Cluster Training With Blood Flow Restriction in Competitive 200-m Freestyle Swimmers

Blood flow restriction (BFR) training involves the application of pneumatic cuffs to the proximal regions of the limbs to partially restrict arterial inflow and venous return during exercise. Cluster resistance training incorporates brief recovery intervals between small groups of repetitions to reduce fatigue and maintain exercise performance.

This matched, non-randomized controlled study investigated the effects of combining individualized BFR with cluster resistance training on swimming performance, physical fitness, and circulating growth factors in competitive swimmers.

Forty competitive swimmers aged 17-20 years participated in the study. Participants were matched according to sex, baseline 200-m freestyle performance, and standing long jump distance and allocated to two parallel groups: an experimental group (n = 20) performing cluster resistance training with individualized BFR and a control group (n = 20) performing the same training program without BFR.

The intervention lasted 10 weeks, comprising five supervised training sessions per week (50 sessions in total). Each session lasted 100 minutes, consisting of a 15-minute warm-up, an 80-minute main training phase, and a 5-minute cool-down. The main phase included 30 minutes of dry-land cluster resistance training followed by 50 minutes of swimming-specific training.

Dry-land resistance exercises were prescribed at 60-70% of one-repetition maximum (1RM). The experimental group performed the resistance exercises with individualized BFR pressures corresponding to 50% of arterial occlusion pressure (AOP) for the upper limbs and 60% for the lower limbs. The control group performed the same exercises without BFR.

Swimming training intensity was prescribed relative to individually assessed maximal heart rate (HRmax). Weekly intensity targets progressed through 60%, 70%, 75%, 85%, 65%, 80%, 90%, 95%, 100%, and 80% of HRmax across the 10-week intervention. These percentages represented prescribed intensity targets rather than intensities maintained continuously throughout each session.

Swimming performance was assessed using a maximal 200-m freestyle test in a standardized 50-m swimming pool with electronic timing. Additional performance assessments included standing long jump distance, mean 50-m split time during a continuous maximal 150-m swim, and repetitions completed during a cadence-controlled Burpee test.

Resting serum concentrations of fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor A (VEGF-A) were assessed using enzyme-linked immunosorbent assays (ELISA). Post-intervention blood samples were collected under standardized fasting conditions 48 hours after the final training session.

The primary outcome was the change in 200-m freestyle performance time from baseline to Week 10. Secondary outcomes included changes in physical-performance measures and resting serum FGF-2 and VEGF-A concentrations.

The study evaluated whether adding individualized BFR to cluster resistance training was associated with greater improvements in swimming performance and selected physiological responses compared with cluster resistance training alone.