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Feedback from meal-related peaks determines diurnal changes in cortisol response to exercise
The Journal of Clinical Endocrinology and Metabolism
|March 1, 1982
Summary
Daily cortisol patterns are shaped by interactions between meals and exercise. Exercise responses are blunted by prior meals or exercise, demonstrating feedback mechanisms override circadian rhythms.
Area of Science:
- Endocrinology
- Chronobiology
- Exercise Physiology
Background:
- Cortisol secretion exhibits diurnal variations influenced by daily activities.
- Understanding the interplay between meals, exercise, and cortisol is crucial for interpreting physiological responses.
Purpose of the Study:
- To investigate diurnal variations in cortisol response to exercise.
- To assess the relationship between daily cortisol patterns and meal/exercise timing.
Main Methods:
- Compared daily cortisol patterns on control days versus days with exercise at different times.
- Monitored cortisol levels in relation to meal intake and exercise sessions throughout the day.
Main Results:
- A significant midday cortisol peak correlated with the noon meal.
- Exercise during quiescent periods elicited similar cortisol increases, but evening exercise showed lower peaks due to reduced basal levels.
- Both meal-induced peaks and exercise-induced cortisol rises inhibited subsequent responses, indicating feedback mechanisms.
Conclusions:
- Daily cortisol patterns are a result of interactions between meal-related peaks and exercise-induced increases.
- Feedback mechanisms, particularly those related to meals and prior exercise, play a primary role in modulating cortisol responses, overriding circadian rhythm influences.