Week 2 - Hormonal responses to exercise

Question 1

How is plasma glucose during exercise maintained

Answer 1

Mobilisation of glucose from liver glycogen stores
Mobilisation of FFA from adipose tissue
Gluconeogenesis from amino acids, lactic acid and glycerol
Blocking the entry of glucose into cells

Question 2

How is blood glucose homeostasis controlled by hormones during exercise

Answer 2

Permissive or flow acting (Thyroxine, cortisol and growth hormone)
Gast acting (Epinephrine, norepinephrine, insulin and glucagon)

Question 3

What is the role of thyroid hormones (ON SHEET)

Answer 3

Influences rhe number of receptors on the surface of a cell for other hormones to interact with
The affinity of the receptor for the hormone

Question 4

Whats the role of Triiodothyronine (ON SHEET)

Answer 4

Enhance the effect of epinephrine to mobilise free fatty acids from adipose tissue
No real change in thyroid hormones during exercise
Hypothyroid state interferes with the ability of other hormones to mobilise fuel for exercise

Question 5

Whats the main roles of growth hormone (ON SHEET)

Answer 5

Essential for growth of all tissues
Spares plasma glucose

Question 6

How does growth hormone help growth of all tissue (ON SHEET)

Answer 6

Increases amino acid uptake and protein synthesis

Question 7

How does growth hormone spare plasma glucose (ON SHEET)

Answer 7

Reduce the use of plasma glucose
Increase gluconeogenesis
Mobilise fatty acids from adipose tissue

Question 8

How does growth hormone effect performance

Answer 8

GH increases protein synthesis - used to treat childhood dwarfism
High does have more adverse effects than benefits
No evidence that GH promotes strength gains
Difficult to detect usage by athletes
Questionable benefits as anti aging therapy

Question 9

How does exercise intensity effect GH

Answer 9

Increase in plasma GH with increased intensity

Question 10

What is cortisol

Answer 10

Steroid hormone derived from cholesterol
and secreted from the adrenal cortex

Question 11

What stimulates cortisol

Answer 11

Stress via adrenocoricotropic hormone
Exercise

Question 12

What are some considerations for cortisol

Answer 12

Diurnal variation - concentrations peak in the am and drop throughout the day
Events other than exercise e.g emotional arousal

Question 13

How does cortisol percentage change in relation to exercise intensity

Answer 13

Linear relationship

Question 14

What are catecholamines

Answer 14

Secreted from the adrenal medulla
Epinephrine 80% norepinephrine - fast acting hormones
Bind to adrenergic receptors
Also known as adrenaline and noradrenaline

Question 15

What are the effects of epinephrine and norepinephrine on various tissues

Answer 15

Increased glycogenolysis
Increased lipolysis
Increased vasoconstriction

Question 16

Whats the effect of endurance training on catecholamines

Answer 16

Endruance training casues a very rapid decrease in catecholamine responses to fixed intensity exercise bout

Question 17

What are the catecholamine responses to supramaximal exercise

Answer 17

Trained individuals have a greater capacity to increase catecholamines compared to untrained individuals
Regular stimulation of the SNS increases capacity to respond to extreme challenges

Question 18

How does high intensity exercise impact glycogen availability

Answer 18

High-intensity exercise results in greater and more rapid glycogen depletion

Question 19

How does high intensity exercise impact plasma epinephrine

Answer 19

Results in greater increases in plasma epinephrine.

Question 20

What is the role of the pancreas

Answer 20

Secretes counter-regulatory hormones fro the islets of Langerhans
Insulin - promotes glucose storage, amino acids and fat
Glucagon - promotes the mobilisation of fatty acids and glucose
Stimulates gluconeogenesis in the liver

Question 21

Whats the relationship between glucaogn and insulin

Answer 21

The ratio of glucagon and insulin provides control over the mobilisation of glucose and FFA

Question 22

How is plasma insulin effected during exercise

Answer 22

During moderate-intensity exercise insulin concentrations can drop by 50%
Decreased plasma insulin concentrations during moderate intensity long term exercise

Question 23

How is plasma glycagon effected during exercise

Answer 23

Following an endurance training program the glucagon response is diminished to the point that there is little to no increase during exercise

Question 24

What is the hormone-substrate interaction

Answer 24

Hormones that are elevated with exercise favor the mobilisation of FFA
However in spite of this persisting hormonal stimulation FFA oxidation decreases during heavy exercise

Question 25

Why does FFA oxidation decrease during heavy exercise

Answer 25

May be due to:
High levels of lactic acid
Elevated h+ concentrations inhibits HSL
Inadequate blood flow to adipose tissue
Inadequate blood flow to adipose tissue
Insufficient albumin to transport FFA in plasma
Therefore decreased FFA and increased glucose use

Question 26

What is the impact of endurance training on lactate

Answer 26

Decreases the lactate concentration at any fixed work rate, which reduces this inhibition to FFA mobilization from adipose tissue
combined with the training- induced increase in mitochondria, the trained person can use more fat as a fuel, spare the limited CHO stores