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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 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.
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