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Corticotroph axis sensitivity after exercise in endurance-trained athletes
M Duclos1, J B Corcuff, L Arsac
1Laboratoire de Biologie Appliquée à L'Education Physique et aux Sports et Laboratoire Performance Sportive et Santé, Université de Bordeaux II, France. Martine.Duclos@biosport.U-Bordeaux2.fr
Clinical Endocrinology
|June 26, 1998
Summary
Endurance training in athletes leads to a blunted pituitary response to cortisol, suggesting a recalibration of the hypothalamo-pituitary adrenal (HPA) axis. Saliva cortisol measurements are more sensitive for detecting these changes.
Area of Science:
- Endocrinology
- Exercise Physiology
- Human Physiology
Background:
- The hypothalamo-pituitary adrenal (HPA) axis regulates the body's response to stress.
- Endurance training is known to cause moderate, sustained increases in cortisol levels.
- Understanding HPA axis adaptation to chronic physical stress is crucial for athletes' health and performance.
Purpose of the Study:
- To investigate the adaptation of the human HPA axis in endurance-trained athletes.
- To evaluate HPA axis sensitivity following repeated physical stress and sustained cortisol increases.
- To compare saliva and plasma cortisol measurements in assessing HPA axis function.
Main Methods:
- Studied 8 endurance-trained athletes under resting and post-exercise conditions.
- Administered adrenal (ACTH) and pituitary (CRH/LVP) stimulation tests.
- Measured cortisol levels in both saliva (Fs) and plasma (Fp) before and after stimulation.
Main Results:
- Cortisol levels were significantly higher in athletes post-exercise compared to rest (P < 0.001).
- Both pituitary and adrenal stimulation resulted in similar cortisol increases in plasma and saliva post-exercise versus rest.
- Saliva cortisol showed significantly greater relative increases (delta %) than plasma cortisol under stimulation (P < 0.05).
Conclusions:
- Endurance-trained athletes exhibit normal ACTH and adrenal responses to stimulation despite elevated cortisol.
- Results suggest decreased pituitary sensitivity to cortisol negative feedback, not decreased adrenal sensitivity.
- Saliva cortisol assays are highly effective for studying HPA axis physiology under basal and dynamic conditions.