Effect Of Low Load Functional Training Combined With Blood Flow Restriction In Patients With Knee Osteoarthritis

Muscle strength training is an effective treatment for knee osteoarthritis (OA), however, severe knee pain often appears after heavy load training. Nowadays, low load resistance training with blood flow restriction (LLRT+BFR) can achieve comparable outcomes as high load training. However, inconsistent evidence was found for the effects of LLRT+BFR on performance-based daily activities in knee OA patients. PURPOSE: To investigate the effect of LLRT+BFR on pain, physical performance, function, muscle thickness and quality in knee OA patients. METHODS: Forty-two mild to severe knee OA patients were randomized into two groups: LLRT (20-30% 1-RM) with BFR [LLRT+BFR] and without BFR [LLRT]. Both groups received an 8-week supervised functional movement training including squat and lunge. Outcomes including pain, weight-normalized maximum isometric muscle strength (knee extension, knee flexion, hip abduction and hip extension), prediction of 1-RM squat, physical performance (30s sit to stand, 20s stair climbing and 40 m fast-paced walk), The Knee injury and Osteoarthritis Outcome Score (KOOS), quadriceps muscle thickness and muscle echo intensity were tested in 3 timepoints (baseline, 4 weeks and 8 weeks after training). Generalized estimating equations were used to analyze the data. RESULTS: After 4 weeks of training, the LLRT+BFR group demonstrated its superior effects to the LLRT group in decreasing pain during exercise (-40% vs. -25%, p = 0.028), increasing the number of steps during 20s stair climbing (11% vs. 6%, p = 0.021) and knee extension strength (17% vs. 5%, p = 0.022). After 8 weeks of training, LLRT+BFR showed better outcomes than LLRT in decreasing pain during daily activity (-64% vs. -38%, p = 0.013), improving KOOS-sports subscale (39% vs. 16%, p = 0.01), increasing knee flexion strength (36% vs. 19%, p = 0.033), increasing vastus medialis thickness (12% vs. 6%, p = 0.017), decreasing rectus femoris echo intensity (-13% vs. 4%, p < 0.001), and increasing predicted 1-RM squat (85% vs. 49%, p = 0.008). CONCLUSION: LLRT+BFR demonstrated earlier and better effects than LLRT alone on pain reduction, strength gain, and physical performance of daily activities in patients with knee OA. Supported by a NSTC grant (MOST110-2410-H-A49A-513).