Hormonal response to exercise

1. HORMONAL
RESPONSES TO
EXERCISE
DR. NADEEM AHMAD

2. NEUROENDOCRINOLOGY
• The two major homeostatic systems involved in the control
and regulation of various functions are the nervous and
endocrine system
• These two systems often work together to maintain
homeostasis this is called neuroendocrine response
• Endocrine glands release hormones directly into the blood
• Hormones alter the activity of tissues that possess receptors
to which the hormone can bind
• The plasma hormone concentration determines the magnitude
of the effect at the tissue level

3. BLOOD HORMONE
CONCENTRATION
Determined by:
• Rate of secretion of hormone from endocrine
gland
• Rate of metabolism or excretion of hormone
• Quantity of transport protein
• Changes in plasma volume

4. CONTROL OF HORMONE
SECRETION
• Rate at which a hormone is secreted from and
endocrine gland is dependent on
 Magnitude of input
 Stimulatory vs. inhibitory
 e.g., Rate of insulin secretion from the pancreas

5. HORMONE-RECEPTOR
INTERACTIONS
• Trigger events at the cell
• Magnitude of effect dependent on:
• Concentration of the hormone
• Number of receptors on the cell
• Affinity of the receptor for the hormone

6. HORMONE-RECEPTOR
INTERACTIONS
• Hormones bring about effects by:
• Altering membrane transport
• Stimulating DNA to increase protein synthesis
• Activating second messengers
• Cyclic AMP
• Ca++
• Inositol triphosphate
• Diacylglycerol

7. CYCLIC
AMP
“SECOND
MESSENGE
R”
MECHANIS
M

8. OTHER
“SECOND
MESSENGER”
SYSTEMS

9. HORMONES:
REGULATION AND ACTION
• Hormones which are secreted from endocrine glands
• Hypothalamus and pituitary glands
• Thyroid and parathyroid glands
• Adrenal glands
• Pancreas
• Testes and ovaries

10. HYPOTHALAMUS
•Controls activity of the anterior
and posterior pituitary glands
•Influenced by positive and
negative input

11. GROWTH HORMONE
• Secreted from the anterior pituitary gland
• Essential for normal growth
• Stimulates protein synthesis and long
bone growth
• Increases during exercise
• Mobilizes fatty acids from adipose tissue
• Aids in the maintenance of blood glucose

12. POSTERIOR PITUITARY GLAND
• Secretes oxytocin and antidiuretic hormone (ADH) or vasopressin
• Reduces water loss from the body to maintain plasma volume
• Stimulated by:
• High plasma osmolality and low plasma volume due to
sweating
• Exercise

13. CHANGE IN THE PLASMAADH
CONCENTRATION DURING EXERCISE

14. THYROID GLAND
• Triiodothyronine (T3) and thyroxin (T4)
• Important in maintaining metabolic rate and allowing
full effect of other hormones
• Calcitonin
• Regulation of plasma Ca++
• Parathyroid Hormone
• Also involved in plasma Ca++
regulation

15. PARATHYROID GLAND
• Parathyroid gland releases parathyroid hormone in response to low
plasma Ca++ concentration
• Hormone stimulates bone to release calcium into plasma
• It also increases the renal absorption of Ca++
• It stimulates the kidney to convert a form of vitamin D ( D3) into a
hormone that increases absorption of Ca++ from GIT tract

16. ADRENAL GLAND
• Adrenal Medulla
• Secretes catecholamine's, Epinephrine and
Norepinephrine
• Increases
• HR, glycogenolysis, lipolysis,

17. ADRENAL CORTEX
•Mineralocorticoids (aldosterone)
•Maintain plasma Na+
and K+
• Regulation of blood pressure

18. ADRENAL CORTEX
•Glucocorticoids (Cortisol)
•Stimulated by exercise and
long-term fasting
•Promotes the use of free fatty
acids as fuel
•Stimulates glucose synthesis
•Promotes protein breakdown

19. ADRENAL CORTEX
• Sex steroids ( androgens and estrogens)
 Supports prepubescent growth
 Androgens being associated with post
pubescent sex drive in women

