Attenuating inter-limb strength asymmetry: effects of blood flow restriction therapy applied to the weaker lower limb

Abstract Background Inter-limb strength asymmetries are common and can impact functional performance. Blood flow restriction (BFR) training has shown potential to improve strength in the lower limbs, but its effects on reducing asymmetries remain unclear. Aim This study investigated whether a 12-week graded walking program with BFR applied to the weaker lower limb would reduce inter-limb strength asymmetries. Methods A 12-week within-subject, non-randomized intervention study was conducted in healthy asymptomatic adults. Thirty-two participants (20 males, 12 females; 31.1 ± 9.5 years) with inter-limb strength asymmetries ≥ 10% were included. BFR was applied unilaterally to the weaker limb (WL) using a cuff positioned at the gluteal fold and inflated to 90% of each participant’s arterial occlusion pressure (AOP) while the contralateral limb served as the control (CL). Training was performed three times per week (one supervised, two home-based sessions). Isometric knee extensor and flexor strength (assessed using an isokinetic dynamometer) and muscle thickness (assessed by ultrasound) were evaluated before and after the intervention. Results Both limbs showed significant improvements in knee extensor strength ( p < 0.001), with greater gains in the WL (17.5%) vs. CL (6.3%). Knee flexor strength also improved significantly ( p < 0.001) in both limbs, with a small difference between WL (8.7%) and CL (7.4%), suggesting a limited BFR effect. No significant changes in muscle thickness were observed ( p > 0.05). Conclusions A 12-week BFR walking program applied to the weaker limb improved knee extensor strength, particularly in the occluded limb, and reduced inter-limb strength asymmetries. Trial Registration Number Brazilian Registry of Clinical Trials (RBR-5gqgs99), registered November 7th, 2024.