CH.16: Plyometric Training

plyometric exercise

-activities that enable the muscle to reach maximal force in the shortest time possible -plio=more, metric= measure -a quick, powerful movement using a prestretch, or countermovement, that involves the stretch-shortening cycle -*purpose*-increases the power of subsequent movements by using both the natural elastic components of muscle and tendon and the stretch reflex

plyometric and aerobic exercise

-aerobic exercise may have a negative effect on power production, so it is advised to perform plyometrics before endurance training -appropriate for sports with aerobic and anaerobic components (ex. soccer, basketball)

phase II: amortization

-aka: transition phase -time between the eccentric and concentric phases -there is a delay between the eccentric an concentric muscle actions during which Type Ia afferent nerves synapse with the alpha motor neurons in the ventral root of the spinal cord -the alpha motor neurons then transmit signals to the agonist muscle group -this phase of the SSC is crucial in allowing greater force production- its duration must be kept short -if this phase lasts too long, the energy stored during the eccentric phase dissipates as heat, and the stretch reflex will not increase muscle activity during the concentric phase -ex. (long jump) - time when the jumper has touched down and movement has stopped- once movement begins again, the phase has ended

proper footwear

-ankle and foot support -lateral stability -wide, nonslip sole -running shoes may invite ankle problems due to narrow sole and poor upper support -inefficient foot support: arch/lower leg injuries -insufficient cushioning: damage to proximal joints (ex. knee, hip)

lower body plyometrics

-appropriate for all sports -examples: -jumps in place -standing jumps -multiple hoops and jumps -bounds -box drills -depth jumps

physical characteristics

-athletes who weigh more than 220 pounds: -may be at an increased risk for injury -should avoid high-volume, high-intensity plyometrics -should not perform depth jumps from heights greater than 18in -previous injuries: athletes with a history of muscle strains, pathological joint laxity, or spinal dysfunction should use caution with plyometrics

*recovery*

-because plyometric drills require maximal efforts to improve anaerobic power, adequate recovery is required -48-72 hours is the typical recovery time (not to be performed 2 days in a row)

training area

-bounding and running: at least 30m (some may need 100m straightaway) -standing, box, and depth jumps: 3-4m ceiling height

equipment

-boxes: -sturdy -non-slip top that is at least 18x24in -height 6-42in -constructed of sturdy wood or heavy-guage metal

potentiation

-change in the force-velocity characteristics of the muscle's contractile components caused by stretch of the concentric muscle action by use of the stretch reflex

supervision

-close monitoring of athletes is necessary to ensure proper technique

plyometric exercise and resistance training

-combine lower body resistance training with upper body plyometrics and vice versa -performing heavy resistance training and plyometrics n the same day is not usually recommended -however, some athletes may benefit from complex training (high intensity resistance exercise followed by plyometrics)- adequate recovery would be required needed between plyometrics and other high-intensity training -traditional resistance training exercises may be combined with plyometrics to further enhance gains in muscular power

*age considerations*

-consider: adolescents and masters

*mode*

-depends on the body region performing the given exercise: lower body, upper body, or trunk plyometrics

*mechanical model of plyometric exercise*

-elastic energy in the musculotendinous components is increased with a rapid stretch and then stored -when this movement is immediately followed by a concentric muscle action, the stored elastic energy is released, increasing the total force production -main component of this model: series elastic component

stretch-shortening cycle (SSC)

-employes the energy storage capabilities of the series elastic component and stimulation of the stretch reflex to facilitate a maximal increase in muscle recruitment over a minimal amount of time -3 phases: I: eccentric phase II: amortization phase III: concentric phase

bounds

-exaggerated movements with greater horizontal speed than other drills -volume measured by distance or reps -single, double leg, or alternate leg bounds

technique

-for lower body plyometrics, proper landing is essential (particularly for depth jumps) -the shoulders should be over the knees during landing, which the jumper accomplishes through flexion of the ankles, knees, and hips

upper body plyometrics

-for sports such as baseball, softball, tennis, golf, and throws in track and field -includes: -medicine ball throws/catches -several types of push-ups

speed

-greater speed increases intensity of the drill

3. Methods of Safely and Effectively Performing Specific Plyometric Exercises

-includes: -*age considerations* -*plyometrics and other forms of exercise* -*safety considerations*

