Hormones and Exercise

Endocrine System

• 3 Components:

– Host organ

– Hormones

– Target (receptor) cells or organs

Types of Glands

• Endocrine gland – secrete hormones that diffuse into the bloodstream.

• Exocrine gland – have secretory ducts that lead directly to specific compartment or surface that requires the hormone; e.g. sweat glands and glands of upper digestive tract.

Hormones & Function

• Hormones – chemical substances that carry messages to regulate growth, metabolism, and reproduction. Hormones also enhance body’s ability to respond to physical and psychological stress.

Anterior Pituitary Hormones
and Exercise

• Growth Hormone – stimulates tissue growth, mobilizes fat for energy, and inhibits CHO metabolism; ↑ with exercise

• Prolactin – inhibits testosterone, and mobilizes fat for energy; ↑ with exercise

• Endorphins – block pain and promote euphoria;

↑ with long-duration exercise

Posterior Pituitary Hormones
and Exercise

• Vasopressin (ADH) – controls water excretion by kidneys; ↑ with exercise

Adrenal Cortex Hormones
and Exercise

• Cortisol – promotes fat and protein catabolism, conserves blood sugar; ↑ with intense exercise

• Aldosterone – promotes sodium, potassium, and water retention by the kidneys; ↑ with exercise

Adrenal Medulla Hormones
and Exercise

• Epinephrine (adrenaline) – facilitates sympathetic activity, increases heart activity, regulates blood vessels, increases glycogen catabolism and fat release; ↑ with intense exercise

• Norepinephrine – similar functions as epinephrine; ↑ with exercise

Thyroid Hormones
and Exercise

• Thyroxine (T₄) & Triiodothyronine (T₃) – stimulate metabolism and regulate cell growth and activity; ↑ with exercise

Pancreatic Hormones
and Exercise

• Insulin – promotes glucose transport into cells and promotes fatty acid and amino acid transport into cells; ↓ with exercise

• Glucagon – promotes release of glucose from liver to blood, increases fat metabolism, and reduces amino acid levels; ↑ with exercise

Parathyroid Hormone
and Exercise

• Parathyroid hormone – raises blood calcium and lowers blood phosphate; ↑ with long-term exercise

Ovary Hormones
and Exercise

• Estrogen and Progesterone – control menstrual cycle, increase fat deposition, and promote female gender characteristics;

↑ with exercise depending on phase of menstrual cycle.

Testicular Hormones
and Exercise

• Testosterone – controls muscle size, increases red blood cells, decreases body fat, and promotes male gender characteristics; ↑ with exercise

Hormonal Problems

• Aldosterone

– Increased production of this hormone is associated with high blood pressure; often times in obese teenagers

• Associated with:

– ↓ salt sensitivity (increased body water)

– ↑ sodium intake

– ↓ sensitivity to insulin’s effects

Hormonal Problems

• Diabetes Mellitus

• Type I diabetes – lack of or no secretion of insulin from pancreas

– dependence on exogenous insulin

• Type II diabetes – cells resist insulin’s effects

– May need exogenous insulin or must exercise to improve body’s ability of glucose uptake

Diabetes and Exercise

• Type I Diabetes

– Problems:

• Hypoglycemia can result with exercise if insulin has been taken recently

• Hyperglycemia can result with exercise if no insulin taken for long period of time

Exercise Guidelines for
Type I Diabetes

• Monitor blood glucose before, during, and after exercise

• Ingest 15-30 grams of CHO for each 30 min of intense exercise

• Consume CHO snack after exercise

• Decrease insulin dose

• Avoid exercising the muscles where insulin injection was given for 1 hour

• Avoid exercising in late evening

Exercise Guidelines for
Type II Diabetes

• Similar to Type I

Exercise Benefits for
Individuals with Diabetes

• Improved glycemic control (increased sensitivity of tissues to insulin so better uptake of glucose)

• Decreases cardiovascular risk factors

• Promotes weight loss

• Decreases anxiety levels

When Exercise Should be Avoided in Diabetics

• Retinal hemorrhage or recent eye surgery

• Fever or infection is present

• Blood glucose < 80 mg/dl

– Eat extra CHO until glucose is above 120 mg/dl before exercising

• Blood glucose > 250 mg/dl and urine ketones are present

– Decrease blood glucose with insulin injection

Hormonal Response to
Exercise Training

• After training, exercise at same absolute intensity will result in a lower hormonal response in most cases

Specific hormone responses to Training

• Human growth hormone - ↓ response with exercise; higher resting values

• Prolactin - ↓ resting values

• Testosterone - ↓ resting values in women but possible ↑ in men with resistance training

• Vasopressin (ADH) - ↓ response with exercise

Specific hormone responses to Training

• Cortisol - slight ↑ with exercise in trained

• Epinephrine & Norepinephrine - ↓ response with exercise

• Insulin - ↓ response with exercise due to increase in sensitivity

• Glucagon - ↓ response with exercise

Immune System
and Exercise