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Exercise hyperthermia as a factor limiting physical performance: temperature effect on muscle metabolism.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 1, 1985
Summary
Trunk cooling significantly improves endurance during prolonged exercise in dogs by mitigating muscle hyperthermia. This enhances muscle energy metabolism and reduces fatigue, suggesting hyperthermia limits endurance performance.
Area of Science:
- Exercise Physiology
- Muscle Metabolism
- Thermoregulation
Background:
- Prolonged heavy exercise leads to increased body temperature and can impair muscle energy metabolism.
- Hyperthermia during exercise may be a limiting factor for endurance performance.
Purpose of the Study:
- To investigate the effects of trunk cooling on muscle energy metabolism and endurance during prolonged heavy exercise in dogs.
- To determine the relationship between muscle temperature and metabolic changes during exercise.
Main Methods:
- Comparison of muscle high-energy phosphates, glycogen, glycolytic intermediates, pyruvate, and lactate in dogs during exhaustive exercise with and without trunk cooling.
- Measurement of rectal and muscle temperatures.
- Correlation analysis between muscle lactate content and muscle temperature.
Main Results:
- Trunk cooling increased exercise duration by approximately 45% and reduced rectal and muscle temperatures.
- Cooling led to less decrease in high-energy phosphates (ATP + CrP), slower glycogen depletion, and smaller increases in AMP, pyruvate, and lactate.
- Muscle lactate content was positively correlated with muscle temperature.
Conclusions:
- Hyperthermia during prolonged exercise adversely affects muscle metabolism, shifting the balance of high-energy phosphate resynthesis and accelerating glycolysis.
- Trunk cooling improves endurance by mitigating hyperthermia and preserving muscle energy stores.
- Muscle temperature is a critical factor influencing metabolic responses and endurance capacity.