Plyometric training Flashcards
What is plyometrics?
A pre-stretch (countermovement) followed by a forceful contraction
What are 2 reasons for increased force?
Both mechanical and neural
What happens at the ‘parallel elastic component’?
A passive force is exerted with unstimulated muscle stretch
What body parts are involved in the parallel elastic component?
Epimysium, perimysium, endomysium and sarcolemma
What happens at the contractile component?
Primary source of muscle force during concentric action
What happens at the series elastic component?
When stretched, acts as a spring and stores elastic energy that increases force production
If a concentric action does not follow the stretch, what is the energy released as?
Heat energy
How long does the concentric action have following the eccentric action?
1 second
What happens when muscle spindles are stimulated?
Stretch reflex is released, sending input via the spinal chord to Type 1 nerve fibres
What is another name for type 1 nerve fibres?
Afferent nerves
What is the stretch reflex?
Involuntary response to an external stimulus that stretches the muscle
What are the 3 phases of plyometric action?
Eccentric phase, amortisation phase and concentric phase
What is another name for amortisation phase?
Electromechanical delay
What is stretched during the eccentric phase?
Muscle agonist
What happens to the muscle spindles during the eccentric phase?
They stretch
What is stored during the eccentric phase?
Elastic energy
What is the amortisation phase?
Phase between eccentric and concentric phase
What do the afferent nerves synapse with?
Alpha motor neurons
Where do the alpha motor neurons transmit signals?
Agonist group
What effects the time of the electromechanical delay?
Distance of muscles away from spinal chord
How long is the delay for quadriceps and calf muscles?
Quads 20-30ms. Calfs 30-45ms
What is shortened in concentric phase?
Agonist muscle fibres
Where is elastic energy released from in the concentric phase?
Series elastic component
How much does plyometric training improve jump height?
5-9%
Why might plyometrics help running economy?
50% elastic energy attained in the recovery of SSC
What is the ground reaction time for fast plyometrics?
100-125ms
What is the ground reaction time for slow plyometrics?
300-500ms
What does fast plyometrics require enhancement of?
Neural activity
What does slow plyometrics require enhancement of?
Muscle spindle activity
What does intensity of plyometrics refer to?
Amount of stress placed on muscles, connective tissue and joints
What frequency is recommended
2-4 sessions a week
What is recommended recovery between rep?
10-15 seconds
What is recommended recovery between sets?
2-3 mins
