Plyometrics:Reactive/Power

Training

Reactive Training• Reactive training:

– A quick powerful movement involving an eccentric contraction, followed immediately by an explosive concentric contraction

– This is accomplished through plyometric exercises

• Plyometrics are activities that enable a muscle to reach maximal force in the shortest amount of time possible. This is called the rate of force production

Plyometrics This type of training involves powerful

muscular contractions in response to a rapid stretching of the involved musculature.

These powerful contractions are not a pure muscular event; they have an extremely high degree of central nervous system involvement.

Reactive training improves neuromuscular efficiency

Plyometrics• Plyometric exercises can be

incorporated once a client has achieved proper core and balance stabilization

• Ultimate goal of plyometrics is to increase the reaction time of:

Plyometrics A good example of this is watching any

basketball player jump. They jump higher when they can take a few

steps before the jump. The reason for this is that the few steps create

momentum. This momentum is used to create a bigger and

faster “load” on the leg plant prior to jumping. The response to this greater load is a greater

contraction by the legs and a higher jump height. The same phenomenon exists with all explosive

actions.

Mechanical Model of Plyometric Exercise

• Elastic energy is stored following a rapid stretch, then released during a concentric muscle action increasing total force production

• The mechanical model presents the function of the musculotendionous unit as a relationship between three mechanical components

Mechanical Model of the Muscle• Three elements compose the

mechanical model of the muscle influencing its mechanical behavior and effecting contraction:

Contractile Component• The contractile

component represents the muscle fibers, which are the active part of the muscle and are competent to produce tension

Parallel Elastic Component• The parallel

elastic component represents the connective tissue surrounding each muscle fiber, groups of fibers and the whole of the muscle.

Series Elastic Component• The series elastic element refers mainly to the

tendons of the muscle which are placed "in series" with the contractile and parallel elastic elements.

• When the muscle-tendon unit is stretched during an eccentric contraction, the SEC acts as a spring and is lengthened, storing elastic energy

• If the muscle immediately begins a concentric contraction, the stored energy is released

Neurophysiological Model of Plyometric Exercise

• This model represents the

• Plyometric exercise is composed primarily of

• Muscle spindles are sensitive to the rate and magnitude of a ; when a quick stretch is detected muscle activity increases

Neurophysiological Model of Plyometric Exercise

• Stretch Reflex:–The body’s involuntary response to an

external stimulus that stretches the muscles• When muscle spindles are stimulated, the

stretch reflex is stimulated, sending input to the spinal cord via nerve fibers

• The nerve impulses travel to the agonist muscle fibers, causing a reflexive muscle action

Stretch Shortening Cycle (SSC)• The stretch-shortening cycle (SSC)

employs both the energy storage of the SEC and stimulation of the stretch reflex to facilitate maximal increase in muscle recruitment over a minimal amount of time

• A fast rate of musculotendinous stretch is vital to muscle recruitment and activity resulting from the SSC

Stretch-Shortening Cycle

• The SSC Model involves three phases:

Phase I: Eccentric Phase• Stretch of the agonist muscle• Preloading the agonist muscle group• The SEC (muscle-tendon unit) stores elastic

energy • Muscle spindles are stimulated• Signal is sent to the spinal cord• Example: A basketball jump shot• The person performs a half-squat before

jumping up• The time from the beginning of the squat to the

bottom of the movement is the eccentric phase

Phase II: Amortization• Amortization or Transition Phase is the time

between the eccentric and concentric phases• Pause between Eccentric to Concentric muscle

actions• Spinal Cord begins to transmit signals to the

agonist-stretched-muscle group• If the amortization phase lasts too long, the energy

stored during the eccentric phase will be dissipated as heat

• Example: Basketball jump shot• From the downward half-squat as soon as upward

movement begins, amortization phase has ended

Phase III: Concentric Phase• Shortening of agonist muscle fibers

• Elastic energy is released from the SEC to increase force production

• The stretched muscle is stimulated neurally

• Example: Following the half-squat in the jump shot, the individual moves upward

Explain the SSC with a Basketball Jump Shot

Phase I:

Phase II:

Phase III:

Stretch Shortening CycleBasketball Jump Shot

• Phase I: Eccentric PhaseThe agonist muscles (quadriceps)undergo a rapid stretch• Phase II: Amortization

PhaseThere is a delay in the movement• Phase III: Concentric PhaseThe quadriceps actsconcentrically to extend the knee,allowing the person to push offthe ground

Plyometric Program Design

• Ideal when the goal is to improve muscular power

• Power: The time rate of doing work – Force x distance/time– Force x velocity

• Examples: police officers having to run quickly and change direction or jump over obstacles, firefighters, warehouse workers lifting boxes…

Plyometric Program Design• Exercise Selection:

– Safe– Done with supportive shoes– Performed on a proper training surface

• Performed with proper supervision• Progressive:

– Simple to complex– Known to unknown– Stable to unstable– Body weight to loaded– Activity specific

Plyometric Program Design• Variables:

– Plane of motion– Type of resistance

• MB– Type of implements

• Boxes• Cones• Hurdles

– Muscle action (eccentric, isometric, concentric)

– Speed of motion– Duration– Frequency

Plyometric Program Design

• Be systematic

• Be progressive

• A client must exhibit proper levels of core strength and balance before progressing into reactive training

Age Considerations• Adolescents

– Consider both physical and emotional maturity.

