3.2 Muscle Physiology

Question 1

What is an agonist and what is it also known as

Answer 1

The muscle that is primarily responsible for the movement
-Prime mover

Question 2

What is a synergist

Answer 2

A muscle that assists the agonist in performing the movement

Question 3

What is the antagonist

Answer 3

The muscle that opposes the movement of the agonist

Question 4

What is a stabiliser

Answer 4

A muscle that stabilises the joint during movement to ensure smooth action

Question 5

Give an example of opposing muscles and indicate which is the flexor and which is the extensor

Answer 5

Biceps and triceps oppose each other. The biceps are the flexor and the triceps are the extensor.

Question 6

What happens to bend the arm

Answer 6

The biceps (flexor) contract and the triceps (extensor) relax

Question 7

What happens to straighten the arm

Answer 7

The triceps (extensor) contract and the biceps (flexor) relax

Question 8

What are the 2 categories of muscle contractions

Answer 8

Isotonic and Isometric

Question 9

What are isotonic contractions

Answer 9

Where the muscle changes length during contraction

Question 10

What are isometric contractions

Answer 10

Where the muscle does not change length during contraction (e.g holding a weight without moving it)

Question 11

Describe the 2 types of isotonic contraction

Answer 11

Concentric contractions - where the muscle shortens as it contracts (e.g lifting a weight)

Eccentric contractions - where the muscle lengthens under tension (e.g lowering a weight)

Question 12

Rank concentric, isometric and eccentric contractions in terms of maximal force

Answer 12

Eccentric Highest
Isometric
Concentric Lowest

Question 13

Rank concentric, isometric and eccentric contractions in terms of maximal energy expenditure

Answer 13

Concentric Highest
Isometric
Eccentric Lowest

Question 14

Describe the relationship between internal force and load for eccentric, isometric and concentric contractions

Answer 14

Concentric - Force>Load
Isometric - Force = Load
Eccentric - Force<Load

Question 15

Describe Type 1 muscle fibres

Answer 15

Slow twitch fibres that use aerobic respiration to metabolise carbohydrates and lipids

Question 16

Describe 2A muscle fibres

Answer 16

Type 2A muscle fibres are intermediate fast twitch fibres. They use aerobic and anaerobic respiration to metabolise lipids and carbohydrates

Question 17

Describe 2X muscle fibres

Answer 17

Fast twitch fibres that use anaerobic respiration to metabolise carbohydrates

Question 18

What are the 3 muscle fibre types

Answer 18

Type 1 (slow twitch)
Type 2A (intermediate fast twitch)
Type 2X (fast twitch)

Question 19

Rank type 1, 2a and 2x in terms of which fatigue most easily

Answer 19

2x Easily Fatigues
2a
1 Fatigue resistant

Question 20

Rank type 1, 2a and 2x in terms of the highest activation threshold

Answer 20

2x Highest threshold
2a
1 Lowest threshold

Question 21

Rank type 1, 2a and 2x in terms of which generates the most force

Answer 21

2x Most force
2a
1 Least force

Question 22

Rank type 1, 2a and 2x in terms of which has the most muscle fibres its the motor unit

Answer 22

2x Most fibres
2a
1 Least fibres

Question 23

Generally, which have more fast twitch fibres, flexors or extensors?

Answer 23

Extensors usually have more fat twitch fibres than flexors

Question 24

Describe muscle plasticity and give examples

Answer 24

Where muscles are trained over time to meet certain demands and more/less of each muscle type can develop based on needs. For example, more endurance training would lead to a greater proportion of slow twitch muscles but more power training would lead to a greater proportion of fast twitch muscles.

Question 25

How can muscle fibre proportions be measured

Answer 25

In a muscle biopsy

Question 26

What are the 4 types of muscle adaptation

Answer 26

-strength adaptation (hypertrophy) -endurance adaptation -neural adaptation -atrophy

Question 27

What is hypertrophy

Answer 27

The enlargement of muscle fibres in response to strength/resistance training

Question 28

Explain the 3 mechanisms of increasing hypertrophy

Answer 28

muscle tension - stimulates pathways to promote muscle growth muscle damage - microtears trigger repair mechanisms to synthesis new muscle proteins metabolic stress - accumulation of metabolism bi-products like lactate induce cellular changes to enhance protein synthesis causing muscle growth

Question 29

Give 3 ways hypertrophy can be optimised

Answer 29

-progressive intensity/load overload -training volumes -adequate recovery and nutrition (especially protein)

Question 30

What is the endurance adaptation

Answer 30

Improved endurance in muscle stamina and aerobic capacity due to sustained low intensity activity

Question 31

Explain 3 mechanisms of increasing the endurance adaptation

Answer 31

-endurance training increases mitochondrial density -endurance training promotes growth of capillary network around fibres -endurance training increases myoglobin content which helps transport oxygen within muscle cells

Question 32

What is the optimal training routine for the endurance adaptation

Answer 32

Moderate intensity, long duration training. Done regularly

Question 33

What is the athlete paradox

Answer 33

That endurance athletes have intramyocellular lipids (IMCLs) deposited closer to the mitochondria which increases their capacity to use fat as a fuel source

Question 34

What is the neural adaptation

Answer 34

Changes in the nervous system that enhance muscle coordination, motor unit recruitments and overall movement efficiency

Question 35

Describe the 3 mechanisms of improving neural adaptation

Answer 35

-resistance training improving motor unit recruitment allowing for greater force production -increasing rate at which motor neurons send signals, improving contraction speed and efficiency -greater coordination between motor units allows for smoother and more powerful movements+reduced coactivation of antagonist muscles enhances movement efficiency

Question 36

What is muscular atrophy

Answer 36

A reduction in muscle size and function

Question 37

What are the 3 causes of muscular atrophy

Answer 37

-ageing (sarcopenia where muscle mass naturally declines with age) -disease (causing prolonged inactivity of muscles) -injury (muscle inactivity during rehab)

Question 38

What are 3 ways to prevent/reverse muscular atrophy

Answer 38

-nutrition -rehabilitation -regular exercise