SNOWMASS, COLO. — Admonitions persist against patients with polymyositis and dermatomyositis engaging in exercise, despite research showing it can be beneficial, Ingrid E. Lundberg, M.D., said at a symposium sponsored by the American College of Rheumatology.
Creatine supplements may also help improve function.
The notion that exercise could aggravate myositis stems in part from observations of muscle inflammation among marathon runners, Dr. Lundberg explained.
No study has ever shown harm with exercise in polymyositis or dermatomyositis patients, and yet medical textbook articles continued to suggest that such patients should avoid exercise, said Dr. Lundberg of the rheumatology unit at Karolinska University Hospital, Stockholm.
Now, a group of researchers including Dr. Lundberg and her colleagues are conducting small studies whose findings challenge the idea that exercise increases inflammation. In fact, many have found that exercise actually improves function.
In one observational study involving 10 patients with stable chronic polymyositis or dermatomyositis following an exercise program, none of the participants developed signs of aggravated disease activity as measured by MRI, plasma creatine phosphokinase level, and biopsy. Instead, all participants had improvements in their muscle function, according to an index test; among six of the patients the improvement was significant, Dr. Lundberg said at the symposium.
The 12-week program involved 15 minutes of resistance strength training and 15 minutes of walking 5 days a week.
In addition, the patients experienced reductions in their “bodily pain,” according to measures on the Short Form 36 health survey questionnaire (Rheumatology 1999;38:608-11).
Another study conducted around the same time assessed the effects of aerobic training rather than strength training. In that investigation, eight patients were assigned to a program that included stationary cycling and step aerobics. They were compared with five control patients given no intervention. At the end of 6 months, the patients who trained had a mean 28% increase in aerobic capacity and a 34% increase in muscle torque strength. They also had a mean 8% decrease in their resting heart rate (Br. J. Rheumatol. 1998;37:1338-42). There was no change in the controls.
Findings from another study, conducted by Dr. Lundberg and her colleagues, suggest that exercise may even be beneficial in early active disease.
In a study presented at the American College of Rheumatology last year, they found that creatine paired with exercise significantly improved muscle function over exercise alone. For that study, 18 patients were assigned to a combination program of creatine and exercise, and 19 patients to exercise alone. The patients assigned to creatine took a loading dose of 30 g/kg a day for 8 days and then a daily dose of 3 g/kg for 6 months.
At follow-up, the patients who took creatine had an average 13% improvement on a test of physical activity that included a 5-minute walking test and climbing stairs. That compared with an average 3% improvement for those in the control group.
Corticosteroid treatment remains the standard initial therapy for polymyositis and dermatomyositis, but physicians should keep in mind that it's not an evidence-based approach, she said. Controlled clinical trials of corticosteroids in these patients have never been conducted, so there are no data on optimal starting dosages, or on how long one should treat before attempting to taper, she said.
Most experts recommend starting prednisone at 40-60 mg daily for about 1 month, and then slowly tapering the corticosteroid while monitoring plasma creatine phosphokinase levels.
Dr. Lundberg, however, said she recommends following muscle function before tapering because muscle function returns more slowly than do normal levels of creatine phosphokinase, and the return of muscle strength may take more than a month.
Studies have shown that 75% of patients respond to corticosteroid therapy, but few recover muscle function fully, and there is a high rate of adverse effects.
Azathioprine, 2 mg/kg a day, can be added to the prednisone to decrease corticosteroid exposure; methotrexate, 7.5-25 mg/wk, also can be effective for patients who do not respond to prednisone.
Any patient who doesn't respond to corticosteroid treatment should have their diagnosis reevaluated before continuing treatment, with either a repeat MRI or a new muscle biopsy, she advised.
Cyclosporine has been shown to be as effective as methotrexate and may even be preferable for those patients with concurrent interstitial lung disease.
Experimental treatments for myositis include tacrolimus, which showed “impressive” results in a small, open-label trial of eight patients who were not responsive to corticosteroids and anti-tumor necrosis factor therapy. However, outcomes involving 13 similar patients at Dr. Lundberg's institution were not as favorable. Of those patients, three had some improvement, but not in muscle function, two worsened, and the rest did not respond. Moreover, muscle inflammation did not appear to be impacted.