ABSTRACT
The umbrella term for male sex hormones is ‘androgens’; these have anabolic (protein synthesizing) effects as well as androgenic (virilizing) effects. The principal androgen is testosterone. Alongside oestrogen, it is the final product of the hypothalamic–pituitary–gonadal (HPG) axis. Endogenous stimuli such as biological rhythms or the hormones themselves, as well as external stimuli, activate the HPG axis. External stimuli include physical exercise and other forms of stress (mental, psychosocial), and they have a prolonged effect on androgen levels. Because the HPG axis interacts extensively with the hypothalamic–pituitary–adrenal (HPA) axis, somewhat similar to cortisol, testosterone increases after acute exercise once a specific intensity threshold is reached.
