The Hypothalamic-Pituitary-Adrenal (HPA) Axis is the interaction/hormonal communication between the Hypothalamus, Pituitary Gland, and Adrenal Glands. Its primary responsibility is to respond to stress (including exercise as it is a stressor to the body) by secreting hormones such as cortisol, adrenaline, DHEA/DHA, and small amounts (relative to the gonads) of Testosterone, Estrogen, and Progesterone.
The Hypothalamic-Pituitary-Gonadal (HPG) Axis is the interaction/hormonal communication between the Hypothalamus, Pituitary Gland, and the sex organs (Testes/Ovaries) and primarily is involved with reproduction and immune response by secreting testosterone, estrogen, LH, FSH, and GnRH.
The HPA and HPG influence each other in reciprocal ways. As an example, testosterone or estrogen can modulate the HPA Axis, however during chronic stress (excessive activation of the HPA Axis), testosterone and estrogen become suppressed.
During Puberty, 3 major stages occur:
- Adrenarche: The adrenal glands become upregulated which leads to pubic hair, oily skin, body odor, and sexual desire.
- Gonadarche: The ovaries and testes begin to grow with an increase in sex steroids.
- Menarche/Spermarche: first menstruation for females and the beginning of sperm production in males.
Understanding the hormonal changes during puberty is paramount when training/programming for young adults and athletic development.