Hypothalamus-Pituitary-Gonadal Axis in ATHLETICS Dr.Sh.Hezarkhani

Male Gonadal Axis

Hypothalamus-Pituitary-Gonadal Axis The effects of physical activity on the male reproductive axis vary with the : 1) intensity and duration of the activity 2) fitness of the individual 3) his nutritional-metabolic status.

Male Gonadal Axis Relatively short, intense exercise usually increases testosterone levels while more prolonged exercise usually decreases serum testosterone levels

Male Gonadal Axis Endurance and other forms of training can induce subclinical inhibition of normal reproductive function although clinical expression of reproductive dysfunction with exercise is uncommon in men

Male Gonadal Axis Increased serum testosterone levels have been reported during: - relatively strenuous free and treadmill running - weight training - ergometer cycling The testosterone response has been reported to increase with increased exercise load

Male Gonadal Axis Acute exercise-induced testosterone increments are also seen in older men the exercise-associated increment in circulating testosterone is not mediated by LH specific testicular mechanisms are involved

Male Gonadal Axis more prolonged exercise suppression of serum testosterone

Male Gonadal Axis The decrease of testosterone synthesis, is due to : 1) gonadotropins 2) cortisol or catecholamine levels 3)accumulation of metabolic waste materials

Male Gonadal Axis The fall in serum testosterone must result from: 1- decreased production rates 2-decreased binding 3- increased clearance

Male Gonadal Axis Endurance and other forms of training can induce subclinical inhibition of normal reproductive function. Libido may also be reduced in some athletes during intense endurance training periods, due to reduced testosterone levels and to chronic fatigue.

Male Gonadal Axis Semen analysis ↑ β-endorphin ↓ or ↑ PRL ↑ cortisol

Female Gonadal Axis

can be affected by 1- physical and 2- psychological factors

Female Gonadal Axis Many female athletes develop : - Delayed menarch - oligomenorrhea - amenorrhea - and luteal phase defects

Female Gonadal Axis -Negative energy balance -leptin -which serves as a signal to the CNS with information on the critical amount of adipose tissue stores that is necessary for GnRH secretion and pubertal activation of the hypothalamic-pituitary-gonadal axis

Female Gonadal Axis Possible alternative mechanisms : - stress-induced activation of the H-P-A axis - endogenous opioid peptides - catecholestrogens - hyperandrogenism.

Prolactin -transiently increase with exercise -proportional to the exercise intensity -PRL increments occur when the anaerobic threshold is reached

Prolactin Prolactin correlated with levels of: - POMC derivatives - ACTH - β-endorphins -changes in body temperature - dehydration -is exaggerated by stress - is reduced with habituation and hypoxia