Different suggestions for different muscle diseases
… a middle-aged, overweight person with myasthenia gravis who is able to walk?
Unfortunately, even when MG is under control, as it usually is these days thanks to effective medications, lack of endurance when exercising and excess weight gain as a side effect of medication and inactivity remain problematic. People should not exercise to exhaustion but may undertake submaximal aerobic exercise, such as walking, swimming or using a stationary bicycle. It’s also OK to try some mild resistance exercise, using light weights (no more than 5 to 10 pounds) or stretchable bands. Several short periods of exercise are better than one long one.
… an elementary-school child with Duchenne muscular dystrophy who uses a wheelchair occasionally?
The child with DMD who is beginning to need a wheelchair for distances, such as at the mall, is beginning to experience the effects of deteriorating muscle fibers. The fibers are degenerating because they lack dystrophin, which helps keep them intact, and so they’re excessively fragile.
Doctors disagree about exercise in DMD, but most don’t feel a child should become a couch potato. Doing no exercise at all leads to weight gain, depression and stiff joints, and may even contribute to muscle atrophy.
Children with DMD should avoid exercise that involves “eccentric” contractions. This type of exercise can severely damage muscle fibers that may not be able to regenerate. Eccentric muscle contractions occur when muscles are used as brakes, such as when walking down a steep hill or slowly lowering a weight. Weight lifting is an example of an activity that requires a lot of eccentric contractions.
After being cleared by a cardiologist, a child with DMD may undertake submaximal aerobic exercise, such as walking or swimming, while keeping an eye out for warning signs of overexertion. (See “Warning: Read Me First!”) Children with DMD always can do passive or active range-of-motion exercise, and physical therapists often recommend stretching of the heel cords to prevent stiffening of the ankle joints.
… a child with type 2 spinal muscular atrophy who uses a power chair full time?
The child with SMA is in a somewhat different situation from a child with DMD, even though they both may use wheelchairs.
In SMA, which is primarily a disease of the muscle-controlling nerve cells (motor neurons) in the spinal cord, there isn’t as much concern about direct damage to muscles as there is in DMD. If the child is comfortable doing a particular exercise, the exercise is probably all right.
There’s a theoretical concern that exercising too hard or too long with SMA might cause stressed motor neurons to wear out faster than they might otherwise, but that hasn’t been proven.
In general, submaximal aerobic exercise, light resistance exercise and range-of-motion exercise are fine.
… a 25-year-old with Charcot-Marie-Tooth who can walk with the use of ankle-foot orthoses?
CMT is a disease of the peripheral nerves, which are made up of bundles of nerve fibers that connect the spinal cord with the muscles. It causes loss of motor function, particularly in the forearms and hands and in the lower legs and feet, and often some loss of sensation, especially in those areas.
Exercise may not change strength, dexterity or sensation in the affected areas, because the primary problem is faulty maintenance of the nerve fibers themselves or the coating that surrounds them. This type of defect does not respond to exercise. Exercise may help if some component of the weakness is due to disuse.
However, as with any condition in which mobility is impaired, it’s important to keep putting the affected joints through their range of motion. And it’s important for cardiovascular health, psychological health and prevention of obesity to keep moving in general.
Anything someone with CMT can do without causing pain or increased weakness is probably fine, although checking with a physician about any specific situation is always advisable.
… a 10-year-old child with dermatomyositis whose disease has been well controlled by medication for several months, but who still tires easily with any exertion?
Children with DM (and their parents) face a complicated set of problems. In this disease, the person’s immune system mistakenly sets up a severe inflammatory reaction that affects the blood vessels, muscle fibers, joints, skin and sometimes other organs. Chronic fever is not uncommon, and some patients feel lethargic much of the time.
The goal should be to preserve as much normal growth and development as possible (which requires exercise), stave off excess weight gain from immobility and drug side effects, help joints stay flexible and not exacerbate the inflammatory process (which over-exercising can do). During severe disease activity, when muscles are too weak to work against gravity, a child with DM should do very little exercise other than passive or assisted range of motion.
When the disease has been brought under control to the extent that muscles can work against gravity, children can engage in active range of motion; light aerobic exercise, (such as walking or swimming); and mild strengthening exercise, such as using a stretchable therapeutic band.
… a 20-year-old male college student with McArdle disease?
McArdle disease, which is caused by the lack of an enzyme that normally breaks down glycogen (animal starch) to generate energy in muscle cells, poses some unique challenges with respect to exercise.
In McArdle disease, unlike most other neuromuscular disorders, what one can do and what one should do are very different things. Moderate exercise, such as brisk walking, may be achievable but may cause severe muscle injury even if the pain or cramping it causes are tolerable. Weight lifting or picking up a heavy object of any kind can cause more injury than the initial pain might indicate.
In this condition, even mild cramping or burning or aching pain in the muscles can indicate muscle breakdown.
It’s tempting for a young man who may look fit and strong to engage in strenuous workouts or sports, but if that young man has McArdle disease, he should never push past pain.
After exercising moderately for about 10 minutes, the typical McArdle patient is able to tolerate an aerobic activity much more easily. This “second wind” is believed to occur because fuel for energy production in the form of glucose (sugar) has arrived at the muscles through the bloodstream.
The “second wind” phenomenon has led to the idea of boosting energy by ingesting sugar right before exercising, such as a soda or a candy bar. Research confirms that this approach does help with exercise tolerance and injury prevention. However, it also can cause serious weight gain, so its use is limited.
Exercise generally should be limited to submaximal aerobic workouts, as long as they’re comfortable, and perhaps light resistance exercise, lifting no more than 5 to 10 pounds and stopping when pain begins.