Regular cycling helps patients with myotonic dystrophy

An older adult uses a stationary bike, assisted or encouraged by another person.

Regular exercise greatly improves mobility in patients with myotonic dystrophy, a disease that causes muscle degeneration, a McMaster-led study finds. (Shutterstock image)

Regular cycling can greatly improve mobility in patients with myotonic dystrophy (MD), a genetic disease that causes muscle degeneration, a study led by McMaster researchers finds.

Cycling for 35 minutes, three times a week, for 12 weeks led to a 32-per-cent increase in overall fitness in people with MD, senior author Mark Tarnopolsky says.

Patients who took part in the study also saw a 1.6-kilogram increase in their muscle mass and a two-per-cent reduction in body fat. They were also able to walk an extra 47 metres in six minutes, when tested by researchers at the end of the 12-week trial.

Tarnopolsky’s team recruited 11 patients with MD to examine how effective cycling was in restoring and maintaining their physical health. Researchers also studied the underlying molecular mechanisms through which exercise strengthens the skeletal muscles, which can be severely weakened by MD.

“Exercise really is medicine — we just need to get the message out,” says Tarnopolsky, a professor of pediatrics and medicine.

“Myotonic dystrophy is a progressive condition that will impair your mobility and can put you in a wheelchair.” There is no cure for it and only regular exercise helps patients achieve better function, Tarnopolsky says.

“MD itself is really a form of accelerated aging,” he says

The study was recently published in The Journal of Clinical Investigation.

Some MD patients are even advised by their doctors not to exercise, for fear of making their condition worse, but that is now proven false, Tarnopolsky says.

Previous research on mouse models showed a range of similar physiological benefits from regular exercise, study authors say.

MD is the most commonly diagnosed type of muscular dystrophy in adults, and the second-most prevalent of all muscular dystrophies, Tarnopolsky says.

MD’s main symptoms include severe skeletal muscle atrophy, general muscle weakness, reduced lung capacity and impaired heart function. Other symptoms may include cataracts, endocrine disorders including diabetes, and gastrointestinal disorders.

Roughly 19,000 Canadians live with MD or another type of muscular dystrophy, Tarnopolsky says.

External funding for this study was provided by the Canadian Institutes of Health Research.

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