STOCKHOLM, Sweden—Although patients with chronic polymyositis (PM) and dermatomyositis (DM) have been advised to refrain from exercise fearing it could aggravate their disease, an intensive 45-minute resistive exercise program can improve patients' muscle strength and activity limitations without increasing inflammation, according to findings reported in Arthritis & Rheumatism.¹

"This intensive exercise program can be safely used with beneficial effects leading to reduced muscle impairment and, to some extent, reduced activity limitation and disease activity in patients with chronic polymyositis or dermatomyositis," conclude researchers led by Helene Alexanderson, RPT, PhD, of the Karolinska Hospital, in Stockholm, Sweden. However, the program is not set in stone, she notes. "The exercise program may have to be adjusted due to pain levels in joints and tendons for patients with arthritis-associated myositis."

The study included 9 patients (median age 53 years) with chronic PM or DM, who participated in an exercise program for 3 days per week for 7 weeks. The program included a 10-minute warm-up, followed by 45-minutes of exercise targeting the deltoid muscles, quadriceps, latissumus dorsi/biceps, gastricnemius, and trunk muscles. The exercises were performed in three sets, separated by 90-second rests, and ended with a cool-down period of stretching for 5 minutes.

At baseline and after 7 weeks of exercise, researchers administered a six-item core set of disease activity measures and biopsied muscle samples of the vastus lateralis. In addition, assessments of impairment (10 to15 voluntary repetition maximum [VRM], the Functional Index 2 [FI-2], the Grippit, and pain rated on the Borg CR-10 scale), of activity limitation (Myositis Activities Profile), and of participation restriction (impact of disease on patients' well-being) were performed 4 weeks prior to and at baseline, and after 7 weeks of exercise.

First, do no harm

On a group level there were no significant differences between assessments of impairment at 4 weeks before baseline compared with baseline; however, the group improved significantly regarding 10 to 15 VRM and FI-2 (P <.05). All patients responded to impairment reduction and two patients were activity limitation responders. Participation restriction remained unchanged in the group. Two patients were responders to disease activity reduction. Importantly, no patient had signs of increased muscle inflammation in the muscle biopsy sample after 7 weeks of exercise.

The new study is not definitive. "Further studies exploring disease mechanisms causing impairment and evaluating long-term effects of exercise need to be conducted," the study authors conclude.

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Reference

1. Alexanderson H, Dastmalchi M, Esbjörnsson-Liljedahl M, et al. Benefits of intensive resistance training in patients with chronic polymyositis or dermatomyositis. Arthritis Rheum. 2007;57:768-777.