EFFECT OF ATHLETIC PERFORMANCE ON HORMONAL SYSTEMS Dr.Sh.Hezarkhani.
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Transcript of EFFECT OF ATHLETIC PERFORMANCE ON HORMONAL SYSTEMS Dr.Sh.Hezarkhani.
EFFECT OF ATHLETIC
PERFORMANCE ON HORMONAL
SYSTEMSDr.Sh.Hezarkhani
Catecholamines• norepinephrine and epinephrin• Both these hormones
progressively increase as workload increases.
• Following exercise, resting concentrations are achieved within 30 minutes after exercise.
Catecholamines
•Mild exercise: produces little or no response
•Moderate exercise: levels Norepinephrine significantly increases with minimal change in circulating epinephrine.
• Intense or prolonged exercise :both hormones increase significantly
Catecholamines
• Catecholamines respond rapidly to exercise
Acute, short duration maximal exercise
as well as intense or prolonged exercise
can significantly increase norepinephrine and epinephrine
The effects of catecholamine release
include:• increased glycogenolysis • increased FFA concentrations• cardiovascular adaptations to
exercise• redistribution of circulation to
working muscles and to the skin• and mental performance
improvement
Fluid Homeostasis:
• During physical exercise, there is a considerable loss of water and electrolytes in sweat
• to maintain body temperature by dissipating heat generated from muscle use.
The maintenance of fluid and electrolyte homeostasis depends
on the action of:• vasopressin (AVP)• natriuretic peptides• renin-angiotensin-aldosterone
(RAA) axis• and catecholamines
AVP
• AVP concentrations increase during exercise and persist elevated for more than 60 minutes following maximal exercise.
• The stimulus for the increase in AVP is :
the increase in plasma osmolality and reduction in blood volume
ANP and BNP• Atrial natriuretic peptide (ANP)
and brain natriuretic peptide (BNP), which may be altered by exercise, also elicit a natriuretic effect.
• ANP increase is transitory in exercise of extended duration, with hormone values returning to resting levels over time
RAA• The RAA system is closely coupled
and responds to exercise.• Increased values of plasma renin
activity (PRA) are reported following maximal exercise.
• Elevated levels of aldosterone may persist for days after the end of exercise depending on water and sodium intake.
PRA, A-II, and aldosterone increment is
modulated by:• the sympathetic nervous
system• sodium intake• potassium balance• and levels of ACTH.
Hypothalamus-Pituitary-Adrenal Axis
•Glucocorticoids•Mineralocorticoids•Endorphins
Glucocorticoids• exercise of an appropriate intensity is
a potent stimulus for cortisol secretion• Physical exercise induces an effect on
ACTH and cortisol secretion greater than CRH alone
• Increases in plasma lactate is one of the mechanisms responsible for activation of the HPA axis during exercise
• A-II and interleukins, are also capable of activating the HPA axis.
• Signals of afferent nerves
• Activation of the HPA axis during aerobic exercise is proportional to the :
relative intensity of the exercise and independent of the fitness level of
the subject
• Duration of the physical activity may be important in determining the response of plasma cortisol to exercise
The cortisol response is influenced by the type of
exercise• intermittent exercise of
varying intensities, does not induce activation of the HPA axis
• Isometric exercise , induces activation (intensity-dependent)
•Anaerobic exercise induces a greater increase in plasma cortisol than aerobic exercise of the same total work output
• The response of the HPA axis to physical activity is independent of
Age and Gender
•Overtraining syndrome
RAA system• PRA, A-II, and aldosterone
increase during exercise following :
1) the activity of the sympathetic nervous system
2) sodium intake 3)potassium balance 4) levels of ACTH.
β-endorphin• depending on intensity and
duration of the physical activity. • β-endorphin increases are also
induced by anaerobic exercise and by incremental exercise that reaches anaerobic stages.
modulation of pain
and
the improvement of mood.
Detraining syndrome
•β-endorphin deficiency • Sudden cessation of regular
training• Depressed mood
Hypothalamus-Pituitary-Gonadal Axis
•Male 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• and 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
•suppression of serum testosterone levels occurs
during to more prolonged exercise
Male Gonadal Axis• decrease of testosterone
synthesis, is due to :
1) decreased gonadotropins 2) increased cortisol or
catecholamine levels
3)accumulation of metabolic waste materials
Male Gonadal Axis
• The fall in serum testosterone must result from:
decreased production rates decreased binding 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 physical and psychological
factors• 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 :
• the 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
GH/IGF-I Axis
•Physical exercise is an important environmental regulator of the GH/IGF-I axis activity.
GH/IGF-I Axis• The GH response to exercise is
dependent on the:
duration and intensity of the exercise
Type of the exercise
the fitness level of the exercising subject
the refractoriness of pituitary somatotroph cells to the exercise stimuli
other environmental factors(NO,lactate)
GH/IGF-I Axis• The neuroendocrine pathways
that regulate GH secretion during exercise include the :
• Cholinergic• Serotoninergic• α-adrenergic• dopaminergic
• and opioidergic systems
GH/IGF-I Axis
↓ fluid intak→ ↓GH ↑ fat diet → ↓GH ↑ tempreture → ↑ GH Obesity & PCOS → ↓GH
GH secretion is greater in women than in men
The acute GH response to aerobic or resistance exercise is reduced with age
↑ GHBP
• Exercise leads to increases in IGF-I levels(GH-independent mechanisms)
• Hemodynamic or metabolic effects of exercise per se might play a role
• long periods of exercise training are able to stimulate IGF-I gene expression
• ↑IGFBP1
Hypothalamus-Pituitary-Thyroid Axis
•rT3 increase, particularly when a caloric energy deficiency is associated with exercise.
• TSH, T4, fT4, T3, and fT3 levels have been reported to be unaffected, increased, or decreased, varying with the:
type and duration of exercise ambient temperature(TSH &FT4↑→↓ ) and energy intake
Insulin and Glucose Metabolism
•Physical activity affects the metabolism of glucose and other intermediate substrates in normal subjects and in subjects with diabetes mellitus.
• The effects of exercise on carbohydrate metabolism are complex and involve :
1) type, intensity, and duration of exercise
2) changes in body composition 3) alterations in other
behaviors(food intake, degree of insulin deficiency, and a complex time-course of the glucose-insulin response)
Maintaning euglycemia during exercise
• Activity of α adrenergic system :↓INS
• ↑Glucagon ,NE,E