*equipment and facilities*

-includes: -landing surface -training area -equipment -proper footwear -supervision -depth jumping

*safety considerations*

-includes: -pre-training evaluation of the athlete -equipment and facilities

*plyometrics and other forms of exercise*

-includes: -plyometric exercise and resistance training -plyometric and aerobic exercise

box drills

-increase the intensity of multiple hops and jumps using a box -box can be used to jump on or off -one, both, or alternating legs

phase I: eccentric

-involves preloading the agonist muscle group(s) -the SEC stores elastic energy, and the muscle spindles are stimulated -as the muscle spindles are stretched, they send a signal to the ventral root of the spinal cord via the Type Ia afferent nerve fibers -ex. (long jump) - the time from touchdown of the foot to the bottom of the movement

*neurophysiological model of plyometric exercise*

-involves the potentiation of the concentric muscle action by use of the stretch reflex -the reflexive component of plyometric exercise is primarily composed of muscle spindle activity -during plyometric exercises, the muscle spindles are stimulated by a rapid stretch, causing a reflexive muscle action -the reflective response potentiates (increases) the activity of the agonist muscle, thereby increasing the force the muscle produces

trunk plyometrics

-it is difficult to perform true plyometric drills that directly target trunk musculature because all the requisite plyometric elements may not be present -trunk exercises may be performed "plyometrically" by making them shorter and quicker to allow stimulation and use of the stretch reflex -ex. medicine ball sit-up modified by decreasing the ROM and time

jumps in place

-jumping and landing in the same spot -performed repeatedly -vertical component of jumping -ex. squat jump, tuck jump

strength

-lower body: -athlete's 1RM squat should be at least 1.5 times the body weight -upper body: -bench press 1RM should be at least athlete's body weight for athletes over 220lbs and 1.5x the body wight for athletes under 220lbs -alternate measure: perform 5 clap pushups in a row

speed

-lower body: the athlete should be able to perform 5 reps of the squat with 60% body weight in 5 seconds or less -upper body: the athlete should be able to perform 5 reps of the bench press with 60% body weight in 5 seconds or less

standing jumps

-maximal efforts with recovery between reps -vertical and horizontal components of jumping -ex. vertical jump, jumping over barriers

landing surface

-must have adequate shock-absorbing properties (ex. grass field, suspended floor, or rubber mat) -not recommended: concrete, tile, hardwood -mats thicker than 6in and mini trampolines are not effective for plyometric training because it lengthens the amortization period

2. Plyometric Program Design

-must include: -*mode* -*intensity* -*frequency* -*duration* -*recovery* -*progression* -*warm-up period*

pre-training evaluation of the athlete

-must understand proper technique -must possess a sufficient base of strength, speed, and balance -must be physically and psychologically mature

masters

-orthopedic conditions and previous surgeries must be considered -high intensity plyometrics should be used with caution in healthy masters and is contraindicated in individuals with previous surgeries/orthopedic conditions -prgoram should include: -no more than 5 low-moderate intensity exercises, -the volume should be lower than a standard program --the recovery time should be 3-4 days

1. Plyometric Mechanics and Physiology

-plyometric training improves the production of muscle force and power -explained by 2 models: *mechanical* and *neurophysiological*

*progression*

-progressive overload: the systematic increase in training frequency, volume, and intensity in various combinations -depends on the sport, training phase, and design of the program

muscle spindles

-proprioceptive organs that are sensitive to the rate and magnitude of a stretch -when a quick stretch is detected, muscular activity reflexively increases

depth jumping

-recommended height: 16-42 inches (30-32 norm.) -athletes over 220lbs: 18in or less

multiple hops and jumps

-repeated movements -combination of jumps in place and standing jumps -ex. zigzag hop