20. PANCREAS
• Secretes digestive enzymes and bicarbonate into small intestine
• Releases
• Insulin - Promotes the storage of glucose, amino acids, and
fats
• Glucagon - Promotes the mobilization of fatty acids and
glucose
• Somatostatin - Controls rate of entry of nutrients into the
circulation

21. TESTES
• Release testosterone
• Anabolic steroid
• Promotes tissue (muscle) building
• Performance enhancement
• Androgenic steroid
• Promotes masculine characteristics

22. CONTROL OF TESTOSTERONE SECRETION

23. ESTROGEN
• Group of hormones it includes estradiol,
estrone and estriol
• Establish and maintain reproductive function
• Levels vary throughout the menstrual cycle

24. CONTROL OF ESTROGEN
SECRETION

25. MUSCLE GLYCOGEN
UTILIZATION
• Breakdown of muscle glycogen is under dual control
• Epinephrine-cyclic AMP
• Ca2+-calmodulin
• Delivery of glucose parallels activation of
muscle contraction
• Glycogenolysis – breakdown of glycogen

26. MUSCLE GLYCOGEN
UTILIZATION
• Glycogenolysis is related to exercise intensity
• High-intensity of exercise results in greater and
more rapid glycogen depletion
• Plasma epinephrine is a powerful simulator of
glycogenolysis
• High-intensity of exercise results in greater
increases in plasma epinephrine

27. MAINTENANCE OF PLASMA
GLUCOSE DURING EXERCISE
• Mobilization of glucose from liver glycogen
stores
• Mobilization of FFA from adipose tissue
• Spares blood glucose
• Gluconeogenesis from amino acids, lactic acid,
and glycerol
• Blocking the entry of glucose into cells
• Forces use of FFA as a fuel

28. BLOOD GLUCOSE HOMEOSTASIS
DURING EXERCISE
• Permissive and slow-acting hormones
• Thyroxin
• Cortisol
• Growth hormone
• Act in a permissive manner to support
actions of other hormones

29. CORTISOL
• Stimulates FFA mobilization from adipose
tissue
• Mobilizes amino acids for gluconeogenesis
• Blocks entry of glucose into cells

30. PLASMA CORTISOL DURING EXERCISE
• At low intensity
• plasma cortisol decreases
• At high intensity
• plasma cortisol increases

31. GROWTH HORMONE
• Important in the maintenance of plasma
glucose
• Decreases glucose uptake
• Increases FFA mobilization
• Enhances gluconeogenesis

32. BLOOD GLUCOSE HOMEOSTASIS
DURING EXERCISE
• Fast-acting hormones
• Norepinephrine and epinephrine
• Insulin and glucagon
• Maintain plasma glucose
• Increasing liver glucose mobilization
• Increased levels of plasma FFA
• Decreasing glucose uptake
• Increasing gluconeogenesis

33. EPINEPHRINE & NOREPINEPHRINE
DURING EXERCISE
•Increase linearly during exercise
•Favor the mobilization of FFA and
maintenance of plasma glucose

34. CHANGE IN PLASMA CATECHOLAMINE'S
DURING EXERCISE

35. EPINEPHRINE & NOREPINEPHRINE
FOLLOWING TRAINING
• Decreased plasma levels in response to
exercise bout
• Parallels reduction in glucose mobilization

36. INSULIN DURING EXERCISE
• Plasma insulin decreases during exercise
• Prevents rapid uptake of plasma glucose
• Favors mobilization of liver glucose and lipid FFA
• Trained subjects during exercise
• More rapid decrease in plasma insulin
• Increase in plasma glucagon

37. FREE FATTY ACID MOBILIZATION
DURING HEAVY EXERCISE
• FFA mobilization decreases during heavy exercise
• This occurs in spite of persisting hormonal
stimulation for FFA mobilization
• May be due to high levels of lactic acid
• Promotes resynthesis of triglycerides
• Inadequate blood flow to adipose tissue
• Insufficient transporter for FFA in plasma

38. THANK YOU