Exercise Physiology - The neuromuscular system

Question 1

what are the 3 main types of muscle fibre

Answer 1

• slow oxidative (type I)
• fast oxidative (type IIa)
• fast glycolytic (type IIx)

Question 2

what is the definition of aerobic

Answer 2

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

Question 3

what is the definition of anaerobic

Answer 3

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

Question 4

what are the slow twitch muscle fibres (type I)

Answer 4

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.

Question 5

what are fast twitch muscle fibres (type II)

Answer 5

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

Question 6

what are the two types of fast twitch muscle fibres

Answer 6

• type IIa fast oxidative glycolytic
• type IIx fast glycolytic

Question 7

what are the key things to remember about type IIa fast oxidative glycolytic fibres

Answer 7

• more resistance to fatigue
• perfect for events like the 1500m
• allow for a longer burst of energy than the type IIx fast glycolytic

Question 8

what are the key things to remember about type IIx fast glycolytic fibres

Answer 8

• 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

Question 9

make sure to know some of the key differences between each of the muscle fibre types

Answer 9

as shown by table 2 on page number 31

Question 10

what is a motor unit?

Answer 10

a motor neurone and its muscle fibres

Question 11

what is a motor neurone

Answer 11

nerve cells which transmit the brains instructions as electrical impulses to the muscles

Question 12

what is a neuromuscular junction

Answer 12

where the motor neurone and the muscle fibre meets

Question 13

what is key to remember about a muscle fibres and motor neurone units

Answer 13

only one type of muscle fibre can be found in one particular motor unit

Question 14

what is the all or nothing law

Answer 14

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

Question 15

what are the 2 classification of motor units

Answer 15

fast twitch (if they contain fast twitch muscle fibres) or slow twitch (if they contain slow twitch muscle fibres)

Question 16

what is wave summation

Answer 16

where there is a repeated nerve impulse with no time to relax so smooth, sustained contraction occurs rather than twitches

Question 17

what is tetanic contraction

Answer 17

a sustained muscle contraction caused by a series of fast repeating stimuli

Question 18

what is spatial summation

Answer 18

when the strength of a contraction changes by altering the number and size of the muscles motor units

Question 19

what does a twitch mean

Answer 19

a single contraction

Question 20

what determines the strength of the muscles response

Answer 20

the number of motor units activated

Question 21

what are most of our skeletal muscle doing at rest

Answer 21

they are in a stage of partial contraction.

Question 22

what is wave summation

Answer 22

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.

Question 23

Explain how wave summation allows a gymnast to gain the required height in a floor routine?

Answer 23

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)

Question 24

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?

Answer 24

* 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

Question 25

what is PNF (proprioceptive neuromuscular facilitation) stretching

Answer 25

Isometric muscle contraction completed immediately before a passive stretch to help achieve autogenic inhibition.

Question 26

what is the CRAC technique

Answer 26

* **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

Question 27

what are muscle spindles

Answer 27

these detect how far and how fast a muscle is being stretched, and produce the stretch reflex

Question 28

what are the golgi tendon organs

Answer 28

these, are activated when there is tension in the muscle.

Question 29

what is isometric contraction

Answer 29

where there is tension in a muscle, but no visible movement

Question 30

what is autogenic inhibition

Answer 30

where there is a sudden relaxation, in response to high tension. The receptors, involved in this process are Golgi Tendon organs

Question 31

what are proprioceptors

Answer 31

these are sensory organs, in the muscles, tendons and joints that inform the body, of the extent of movement that has taken place

Question 32

what is the role of muscles spindles, in PNF stretching

Answer 32

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)

Question 33

what is the role of the Golgi tendon organs, in PNF stretching

Answer 33

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.