Adaptations

Question 0

What are the consequences of short, high intensity exercise?

Answer 0

Cannot deliver extra oxygen and glucose to muscles in time —> short term energy used (ATP & creatine phosphate) —-> anaerobic respiration —-> lactate + H+ (acidosis = cramps)

(note: glucose-6-phosphate produced by muscle glycogenolysis can produce glucose without using ATP)

Question 1

What are three key things the body needs to do to maintain life during exercise? What does the magnitude of this response depend on?

Answer 1

• meet acute oxygen and metabolic fuel needs of muscles
• dispose of CO2 and other waste products of metabolism
• maintain homeostasis

Magnitude:

• type of exercise (muscles used)
• intensity & duration of exercise
• physical condition/nutritional state of individual

Question 2

What are the consequences of medium intensity exercise?

Answer 2

• glycolysis: insulin inserts GLUT4 to allow glucose to enter muscle, and glucagon stimulates glycogenolysis in the liver
• some fatty acids used (beta-oxidation)
• adrenaline stimulates glycogenolysis (by stimulating glycogen phosphorylase)

Question 3

What are the consequences of long, low-intensity exercise?

Answer 3

Depletion of muscle glycogen —> liver glycogen used —-> fatty acids used

Slow decrease in insulin & glucagon, sharp increase in adrenaline & GH + slow increase in cortisol (stress response)

Cortisol stimulates lipolysis & gluconeogenesis (stimulates PEPCK & fructose-1,6-bisphosphatase)

Question 4

What are the long-term effects of exercise?

Answer 4

• decreased heart rate (hypertrophy of left ventricle)
• muscle fibre hypertrophy & hyperplasia
• increased myoglobin (oxygen “storage”)
• better beta-oxidation capacity & glucose transport capacity
• increased glycogen storage