Effects of blood flow restriction exercise with very low load and low volume in patients with knee osteoarthritis: protocol for a randomized trial

BACKGROUND: Knee osteoarthritis (OA) is characterized by chronic pain, physical dysfunction, and reduced quality of life. Low-load resistance exercises with blood flow restriction (BFR) have presented results similar to those of high-intensity resistance exercise (HIRE) without BFR provided that the exercise volume in both is paired. However, it is unclear whether BFR exercise with reduced load and volume generates clinical improvements similar to those of HIRE. The aim of the proposed study is to evaluate the effects of BFR resistance exercise with very low load and low volume against HIRE in patients with knee OA for the outcomes of knee pain, muscle performance, physical function, disease severity, quality of life, perceived exertion during the exercises, adherence, and patient satisfaction with treatment. METHODS: This two-arm, prospectively registered, randomized controlled trial with blinded assessors and volunteers will involve 40 patients with knee OA. Two weekly treatment sessions will be provided for 12 weeks. Patients will perform very low-load (10% of 1-RM) and low-volume BFR exercise or HIRE (60% of 1-RM) for strengthening thigh muscles. The primary outcome will be the knee pain measured after 12 weeks of treatment. The secondary outcomes include knee pain 6 months after randomization, physical function, disease severity, quality of life, muscle performance, knee pain and perceived exertion during exercise, adherence, and patient satisfaction with treatment. DISCUSSION: If the improvements in the outcomes are similar in the two groups, BFR exercise with reduced load and volume may be an interesting alternative in the treatment of knee OA, especially when exercises with high loads generate joint pain. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clínicos (REBEC), RBR-6pcrfm. Registered on July 10, 2018. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-019-3238-2) contains supplementary material, which is available to authorized users.