Sixty-seven patients with classical or definite rheumatoid arthritis (RA) were studied concerning the effects of standardized physical training on muscle function in the lower extremities. The patients were randomly assigned to four different training groups and were given 6 weeks of training supervised by a physiotherapist at a health care centre. The groups differed according to type (dynamic or static) and extent (12 or 4 times) of training. During this training period as well as for an additional 3 months, the patients carried out programs of exercise at home (either dynamic or static). A significantly greater increase in function during the 6-week period as regards muscle strength, endurance, aerobic capacity, and functional ability was found for the dynamic as compared with the static groups. The findings at follow-up 3 months later were similar. The effectiveness of the programs did not vary with the extent of training. In conclusion, in RA patients, dynamic training gives a greater increase in physical capacity than does static training.