Blood flow restriction with different loads versus moderate intensity resistive exercises in patients with knee osteoarthritis: a single-blind randomized controlled trial

Abstract Background Knee osteoarthritis (KOA) is a common condition causing pain, muscle weakness, and functional impairment. In addition, many patients cannot tolerate resistance training due to pain. Blood flow restriction (BFR) has been proposed as a low-load alternative strategy to improve muscle function, but the effectiveness of passive BFR application remains unclear in KOA. Therefore, this study compared passive BFR at 50% and 70% limb occlusion pressure (LOP) with moderate-intensity resistance training (MI-RT) in KOA. Methods A three-arm, parallel groups, single-blind randomized controlled trial was conducted on 75 Patients, aged 45–60 years, diagnosed with KOA. They were randomly assigned to receive 16 sessions (twice weekly for eight weeks) for either the study groups (BFR-50% LOP; BFR-70% LOP) or the control group (MI-RT). The primary outcomes were quadriceps torque and normalized torque. Pain intensity, functional mobility, functional ability, KOA impact, Rate of Perceived Exertion, and global perceived improvement were secondary outcomes. Measures were recorded at baseline, 4, and 8 weeks. Results All interventions produced significant improvements over time across all outcomes ( p < 0.001). Compared with both BFR groups, MI-RT produced greater increases in quadriceps torque than BFR-50% LOP (MD = 18.57 N.m, p < 0.001) and BFR-70% LOP (MD = 13.81 N.m, p = 0.004) at week 8, with significant increases in perceived exertion, whereas no changes in exertion were observed in either BFR group. The BFR-70% LOP group demonstrated greater improvement in lower-extremity functional ability than MI-RT (MD = 6.8 points, p = 0.02) and BFR-50% LOP (MD = 15.9 points, p < 0.001). However, no significant between-group differences were observed for pain intensity, KOA impact, functional mobility, or perceived improvement. Conclusion MI-RT was the most effective intervention for improving quadriceps strength, whereas passive BFR at 70% LOP yielded the greatest improvements in lower-extremity functional ability while requiring less perceived exertion. These findings suggest that passive BFR at 70% LOP may be a feasible rehabilitation option for patients with knee osteoarthritis who cannot tolerate resistive exercise. Passive BFR at 50% LOP produced smaller functional improvements than the other interventions. Trial registration The study was registered at ClinicalTrials.gov (No: NCT06637124) on September 24, 2024. URL: https://share.google/fuSDVPVt2pxG7M1HU .