Baseball Pitchers’ Kinematic Sequences and Their Relationship to Elbow and Shoulder Torque Production PDF Free Download
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Baseball Pitchers’ Kinematic Sequences
and Their relationship to Elbow and
Shoulder Torque Production
Scarborough DM1, Linderman SE1, Sanchez JE1, Berkson EM1,2
1Sports Medicine Service, Department of Orthopaedic Surgery, Massachusetts General Hospital;
2Harvard University Medical School, Boston, MA
No Disclosures to report.
Background & Purpose
•Kinematic Sequence =the sequential timing pattern of peak angular
velocities of body segments during a pitch
• Provides insight to segment position and motion control that drives the
kinetic chain.
• Previous publications report an ideal Kinematic Sequence (KS) where the
timing of each body segment’s peak angular velocity occurs in a proximal-to-
distal (PDS) pattern resulting in greater ball velocity and reduction in throwing
arm injury risk.1,2
• A recent study revealed that baseball pitchers perform a variety of KSs.3
•High elbow valgus, external rotation and extension torques are associated with
increased vulnerability to joint injury, but to date there is no known investigation
of the relationship of Kinematic Sequences and throwing arm joint torques.4,5
The purpose of this study was to:
1) identify the number of different KSs performed by each pitcher and
2) compare elbow valgus and shoulder external rotation (ER) and extension (Ext)
torques between the 3primary KSs performed during the fastball pitch.
Subjects:
•14 male collegiate pitchers
•Mean age 20.57 ±1.91 yrs
Materials and Methods
Test Protocol:
• Full body kinematics captured via Vicon MX 3D motion analysis system (360 Hz)
• Each pitcher threw 10 - 12 fastballs from a standardized pitching mound the full
60’ 6“ length over home plate to strike zone target
• A Stalker ATS 5.0 radar gun recorded pitch speed
Biomechanical calculations:
• 15 segment 6 degree-of-freedom
model
• Upper body segments were defined
in accordance with International
Society of Biomechanics definitions6
Data Analysis
Kinematic Sequence
The timing of peak angular
velocities for 5 body segments
(Pelvis, Trunk, Arm, Forearm and
Hand) were recorded to generate
each pitch’s Kinematic Sequence
(Figure 1)
Figure 1. Altered distal upper extremity Kinematic Sequence
Pelvis Trunk Arm Hand Forearm
Kinematic Sequence Naming
Each Kinematic Sequence was named in reference to the ideal PDS: The first
segment noted out of order in the PDS sequence (Figure 2)
Pelvis Trunk Arm Forearm
Hand
Figure 2. Body positioning
at the time of peak
angular velocity for the 5
segments of the Altered
distal upper extremity
Kinematic Sequence.
Shoulder Variable Definitions:
External Rotational torque: The required force to rotate the humerus about the
vertical axis Externally (+) in the Z plane (N-m).
Extension torque: The required force to rotate the humerus about the frontal axis
into Flexion (+) or Extension (-) in the X plane (N-m).
Data Analysis
Data:
• Strike zone fastball pitch trials were included in analysis
• Average fastball velocity = 34.51 m/s (±1.99)
• 119 fastball pitches (average of 8.5 ±2.71 pitches per player)
• Kinematic body segment position data calculated in Visual 3D™ (C-Motion)
Analyses:
ANCOVA statistical analyses were performed
to compare joint torques across KS groups
with ball velocity as a covariate.
