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chapter 9. Plyometrics. Plyometrics. = Quick movement of eccentric activity rapidly followed by a burst of concentric activity to produce a powerful movement Purpose: increase power of movements Plio = more Metric = measure.
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chapter9 Plyometrics
Plyometrics • = Quick movement of eccentric activity rapidly followed by a burst of concentric activity to produce a powerful movement • Purpose: increase power of movements Plio = more Metric = measure
Mechanical Components • Muscle lengthening increases elastic tension of noncontractile tissue stored elastic (potential) energy. • If immediately followed by a rapid concentric contraction, release of elastic energy contributes to total muscle output.
Neurological Components • Muscle stretch (eccentric lengthening) stimulates the muscle spindle to create a reflex shortening (concentric). • Movement must occur rapidly for the stretch reflex to occur.
Influential Factors • Strength • Flexibility • Speed of movement • Efficiency of movement (coordination)
Plyometric Phases: Stretch-Shortening Cycle 1. Eccentric phase • Muscle lengthens to take up slack and stretch elastic components. • “Sets” the muscle. • Stores potential energy as elastic energy. • Muscle spindle responds to a rapid stretch and accommodates to a slow stretch. • Best with rapid eccentric movement in a partial range of motion. (continued)
Plyometric Phases: Stretch-Shortening Cycle (continued) 2. Amortization phase • Must immediately follow the eccentric phase • = Time it takes to transfer from eccentric to concentric motion • Too much time: potential energy absorbed and dispersed, and spindle reflex overridden by cognitive functions (continued)
Plyometric Phases: Stretch-Shortening Cycle (continued) 3. Concentric phase • Stretch reflex causes increased muscle activity. • Stored (potential) energy is released to increase output. • The combined result is greater muscle performance.
Pre-Plyometric Considerations • Plyometrics is used in therex near the end of the program. • Used with patients returning to power-based sports: basketball, volleyball, gymnastics, track and field, softball, baseball, skating, swimming, soccer, football • Serve as a bridge between therex and sport-specific activities
Plyometric Program Design Mode of training: based on body part Lower-body plyometrics • Jumps in place • Standing jumps • Multiple hops and jumps • Bounds • Box drills • Depth jumps (continued)
Plyometric Program Design (continued) Upper-body plyometrics • Medicine-ball throws • Medicine-ball catches • Push-ups Trunk plyometrics • Medicine-ball sit-ups • Plyometric sit-ups (continued)
Plyometric Program Design (continued) • Intensity: stress of the activity • Volume: • Lower extremity: number of foot contacts • Upper extremity: reps and sets or number of throws • Beginner: 80-100/session • Intermediate: 100-120/session • Advanced: 120-140/session • Recovery: between reps = 5-10 s; between sets = 2-3 min • Frequency: once a week to three times a week (QW – TIW)
Program Considerations • Age: <16 years • Weight: >220 pounds • Competitive level • Surface: not too hard, not too soft • Footwear: stable yet absorbing • Progression: allow for overload adaptations • Goals based on individual needs
Precautions • Time: early in the session • Delayed-onset muscle soreness • Proper supervision • Depth jumps • Max = 48 in. • Range = 16 to 42 in. • Norm = 30 to 32 in. (if >220 lb, range = 20 to 30 in.) • Contraindications • Acute inflammation • Post-op • Instability
Exercise Progression • Beginning stages • Double-leg takeoffs • Increasing difficulty levels dependent on athletic level, learning aptitude • With increased mastery, amplitude increases • Consistent emphasis • Coordination • Correct movement and motor patterns
Exercise Techniques • Landing exercises • To teach proper foot strike • Use of ankle, knee, and hip to absorb shock • Correct body alignment • Stabilization jumps • To reinforce correct landing technique • Raise levels of eccentric and stabilization strength • Same as landing exercises, but landing position is held 5 s before next jump (continued)
Exercise Techniques (continued) • Jumping up • To teach takeoff action and arm use • For jump on box: Emphasize arm swing, Jump up with leg tuck • In-place bouncing movements • For quick reaction off ground and vertical displacement • Tuck jump, scissors jump, increasing vertical jump (continued)
Exercise Techniques (continued) • Short jumps • To teach horizontal displacement of center of gravity • Two-foot takeoffs multiple-step takeoffs, power skipping • Long jumps • To add more horizontal velocity • Leg bounding, bounding hops
Exercise Techniques (continued) • Shock jumps • To raise explosive power to highest levels • Impose high neural demand • Advanced form of training—require a large training base • Jump boxes, rebound hurdles
Equipment • Boxes: 16 in. to 48 in. (non-slip surfaces on floor, boxes) • Cones • Hurdles • Medicine balls • Other equipment
Precautions • Increase one factor q 3 d, especially in early phases. • Provide constructive cues to correct performance. • Avoid pain and swelling. • Understand tissue integrity: Be alert to progression tolerance. • Understand patient’s confidence level.
