Progressive resistance exercise in women with osteoarthritis of the knee: a randomized controlled trial

Objective: To determine the effect of a progressive resistance exercise (PRE) program on women with osteoarthritis (OA) of the knee. Methods: Eligible subjects included women aged 40 to 70 years with pain between 3 and 8 on a 10-cm pain scale. Among the 144 subjects screened, 60 met the eligibility criteria and were randomized to the experimental group (EG) or control group (CG). Subjects in the EG participated in a 12-week PRE program twice a week and CG remained on a waiting list for physical therapy. The PRE program consisted of strengthening exercises for knee extensors, knee flexors, hip abductors and hip adductors, all performed with 50% and 70% of the one-repetition maximum (1RM) using machines with free weights. Resistance was reevaluated every two weeks. Assessments of pain, muscle strength, walking distance, function and quality of life were performed at baseline, six weeks and 12 weeks by a blinded assessor. Results: Twenty-nine female subjects were randomly assigned to the EG and 31 were randomly assigned to the CG. Repeated-measures ANOVA revealed significantly better results in the EG pain (from 7.0 +/- 1.3 to 4.3 +/- 3.1 in the EG and from 7.0 +/- 1.2 to 6.6 +/- 1.5 in the CG - p<0.001), function (p<0.001), some domains of quality of life (physical function: p=0.002; physical role limitation: p=0.002; and pain: p=0.044) and muscle strength (extensors: p<0.001; flexors: p=0.002; and abductors: p<0.001). Conclusion: The PRE program was effective in reducing pain and improving function, some quality of life domains and strength in women with OA of the knee.