3.2 Muscle Physiology Flashcards
What is an agonist and what is it also known as
The muscle that is primarily responsible for the movement
-Prime mover
What is a synergist
A muscle that assists the agonist in performing the movement
What is the antagonist
The muscle that opposes the movement of the agonist
What is a stabiliser
A muscle that stabilises the joint during movement to ensure smooth action
Give an example of opposing muscles and indicate which is the flexor and which is the extensor
Biceps and triceps oppose each other. The biceps are the flexor and the triceps are the extensor.
What happens to bend the arm
The biceps (flexor) contract and the triceps (extensor) relax
What happens to straighten the arm
The triceps (extensor) contract and the biceps (flexor) relax
What are the 2 categories of muscle contractions
Isotonic and Isometric
What are isotonic contractions
Where the muscle changes length during contraction
What are isometric contractions
Where the muscle does not change length during contraction (e.g holding a weight without moving it)
Describe the 2 types of isotonic contraction
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)
Rank concentric, isometric and eccentric contractions in terms of maximal force
Eccentric Highest
Isometric
Concentric Lowest
Rank concentric, isometric and eccentric contractions in terms of maximal energy expenditure
Concentric Highest
Isometric
Eccentric Lowest
Describe the relationship between internal force and load for eccentric, isometric and concentric contractions
Concentric - Force>Load
Isometric - Force = Load
Eccentric - Force<Load
Describe Type 1 muscle fibres
Slow twitch fibres that use aerobic respiration to metabolise carbohydrates and lipids
Describe 2A muscle fibres
Type 2A muscle fibres are intermediate fast twitch fibres. They use aerobic and anaerobic respiration to metabolise lipids and carbohydrates
Describe 2X muscle fibres
Fast twitch fibres that use anaerobic respiration to metabolise carbohydrates
What are the 3 muscle fibre types
Type 1 (slow twitch)
Type 2A (intermediate fast twitch)
Type 2X (fast twitch)
Rank type 1, 2a and 2x in terms of which fatigue most easily
2x Easily Fatigues
2a
1 Fatigue resistant
Rank type 1, 2a and 2x in terms of the highest activation threshold
2x Highest threshold
2a
1 Lowest threshold
Rank type 1, 2a and 2x in terms of which generates the most force
2x Most force
2a
1 Least force
Rank type 1, 2a and 2x in terms of which has the most muscle fibres its the motor unit
2x Most fibres
2a
1 Least fibres
Generally, which have more fast twitch fibres, flexors or extensors?
Extensors usually have more fat twitch fibres than flexors
Describe muscle plasticity and give examples
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.
How can muscle fibre proportions be measured
In a muscle biopsy
What are the 4 types of muscle adaptation
-strength adaptation (hypertrophy)
-endurance adaptation
-neural adaptation
-atrophy
What is hypertrophy
The enlargement of muscle fibres in response to strength/resistance training
Explain the 3 mechanisms of increasing hypertrophy
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
Give 3 ways hypertrophy can be optimised
-progressive intensity/load overload
-training volumes
-adequate recovery and nutrition (especially protein)
What is the endurance adaptation
Improved endurance in muscle stamina and aerobic capacity due to sustained low intensity activity
Explain 3 mechanisms of increasing the endurance adaptation
-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
What is the optimal training routine for the endurance adaptation
Moderate intensity, long duration training. Done regularly
What is the athlete paradox
That endurance athletes have intramyocellular lipids (IMCLs) deposited closer to the mitochondria which increases their capacity to use fat as a fuel source
What is the neural adaptation
Changes in the nervous system that enhance muscle coordination, motor unit recruitments and overall movement efficiency
Describe the 3 mechanisms of improving neural adaptation
-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
What is muscular atrophy
A reduction in muscle size and function
What are the 3 causes of muscular atrophy
-ageing (sarcopenia where muscle mass naturally declines with age)
-disease (causing prolonged inactivity of muscles)
-injury (muscle inactivity during rehab)
What are 3 ways to prevent/reverse muscular atrophy
-nutrition
-rehabilitation
-regular exercise
