Plyometrics - Science and Theory Flashcards
state what it is meant by the key term - plyometrics
plyometrics are quick, powerful movement which use a pre-stretch, or countermovement, that involves a stretch-shortening cycle (SSC)
what is the purpose of plyometric exercises?
the purpose of plyometrics is to increase power of the subsequent movement by using the elastic components of muscles and tendons and the stretch reflex
What 3 things must be understand to effectively use plyometrics?
1) mechanics and physiology of plyometrics
2) the principles of plyometric training program design
3) methods to perform plyometrics safely and effectively
what are the 3 theories of plyometric mechanisms and physiology?
1) the ‘Mechanical Model of Plyometric Exercise’
2) the ‘Neurophysiological Model of Plyometric Exercise’
3) the ‘Stretch-Shortening Cycle’ (SSC)
Using 3 points, briefly explain the ‘mechanical model of plyometric exercise’
- elastic energy in the musculotendinuous components is increased with rapid stretch and is then stored
- when immediately followed by a concentric contraction, stored elastic energy is released, increasing total force production
- If the concentric action does not occur, or the eccentric action takes too long, or requires too great a range if motion about the given joint, the stored energy dissipates and is lost as heat
In the mechanical model of plyometrics, what is the main component?
the ‘Series Elastic Component’ (SEC)
Explain what the SEC is (3 points)
- SEC includes some muscular components; the tendons constitute the majority of the SEC
- when the MTU is stretched, the SEC acts as a spring and is lengthened (stores elastic energy)
- concentrically, this contributes to the force as SEC allows muscles and tendons to naturally return to their un-stretched configurations
What is the general consensus of the Neurophysiology model of plyometrics?
this model involves the potentiation of the concentric muscle by use of the stretch reflex
state what it is meant by the key term - Stretch Reflex
the Stretch Reflex is the body’s involuntary response to an external stimulus that stretches the muscle
state what it is meant by the key term - Muscle Spindles
Muscle Spindles are proprioceptive organs that are sensitive to the rate and magnitude of a stretch
Explain the Neurophysiological Model of Plyometric Exercises (3 points)
1) during plyos, spindles are activated by rapid stretch, causing reflexive muscle action
2) this potentiates muscle activity, thereby inc^ power production
3) if concentric action does not occur, eccentric action takes too long, or requires too great a motion around the joint, the stored energy dissipates and is lost as heat
what is the SSC?
the SSC employs the energy storage capabilities of the SEC (series elastic component) and stretch reflex to facilitate a maximal increase in muscle recruitment over a minimal amount of time
what are the 3 phases of the SSC?
1) Eccentric (stretch of agonist)
2) Amortization (pause between eccentric and concentric)
3) Concentric (shortening of agonist muscle fibres)
what are the physiological events occurring during the eccentric phase of the SSC?
- elastic energy stored in elastic components
- muscle spindles stimulated
what are the physiological events occurring during the amortization phase of the SSC?
- type 1a afferent nerve synapses with alpha motor neurones
- alpha motor neurones transmit signals to agonist muscle group
what are the physiological events occurring during the Concentric phase of the SSC?
- elastic energy released from elastic components
- alpha motor neurones stimulate agonist muscle group(s)
state 2 additional facts about the amortization phase of the SSC
1) probably the most crucial phase
2) if the amortization phase lasts too long, energy stored dissipates as heat, and the stretch reflex will not inc^ muscle activity during the concentric phase
What are the 6 ‘Types’ or Lower Body Plyometric Drills?
1) jumps in place
2) standing jumps
3) multiple hops & bounds
4) bounds
5) box drills
6) depth jumps
state 2 introductory facts to plyometric program design
- mode, intensity, frequency, and duration all apply
- lack of research on the optimal prescription so practitioners should always keep up to date with current research on the topic
what is the rationale behind - Jumps in place
- jumping & landing in same spot
- emphasises vertical component
- performed repeatedly with min rest between jumps
- time between jumps in amortization phase
what is the rationale behind - standing jumps
- emphasise horizontal and vertical components
- max effort with recovery between jumps (e.g. - hurdle hops)
what is the rationale behind - Multiple Hops & Bounds
- involves repeated movements and may be viewed as a combination of jumps in place and standing jumps (e.g. - zigzag jumps)
what is the rationale behind - Bounds
- exaggerated movements with greater horizontal speed
- volume typically measured by distance; sometimes repetitions
- usually cover distances > 30m
- include SL & DL bounds
what is the rationale behind - Box Drills
- inc^ intensity of hops & bounds by adding a box
- box used to jump on/off
- box height depends on athlete size, landing surface, and program goals
- may include SL, DL or alt leg
what is the rationale behind - Depth Jumps
- use gravity & athlete weight to inc^ intensity
- box height depends on athlete size, landing surface, and program goals
- may involve SL or DL
state 2 introductory facts about upper body plyometrics
1) rapid, powerful upper body movements are required for many sports
2) studies less intensely and are used far less often than lower body plyometrics
