigue scores and greater lactate reductions than passive rest; however, individual Bonferroni pairwise comparisons for VAS and blood lactate did not reach adjusted significance, and these findings should be considered preliminary. WBV-20 demonstrated statistically confirmed superiority in isokinetic muscle function recovery (Bonferroni p < 0.05 vs. NT, FR, and VFR), suggesting its potential as an effective post-exercise recovery strategy for neuromuscular restoration.