Plyometric Training Ch' 19

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Plyometric TrainingCh. 19
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• Plyometric exercise- quick, powerful movement
  using a prestretch, or counter movement, that
  involves the stretch-shortening cycle (SSC)
• Those activities that allow a muscle to reach max
  force in shortest possible time
• Purpose is to increase power of subsequent mvmts.
  by using both natural elastic components of
  muscle tendon the stretch reflex

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Mechanical Model of Plyometric Exercise

• Elastic energy in musculotendinous components is
  increased with rapid stretch then stored
• When immediately followed by concentric muscle
  action, stored elastic energy is then released,
  increasing total force production
• If concentric muscle action does not occur
  immediately following eccentric action, or if too
  long, or requires too great a motion about a
  given jt., stored energy dissipates is lost as
  heat

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• Series elastic component (SEC)- work horse of
  plyometric exercise
• Acts as spring is lengthened in eccentric
  motion, immediate concentric contraction allows
  SEC to contribute to total force production by
  naturally returning muscles tendons to their
  unstretched configuration
• Includes some muscular components, but tendons
  constitutes majority of SEC

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Neurophysiological Model of Plyometric Exercise

• Involves potentiation of concentric muscle action
  by use of stretch reflex
• Potentiation- change in force-velocity
  characteristics of muscles contractile
  components caused by stretch
• Stretch reflex- bodys involuntary response to
  external stimulus that stretches the muscles

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• Muscle spindle is primarily involved in reflexive
  component of plyometric ex.
• Stimulated by rapid stretch, causing reflexive
  muscle action
• Reflexive response potentiates, or increases,
  activity in agonist muscle, thereby increasing
  force the muscle produces
• If con. action does not immediately follow
  stretch, or too long of time between, or too long
  a ROM, potentiating ability of stretch is negated

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Stretch-Shortening Cycle (SSC)

• Employs energy storage capabilities of SEC
  stimulation of stretch reflex to facilitate a max
  increase in muscle recruitment over minimal
  amount of time
• Involves 3 phases
• Phase I- eccentric phase
• Action preloading(stretch) agonist muscle
  group(s)
• Physiological event elastic energy is stored in
  SEC, muscle spindles are stimulated

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• Phase II- amoritization phase
• Action time(pause) between phases I III
• Time from end of ecc. phase to initiation of con.
  muscle action
• Phys Type Ia afferent nerves synapse with alpha
  motor neurons alpha motor neurons transmit
  signals to agonist muscle group
• Most crucial phase in allowing greater power
  production
• Its duration must be kept short
• If too long stored energy dissipates as heat
  stretch reflex will not increase muscle activity
  during con. Phase

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• Phase III- concentric phase
• Bodys response to eccentric ammoritization
  phases
• Energy stored in SEC is either used or dissipates
  as heat
• Action shortening of agonist muscle fibers
• Phys elastic energy is released from SEC alpha
  motor neurons stimulate agonist muscle group

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Plyometric Program Design

• Plyometric ex. prescriptions similar to RT
  aerobic ex. prescriptions
• Mode, frequency, duration, recovery, progression,
  warm-up

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Mode

• Determined by body region performing the given
  exercise
• Lower-body plyometrics
• Appropriate for virtually any athlete any sport
• Determine what sport requires horizontal,
  lateral,vertical, or quick, powerful mvmts.
  changes of direction in all planes
• Wide variety of lower-body plyometric drills with
  various intensity levels directional mvmts.

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• Jumps in place- drills involve jumping landing
  in same spot
• Emphasize vertical component are performed
  repeatedly, without rest between jumps
• Time between jumps is SSCs amoritization phase
• Squat jump, tuck jump
• Standing jumps- emphasize either horizontal or
  vertical components
• Max efforts with recovery between reps
• Vertical jump, jumps over barriers

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• Multiple hops jumps- involve repeated mvmts.
  may be viewed as combination of jumps in place
  standing jumps
• Zigzag hop
• Bounds- exaggerated mvmts. With greater
  horizontal speed than other drills
• Volume measured by distance, but can be by of
  reps performed
• Normally greater than 98 ft.(30m) may include
  single- double-leg bounds in addition to
  alternate-leg bounds

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• Box drills- increase intensity of multiple hops
  jumps by using a box
• Box may be used to jump on off
• Ht. of box depends on size of athlete, landing
  surface, goals of program
• May involve one, both, or alternate legs

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• Depth jumps- use gravity athletes wt. to
  increase exercise intensity
• Athlete assumes position on box, steps off,
  lands, immediately jumps vertically,
  horizontally, or to another box
• Ht. of box depends on size of athlete, landing
  surface, goals of program
• May involve one or both legs

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• Upper-body plyometrics
• Rapid, powerful upper-body mvmts. are required of
  several sports activities
• Not used as often as lower body have been
  studied less
• Type of activities include medicine-ball throws,
  catches, several types of push-ups

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• Trunk plyometrics
• Can be difficult to target trunk musculature
  because required plyometric elements may not be
  present due to large ROM time needed
• Research supports notion that stretch reflex is
  not sufficiently involved during many trunk
  exercises to potentiate muscle activity
• Ex. may need to be modified to decrease both ROM
  time, allowing agonist muscles to be
  potentiated allowing ex. to be more plyometric
  like

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Intensity

• Refers to amount of stress placed on involved
  muscles, connective tissue, jts. is
  controlled primarily by type of drill performed
• Wide range of intensity
• Skipping-easy
• Depth jumps- more stress
• Generally as intensity increases, volume should
  decrease

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Factors affecting intensity of lower-body
plyometric drills

