Muscle fatigue occurs when the muscles cannot exert normal force, or when more effort than normal is required to achieve a desired level of force. There are a number of causes for fatigued muscles, ranging from exercise-induced fatigue to genetic conditions which lead to muscle weakness. Doctors and researchers have conducted a number of studies to learn how and why muscles get tired or fail to function normally, as muscle fatigue is recognized as a physical issue which can be very dangerous for patients.
In the case of exercise-induced fatigue, muscle fatigue is believed to occur when the body temporarily exhausts its supply of energy. Some studies have also implicated disruptions in the flow of calcium through the muscles. Exercise-induced fatigue is usually not treated as a serious medical problem, because it will resolve after rest, and people can train their bodies to get more endurance so that they will not fatigue as quickly. Muscle fatigue is also directly related to the type of exercise someone engages in, and athletes often vary their routines and the intensity of their workouts for this very reason.
When physical exertion is not the obvious cause of this condition, or when minimal exertion results in severe fatigue, it can become a cause for concern. Weakening muscles are an issue not only because they contribute to a decline in quality of life, but because muscle weakness can eventually lead to heart problems and breathing problems, and some chronic conditions like Lou Gehrig's Disease, also known as ALS, actually cause death via muscle weakness, as the patient becomes slowly paralyzed and stops breathing.
Processes in several areas of the body can contribute to muscle fatigue, including issues with muscles and nerve cells at the site of an area of fatigue, along with problems with the central and peripheral nervous system. When a patient presents with chronic muscle fatigue, a doctor may use a number of tests, including stress tests, to uncover the cause of the muscle fatigue and to learn more about it. The doctor may also look for related symptoms like joint pain, tremors, and so forth.
A number of genetic and acquired conditions can lead to muscle fatigue. The treatments for these conditions vary, depending on the patient and the disease. These treatments can vary from the use of medications to manage or eliminate the condition causing the muscle weakness, to physical therapy which is designed to strengthen and condition the patient's muscles so that he or she will be more functional.