Effect of low-intensity resistance training with blood flow restriction on isometric quadriceps peak torque in knee osteoarthritis

Background: Knee osteoarthritis (OA) is one of the most common chronic progressive diseases impacting people worldwide. Quadriceps muscle weakness contributes to knee-OA-related functional decline. Traditional interventions aimed at increasing muscle strength in knee-OA commonly involve high-intensity resistance training but may result in joint pain due to high compressive forces. An isometric test may be better performed with a lower level of fatigue and obtain greater tolerance for knee-OA subjects due to their articular manifestations. Current recommendations for knee-OA include low-intensity resistance training (LI-RT) performed with blood flow restriction (BFR), a potential intervention for a patient who does not tolerate high loads due to lower mechanical stress. The aim of this study is to determine the effects of blood flow restriction with a low-intensity resistance training program for six weeks on quadriceps muscle strength using an isokinetic dynamometer in patients with knee OA. Methods: Twenty-eight patients aged 50-70 years old with knee-OA in Physical Medicine and Rehabilitation Outpatient Clinic Soetomo Hospital Surabaya were randomized into the control group (CG) and intervention group (IG). Both groups underwent a 6-week supervised training program consisting of LI-RT (30% 1-RM) two sessions/week. The intervention group received an additional application of blood flow restriction on 1/3 of the upper thigh with 50 mmHg occlusion pressure. Both groups were assessed for muscle strength by isometric quadriceps peak torque using an isokinetic dynamometer before and after the protocol. Results: Significant increases were found for isometric peak torque of quadriceps between pre and post-evaluations for LI-RT +BFR group/IG (p-value 0.000) and LI-RT group / CG (p-value 0.002). There was a significant difference in isometric peak torque improvement between the two groups (p-value 0.043). The efficiency of training time in the blood flow restriction group had a larger effect size value. Conclusion: Low-intensity resistance training with BFR was more effective in enhancing the isometric peak torque of quadriceps compared with the low-intensity resistance training only, so it could be added as an alternative intervention for knee-OA patients.