Response to high-intensity eccentric muscle contractions in persons with myopathic disease

Although the response to intense eccentric muscle contractions is well desc ribed in normal subjects, concern exists about possible untoward effects in persons with myopathic diseases. We investigated 14 subjects with slowly p rogressive muscular dystrophies including myotonic muscular dystrophy (n = 9), facioscapulohumeral dystrophy (n = 2), limb-girdle syndrome (n = 2), an d Becker muscular dystrophy (n = 1). Control subjects consisted of 18 able- bodied persons. Subjects performed two sets of eight maximal-effort eccentr ic repetitions of the elbow flexors, with measurement of maximal concentric strength, serum creatine kinase, resting and flexed arm angle, arm circumf erence, and soreness at days 0, 3, and 7. Although the myopathic group had less initial strength, both groups demonstrated a similar response to the p rotocol over 7 days. Both groups had a significant rise in serum creatine k inase, which was still elevated at 7 days (P < 0.05). The control group dem onstrated a slightly greater injury response in terms of soreness, resting and flexed arm angles, and arm swelling. Both groups of subjects appeared t o respond similarly to an acute bout of eccentric contractions. However, th e potential long-term effects of this type of exercise in persons with myop athic diseases remains unknown. (C) 2001 John Wiley & Sons, Inc.