Effects of Acute and Repeated Ischemic Preconditioning on Recovery from Muscle Fatigue after High-Intensity Swim Training in Male Amateur Swimmers.

This study investigated the effects of acute and repeated ischemic preconditioning (IPC) on recovery following high-intensity swim training. Thirty male amateur freestyle swimmers (21 ± 1 years, with at least 2 years of training experience) were randomly assigned to one of three groups: sham IPC (SHAM, n = 10, 4×5 min, 20 mmHg), acute IPC (AIPC, n = 10, 4×5 min, 220 mmHg), or repeated IPC (RIPC, n = 10, 7 days×4×5 min, 220 mmHg). A 7×200m swim incremental load training was conducted 20 minutes after the intervention. External load measures (grip strength, upper limb work, lower limb relative peak torque, average power) and internal load measures [limb circumferences, creatine kinase (CK), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), interleukin-6 (IL-6), C-reactive protein (CRP)] were recorded at baseline, immediately, 24h and 48h post exercise. For external load, RIPC exhibited higher upper limb total work and average power than SHAM at all post-training points (P < 0.05), while AIPC exceeded SHAM at 48h (P < 0.05). For internal load, immediately post-training, RIPC had higher T-AOC, lower MDA and IL-6 than the other two groups (P < 0.05); AIPC showed lower MDA than SHAM (P < 0.05). At 24h, RIPC had higher T-AOC than the other two groups; both RIPC and AIPC had lower MDA and IL-6 than SHAM (P < 0.05). Moreover, RIPC had lower CK than SHAM at 24h and 48h (P < 0.05). Findings indicated that both AIPC and RIPC, compared to SHAM, promoted internal and external recovery following intensive swim training, with RIPC being more effective. These results suggest that incorporating repeated IPC sessions into athletes' training routines could be a practical strategy to optimize recovery and improve subsequent performance.