1.3- NEUROMUSCULAR SYSTEM Flashcards
Explain the role of the muscle spindles and Golgi tendon organs in PNF stretching (3)
Golgi tendons detect stretch/tension Muscles relax Inhibits stretch reflex Designed to stop overstretching allow greater range of movement CRAC ( contract relax/antagonist /contract)
Explain how a performer uses proprioceptive neuromuscular facilitation to increase flexibility (4)
Partner stretch for 8 to 10 secs isomentically contract for 8-10 secs this causes autogenic inhibition preventing the stretch reflex from occuring stretch again for 8-10 secs
What do you understand by the term motor unit? (2)
Motor neurone and its muscle fibres
all fast or slow twitch
All or none law
How are motor units involved in spatial summation? (2)
Causes an increase in strenght of contraction in mucles
uses bigger motor units
more motor units
fast twitch units produce more force
Describe the characteristics of the main muscle fibre type used by marathon runners (4)
Slow oxidative (type I) slow motor neurone conduction capacity High mitochondrial density High capillary density High myoglobin capacity Low force production/power
Analyze how a B player can use their knowledge of the neuromuscular system to jump as high as possible to win a rebound (8)
AO1- KNOWLEDGE OF NEUROMUSCULAR SYSTEM
- There are three muscle fibre types Type 1, 2a, 2x
- Motor unit recruitment is important when jumping (basketball)
- A motor unit is the motor neurone and its muscle fibres
- Spatial summation is when the number and size of motor units changes to suit the strength of contraction
- wave summation is where there is a repeated nerve impulse with no time to relax so a smooth sustained contraction occurs
- all or none law- either all the muscle fibres in a motor unit contract or none of them do
AO2- APPLY
- As the athlete jumps, he needs to ensure spatial summation takes place so that he can vary the number of motor units recruited throughout the muscle to allow fibres in each unit to relax while others are contracting to provide the necessary force
- He will have to use type 11x motor units in the quads, gluteal and gastrocnemius which are the muscles used when jumping
- He needs to recruit a large number of motor units so that more power can be exerted as well as big motor units as the jump in gross motor skills using large muscles
- Wave summation needs to happen as the more frequent the impulses the more power he will be able to apply to his jump and this will provide a smooth sustained muscle contraction
AO3- EVALUATION
- Type 11x fibres will contract to produce the most force to gain the necessary height in the rebound
- As he rebounds the basketball player needs to use wave summation to increase the frequency of stimulation of the muscle fibres in the motor unit so that the next impulse reaches the muscle before it has completely relaxed from the previous meaning the resulting force is greater so the jump is higher
Proprioceptive Neuromuscular Facilitation (PNF) is a specialist training method used by a range of athletes.
Explain the role of proprioceptors in PNF and evaluate its effectiveness as a specialist training method.
Use sporting examples in your answer.
(15)
AO1:
PNF is an advanced stretching technique which aims to improve athletes flexibility and range of motion
One method involves the passive stretch of the target muscle; followed by an isometric contraction; before repeating the passive stretch
The proprioceptors involved in PNF are muscle spindles and Golgi tendon organs.
AO2: 1- PNF stretching can be used to improve performance in sports such as gymnastics and dance.
In these sports a greater range of motion at a joint can allow the performance of more advanced routines.
allows performers to produce more aesthetically pleasing shapes with their bodies
2-In sports such as swimming and sprinting greater flexibility can allow a more efficient technique to be used which in turn can increase the speed of the performer/decrease the effort required to travel at the same speed.
3-In sports such as football and rugby PNF training can be used as an injury prevention method.
If performers have a greater range of movement at their joints they are less likely to incur muscular injuries such and strains and tears
AO3: 1- In sports such as dance and gymnastics, there are great benefits to be had from improved flexibility. Producing more aesthetically pleasing shapes will lead directly to higher scores and in turn a greater chance of success
2-PNF stretching is a very specialized training method focusing on one component of fitness, flexibility. In a large number of sports, other components of fitness may be deemed more important eg anaerobic power in swimming sprints.
3-Due to the passive nature of stretches and the overriding of the stretch reflex, risk of injury is increased if precautions such as a thorough warm-up and a knowledgeable partner are not adhered to.
4-PNF stretching reduces power and speed if performed immediately prior to activity. Therefore this is not an appropriate specialist training method during a warm up for sports requiring these components of fitness.
Explain how a tennis player would increase the force of contraction used to strike the ball during a competitive rally (4)
Recruit bigger motor units
More motor units
Recruit more 2x fibers
Send more impulses down the motor neuron to cause spatial summation
Send the max impulses down the motor neuron
Explain how the Hering Breuer reflex prevents over-inflation of the lungs during exercise (4)
During exercise stretch receptors in the lungs detect over inflation
They send impulses to the respiratory control centers in the medulla oblongata
Impulses send to the expiratory control center
Implus to intercostal nerve
causes increases contrction of abdominals and internal intercostal muscles
causing force of expiration to increase
