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Biochemical adaptations to training: implications for resisting muscle fatigue
K K McCully1, B J Clark, J A Kent
1Department of Biochemistry, University of Pennsylvania, Philadelphia 19104-6089.
Canadian Journal of Physiology and Pharmacology
|February 1, 1991
Summary
Muscle fatigue is linked to metabolic by-products like H+ and inorganic phosphate (Pi). Endurance training reduces these changes, enhancing fatigue resistance by lessening the impact of pH and Pi on force development.
Area of Science:
- Exercise Physiology
- Skeletal Muscle Metabolism
Background:
- Skeletal muscle fatigue is a decline in force-generating capacity during activity.
- Accumulation of intracellular H+ and inorganic phosphate (Pi) are potential causes of muscle fatigue.
Purpose of the Study:
- To investigate the role of muscle metabolites (H+, Pi) in fatigue.
- To examine how endurance training affects muscle metabolism and fatigue resistance.
Main Methods:
- Utilized phosphorus magnetic resonance spectroscopy to study muscle pH and Pi.
- Employed ramp exercise protocols to measure metabolic changes during exercise.
- Compared metabolic responses and fatigue in trained vs. untrained states.
Main Results:
- Muscle fatigue correlates with H2PO4- accumulation under specific exercise conditions.
- Endurance training and chronic electrical stimulation reduce pH and Pi changes at equivalent exercise intensities.
- Reduced metabolic changes during exercise in trained states suggest a mechanism for increased fatigue resistance.
Conclusions:
- Muscle fatigue is influenced by intracellular metabolic by-products.
- Endurance training improves fatigue resistance, partly by altering the metabolic response to exercise.
- Phosphorus magnetic resonance spectroscopy is a valuable tool for studying muscle fatigue mechanisms.