0 5 10 15 20 25 30 35
Altered,Proximal, arm,segment,KS
Altered,Distal,arm,segment,KS
Proximal-to-distal,KS
Number,of,pitches
Analyses of the 119 fastball pitches revealed:
•13 different Kinematic Sequences (KS)
•An average of 3
±
1.41 different Kinematic Sequences performed per pitcher
•NONE of the kinematic sequences followed true ideal Proximal-to-Distal order
• Three primary Kinematic Sequences were performed and named (Figure 3):
1. Altered Distal Upper Extremity (UE) KS
2. Altered Proximal Upper Extremity KS
3. PDS KS: closest KS to the ideal Proximal-to-Distal (PDS)
Results
Pelvis Trunk Arm Simultaneous Forearm & Hand
Pelvis Trunk Arm Hand Forearm
Pelvis Trunk Forearm Hand Arm
Figure 3. Number of pitches performed for three primary Kinematic Sequence patterns.
n= 11
n= 35
n= 20
Analyses of the 3 primary Kinematic Sequences (n= 66):
Statistically significant differences across the sequences were noted for:
• Elbow valgus torque [F(62,2) = 8.785, ɳ2= .221, p < 0.00]
• Shoulder external rotation (ER) torque [F(62,2) = 14.127, ɳ2= .313, p < 0.00]
• Shoulder extension (Ext) torque [F(62,2) = 13.237, ɳ2= .299, p < 0.00] (Figure 4)
Results
Figure 4. Comparison of shoulder and elbow torques across the 3 primary KS sequences
Torque (N-m)
30
40
50
60
70
80
90
100
110
120
130
Elbow&Valgus Shoulder&Ext Shoulder&ER
Proximal-to-distal KS, n= 11 Altered Distal arm segment KS, n= 35
Altered Proximal arm segment KS, n= 20
*
*
*
* p< 0. 05 established level of significance
•Our findings demonstrate that collegiate baseball pitchers performed an
average of 3different kinematic sequence patterns during fastball
pitching.
•This is the first study to demonstrate arelationship between kinematic
sequences (KS) and elbow and shoulder torque production.
•As anticipated, the PDS KSs, the sequence most similar to the ideal
proximal to distal sequencing, produced the least torque across the elbow
and shoulder joints.
•The Distal Upper Extremity KS was most common and generated the
greatest shoulder extension torques.
•The Proximal Upper Extremity KS demonstrated the greatest elbow valgus
and shoulder external rotation torques.
Conclusions
Discussion
•All fastball pitches are not the same. Each player throws different sets of
pitches with different timings.In the small sample in this study, an average
of 3different timings (Kinematic sequences) were used for each player.
•Pitchers try to optimize the kinetic chain to harness power and efficiency.
This is the first study to demonstrate that the concept of optimizing the
Kinematic Sequence is indeed efficient with lower torques.The Kinematic
Sequence most similar to the proximal-to-distal Kinematic Sequence
produce decreased torques in the shoulder and elbow.
•Despite this, the most commonly performed Kinematic Sequences were not
the ideal proximal-to-distal Kinematic Sequence and had greater associated
torques.
•Further study of the influence of Kinematic Sequence patterns on joint
torques in the baseball pitch may provide insight into pitching injuries and
design of injury avoidance programs
REFERENCES:
1Putnam CA. Sequential motions of body segments in striking and throwing skills: Descriptions and explanations. J Biomech.
1993;26(SUPPL. 1):125-135. doi:10.1016/0021-9290(93)90084-R.
2Fortenbaugh D, Fleisig GS, Andrews JR. Baseball pitching biomechanics in relation to injury risk and performance. Sports Health.
2009;1(4):314-320. doi:10.1177/1941738109338546.
3Scarborough DM, Bassett AJ, Mayer LW, Berkson EM. Kinematic sequence patterns in the overhead baseball pitch. Sports
Biomech. 2018; Sep 14:1-18.
4Fleisig GS, Andrews JR, Dillman CJ, Escamilla RF. (1995). Kinetics of baseball pitching with implications about injury mechanisms.
American Journal of Sports Medicine, 23, 233-239.
5Aguinaldo AL and Chambers H. (2009). Correlation of throwing mechanics with elbow valgus load in adult baseball pitchers.
American Journal of Sports Medicine, 37, 2043-2048.
6Wu G et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion--
Part II: shoulder, elbow, wrist and hand. J. Biomech. 2005 May;38(5):981-992.
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