*warm-up*

-should have a general warm-up, stretching, and specific warm-up -the specific warm-up should consist of low-intensity, dynamic movements -types include: -marching -jogging (ex. toe jogging, straight-leg jogging, and butt-kickers) -skipping -footwork (ex. shuttle, shuffle, pattern, and stride drills) -lunging

series elastic component (SEC)

-tendons constitute the majority of of the SEC -when the musculotendinous unit is stretched, as in an eccentric muscle action, the SEC acts as a spring and is lengthened; as it lengthens, elastic energy is stored -if the muscle begins a concentric muscle action immediately after the eccentric action, the stored energy is released -this allows the SEC to contribute to the total force production by naturally returning the muscles and tendons to their unstretched configuration -contractile component (actin, myosin, and cross-bridges): primary source of muscle force during concentric muscle action -parallel elastic component (epimysium, perimysium, endomysium, and sarcolemma): exerts a passive force with unstimulated muscle stretch

*intensity*

-the amount of stress placed on involved muscles, connective tissues, and joints -controlled primarily by the type of drill performed -as intensity increases, volume should decrease -factors affecting intensity of lower body plyometrics: -points of contact -speed -height of drill -body weight

stretch reflex

-the body's involuntary response to an external stimulus that stretches the muscles

phase III: concentric

-the body's response to the eccentric and amortization phases -the energy stored in the SEC during the eccentric phase either is used to increase the force of the subsequent movement or is dissipated as heat -this stored elastic energy increases the force produced during the concentric phase movement beyond that of an isolated concentric muscle action -in addition, the alpha motor neurons stimulate stimulate the agonist muscle group, resulting in a reflexive concentric muscle action -high stretch rate results in greater muscle recruitment and activity ex. (long jumper) - concentric phase occurs as soon as the movement begins in an upward direction

balance

-the following must be held for 30 seconds: -beginngers: double and single leg standing -intermediate: double and single leg quarter squat -advanced: double and single leg half squat

body weight

-the greater the athlete's body weight, the more stress that is placed on muscles connective tissues and joints -external weight can be added to increase intensity

points of contact

-the ground reaction force during single-leg body plyometric drills places more stress on an extremity's muscles, connective tissues, and joints than during double-leg plyometric drills

height of the drill

-the higher the body's center of gravity, the greater the force on landing

*frequency*

-the number of plyometric training session per week -typically ranges from 1-3 depending on sport and time of year

*volume*

-the number of reps and sets performed during a given training session -typically expressed as the number of foot contacts per workout -beginner: 80-100 -intermediate: 100-120 -advanced: 120-140

depth jumps

-use gravity and athlete's weight to increase exercise intensity -assumes a position on a box, steps off, lands, and immediately jumps vertically, horizontally, or to another box -may involve one or both legs

adolescents

-while growth plates are open, highly intense activity and injury may cause them to close prematurely -depth jumps and other high intensity lower-body exercises are contraindicated -gradual progression is important and focus should be on quality of movement

Which of the following work-to-rest ratios is the MOST appropriate to assign to a plyometric training workout? 1:5 1:4 1:3 1:2

1:5

Which of the following should be asses before beginning a lower body plyometric training program? balance, strength, speed, lean body mass

balance, speed, strength

All of the following are phases of the stretch-shortening cycle EXCEPT a. amortization. b. concentric. c. eccentric. d. isometric.

d. isometric.

Which of the following types of plyometric drills is generally considered to be the most intense? jumps in place, bounds, depth jumps, box jumps

depth jumps

Which of the following structures detects rapid movement and initiates the stretch reflex? Golgi tendon organ, muscle spindle, extrafusal muscle fiber, Pacinian corpuscle

muscle spindle

Which of the following is the BEST surface on which to perform lower body plyometric drills? trampoline, exercise matt, asphalt, suspended wood floor

suspended wood floor

Which of the following is a primary component of the series elastic component? tendon, muscle fiber, actin, ligament

tendon