Efficacy of Blood Flow–Restricted, Low-Load Resistance Training in Women with Risk Factors for Symptomatic Knee Osteoarthritis

ObjectiveTo assess whether concurrent blood flow restriction (BFR) during low-load resistance training is an efficacious and tolerable means of improving quadriceps strength and volume in women with risk factors for symptomatic knee osteoarthritis (OA).DesignRandomized, double-blinded, controlled trial.SettingExercise training clinical research laboratory.ParticipantsWomen over age 45 years with risk factors for symptomatic knee OA.MethodsParticipants were randomized to either low-load resistance training (30% 1RM) alone (control) or with concurrent BFR and completed 4 weeks of 3 times per week leg-press resistance training. Those randomized to BFR wore a cuff that progressively restricted femoral blood flow over the weeks of training. Intergroup differences in outcome measures were compared using regression methods, while adjusting for BMI.Main Outcome MeasuresIsotonic bilateral leg press strength, isokinetic knee extensor strength, and quadriceps volume by magnetic resonance imaging were assessed before and after participation. Secondary measures included lower limb muscle power (leg press and stair climb). Knee pain was assessed to determine tolerance.ResultsOf 45 women who consented to study participation, 40 completed the program. There were no significant intergroup differences in baseline characteristics except that body mass index was lower in the BFR group (P = .0223). Isotonic 1RM improved significantly more in the BFR group (28.3 ± 4.8 kg) than in the control group (15.6 ± 4.5 kg) (P = .0385). Isokinetic knee extensor strength scaled to body mass increased significantly more in the BFR group (0.07 ± 0.03 nm/kg) than in the control group (−0.05 ± 0.03 nm/kg) (P = .0048). Changes in quadriceps volume, leg press power, and knee-related pain did not significantly differ between groups.ConclusionsAddition of BFR to a 30% 1RM resistance training program was effective in increasing leg press and knee extensor strength in women at risk for knee OA, in comparison with the same program without BFR.