Methods Seventy-five women with RA according to the 1987 ACR criteria were examined. Mean age was 62 ± 13 years, median disease duration 11 (1–51) years. Sixty-three were or had been on steroids [median cumulative prednisolone dose 2.5 (0.05–66) g]. Sixty-seven age-, weight- and height-matched healthy women served as controls. Maximal voluntary knee extensor and flexor strength (Nm) was assessed at 30o/s by an isokinetic dynamometer. Walking ability was expressed as walking and stair climbing speed (m/s). Markers of disease activity included number of swollen and tender joints, pain as recorded by the patients on a visual analogue scale (VAS), and disability as scored by the Stanford Health Assessment Questionnaire (HAQ). Statistics: non-parametric.

Results Muscle strength, walking speed and stair climbing speed were on average reduced by 30%, 28% and 54% (p < 0.0001), respectively, compared to the controls. Significant correlations were found between knee extensor strength and walking speed (r = 0.79, p < 0.0001) and stair climbing speed (r = 0.69, p < 0.0001). Similar correlations were found for flexor strength. The correlations remained significant (Rpartial ranging from 0.64 to 0.69, p < 0.0001) in multiple regression analyses adjusting for age, height, weight, disease duration, number of swollen and tender joints, VAS- and HAQ-score.

Conclusion In conclusion, leg muscle strength is considerably reduced and is an important determinator of walking ability in RA.