Myasthenia gravis, an autoimmune disorder that results in weakness of the skeletal muscles, can have a severe impact on a person's lifestyle. Muscle strength is typically highest after periods of rest and lowest after periods of exertion. However, a moderate amount of exercise can reduce the intensity and frequency of the recurring bouts of muscle fatigue, because people who are more fit will be more resistant to the disease and experience less severe symptoms. Exercise can also combat the weight gain and bone weakening that are side effects of the steroid-based drugs sometimes prescribed for myasthenia.
Cause of Fatigue
Muscle fatigue in people with myasthenia gravis is the result of blocked nerve signals. In a normally functioning connection between a nerve and a skeletal muscle, the nerve end releases the chemical neurotransmitter acetylcholine, or ACh, into a space called the neuromuscular junction. The ACh then binds to the muscle's ACh receptors, triggering muscle contraction. Myasthenia causes the body to produce antibodies that attack these ACh receptors in the neuromuscular junction. Because many of these receptors become damaged or destroyed in people with myasthenia, the signal for muscle contraction is much less effective than usual, resulting in chronic muscle weakness.
Levels of Exercise
Exercise regimens for people with myasthenia gravis are designed to improve strength and stamina for easier completion of daily tasks. For a person who is extremely weak, exercise may begin with the help of a therapist who can initiate motions that allow for some input from the person. As the person gains strength, he will be able to perform more extensive range-of-motion exercises on his own. Stronger people with myasthenia can carry out more demanding isotonic strengthening exercises. The level of training a person takes on should be determined by the point at which the last repetition is a challenge but not impossible. Aerobic exercises such as running and biking, and other sports such as tennis or softball, are also beneficial forms of exercise. In all cases, the person should rest when she begins to feel tired or worn down.
Avoiding Overexertion
Although exercises can help people with myasthenia maintain their usual lifestyles, it is important for them to avoid overexertion, which can lead to a dangerous level of exhaustion. People with myasthenia can minimize the occurrence of muscle fatigue by investing in household devices and lifestyle choices that decrease the effort needed for everyday tasks and personal hygiene. These conveniences allow people with myasthenia to expend as little energy as possible when their strength is low, or to save their energy for other activities such as planned periods of exercise. Physical exertion in moderation is good; however, excessive strain can have harmful effects such as shortness of breath, difficulty swallowing and vision problems.
Additional Considerations
Extreme temperatures can aggravate the symptoms of myasthenia gravis. It is best to exercise in a stable, moderate climate and to avoid extended exposure outdoors when it is very hot or very cold. It is common for people with myasthenia to feel best and strongest in the morning, so this may be the optimal time for exercise. Taking prescribed myasthenia medications before exercising and staying well hydrated while working out will help prevent muscle fatigue.