– The primary goal is to develop neuromuscular control and anaerobic skills that will carry over into adult athletic participation.

– Gradually progress from simple to complex

– The recovery time between workouts should be a minimum of two to three days.

Age Considerations• Older Adults:

– Can perform plyometric exercises as long as modifications are made for orthopedic conditions and joint degeneration

– The plyometric program should include no more than five low- to moderate-intensity exercises

– The volume should be lower, that is, should include fewer total foot contacts than a standard plyometric training program

– The recovery time between plyometric workouts should be three to four days

Contraindicated Populations• Plyometric training may alter

bone structure; spine height has been shown to decrease by up to 2 mm following a depth jumping program (high intensity)

• Research has yet to determine the age at which one can participate in a plyometric training program

Contraindicated Populations• Adolescents should be careful

because of epiphyseal plate closures • Older adults should be careful

because of osteoporosis• Clients who never participated in

resistance training should be precluded

• Plyometric training requires strength and muscle control

Needs Analysis• Analyze needs of the client:1. Age (safest over the age of 13)2. Training experience and current level of training

(more than three months of resistance training)3. Injury history (no current injuries)4. Fitness Evaluation: what are the client’s current

abilities (beginner, intermediate, advanced)?5. Training Goals: does the client want to improve

a skill or a particular move (volley ball spike, tennis serve, baseball pitch…) or on the job activity

Mode (Type)• Determined by the general body

parts that are performing the given exercise

• Example: –Depth Jump is a lower body

plyometric exercise

–MB Chest Pass is an upper body plyometric exercise

Lower Body Plyometrics• Jumps-In-Place:

– Squat jump and tuck jump

• Standing Jumps: – Vertical jump and jumping over barriers

• Multiple hops and jumps

• Bounding and skipping

• Box Jumps

• Depth Jumps

Squat Jump

1. Stand with feet shoulder-width apart

2. Draw naval in and activate gluteals

3. Jump up, extending arms overhead

4. Land softly, maintaining optimal alignment and repeat immediately

Tuck Jumps

• Stand with feet shoulder-width apart

• Draw naval in and activate gluteals

• Jump up, bringing knees to chest

• Land softly, maintaining optimal alignment

Box Jumps

• Stand in front of a box or platform with feet shoulder-width apart

• Draw in navel and activate gluteals

• Using arms, jump up and land on top of box, keeping toes pointing straight ahead and knees over toes

• Step off box

Bounds• Jog into the start of the drill for forward

momentum.• After a few feet, forcefully push off with the left

foot and bring the leg forward. At same time drive your right arm forward.

• Repeat with other leg and arm• This exercise is an exaggerated running motion

focusing on foot push-off and air time

Depth Jumps• Stand on a box or platform with feet shoulder-

width apart

• Draw in naval and activate gluteals

• Using arms, jump off the box and land on floor, keeping toes pointing straight ahead and knees over toes

Upper Body Plyometrics

• Not used as often–MB Chest Pass

–MB Slam

–Two-Hand Overhead Throw

–Single-Arm Throw

–Depth Push-Up

–Push-Up with a Clap

–Power Drop

Overhead Throw and Side Throw

Overhead Back Toss• Stand with feet slightly wider than hip-width apart. • Have a partner or trainer stand approximately 10-15

yards behind you.• Grasp MB and lower body into a squat position.• Explode up extending the entire body and throwing

medicine ball up and over the body.• The goal is to throw the ball behind you as far as you

and generating most of the power in the legs.

MB Slams• Stand with feet parallel, shoulder-width apart

• Pull MB back behind head and forcefully throw ball down on the ground as hard as possible.

• Catch the ball on the bounce from the ground and repeat according to prescribed repetitions

Plyometric Push-Up• Get into a push-up position.

• Lower yourself to the ground and then explosively push up so that your hands leave the ground.

