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
why is it generally difficult to perform trunk plyometrics?
- it is difficult to perform trunk plyometrics that directly target the trunk musculature because all the requisite plyometric elements may not be present
- research suggests that there is not many exercises that potentiate the concentric portion
- most trunk plyos will need to be performed with 1/2 ROM
what is the law of inc^ latency period?
stretch reflex latencies largely depend on nerve conduction velocities and therefore inc^ with distance from spinal cord
although no research has addressed abdominal stretch reflexes, it may be assumed that the latencies are shortened as the muscles are closer to the spinal cord
state what it is meant by the key term - Plyometric Intensity
plyometric intensity refers to the amount of stress placed on the involved muscles, connective tissue, and joints and is controlled primarily by the type of drill performed
what is the volume intensity relationship with plyos?
generally, as volume inc^, intensity should dec^ (vise versa)
What 4 factors mainly effect the intensity of plyometric exercises?
1) points of contact
2) speed
3) height of the drill
4) body weitht
Explain how points of contact change plyo drill intensity
- GRF during SL lower-body plyos place more stress on extremity muscles, connective tissue, and joints
Explain how speed change plyo drill intensity
greater speed inc^ drill intensity
Explain how height of drill change plyo drill intensity
the higher the athlete’s centre of gravity, the greater the force of landing
Explain how body weight change plyo drill intensity
- the greater the athlete’s BW, the more stress is placed on the muscles, connective tissues, and joints
- external weights can be assed to inc^ drill intensity
What factors should determine the frequency of plyometric training?
sport demands, intensity/volume of weekly training, time during competitive season
what do researchers suggest is optimal for plyometric training frequency ?
1-3 sessions per week; 48-72 hrs recovery between plyo sessions
What should recovery time be during plyos?
work rest ratio of 1:5 or 1:10
e.g. - if it takes 20 seconds to perform the set, 1 min 40 secs at the 1:5 ratio
How is volume typically represented with plyo training?
- usually represented as sets and reps per week
- can be represented as number of foot contacts per week
- can be represented as distance
plyometric training must abide the law of Progressive Overload, which is what?
Progressive Overload is the systematic increase in training volume, frequency, and intensity in various combinations over time
What are the 5 steps of warming up for a plyometric training session?
1) marching
2) jogging
3) skipping
4) footwork
5) lunging
Explain how marching can be used to help warm-up for plyos
- mimics running movements
- emphasises posture and movement technique
- enhances proper lower body movements for running
Explain how jogging can be used to help warm-up for plyos
- prepares for higher intensity impacts
- toe jogging emphasises quick reaction
- straight leg jogging prepares for impact of plyos
- butt kicks
Explain how skipping can be used to help warm-up for plyos
- exaggerated form of reciprocal lower & upper extremity movements
- emphasis on quick take-off and landing (mimics plyos)
Explain how footwork can be used to help warm-up for plyos
- drills that target COD
- preps for COD in plyos
Explain how lunging can be used to help warm-up for plyos
- based on forward step lunge exercise
- can be multi-directional
when working with adolescent athletes, analysis into their body development gives us some insight into what 2 things?
1) if epiphyseal plates of pre-pubescent bones are yet to close, depth jumps and other high intensity plyos should be avoided
2) whilst growth plates are open, high intense activity and injury can cause premature closure, resulting in limb length discrepancies
what is most important when using plyos with adolescent athletes?
most important to focus on the quality of the movement to develop the techniques needed for higher intense plyos
What 2 primary considerations must we make when designing a plyo program for masters athletes?
1) pre-existing orthopaedic conditions (e.g. - osteoarthritis)
2) joint degeneration
How do guidelines for plyo training differ with masters athletes? (3 points)
1) no more than 5 low-mod intense plyos
2) lower volume (in distance, sets/reps, foot contacts)
3) recovery between sessions at 3-4 days
What 3 guidelines are there to combine Plyometric Trining and Resistance Training?
