Effects of Blood Flow Restriction Training on Strength and Functionality in People With Knee Arthropathies: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials

Background: Previous meta-analyses show contrasting findings regarding the effects of blood flow restriction training (BFRT) in different knee conditions. Furthermore, no previous dose-response analysis has been conducted to determine the dose of BFRT required for maximal strength and functionality adaptations. Objective: To analyze the evidence on the effects of BFRT on strength and functionality in patients with knee osteoarthritis or rheumatoid arthritis through a systematic review with dose-response meta-analysis. Methods: Included studies met the following criteria: participants with knee osteoarthritis or rheumatoid arthritis; low-load resistance BFRT as intervention; control group with traditional moderate or high intensity resistance training (MIRT and HIRT); include muscle strength and functionality as primary and secondary outcome measures, respectively; and only randomized controlled trials. A random-effects and a dose-response model estimated strength and functionality using estimates of the total repetitions performed. Results: We included five studies with a sample of 205 participants. No statistically significant differences were found between BFRT and MIRT or HIRT for strength (SMD = -0.06; 95% CI = -0.78-0.67; and p > 0.05) and functionality (SMD = 0.07; 95% CI = -0.23-0.37; and p > 0.05). We found an inverted U-shaped association between the increase in total repetitions and strength gain and between the increase in total repetitions and functional improvement. Conclusions: People with knee osteoarthritis or rheumatoid arthritis can use low-load BFRT for strength and functionality as a similarly effective alternative to MIRT and HIRT. A total of 2000 repetitions per BFRT program are necessary to maximize strength gains in these patients, while functional improvement requires 1800 total repetitions.