Terms
Hormonal
Response to
Exercise
How Hormones
work
Control of
Hormone Secretion
Hormonal Response to Exercise
Description
 The endocrine system communicates messages that influence
physiological responses and adaptations in the body.
 Hormonal concentrations drastically change with exercise to modulate
physiological functions.
 Changing the synthesis rate of intracellular proteins
 Altering enzyme activity
 Modifying cell membrane transport
 Inducing secretory activity
 Plasma amino acid concentration
 Plasma glucose concentration
 Parasympathetic and Sympathetic neurons
 Plasma epinephrine
 Other hormones
All these factors affect how pancreas produces and releases insulin
Rate of Metabolism or Excretion of Hormone in the Liver & Kidneys
 Exercise -> Decrease Inactivation and Excretion -> Increase Plasma
Concentraiton
Quantity of transport protein binding with hormone
 Increase in Quantity of Transport Protein -> Decrease in amount of Free
Hormone
Changes in plasma volume during exercise
 Exercise -> Decrease in Hormone plasma volume -> Increase Secretion
of Hormone
Hormones:
Regulation and
Action

Hormone Actions
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Hypothalamus
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Hormones are secreted from endocrine glands
o Hypothalamus and pituitary glands
o Thyroid and parathyroid glands
o Adrenal glands
o Pancreas
o Testes and ovaries
“Affects all aspects of human function:
regulate growth, metabolism, and reproduction with heightened acute
and chronic response to physical and psychological stress
maintain internal homeostasis by modulating electrolyte and acid-base
balance and adjusting energy metabolism to power biologic work”
Controls activity of the anterior and posterior pituitary glands
Influenced by positive and negative input
Endocrine Glands
Anterior Pituitary
Gland
Growth Hormone
(Somatotropins)
Positive and Negative Input to the Hypothalamus

Promotes cell division and proliferation throughout the body.
o Relates more to peak exercise intensity than exercise duration
or total exercise volume
o Facilitates protein synthesis
o Increases during exercise to mobilize fatty acids from adipose
tissue
o Aid in the maintenance of blood glucose
GH in Glucose
Sparing in Exercise

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Thyrotropin
(Thyroid
Stimulating
Hormone)


Calcitonin

Parathyroid Gland

Corticotropin
(ACTH)


