Effect of muscle strengthening exercises on the muscle strength in patients with osteoarthritis of the knee

The purpose of the present study was to investigate the short-term effects of muscle strengthening exercises on the muscle strength in patients with osteoarthritis (OA) of the knee, and to determine whether the beneficial effects of the exercises on the muscles strength, if any, would be maintained over the long-term. Twenty-six patients (mean: 62.8 years) with mild-to-moderate OA of the knee were instructed to perform the exercises, which consisted of once-weekly facility-based strengthening exercises of the knee extensor and flexor muscles with a Medx knee machine at the intensity of 50% of the maximum peak torque (MPT) measured at the baseline (20 times × 3 sets per week), together with daily home-based isometric strengthening exercises (setting and straight leg raising) of the extensor and flexor muscles of the knee (30 times per day). The beneficial effects of the exercises on the MPT values of both the extensor and flexor muscles of the knee that began to be observed from 3 to 6 months after the start of the exercise regimen, regardless of the gender, age, body mass index, or baseline MPT values of the muscles, were maintained for up to 1–3 years, but tended to be no longer observed at 5 years. The present study showed the short-term efficacy of combined facility- and home-based muscle strengthening exercises for the muscle strength in patients with mild-to-moderate OA of the knee, as well as the loss of the beneficial effect of the exercise regimen on the muscle strength over the long-term.