Isokinetic and isometric muscle strength in patients with rheumatoid arthritis. The relationship to clinical parameters and the influence of corticosteroid.

The isometric and isokinetic muscle strength of the legs in forty-six women with rheumatoid arthritis was measured using a Cybex II dynamometer. Twenty-six of the patients had been treated with corticosteroid - prednisone - some for several years (mean 8 years, range 1-35). Twenty-three healthy age-matched women served as a comparable group (controls). In patients treated with prednisone the mean maximal isokinetic muscle strength of the knee extensors was between 64 +/- 26 Nm (SD) and 43 +/- 18 Nm (SD) at the preset angular velocities 30 degrees/s and 180 degrees/s, respectively, which was a reduction to 54%-55% of that found in controls (p less than 0.001). In patients who had not received prednisone the mean maximal isokinetic strength was between 99 +/- 39 Nm (SD) and 67 +/- 27 Nm (SD) which was a reduction to 84%-86% of that found in controls (p less than 0.05). The force velocity curve showed a parallel decrease in maximal strength with increasing velocity when comparing patients with rheumatoid arthritis to controls. Also on measuring the isokinetic muscle strength of plantar flexors a significantly lower mean maximal torque was found in patients treated with prednisone, (33 +/- 21 Nm (SD) (p less than 0.01] as compared with a control group (50 +/- 28 Nm (SD]. The patients who had not been treated with prednisone showed a lower, but not significantly lower isokinetic strength of the plantar flexors, 46 +/- 22 Nm (SD) at a corresponding angular velocity, 30 degrees/s.(ABSTRACT TRUNCATED AT 250 WORDS)