Enhancement of hypothalamic-pituitary activity in male athletes: evidence of a novel hormonal mechanism of physical conditioning

Flavio A Cadegiani,Claudio E Kater

doi:10.1186/s12902-019-0443-7

Abstract

BackgroundExercise is known to induce multiple beneficial conditioning processes. Conversely, although exercise may generate several hormonal effects, an intrinsic hormonal conditioning process has not been reported. In the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study, we observed inherent and independent conditioning processes of the hypothalamic-pituitary axes in athletes. Our objective is to describe the theory of the novel hormonal conditioning mechanism using the findings from the EROS study.MethodsIn this cross-sectional study, we selected 25 healthy athletes (ATL) and 12 non-physically active healthy controls (NPAC), 18–50 years old, males, with BMI 20–30 kg/m2, with similar baseline characteristics, who underwent gold-standard exercise-independent tests: cosyntropin stimulation test (CST) and insulin tolerance test (ITT), to evaluate cortisol response to CST, and ACTH, cortisol, GH, and prolactin responses to an ITT.ResultsResponses to ITT were significantly earlier and higher in ATL than NPAC for cortisol [Mean ± SD: 21.7 ± 3.1 vs 16.9 ± 4.1 μg/dL; p < 0.001], GH [Median (95% CI): 12.73 (1.1–38.1) vs 4.80 (0.33–27.36) μg/L; p = 0.015], and prolactin [24.3 (10.5–67.45) vs 10.50 (6.21–43.44) ng/mL; p = 0.002]. Cortisol response to CST was similar between ATL and NPAC. During ITT, cortisol, GH, and ACTH mean increase in ATL were 52.2, 265.2, and 18.6% higher than NPAC, respectively. Prolactin response was absent in NPAC, while present in ATL.ConclusionsWe found sufficient evidence to propose the existence of a diffuse enhancement of the hypothalamic-pituitary activity in athletes, not restricted to any axis, showing an intrinsic and independent process of “hormonal conditioning” in athletes, similar to those observed in the cardiovascular and neuromuscular systems. This novel conditioning process may be the missing link for understanding the improved responses observed in athletes to harmful situations, traumas, infections, inflammations, and psychiatric conditions.

Highlights

Exercise is known to induce multiple beneficial conditioning processes
Hormonal responses have been determined in ATL and compared to athletes affected by overtraining syndrome (OTS) [17,18,19], it remains unclear whether the responses in ATL were different from those in non-physically active control subjects (NPAC)
We evaluated the peripheral component of the hypothalamic-pituitary-adrenal (HPA) axis with a cosyntropin stimulation test (CST), which directly evaluates adrenal responses to synthetic adrenocorticotropic hormone (ACTH) [24], and whose impaired responses are indicative of primary adrenocortical dysfunction

Summary

Introduction

Exercise is known to induce multiple beneficial conditioning processes. exercise may generate several hormonal effects, an intrinsic hormonal conditioning process has not been reported. In the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study, we observed inherent and independent conditioning processes of the hypothalamic-pituitary axes in athletes. Cadegiani and Kater BMC Endocrine Disorders (2019) 19:117 processes that occur in response to repeated and progressive athletic training These include adaptations of the cardiovascular and autonomic systems [9, 10], improvements in skeletal muscle [11], and pain modulation [2], as well as neurological [12] and psychiatric [13] responses. While basal and resting hormones have been compared between healthy athletes (ATL) and non-physically active control subjects (NPAC) in previous studies [17], none have assessed hormone responses to any type of exercise-independent stimulus. Such exercise-induced tests depend on musculoskeletal and cardiovascular signaling to the hypothalamus and pituitary and any differences in hormonal responses could be attributed to differences in signaling, and not to the hormonal changes

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