| MadSci Network: Anatomy |
Alison,
This is a brief reference, I found on muscle fatigue. It is short, but I think it answers the root of your question.
If you need any clarification or I may be of further assistance, please do not hesitate to contact me.
Thank you for your question and I hope this is of assistance.
Muscle Fatigue and Weakness: Definition.
By William M. Fowler, Jr., MD.
Used in the global sense of the word, weakness is a spectrum ranging from a complaint of fatigue through frank outright paralysis. Like pain, muscle fatigue is a subjective symptom, while weakness is a measurable observation.
From a practical standpoint, fatigue can be thought of as short lasting weakness. In successfully treated myasthenia gravis, for example, there is rarely any muscle wasting or long-lasting loss of strength. Fatigue occurs following prolonged muscle contractions, with a relatively rapid return of strength following rest.
From an experimental standpoint, muscle fatigue is a gradual linear reduction of muscle force (strength) generating capacity. Complete muscle exhaustion occurs when the target force can no longer be maintained at all. At this point, the muscle fibers are depleted of the main fuel, glycogen. The causes of muscle fatigue remain unknown although the primary problem appears to be a breakdown in calcium metabolism.
Muscle fatigue is the predominant symptom in Post Polio Muscular Atrophy and the rare metabolic muscle diseases, as well as in Myasthenia Gravis. In addition, many clinicians now feel that fatigue, as a physical impairment, may be more of a disability than actual weakness in muscle-wasting neuromuscular diseases.
Dr. Linda J. Weyandt MD/ CRNA
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