1) combine lower body RT with upper plyos (vice versa)
2) performing heavy RT with high intensity plyos on same day not usually recommended
- adequate recovery between sessions is needed if this is done as some athletes can benefit from it
3) traditional RT may be combined with plyos to further inc^ power
- e.g. - 30% 1RM jump squats
What 6 safety considerations must we adhere to when using plyometrics?
1) pre-training evaluation of the athlete
2) technique
3) strength
4) speed
5) balence
6) physical characteristics
Explain the following safety consideration when using/considering using plyometrics - pre-training evaluation of the athlete (2 points)
- athlete must possess pre-plyo strength, speed and balance
- must be physiologically and psychologically mature to perform correctly & adhere to
Explain the following safety consideration when using/considering using plyometrics - Technique (3 points)
- S&C must give correct visual & verbal guidance
- landing is essential –> shoulders must land above knees –> achieved by ankle, knee, and hip flexion
- of centre of gravity is offset from base of support, balance is hindered
Explain the following safety consideration when using/considering using plyometrics - strength (4 points)
- lower body plyos –> squat should be 1.5x BW
- upper body for athletes 220 lbs+ –> BP must be 1x their BW
- upper body for athletes < 220 lbs –> BP must be 1.5x BW
- or, 5 clapping press ups in a row
Explain the following safety consideration when using/considering using plyometrics - Speed (2 points)
- lower body plyos –> 6 squats in 5 seconds with 60% BW
- upper body plyos –> 6 BP in 5 seconds with 60% BW
Explain the following safety consideration when using/considering using plyometrics - Balance
- plyos require non-traditional movement patterns, SL, and DL variations
- require a stable and solid base of support
- must hold for 30 secs: standing DL/SL, quatre squat SL/DL, half squat DL/SL
Explain the following safety consideration when using/considering using plyometrics - Balance (3 points)
- plyos require non-traditional movement patterns, SL, and DL variations
- require a stable and solid base of support
- must hold for 30 secs: standing DL/SL, quatre squat SL/DL, half squat DL/SL
Explain the following safety consideration when using/considering using plyometrics - physical characteristics
- heavy athletes (220 lbs +) = greater risk of injury –> compressive forces –> should have lower volume & intensity –> max depth jump @ 18 inches
- bone characteristics (weak bones = plyos bad)
- previous injury - can inc^ risk of re-injury with such an intense form of training
What 6 considerations must we take on board when deciding if plyometric training is suitable?
1) Landing Surface
2) Training Area
3) Equipment
4) Proper Footwear
5) Supervision
6) Depth Jumping?
What 6 considerations must we take on board when deciding if plyometric training is suitable?
1) Landing Surface
2) Training Area
3) Equipment
4) Proper Footwear
5) Supervision
6) Depth Jumping?
Explain the following safety consideration of plyometrics - Landing Surface (4 points)
- shock absorbant qualities
- concrete not recommended
- excessively thick surfaces can elongate amortization phase (no SSC)
- trampolines not recommended as inc^ amortization phase
Explain the following safety consideration of plyometrics - Training Area (3 points)
- space depends on drill
- running & bounds = 30 - 100m
- ceiling must be 3-4 m for box drills
Explain the following safety consideration of plyometrics - Equipment (3 points)
- boxes must be sturdy & non-slip
- landing surfaces minimum 18 by 24 inches
- adding non-slip properties to landing surface = essential
Explain the following safety consideration of plyometrics - Proper Footwear (4 points)
- good ankle/foot support
- narrow shoes can cause ankle issues, especially with lateral movements
- insufficient support may lead to lower-extremity injury and arch
- lack of cushioning may cause proximal joint damage (e.g. - knees, hips)
Explain the following safety consideration of plyometrics - Supervision
- athletes must be monitored ideally all the time to ensure proper and safe technique
Explain the following safety consideration of plyometrics - Depth Jumping
- 48 inches sufficient for depth jumps
- too high inc^ injury risk as inc^ force needed to overcome
- too high can inc^ amortization phase
- usual height is 30-32 inches
