Effectiveness of blood flow restriction (BFR) training on knee stability, strength, and aerobic performance during aerobic cycling exercise in healthy adults: A randomized controlled trial

Introduction: Blood Flow Restriction (BFR) training during strength training has been shown to lead to several physical improvements. However, its use during aerobic exercise has yet to be fully documented. This randomized controlled trial assessed the effects of blood flow restriction (BFR) on balance, knee stability, quadriceps strength, and submaximal VO2 after cycling training. Methods: Fifty-two healthy adults (58% women) were randomly assigned to a control group without BFR (CON) and four BFR groups: 60% occlusion in one (60UNIL) or both legs (60BILAT) and 80% occlusion in one (80UNIL) or both legs (80BILAT). Single-leg balance with eyes open and closed, knee stability (i.e., dynamic knee valgus) during a step-down, isokinetic quadriceps strength at 60°, 180°, and 300°/second, and submaximal VO2 were assessed at baseline, and three- and six-week follow-up. All participants performed cycling training thrice weekly for six weeks, pedaling at 70 revolutions/minute for 15 min. Repeated measures analysis of variance was performed for each outcome measure. Results: Quadriceps strength at 180°/second showed statistically significant changes across time for all groups. Quadriceps strength at 300°/second showed statistically significant differences across time for the 60% occlusion groups. However, only the 60UNIL showed statistically significant changes in quadriceps strength at three weeks. Conclusions: BFR during cycling does not seem to improve balance, knee stability, quadriceps strength at 60°/second, or submaximal VO2. Unilateral BFR with 60% occlusion improved quadriceps strength and endurance three weeks after cycling.