Lecture 15 - Exercise: Muscle Bone And Systemic Changes

Question 1

Muscle fatigue

Answer 1

• reversible weakness associated with intense actibity

- eg: run up a mountain

Question 2

Muscle damage

Answer 2

• mild self repairing condition
• muscular dystrophy is characerised by greatly increased stretch induced damage
• eg: run down a mountain

Question 3

Delayed onset msucle soreness

Answer 3

• a form of muscle damage
• reduced force, takes days to recover
• loss of muscle enzymes in the blood
• overstretched sarcomeres
• mainly occurs in contractions involving stretching

Question 4

When are sarcomere unstable

Answer 4

• on the descending aspect of the tension length curve

Question 5

Satellite cell activation and regeneration

Answer 5

• SM contain satellite cells which can divide, form new muscle cells and fuseto form a replacement multinucleate muscle fiber

Question 6

Exercise induced hypertrophy : How

Answer 6

• may involve exercise-induced muscle damage
• involves increased protein synthesis, reduced protein breakdown
• myofibrils thicken
• increased number of sarcomeres
• synthesis of more muscle proteins

Question 7

Exercise and formation of bone

Answer 7

• exercise promotes laying down of new bone more distally

Question 8

Cardiovascular response: why does HR increase

Answer 8

• withdrawal of PNS activity

- increased SNS activity

Question 9

Systemic changes in exercise

Answer 9

• systemic wide vasoconstriction but local vasodilation

Question 10

Muscle mass and VO2

Answer 10

• there is a linear relationship between the total amount of power produced and the amount of oxygen required for taht production of power in one muscle

Question 11

Substrates and ATP generation changes over time

Answer 11

• non oxidative pathway initially and then the glycolysis pathway kicks in
• after 6 hours of exercise, there is a major shift away from glucose oxidation to FA oxidation over time

Question 12

Substrates and ATP generation changes with intensity

Answer 12

• the amount of energy required to support more activity
• optimal fat burning range is around 65%
• if you work harder, more utilisation of muscle glycogen

Question 13

Duchenne muscular dystrophy

Answer 13

• 1 in 3500 male birth
• muscle nromal at birth and then increasing muscle weakness with age
• mild intellectual impairment
• cardiac involvement

Question 14

Why does absence of dystrophin cause muscle damage

Answer 14

• dystrophin is a cytoskeletal protein which connects the contractile proteins to a group of proteins in the cell membrane
• dystrophic muscle is more susceptible to stretch induced muscle damage

Question 15

Exercise as a therapeutic modality

Answer 15

• increased energy expenditure decreases lipid content thereby reducing the processes that inhibits insulin signalling
• increased utilisation of glucose leads to upregulation of processes involved in glucose metabolism
• also net improvement in insulin sensitivity

Question 16

Cardiac output is worload dependent

Answer 16

Predominanlty due to increased HR and to a lesser extent to SV