Effect of Exercise on Different Muscle Diseases

Disease category Nerve or muscle problem Implications

Muscular Dystrophies

Duchenne, Becker, congenital, distal, Emery-Dreifuss, facioscapulohumeral, limb-girdle, myotonic, oculopharyngeal

These are degenerative muscle diseases, meaning the normal ability of muscle to regenerate and repair damage is limited, resulting in a net loss of muscle tissue over time.

Some (BMD, DMD and some LGMD forms) involve fragile membranes around skeletal and/or cardiac muscle fibers.

Many muscular dystrophies (DMD, BMD, some LGMD, EDMD, myotonic MD) involve cardiac muscle deterioration or abnormal heart rhythms.

• Muscle fibers can be damaged by strenuous exercise, and the dam- aged sustained may be permanent.

• In DMD, BMD and the sarcoglycan-deficient LGMDs, exercise involv- ing eccentric (lengthening) contractions is particularly damaging.

• If the heart’s pumping ability or rhythm is affected by the disease, sudden, strenuous exercise could trigger an acute heart problem, respiratory problem or even death. A cardiologist should be consulted before undertaking an exercise program.

Warning signs of an acute cardiac problem are chest pain, shortness of breath, nausea, sweating without strenuous exercise, a feeling of fullness or pressure in the chest, or a gurgling sound durinig breathing (a sign that fluid may be backing up into the lungs).

Motor Neuron Diseases

amyotrophic lateral sclerosis, spinal muscular atrophy (all types), spinal-bulbar muscular atrophy

Nerve cells in the central nervous system (spinal cord and brain) that control muscle movement are lost, leaving muscles “orphaned” and undernourished.

• Theoretically, remaining nerve cells can become overburdened if too much is required of them with exercise.

Inflammatory Myopathies

dermatomyositis, polymyositis

Muscle fibers are attacked by the immune system, causing inflammation and tissue destruction.

• Exercise should vary with disease activity. During severe disease activity, when strength is very poor, assisted or passive range-of-motion exercise can be undertaken. During periods of mild to moderate disease activity, when muscles can work against gravity, light aerobic exercise, isometric strengthening, and active range-of-motion exercise are recommended. When the disease is inactive (in remission), recreational aerobic and progressive resistance exercise are OK.

Diseases of the
Neuromuscular Junction

myasthenia gravis

Communication between nerve fibers • Exercise can be undertaken when the disease is under good con- and muscle fibers is compromised, trol. In periods of acute disease exacerbation, or when the disease in most cases by a mistaken attack is not well controlled, exercise may increase weakness. on the neuromuscular junction by the

• Exhaustion, lasting joint or muscle pain, or shortness of breath
immune system.
means the exercise is too strenuous.

• If on prednisone, mild exercise can help offset side effects, such as weight gain, bone loss, high blood pressure, high blood sugar, depression and anxiety.

Peripheral Nerve Diseases

Charcot-Marie-Tooth disease, Dejerine-Sottas disease,

In CMT, and DSS, nerve fibers and/ or the insulation around them are abnormal, compromising communication to muscle fibers.

• Exercise is good for the heart and lungs but will not overcome muscle wasting, which is the result of damage to nerve fibers and loss of input from the nervous system.

• Low-impact exercise, such as swimming or biking, or yoga, is bet- ter than high-impact exercise

Friedreich’s ataxia

In FA, an abnormal cellular distribution of iron leads to diminished cellular energy production, with damage to the heart and nerves

• Moderate exercise may help slow the loss of motor skills in FA and help offset weight gain.

• Cardiac precautions apply. No exercise should be undertaken with- out consulting a cardiologist.