Exercise Physiology - The neuromuscular system Flashcards
what are the 3 main types of muscle fibre
- slow oxidative (type I)
- fast oxidative (type IIa)
- fast glycolytic (type IIx)
what is the definition of aerobic
literally means ‘with oxygen’ so it refers to exercise that is low to medium intensity where the oxygen demand of the muscles can be met
what is the definition of anaerobic
means ‘without oxygen’ and refers to exercise at high intensity such as sprinting, where the demand or oxygen by the muscles is so high that it cannot be met
what are the slow twitch muscle fibres (type I)
these fibres have a slower contraction speed, than fast twitch fibres and are better adapted to lower intensity such as long distance running. they produce most of their energy aerobically.
what are fast twitch muscle fibres (type II)
these fibres have a much faster contraction speed and can generate a greater force of contraction. However they also fatigue very quickly and are used for short, intense bursts of effort. they produce most of there energy anaerobically
what are the two types of fast twitch muscle fibres
- type IIa fast oxidative glycolytic
- type IIx fast glycolytic
what are the key things to remember about type IIa fast oxidative glycolytic fibres
- more resistance to fatigue
- perfect for events like the 1500m
- allow for a longer burst of energy than the type IIx fast glycolytic
what are the key things to remember about type IIx fast glycolytic fibres
- they fatigue much faster than type IIa fast oxidative glycolytic fibres
- they are used for highly explosive events such as the 100m sprint
- perfect for when a short burst of energy is required
make sure to know some of the key differences between each of the muscle fibre types
as shown by table 2 on page number 31
what is a motor unit?
a motor neurone and its muscle fibres
what is a motor neurone
nerve cells which transmit the brains instructions as electrical impulses to the muscles
what is a neuromuscular junction
where the motor neurone and the muscle fibre meets
what is key to remember about a muscle fibres and motor neurone units
only one type of muscle fibre can be found in one particular motor unit
what is the all or nothing law
where a sequence of impulses has to be of sufficient intensity to stimulate all of the muscle fibres in a motor unit in order for them to contract, if not none of them contracting
what are the 2 classification of motor units
fast twitch (if they contain fast twitch muscle fibres) or slow twitch (if they contain slow twitch muscle fibres)
what is wave summation
where there is a repeated nerve impulse with no time to relax so smooth, sustained contraction occurs rather than twitches
what is tetanic contraction
a sustained muscle contraction caused by a series of fast repeating stimuli
what is spatial summation
when the strength of a contraction changes by altering the number and size of the muscles motor units
what does a twitch mean
a single contraction
what determines the strength of the muscles response
the number of motor units activated
what are most of our skeletal muscle doing at rest
they are in a stage of partial contraction.
what is wave summation
Wave summation: where there is a repeated nerve impulse thus, there is no time to relax so a smooth sustained contraction occurs, rather than twitches. The greater the frequency of stimuli, the greater the tension developed by the muscles.
Explain how wave summation allows a gymnast to gain the required height in a floor routine?
Wave summation will allow the gymnast to produce a more powerful contraction (1) because the muscle is stimulated again before it is relaxed (1) therefore the gymnast will be able to apply greater force to adjust the height achieved to match the requirements of the technique performed. (1)
All gymnastic events, require controlled powerful movements. How can a performer vary the strength of muscular contractions to ensure that a skill is completed correctly?
* Greater the force needed; the larger motor units required
* More units recruited
* Need fast twitch fibres rather than slow twitch fibres
* Spatial summation
* All or nothing law
* Motor unit unable to relax/increase force
what is PNF (proprioceptive neuromuscular facilitation) stretching
Isometric muscle contraction completed immediately before a passive stretch to help achieve autogenic inhibition.
what is the CRAC technique
- Contract: passive stretch (eccentric contraction) until muscle spindle apparatus is stimulated (stretch reflex)
- Relax
- Isometric contraction (hold) – autogenic inhibition is where the Golgi tendon organ takes over.
- Contract: followed by a passive stretch (eccentric contraction) until muscle spindle apparatus is stimulated)
- repeat
what are muscle spindles
these detect how far and how fast a muscle is being stretched, and produce the stretch reflex
what are the golgi tendon organs
these, are activated when there is tension in the muscle.
what is isometric contraction
where there is tension in a muscle, but no visible movement
what is autogenic inhibition
where there is a sudden relaxation, in response to high tension. The receptors, involved in this process are Golgi Tendon organs
what are proprioceptors
these are sensory organs, in the muscles, tendons and joints that inform the body, of the extent of movement that has taken place
what is the role of muscles spindles, in PNF stretching
they respond, to how much a muscles is being stretched, if it becomes over stretched, the central nervous system sends a impulse which triggers the stretch reflex, to prevent injury (causing the muscle to contract)
what is the role of the Golgi tendon organs, in PNF stretching
when the muscle is contracted isometrically in PNF, they sense the increase in muscle tension and send inhibitory signals to the brain which allows the antagonist muscle to relax and lengthen. this is known as autogenetic inhibition.
