!!! Functional roles of muscles and types of contraction Flashcards
What is the agonist and antagonist?
- Agonist is the muscle which creates movement at a joint.
2. Antagonist is the muscle which opposes the agonist, providing a resistance for co-ordinated movement.
What is the fixator?
The fixator is a muscle that stabilises one part of a body while another part moves
E.g. the trapezius during the flexion of the elbow.
What is energy?
Energy is the ability to work, measured in joules or calories.
What are the different types of contraction?
- Isotonic, muscle changes length to produce force:
- Concentric, muscle shortens to produce force e.g. upward phase of bicep curl, the biceps brachii concentrically contracts to lift weight
- Eccentric, muscle lengthens to produce force e.g. downward phase of bicep curl, the biceps brachii eccentrically contacts to lower weight - Isometric, muscle contracts but does not change length and no movement is created e.g. rugby players crouching in a scum.
What are motor neurones?
- Motor neurons are specialised cells which transmit nerve impulses rapidly to a group of muscle fibres
- They have a cell body in the brain or the spinal chord with an extending axon which branches to connect motor end plates to a group of muscle fibres.
What is a motor unit?
A motor unit is the motor neurons and it’s muscle fibres.
How does the motor unit cause contraction?
- Nerve impulse is initiated in the motor neuron cell body
- Nerve impulse is conducted down the axon of the motor neuron by a nerve action potential to the synaptic cleft
- Neurotransmitter called acetylcholine is secreted into the synaptic cleft to conduct the nerve impulse across the gap
- If the electrical charge is above threshold, the muscle fibre will contract
- This happens in an ‘all or nothing’ fashion (depending on whether the stimulus is above threshold, all muscle fibres give either a complete contraction or no contraction at all).
What are the characteristics of slow oxidative muscle fibres, with an example?
Structural characteristics:
- Small neuron size
- Few fibres per neuron
- High capillary density
- High mitochondria density
- High myoglobin density
- Low PC stores
Functional characteristics:
- Slow speed of contraction
- Low force of contraction
- High fatigue resistance
- High aerobic capacity
- Low anaerobic capacity
Endurance athletes e.g. marathon runners.
What are the characteristics of fast oxidative glycolytic muscle fibres, with an example?
Structural characteristics:
- Large neuron size
- Many fibres per neuron
- High capillary density
- Moderate mitochondria density
- Moderate myoglobin density
- High PC stores
Functional characteristics:
- Fast speed of contraction
- High force of contraction
- Moderate fatigue resistance
- Moderate aerobic capacity
- Moderate anaerobic capacity
High-intensity athletes e.g. 800m runners.
What are the characteristics of fast glycolytic muscle fibres, with an example?
Structural characteristics:
- Large neuron size
- Many fibres per neuron
- Low capillary density
- Low mitochondria density
- Low myoglobin density
- High PC stores
Functional characteristics:
- Fast speed of contraction
- High force of contraction
- Low fatigue resistance
- Low aerobic capacity
- High anaerobic capacity
Explosive athletes e.g. 100m runners.
Who would need all 3 muscle fibres?
A games player.
What are slow oxidative muscle fibres, what should be considered in training/recovery?
- They are recruited and provide energy for sub-maximal aerobic work
- They contract intermittently to give overall low force of contraction
- Individual fibres will recover very quickly
- In training a 1:1 or 1:0.5 work:relief ratio should be used, e.g. 3 minutes of moderate running with a relief of 90 seconds
- Training can be performed on a daily basis, as low-intensity training does not cause fibre damage
- Low-intensity use of SO fibres is advised between heavy weight training sessions to increase blood flow and enhance healing process.
What are fast oxidative glycolytic muscle fibres, what should be considered in training/recovery?
- They are designed to produce a large amount of force quickly
- They have capacity to resist fatigue
- They are more likely to be used in high-intensity activities lasting a few minutes e.g. 800m.
What are fast glycolytic muscle fibres, what should be considered in training/recovery?
- If fast glycolytic fibres have been used to exhaustion, it takes 4-10 days to recover
- Maximal weight training sessions should leave 48 hours before using the same muscle group again.
