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--Michael
H. Brooke., M.D. |
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| Any disturbance in the biochemical pathways that support
ATP levels in the muscle inevitably results in exercise
intolerance. One common symptom is muscle fatigue, a sense that the muscle will no longer perform in a normal fashion. This is true fatigue and not simply a feeling of tiredness or weariness. It may be difficult for the patient to describe the fatigue in terms that the physician can understand because it has nothing to do with the sensations experienced by a healthy person after strenuous exercise. It has an unpleasant quality, and patients describe it in terms of a barrier through which they cannot break. Other symptoms include muscle pain and sometimes muscle cramps. The normal fatigue of strenuous exercise is painless. Muscle pain following strenuous exercise, for instance the next day, is almost universal in the untrained individual, but pain during exercise is more the hallmark of disturbed muscle function. Normally functioning muscle appears to have a series of safety mechanisms that prevent humans from exercising it to the point of destruction. In the metabolic muscle diseases, maintenance of ATP levels is impaired, and the protective mechanism that functions in the normal person is absent. If exercise is forced in a patient with a metabolic myopathy, muscle pain develops, and a muscle contracture subsequently may be found, in which state the muscle is hard, swollen, and tender. This reflects actual destruction of the muscle. Fatigue, muscle pain, contracture, and myoglobinuria are the increasingly severe effects of the biochemical defect. It should be noted that a tissue in which ATP levels are depleted is probably dead tissue. Even in the metabolic myopathies, the muscle seldom reaches this critical state. What does happen, however, is that most of the support pathways are overworked with the production of unwelcome by-products which are probably responsible for the symptoms. |
Dr. Brooke is Director of the Muscle Disease Research Center at the University of Alberta in Edmonton. --Reprinted with permission from http://plaza.v-wave.com/mbrooke/ublish/page12.html |
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| Related
links:
Matter over Mind: The Realities of a Common Muscle Disease CPT deficiency article by Georgirene Vladutiu, Ph.D.
Running on Empty |
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To
read Dr. Brooke's comments about CPT deficiency, visit 
A
common complaint is that the patient feels that activity is
limited because he or she just "runs out of gas."
This is an apt analogy that draws attention to the fact that
skeletal muscle is a sophisticated "machine" which
is powered by a remarkable "engine" that is able to
convert a variety of fuels to energy. 