Adrenal Cortex

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Opposes the action of insulin (“anti-insulin effect”) to reduce the use of
plasma glucose
Increases the synthesis of new glucose in the liver (gluconeogenesis)
from amino acids, glycerol, and lactate
Increases the mobilization of fatty acids from adipose tissue to increase
the use of fat as a fuel
Maintains growth and thyroid gland development and regulation of
hormone output from thyroid gland
o Thyroid gland controls cellular metabolism secretion of which
increases during physical activity
o Secretions are:
o Triiodothyronin (T3 ) - for growth and development,
metabolism, body temperature, and heart rate
o Thyroxine (T4 ) – inactive form that is converted to T3 by the
liver and kidneys
o T4 increases during exercise resulting to core temperature
increase
Thyroid hormones T3 and T4 are important for maintaining the
metabolic rate and allowing other hormones to bring about their full
effect.
Secreted also by the Thyroid Gland
o in a minor way, regulates plasma Ca++
o Calcitonin secretion decreases when there is enough C++ in the
plasma
o Calcitonin blocks the release of Ca++ from bone and stimulates
Ca++ excretion at the kidneys to lower the plasma Ca++
concentration.
o As the Ca++ concentration is decreased, the rate of calcitonin
secretion is reduced.
Secretes Calcium-regulating parathyroid peptide Hormone (parathyroid
hormone[PTH] or parathormone to increase plasma Ca concentrations
o Mobilizes Ca from bone
o Enhances renal Ca reabsorption
o Indirectly increases intestinal Ca absorption by its influence on
vitamin D3
secreted by the hypothalamus by way of anterior pituitary gland
acts on adrenal cortex to promote synthesis and release of cortisol
o increase concentration with increase in exercise duration if
intensity > 25 % of aerobic capacity
o increase rate of gluconeogenesis
o stimulates protein catabolism
Mineralocorticoids (aldosterone),
o involved in the maintenance of the Na + and K+ concentration
in plasma, promotes Na+ reabsorption and K+ secretion in the
kidneys
o consequently, increases plasma volume and blood pressure
Glucocorticoids (cortisol),
o
Control of Cortisol
Secretion
Gonadotropin
Testes
Anabolic Steroids
Control of
Testosterone /
Estrogen Secretion
Undesirable Effects
of Testosterone
Prolactin
inhibits or retards amino acid incorporation into proteins
(cortisol); stimulates conversion of proteins into carbohydrates
(gluconeogenesis); maintains normal blood sugar level;
conserves glucose; promotes metabolism of fat
 High amounts of cortisol will be a negative input in the hypothalamus
and anterior pituitary gland to stop producing more cortisol
 In womeno FSH (Follicle-stimulating hormone) and LH (Luteinizing
hormone) stimulates secretion of estrogen to prepare the
ovum for fertilization in the uterus
 In men
o FSH in stimulates germinal epithelial growth to promote sperm
development
o LH stimulates testes to secrete testosterone
 LH increases in anticipation of exercise and reaches peak during
recovery
 Release testosterone
 Anabolic steroid
o Promotes tissue (muscle) building
o Performance enhancement
 Androgenic steroid
o Promotes masculine characteristics
Increase risk of heart disease due to:
 detrimental effect on ventricular wall mass
 decrease HDL
 increase glucose intolerance
These send a negative input in the hypothalamus and anterior pituitary gland to
stop producing more testosterone
 Inhibin from the seminiferous tubes(testosterone) /Development of
ovum(estrogen)
 Testosterone
 Estrogen
Females Increase male 2° sex characteristics, (deepening of voice and beard
growths
 clitoral enlargement
 disruption of menstrual cycle
Males decrease in testicular function including decrease in sperm production
 gynecomastia
 liver dysfunction
 mood or behavioral changes
 Secreted by the anterior pituitary gland
 Increase secretion with high intensity exercise
 Promotes milk secretion in the mammary gland
 Important in female sexual function
o
Posterior Pituitary
Gland
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Inhibits ovaries and disrupts normal menstrual cycle observed
among athletic women.
Secretes antidiuretic hormone (ADH) or vasopressin
Reduces water loss from the body to maintain plasma volume
Stimulated by:
o High plasma osmolality and low plasma volume due to
sweating
o Exercise
Change in the
Plasma ADH
Concentration
During Exercise
Adrenal Gland
Pancreas
Glucagon and its
Action on Target
Tissues
Medulla
 Catecholamines
o Epinephrine
o Norepinephrine
 Increases cardiac output; increases blood sugar, glycogen breakdown,
and fat mobilization
Cortex
 Mineralocorticoids
o Aldosterone
o Corticosterone
o Deoxycorticosterone
 Glucocorticoids
o Cortisol
 Androgens
Secretes digestive enzymes and bicarbonate into small intestine
Releases
 Insulin – Promotes tissue absorption of glucose and storage as glycogen
 Glucagon - Promotes the mobilization of fatty acids and glucose
 Somatostatin - Controls rate of entry of nutrients into the circulation
Liver
 Increase in:
o Glycogenolysis
o Gluconeogenesis
o Ketone Synthesis
 Decrease in:
o Glycogen synthesis
o Protein breakdown
Adipose Tissue
 Increase in Lipolysis
 Decrease in Triacylglycerol synthesis
Increased Insulin
Promotes
Glycogen, Protein,
and Fat Synthesis
HORMONAL CONTROL OF SUBSTRATE MOBILIZATION DURING EXERCISE
Muscle Glycogen
Breakdown of muscle glycogen is under dual control
Utilization
 Epinephrine-cyclic AMP
 Ca2+-calmodulin
o Delivery of glucose parallels activation of muscle contraction
Glycogenolysis is related to exercise intensity
 High-intensity of exercise results in greater and more rapid glycogen
depletion
Plasma epinephrine is a powerful stimulator of glycogenolysis
 High-intensity exercise results in greater increases in plasma
epinephrine
Glycogen Depletion
During Exercise
Plasma
Epinephrine
Concentration
During Exercise
Maintenance of
Plasma Glucose
During Exercise
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Mobilization of glucose from liver glycogen stores
Mobilization of FFA from adipose tissue
o Spares blood glucose
Gluconeogenesis from amino acids, lactic acid, and glycerol
Blocking the entry of glucose into cells
o Forces use of FFA as a fuel
Permissive and slow-acting hormones
o Thyroxine – increase ability of other hormones to mobilize fuel
for exercise
o Cortisol – decrease rate of glucose utilization by cells,
stimulates FFA mobilization from adipose tissue, mobilizes
protein to yield amino acids for gluconeogenesis in the liver
o Growth hormone – can also influence fat and CHO metabolism
in support of action of cortisol
Act in a permissive manner to support actions of other hormones
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Stimulates FFA mobilization from adipose tissue
Mobilizes amino acids for gluconeogenesis
Blocks entry of glucose into cells
Low intensity exercise – plasma cortisol decreases
High intensity exercise – plasma cortisol increases


Blood Glucose
Homeostasis
During Exercise

Role of Cortisol in
the Maintenance
of Blood Glucose
Cortisol
Plasma Cortisol
During Exercise
Growth Hormone
Amount of GH increases along with exercise intensity
Important in the maintenance of plasma glucose (supports the action of
cortisol)
 Decreases glucose uptake
 Increases FFA mobilization
 Enhances gluconeogenesis
Growth Hormone
in the Maintenance
of Plasma Glucose
Blood Glucose
Homeostasis
During Exercise
Role of
Catecholamines in
Substrate
Mobilization
Effects of Insulin
and glucagon
68
Fast-acting hormones
 Norepinephrine and epinephrine
o Increasing liver glucose mobilization
o Increased levels of plasma FFA
o Decreasing glucose uptake
o Increasing gluconeogenesis
o Linearly increases along the duration of the exercise
 Promote glycogenolysis and Lipolysis
 Blocks entry of glucose into cells, promoting the use of free fatty acids