• Catch your fall with your hands and immediately lower yourself into a push-up again and repeat

Intensity• Plyometric Intensity refers to the amount of

stress placed on muscles, connective tissues, and joints

• Factors affecting Intensity include:– : progress from double to single

leg support places more stress on muscles, connective tissues, and joints

– : greater speed increases intensity– : Raise the body’s center of gravity

by increasing the height of the drill : Greater the individual’s weight

more stress is placed on body. External weight can be added (vests)

Intensity

• Low Intensity: –Squat jump and vertical jump

• Moderate Intensity: –Double leg tuck jump and split squat

jump

• High Intensity: –Depth jump and pike jump

Frequency

• Number of plyometric sessions per week

• plyometric sessions per week

Volume• Number of reps and sets

performed during training sessions

• Lower Body Plyometrics Volume: –Number of foot contacts per

workout or expressed as distance

• Upper Body Plyometrics Volume: –Number of throws or catches

Lower Body Plyometrics Volume Guidelines

Recovery • Recovery between sessions:

– 48-72 hours between sessions• Recovery for depth jumps may consist of 5-10

seconds of rest between reps and 2-3 minutes between sets

• Work to rest ration is 1:5 to 1:10 specific to the plyometric activity

• Drills should not be thought of as cardiorespiratory conditioning exercises but as power training

• Furthermore, drills for a given body area should not be performed two days in succession.

Plyometric Length and Progression• Program Length

– Currently, most programs range from 6 to 10 weeks; however, vertical jump height improves as quickly as four weeks after the start of a plyometric training program

• Progression– Plyometrics is a form of resistance training

and thus must follow the principles of progressive overload (the systematic increase in training frequency, volume, and intensity in various combinations).

Warm-Up• Plyometric

exercise sessions must begin with a general warm-up, stretching, and a specific warm-up

• Specific warm-up should consist of low intensity dynamic movements

Plyometrics, Aerobic Exercise and Resistance Training

• Can combine upper body RT with lower body plyometrics and vice versa

• Performing heavy RT and plyometrics in the same day is not recommended

• Aerobic exercise may have a negative effect on power production

• Perform plyometric exercise before aerobic endurance training

• Some advanced athletes may benefit from complex training, which combines intense resistance training with plyometric exercises

Safety Considerations• Pretraining Evaluation of the Athlete

–Technique

• Before adding any drill, the strength and conditioning professional must demonstrate proper technique to the athlete.

• Proper landing technique is essential to prevent injury and improve performance in lower body plyometrics.

Safety Considerations• Physical Characteristics

–Clients weighing more than 220 pounds may be at increased risk of injury

–Clients who are 220 pounds should avoid high volume high intensity plyometrics

–Clients weighing more than 220 pounds should not perform depth jumps greater than 18 inches

Landing Position• The shoulders are in

line with the knees, which is accomplished through dorsiflexion of the ankle and flexion of the knees and hips

• Knees track along the toes

• This places your center of gravity over the body’s base of support.

• Do not land on your toes or ball of your foot

Pre-training Evaluation: Strength• Lower body plyometrics:

– You should be able to 1 RM squat 1.5 times your BW

• Upper body plyometrics: – You should be able to 1 RM bench press 1.0

times your BW if you weigh 220 lb and 1.5 times your BW if you weigh less than 220 lb.

• An alternative is to perform 5 clap push ups consecutively.

• If standards are not met plyometrics should be delayed.

Pretraining Evaluation: Speed

• Lower Body Plyometrics: –5 squat reps with 60% BW in 5

seconds or less for

• Upper Body Plyometrics: –5 reps of bench press with 60% of

BW in 5 seconds or less

Pretraining Evaluation: Balance• Three balance tests are

listed in order of difficulty• Each test position must be

held for 30 seconds. Tests should be performed on the same surface used for drills.

• Beginners training with plyometrics for the first time must stand on one leg for 30 seconds without falling.

• Advanced athletes must maintain a single-leg half squat for 30 seconds without falling

Equipment and Facilities• Training Area

• The amount of space needed depends on the drill

• Most bounding and running drills require at least 30 m (33 yards) of straightaway, though some drills may require a straightaway of 100 m (109 yards)

• For most standing, box, and depth jumps, only a minimal surface area is needed, but the ceiling height must be 3 to 4 m (9.8-13.1 feet) in order to be adequate

Equipment• Boxes for box

jumps must have a non slip surface

• Boxes range from 6 to 42 inches

• Landing surface of at least 18-24 inches

Landing Surface• To prevent injuries the landing surface

should be shock absorbing

• Recommended Landing Surfaces:

• Concrete, Tile, or Hardwood Floors are not Recommended

Proper Footwear• Good ankle and arch support

• Good lateral stability

NSCA Power Guidelines

• Single–Effort Activity (i.e.power clean): – 3-5 sets– 1-2 reps– 80%-90% Intensity– 2-5 minutes of RI

• Multiple-Effort Activity (i.e.box jumps):– sets– reps– Intensity– minutes of RI