Plyometrics: Reactive/Power Training

1. Plyometrics:Reactive/Power Training

2. 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

3. 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

4. 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:

5. 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.

6. 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

7. Mechanical Model of the Muscle • Three elements compose the mechanical model of the muscle influencing its mechanical behavior and effecting contraction:

8. Contractile Component • The contractile component represents the muscle fibers, which are the active part of the muscle and are competent to produce tension

9. Parallel Elastic Component • The parallel elastic component represents the connective tissue surrounding each muscle fiber, groups of fibers and thewhole of the muscle.

10. 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

12. 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

13. 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

15. 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

16. Stretch-Shortening Cycle • The SSC Model involves three phases:

17. 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

18. 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

19. 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

20. Explain the SSC with a Basketball Jump Shot Phase I: Phase II: Phase III:

21. Stretch Shortening Cycle Basketball Jump Shot • Phase I: Eccentric Phase The agonist muscles (quadriceps) undergo a rapid stretch • Phase II: Amortization Phase There is a delay in the movement • Phase III: Concentric Phase The quadriceps acts concentrically to extend the knee, allowing the person to push off the ground

22. 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…

23. 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

24. 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

25. Plyometric Program Design • Be systematic • Be progressive • A client must exhibit proper levels of core strength and balance before progressing into reactive training

26. 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.

27. 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

28. 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

29. 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

30. Needs Analysis • Analyze needs of the client: • Age (safest over the age of 13) • Training experience and current level of training (more than three months of resistance training) • Injury history (no current injuries) • Fitness Evaluation: what are the client’s current abilities (beginner, intermediate, advanced)? • 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

31. 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

32. 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

33. Squat Jump • Stand with feet shoulder-width apart • Draw naval in and activate gluteals • Jump up, extending arms overhead • Land softly, maintaining optimal alignment and repeat immediately

34. 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

35. 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

36. 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

37. 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

38. 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

39. Overhead Throw and Side Throw

40. 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.

41. 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

42. 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

43. 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)

44. 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

45. Frequency • Number of plyometric sessions per week • plyometric sessions per week

47. 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

48. Lower Body Plyometrics Volume Guidelines

49. 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.

50. 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).