Transcript Plyometrics in Rehabilitation

Rehabilitation Techniques for Sports
Medicine and Athletic Training
William E. Prentice
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Specificity is an important parameter of an exercise
training program
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Jumping movement is inherent in most sports
 Running is a repeated series of jump-landing
cycles
 Therefore, jump training should be used in the
design and implementation of the overall training
program and rehabilitation
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Success in most activities is dependent upon
the speed at which muscular force and power
is generated.
Power combines strength and speed
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Can be increased by increasing the amount of work
or force that is produced and decreasing the amount
of time required to produce force
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Plyometrics is a form of training that
attempts to combine speed of movement
with strength
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Plyometrics=quick, powerful movement
involving pre-stretching of muscle and
activating the stretch-shortening cycle to
produce a subsequently stronger concentric
contraction.
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Takes advantage of stretch-shortening cycle (SSC) to
increase muscular power
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Main purpose of plyometric training is to
heighten the excitability of the nervous system
for improved reactive ability of the
neuromuscular system
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Myotatic stretch reflex used to produce
powerful response of contracting muscles
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Upon landing muscles undergo a lengthening
eccentric contraction to decelerate movement and
pre-stretch the muscles
Pre-stretch energy is then immediately released in an
equal and opposite reaction
 Produces kinetic energy
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Neuromuscular system must react quickly to
produce concentric shortening contraction to
produce upward change in direction
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Plyometric exercise should be used to prepare
athletes for return to activity
Train specific movements in a biomechanically
accurate position
 Specific functional exercise used to emphasize the
rapid change of direction
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 Can be used for upper and lower extremities
 Whether athlete is jumping or throwing the
musculature around the joint must first stretch and
then contract to produce explosive movements
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Stretch-shortening cycle:
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Coupling of eccentric-concentric muscle contraction
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Movement rarely begins from static position
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Preceded by eccentric pre-stretch that loads muscle
and prepares for concentric contraction
 2 components work together to produce response:
 Proprioceptive reflexes
 Mechanical: Elastic properties of muscle fibers
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Three component model
 Contractile component (CC)
 Series Elastic Component (SEC)
 Parallel Elastic Component (PEC)
 All interact to produce a force output
 CC focal point of motor control, however SEC &
PEC provide stability and integrity to fibers as
muscle is lengthened
 During lengthening energy is stored within the
musculature in the form of kinetic energy
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When a stretch is applied , potential energy is
stored
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That energy is applied as it returns to its normal
length when the stretch is released
 Analogy: stretching a rubber band
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Significant increases in concentric muscle force
production has been documented when immediately
preceded by an eccentric contraction
 Uses the elastic energy stored during eccentric
contraction
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Ability to use stored elastic energy affected by 3
variables
 Time
 Magnitude of the stretch
 Velocity of the stretch
 In order to increase concentric force production
eccentric contraction must be of short range and
performed quickly without delay
 If large range, slow, with delay stored energy
will be lost
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Proprioceptive stretch reflex:
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Involve the mechanoreceptors in the muscle:
Muscle spindle:
 When muscle spindle is stretched sensory response
sent to CNS and neurological impulses sent back
to muscle causing motor response
 Strength of muscle spindle response is determined
by rate of stretch
 More rapidly load applied, greater firing
frequency of the spindle and stronger muscle
contraction
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Golgi Tendon Organ:
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Inhibitory effect by contributing a tension limiting
reflex, restricting the amount of force that can be
produced
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Theorized that Plyometrics desensitizes GTO and
allows more force to be produced
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Increased force production seen during SSC due to
combined effects of stored elastic energy and the
Myotatic stretch reflex
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Increased amount of force production dependent upon
the time frame between eccentric and concentric
contractions
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Defined as Amortization Phase
 Electromechanical delay between eccentric and concentric
contractions
 Muscle must switch from overcoming work to acceleration in
opposite direction
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Increased time in amortization phase will lead to decrease
in force production
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Plyometric training can promote changes
within the neuromuscular system
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Allow individual to have better control of
contracting muscle and synergists
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Can increase performance by enhancing nervous
system to become more automatic
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Should begin with establishing adequate
strength base
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Allow body to withstand large stress placed on it
(Safety)
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Allow for greater force production
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Increase in CSD of muscle will increase potential to
store greater amounts of elastic energy
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Biomechanical Examination
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Functional movement screening
Strength test
 Poor strength and mechanics will result in loss of
stability and increased stress absorbed in wt.
bearing tissue
 Decrease performance and increase risk of injury
Stability Test
 Static and Dynamic Balance Test
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Dynamic Movement Test
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Single Leg Hop test-LE
Seated chest pass or sit up and throw test -UE
Flexibility
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General and specific flexibility
 High amount of stress applied to musculoskeletal
system
 Should do general and specific warm up before
plyometric exercise
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Classify individual as beginner, intermediate or
advanced
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Dependent on information found through
biomechanical, stability, and dynamic testing
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Will determine where athlete begins plyometric
program
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Take into consideration tissue healing if post-injury
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Take into consideration sport so Plyometric training
can be specific to athletes position
 SAID Principle!!!!!
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Direction of Body Movement
Weight of Patient
Speed of Execution
External Load
Intensity
Volume
Frequency
Training Age
Recovery
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Beginning of plyometric program emphasize
technique and principles of Plyometrics
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For example, the importance of short amortization
phase
 Minimal time on ground, reverse the landing as quickly
as possible
Focus on body, control, posture and mechanics
 As intensity increases, volume should decrease
 Plyometrics should be used in later phases of
rehabilitation.
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 After appropriate strength base established and athlete
has performed closed chain exercises
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Sound, technical foundation
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Force reduction and force production should be
absorbed throughout entire body
 Ankle, knee, hip, trunk, arms
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Time and coordination of these body segments will
yield positive ground reaction and high rate of force
production
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Specific to individual goals of athlete
Quality of work more important than Quantity
Greater intensity the greater recovery time
required
Low to medium intensity if done at conclusion
of workout, high if done before
When to fatigued to maintain proper technique
exercise should stop
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Progressive in nature
Only 2 to 3 times a week depending on
periodization
Dynamic testing on regular basis to provide
motivational feedback
Proper equipment: footwear, landing surface,
external loads…Safety First!!
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Involve loading of the healing tissue
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Medial and Lateral Loading
 Ability to accept weight on injured extremity and
change direction
 Imperative to return to sport with cutting maneuvers
(Most Sports)
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Rotational Loading
 Same as above
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Shock Absorption (Deceleration Loading)
 Eccentric load of muscle and tendon
 Increase in tensile strength
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Double extremity to Single Extremity
Vertical Hops to Lateral Hops to Diagonal
Hops
Flat surface to box jumps
Non weighted to weighted
Jumps to Hops to Bounding
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Manipulate Volume, frequency, and intensity to
advance program appropriately
Re-evaluate and re-assess athlete to prevent injury
and provide motivational feedback