Predictors of exercise and effects of exercise on symptoms, function, aerobic fitness, and disease outcomes of rheumatoid arthritis

Objective. To determine the effects of participation in a low-impact aerobic exercise program on fatigue, pain, and depression; to examine whether intervention groups compared with a control group differed on functional (grip strength and walk time) and disease activity (total joint count, erythrocyte sedimentation rate, and C-reactive protein) measures and aerobic fitness at the end of the intervention; and to test which factors predicted exercise participation. Methods. A convenience sample of 220 adults with rheumatoid arthritis (RA), ages 40-70, was randomized to 1 of 3 groups: class exercise, home exercise using a videotape, and control group. Measures were obtained at baseline (T1), after 6 weeks of exercise (T2), and after 12 weeks of exercise (T3). Results. Using structural equation modeling, overall symptoms (latent variable for pain, fatigue, and depression) decreased significantly at T3 (P < 0.04) for the class exercise group compared with the control group. There were significant interaction effects of time and group for the functional measures of walk time and grip strength: the treatment groups improved more than the control group (P <= 0.005). There were no significant increases in measures of disease activity. Fatigue and perceptions of benefits and barriers to exercise affected participants' amount of exercise, supporting previous research. Conclusion. This study supported the positive effects of exercise on walk time and grip strength, and demonstrated that fatigue and perceived benefits/barriers to exercise influenced exercise participation. Furthermore, overall symptoms of fatigue, pain, and depression were positively influenced in this selective group of patients with RA ages 40-70 years.