Body temperature, respiration, and acid-base equilibrium during prolonged running

Area of Science:

• Exercise Physiology
• Human Physiology
• Sports Science

Background:

• Maintaining acid-base balance is crucial during intense exercise.
• Elevated body temperature can impact physiological responses during prolonged exertion.
• Understanding respiratory adjustments to heat and exercise is vital for performance and health.

Purpose of the Study:

• To investigate respiratory and acid-base equilibrium during prolonged high-intensity treadmill running.
• To examine the effects of different body temperature levels on these responses.
• To assess physiological stability under conditions of increased core temperature and dehydration.

Main Methods:

• Participants underwent two bouts of prolonged high-intensity treadmill running.
• Incomplete rehydration was used to elevate body temperature.
• Measurements included rectal temperature, plasma volume, arterial lactate, and blood gas parameters (pH, PCO2, HCO3).
• Pulmonary ventilation and ventilatory equivalents were also monitored.

Main Results:

• Rectal temperature significantly increased during both runs and was higher in the second run.
• Plasma volume, arterial lactate, hydrogen ion concentration, PCO2, and bicarbonate remained constant post-transition.
• Pulmonary ventilation and ventilatory equivalent for CO2 were stable throughout each run.
• Arterial PCO2 was lower and ventilatory equivalent for CO2 was higher during the second run.

Conclusions:

• Despite increasing rectal temperature during prolonged running, key physiological variables remain relatively stable after initial exercise adjustments.
• The body demonstrates significant regulation of acid-base balance and respiratory parameters under heat stress during intense exercise.
• These findings suggest resilience in physiological systems to maintain homeostasis during demanding exercise conditions.