The relationship between the leg muscle strength and physical capacity in patients with rheumatoid arthritis, with reference to the influence of corticosteroids

Abstract

It has been shown that patients with rheumatoid arthritis have weak muscles, especially when they are treated with corticosteroids. Forty-six female patients suffering from rheumatoid arthritis were evaluated with regard to the physical capacity in the lower legs by measuring the walking speed and the climbing performance as correlated to the isokinetic muscle strength of the knee extensors and the plantar flexors. Twenty-six of the patients (average age 60 years, range 34-76) had been treated with corticosteroids. Twenty patients (average age 58 years, range 31-72) had never received corticosteroids. The mean maximal isokinetic muscle strength of the knee extensors in corticosteroid treated patients was 62 +/- 28 Nm (SD) at the angular velocity 30 degrees/s, and the mean maximal isokinetic muscle strength of the plantar flexors in the same group of patients was 33 +/- 21 Nm (SD) at the same angular velocity. Compared to patients with rheumatoid arthritis who had never been treated with corticosteroids the reduction in muscle strength was 37% and 28%, respectively (p less than 0.001 and p less than 0.01). The mean walking speed in patients with corticosteroid treatment was 0.9 m/s, which was a 36% reduction as compared with that found in patients who had not received corticosteroids (p less than 0.01). Half of the patients who had not received corticosteroids were able to climb a 50 cm step, while this was possible in only 16% of the group of corticosteroid-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)