Effects of Quadriceps Strengthening Exercise with Blood Flow Restriction on Knee Angular Velocity, Strength, and Balance in Fencers.

The purpose of this study was to investigate the effects of low-load blood flow restriction (BFR) training on lower limb kinematics during the fencing lunge, quadriceps strength, and balance in collegiate fencers. Sixteen collegiate sabre and epee fencers were randomly assigned to either a BFR group (n = 8) or a general leg extension (GLE) group (n = 8). Both groups performed 6 weeks of leg extension training. The BFR group trained at 30% of 1 repetition maximum (1RM) and the GLE group at 70% of 1RM. Due to dropouts, data from 14 participants were included in the final analysis. Primary outcomes were lower limb kinematics during three defined phases of the fencing lunge, quadriceps isometric strength, and static balance, assessed before and after the intervention. Between-group comparisons of change scores (Δ) were evaluated using effect sizes (Rank-biserial r) with 95% confidence intervals (CIs). Between-group Δ comparisons revealed small-to-large effect sizes favoring BFR across rear leg kinematic variables in all fencing lunge phases (r = 0.24-0.52). The largest effect was observed in rear leg hip flexion angle during Phase 3 (r = 0.52, 95% CI: -0.01 to 0.83). Significant between-group differences were found in front leg knee flexion angle during Phase 2 (p = .043) and rear leg hip extension angular velocity during Phase 3 (p = .029). Both groups showed significant increases in rear leg quadriceps strength (p < .05), with no meaningful changes in static balance. These kinematic improvements are functionally relevant, as greater rear leg hip flexion and faster angular velocity during the fencing lunge are associated with increased propulsive force and more effective lunge execution in competitive fencing. Preliminary evidence suggests that low-load BFR training may produce small-to-large effects on rear leg kinematics during the fencing lunge and may enhance quadriceps strength, providing a safe and practical alternative to high-load training for improving fencing performance.