Hypothalamus-Pituitary-Gonadal Axis in ATHLETICS

Dr.Sh.Hezarkhani

Male Gonadal Axis

Hypothalamus-Pituitary-Gonadal AxisThe 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 AxisThe 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 AxisEndurance 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

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