Myopathy and Muscle Disease

Inflammatory myopathies such as polymyositis and dermatomyositis respond to immunosuppression and can improve substantially; metabolic myopathies impose limits on how energy can be used; steroid myopathy improves as the dose comes down; the inherited muscular dystrophies of adult life progress at their own pace. The exercise prescription is different in each, and it cannot be written without the diagnosis.

That is why the neurologist stays in the room. Disease activity, enzyme levels and the drug regimen decide how much load the muscle can take this week, and the programme is adjusted to that rather than to a fixed schedule.

Moderate resistance and endurance training has not been found to accelerate muscle disease, which was the fear for decades, but how much it helps depends on the diagnosis 12. Exercise to exhaustion and heavy eccentric loading of already-weak muscles are avoided, and the line between helpful and harmful training is a matter of dose.

The programme therefore starts below what the patient can do and rises on measured strength and on how the muscle responds over the following days, with hydrotherapy carrying much of the early work because water removes the load of body weight.

Proximal weakness shows up as difficulty rising from a chair, climbing stairs, lifting the arms and turning in bed, and those tasks are trained directly. Where the disease involves the breathing muscles or the swallow, respiratory therapy and speech and language therapy are part of the programme from the start rather than added when a problem appears.

Energy conservation — planning the day so that the muscle is not spent on the wrong things — is taught, because for many patients it changes daily life more than any single exercise.

Strength by dynamometer, timed function tests, walking distance and a fatigue scale, at the start and end of the block. Change is reported as numbers, and the home programme that follows carries the same dose rules so the gains are held without provoking a relapse.

Progressive conditions are reviewed on a schedule, and the programme is rewritten as the disease moves, with equipment provided ahead of need rather than after a fall.

Not equally. In dermatomyositis and polymyositis, a meta-analysis of 19 studies with 298 patients found that exercise moderately improved muscle strength and aerobic capacity without raising muscle enzyme levels, and no disease flares were reported at any stage of the disease 2. The certainty of that evidence was downgraded, but the authors conclude that exercise is probably safe 2.

For inherited muscle diseases the picture is less clear. A Cochrane review of 14 trials found that strength training alone may make little or no difference in facioscapulohumeral and myotonic dystrophy, that aerobic training may improve aerobic capacity in facioscapulohumeral dystrophy, and that the overall evidence remains uncertain 1.