• Points of contact- ground reaction force during
  single-leg lower-body plyometric drills places
  more stress on extremitys muscles, con. tis.,
  jts., than double-leg drills
• Speed- greater speed increases intensity of drill
• Height of drill- higher the bodys center of
  gravity, greater the force on landing

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• Participants weight- greater the athletes wt.,
  more stress placed on muscles, con. tis., jts.
• External wt.(vests, ankle wts., wrist wts.) can
  be added to body to increase drills intensity

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Frequency

• of training sessions per week
• Typically, 1-3 depending on sport time of year
• Recovery time between sessions, 48-72 hrs.
• 2-4 sessions per week with this recovery time
• May vary depending on given sports demands,
  intensity volume of daily workouts, time of
  training cycle

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Recovery

• Drills involve more max efforts to improve
  anaerobic power complete adequate recovery is
  required
• Recovery for depth jumps may consist of 5-10s
  between reps 2-3 min. between sets
• Time between sets is determined by proper
  work-to-rest ratio(15,110) is specific to
  volume type of drill
• Recovery between workouts essential to prevent
  overtraining
• Drills for same body area, never 2 days in a row

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Volume

• of reps sets performed in a given training
  session
• Lower-body typically measured by of foot
  contacts per workout
• May be distance as well bounding
• Upper-body typically measured by of throws or
  catches per workout
• Beginner (no experience) 80-100 contacts
• Intermediate (some exp.) 100-120 contacts
• Advanced (a lot of exp.) 120-140 contacts

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Program Length

• Research yet to determine optimal time
• Typically 6-10 weeks
• Vertical jump has been shown to improve in 4
  weeks
• Should be prescribed similarly to RT aerobic
  training in relation to sports needs

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Progression

• Should follow progressive overload principle of
  systematic increase in training frequency,
  volume, intensity in various combinations
• Typically, as intensity increases, volume
  decreases
• Should progress from low to moderate volumes of
  low-intensity, to low to moderate volumes of
  moderate intensity, to low to moderate volumes of
  high intensity

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Warm-up

• General than specific warm-up
• Should consist of low-intensity dynamic mvmts.
• Marching- mimics running mvmts.
• Emphasizes posture mvmt. technique
• Enhances proper lower-body mvmts. for running

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• Jogging- prepares for impact high-intensity
  plyometric drills
• Toe jogging- not allowing heel to touch ground,
  emphasizes quick reaction
• Straight leg jogging- not allowing or minimizing
  leg flexion in preparation for impact of
  plyometric drills
• Butt-kickers- flexing leg to allow heel to
  touch buttocks

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• Skipping- exaggerated form of reciprocal upper-
  lower-extremity mvmts.
• Emphasis on quick takeoff landing mimics
  plyometric acitivities
• Footwork- drills target changes of direction
• Preparation for changes of direction during
  plyometric drills
• Shuttle, shuffle, pattern, stride drills
• Lunging- based on lunge exercise
• May be multidirectional (forward, side, backward)

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Plyometric exercise resistance training

• Should be designed to allow max efficiency
  physical improvement
• Combine lower-body RT with upper-body
  plyometrics upper-body RT with lower-body
  plyometrics
• Heavy RT plyometrics on same day not usually
  suggested
• Complex training combo of high-intensity RT
  followed by plyos adequate recovery between sets
  reps
• RT exercises combined with plyo mvmts to further
  enhance gains in muscular power
• Squat jump with 30 of 1RM

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Plyometric aerobic exercise

• Many sports involve anaerobic aerobic
  components
• Aerobic ex. may have neg. effect on power
  production, advised to perform plyometric ex.
  before aerobic endurance training

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Safety Considerations

• Pretraining Evaluation of Athlete
• Technique
• proper landing for lower-body plyos shoulders
  over knees with flexion of ankles, knees, hips
• Strength
• 1RM squat should be 1.5 times body wt. for
  lower-body plyos
• 1RM bench press should be1.0 times body wt. if
  over 220 lbs.or 1.5 times body wt. if under 220
  lbs. or five clap push-ups in a row

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• Speed
• Upper-body 5 reps of bench press 60 of body wt.
  in 5s or less
• Lower-body 5 reps of squat 60 of body wt. in 5s
  or less
• Balance- maintenance of a position without moving
  for given period of time
• Standing 30s double-leg/single-leg
• Quarter squat 30s double-leg/single-leg
• Half squat 30s double-leg/single-leg

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• Age
• High-intensity lower-body drills should not be
  done until epiphyseal plates have closed
• Psychologically mature to follow directions
• Physical characteristics
• Athletes over 220 lbs. should avoid high-volume,
  high-intensity drills depth jumps greater than
  18 in.
• Previous injury problems muscle strains,
  abnormalities of spine, etc.

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• Equipment facilities
• Landing surface
• Good grass field, suspended floor, rubber mat
• Bad concrete, tile, hardwood lack
  shock-absorbing properties
• Mats greater then 6 in. extend amoritization
  phase do not allow efficient stretch reflex
• Training area
• Dependent on drill bounding at least 33 yd.
  jumps- ht. of 9.8-13.1 ft.

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• Equipment
• Box hts. 6-42 in. tall, made of sturdy wood or
  heavy-gauge metal nonslip tops
• Nonslip landing surfaces 18 by 24 in.
• Proper footwear
• Good ankle arch support good lateral
  stability wide nonslip sole

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• Supervision
• Monitored to ensure proper technique to reduce
  risk if injury
• Depth jumping
• Suggested ht. 16-42 in., 30-32 in. normal
• Athletes over 220 lbs. no higher than 18 in.

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Implementing Plyometric Program

• Evaluate the athlete
• Equipment facilities provide safe environment
• Establish sport-specific goals
• Determine program design variables
• Teach athlete proper technique
• Properly progress the program