Effect of Low-load resistance training with different degrees of blood flow restriction in patients with knee osteoarthritis: study protocol for a randomized trial

Background: Knee osteoarthritis (KOA) is a common degenerative disease that causes pain, functional impairment, and a reduced quality of life. Resistance training is considered an effective approach to reduce the risk factor of muscle weakness in patients with KOA. Blood flow restriction (BFR) with low-load resistance training have better clinical outcomes than low-load resistance training alone. However, the effective degree of BFR with low-load resistance training has not been determined. The purpose of this study will be to evaluate the effectiveness of different degrees of BFR with low-load resistance training in patients with KOA on pain, self-reported function, physical function performance, muscle strength, muscle mass, and quality of life.Methods: This is a study protocol for a single-blind, randomized, controlled trial. One hundred individuals will be indiscriminately assigned into the following groups: two training groups with a BFR at 40% and 80% limb occlusion pressure (LOP), a training group without BFR, and a health education group. The three intervention groups will perform strength training for the quadriceps muscles twice a week for 12 weeks. The health education group will attend sessions once a week for 12 weeks. The primary outcomes will include pain, self-reported function, and adverse events. The secondary outcomes will include physical function performance, muscle strength of the knee extensors, muscle mass of quadriceps, and quality of life. The intention-to-treat analysis will be conducted for individuals who withdraw during the trial.Discussion: Previous studies have shown that BFR with low-load resistance training is more effective than low-load resistance training alone; however, a high degree of BFR may cause discomfort during training. If a 40% LOP for BFR will produce similar clinical outcomes as an 80% LOP for BFR, resistance training with a low degree of BFR can be chosen for those patients with KOA who are intolerant to a high degree of BFR.Trial registration: Chinese Clinical Trial Registry, ChinCTR2000037859. Registered on 2 September 2020.