boston 2013 What makes the ball go.ppt · PDF fileResults Small vs. Large Knee Flexion ......
Transcript of boston 2013 What makes the ball go.ppt · PDF fileResults Small vs. Large Knee Flexion ......
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What makes the ball go-overview of the kinetic
chain in throwing
W. Ben Kibler, MD
Medical director
BODY ASBODY ASA SYSTEM A SYSTEM
HANAVAN MODELHANAVAN MODEL
33
11
22 7766
9988
OF LINKSOF LINKS(SEGMENTS)(SEGMENTS)
Adapted from Hanavan, EP. Mathematical Model Adapted from Hanavan, EP. Mathematical Model of the Human Body. Wrightof the Human Body. Wright--Patterson Air Force Patterson Air Force
Base, Ohio, 1964, AMRLBase, Ohio, 1964, AMRL--TR, 64TR, 64--102.102.
554411111010
13131212
1414 1515
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THE KINETIC CHAIN
Trunk
Shoulder
ElbowWrist
F
O
R
Legs
Trunk and Back
0
C
E
TIMEAdapted From Groppel
Kinetic ChainTransfer of Forces
• Ground – Foot• Up Leg Knee• Hip Hip• Back• Scapula• Arm• Ball/ Racquet
KINETIC CHAIN LINKLINK
CONTRIBUTIONS
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LONGITUDENAL-%
• Hip/trunk-energy 51, force 54
• Shoulder energy 13 force 21• Shoulder-energy 13, force 21
• Elbow-energy 21, force 15
• Wrist-energy 15, force 10• Kibler WB Clin Sports Med 14: 79-86, 1995
CROSS SECTION• Hip/trunk- ball impact- 10%• Shoulder rotation- 54%• Elbow- 10%• Elbow- 10%• Wrist- 26%
• Elliott et al J Appl Biomech 11: 443-447, 1995
ARM FORWARD MOVEMENT
• Thoracoscapular muscle activation- 40%activation 40%
• Rotator cuff- 18% – Happee et al, Journal of Biomechanics, 28:
1179-1191, 1995
• “Core”- 42%
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Arm motion- ball release
Hirashima, M et al Journal of Neurophysiology 97: 680-691, 2007
Hirashima, M et al Journal of Neurophysiology 97: 680-691, 2007
CORRELATION WITH BALL VELOCITY
• Upper extremity strength- .46
• Lower extremity strength- .89
Kraemer et al, Journal of Sport Kraemer et al, Journal of Sport Rehabilitation, 4: 79Rehabilitation, 4: 79--88, 199588, 1995
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Kinetic chain factors• Interactive moments
– Forearm acceleration due to shoulder h-adductionto shoulder h adduction
– Varus acceleration due to shoulder IR
– Proximal weakness: 17% increased distal loads
Interactive Moments• Forces from position/ motion of
adjacent segments
Equation for the proximal segment:JMpp+ ( M i θ + l M i θ + i θ )A JF(aau)+ (rpMpsinθp + lpMasinθp + ramasinθd)App- (rpmpcosθp + lpmacosθp + ramacosθd)App IMp app- (lp
2md + rdlpmjcosØ) θp IMp app- rdlpmasinØθp
2 IMp app- (rdlpmdcosØ + lcd + rd
2md) θd IMp app+ rdlpmdsinØ θd
2 IMp app- (rpmpcosθp + lpmdcosθp + rdmdcosθd)g IMpg= (lcp + rp
2mp) θ = lppθp= Net moment on proximal segment
Putnam CA. J Biomech 26:125-135, 1993
JF(as)
JF(aau)
JMsJF(as)
JF(aau)
Biomechanics/pitching• Positions – leading with
hips, hands on top, high elbow at stride foot contact, closed shoulder, stride foot towards home plate
• Observation, video• Davis et al AJSM 37(8): 1484-1491, 2009
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Push throughPush through
Pull throughPull through
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WHAT HAPPENS WHEN THE BALL DOESN’T GO IN DYSFUNCTION
KINETIC CHAIN BREAKAGE
• Injury- proximal• Inflexibility- local
(GIRD) distant hip(GIRD), distant- hip• Muscle weakness/
imbalance• Poor mechanics-
local, distant
RESULTS FROM BREAKAGE
• Decreased energy, force to terminal links
• Altered performance• Altered performance-velocity, location
• “Catch up” in distal links to maintain performance
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“CATCH UP”• Increased energy, force need to be
developed in distal links
– Increased mass velocityIncreased mass, velocity, acceleration
• Smaller muscle cross section
• Less time- ball release, impact
“CATCH UP”
344.433.3SHLDR VEL
%Catch UpNormal
Trunk
Shoulder
Elbow
Wrist
F
O
R
8016.259SHLDR
MASS
VEL
20% DECREASE IN TRUNK K.E.
Legs
Trunk and Back
0
R
C
E
TIMEAdapted From Groppel
Results Small vs. Large Knee Flexion
Large Knee Small Knee
Number of players 14 6
Knee Flex @ MER (º)* 16 ± 4 6 ± 3
Ball velocity (m/s) 45 ± 6 45 ± 7
**Significant difference (p<0.05)
** Sign. diff., even when normalized
Ball velocity (m/s) 45 ± 6 45 ± 7
Max. IR Torque (Nm)** 56 ± 18 64 ± 12
Max. Varus Torque (Nm)** 63 ± 14 74 ± 15
Fleisig GS, et.al.Fleisig GS, et.al.
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IMPLICATIONS FOR CLINICALCLINICAL
EVALUATION
IMPLICATIONS
• Body works/fails as a unit
• Alterations in performance parameters may be firstparameters may be first indicators of problems in kinetic chain function
• Weak/tight/imbalanced
IMPLICATIONS
• Visual evaluation
– On field, in office
Vid l ti• Video evaluation
• Dynamic motion
– Baseball positions
– Tennis nodes
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IMPLICATIONS
• In injury, alterations exist and must be evaluated in physical examphysical exam
– Hip/trunk strength
– Back flexibility
– Scapular position/motion
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THE KINETIC CHAIN
Shoulder
ElbowWrist
F
O
R
Legs
Trunk and Back
0
R
C
E
TIMEAdapted From Groppel
Shoulder rotation, flexibility, strength
Internal derangement
Scapular dyskinesis
Leg stability series
Hip rotation
Plank
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CONCLUSIONS• Kinetic chain exam as part
of comprehensive evaluation – observation, video analysis office examvideo analysis, office exam
• Technique modifications• Rehabilitation of entire
kinetic chain, base to scapula to shoulder
THANK YOU