135
vol.2•no.2 SPORTS HEALTH
T
he overhand pitching motion consists of a sequence of
body movements that start when the pitcher lifts the
lead foot, progresses to a linked motion in the hips and
trunk, and culminates with a ballistic motion of the upper
extremity to propel the ball toward home plate. The effective
synchronous use of selective muscle groups maximizes the
efficiency of the kinetic chain (Table 1). The lower extremity
and trunk generate and transfer energy to the upper extremity.
Coordinated lower extremity muscles (quadriceps, hamstrings,
hip internal and external rotators) provide a stable base for
the trunk (core musculature) to rotate and flex. The extremely
rapid rate of this motion makes assessment difficult. The time
elapsed between front foot contact and ball release is only
0.145 seconds,
30
followed by an additional half second for the
ball to reach home plate.
7
Maximum humeral internal rotation
velocity during throwing may reach 7500 to 7700 degrees per
second.
8,21
Extreme degrees of external rotation of the shoulder,
coupled with forward linear trunk motion, allow a greater
distance for the accelerating force to be applied to the ball,
generating top velocity.
26
An intricate relationship between the
dynamic stabilizers (rotator cuff, pectoralis major, and latissimus
dorsi) and static stabilizers is required to simultaneously supply
the range of motion, force, and stability of the glenohumeral
joint. This integrated effort relies on the trapezius, rhomboids,
levator scapulae, and serratus anterior muscles for stabilization,
positioning, and synchronous scapular motion. The scapula
acts synchronously with the rotator cuff to maintain the
glenohumeral center of rotation within a physiologic range
during the pitching motion.
13,18,20
Because the throwing motion occurs almost exclusively above
90° of abduction, the inferior glenohumeral ligament and
capsule act as the primary static anterior restraint. The deltoid
elevates the humerus while the rotator cuff adjusts the position
of the humeral head on the glenoid.
16
The pectoralis major and
latissimus dorsi power the shoulder forward.
16
A pitcher’s velocity, consistency, and durability may be
linked to kinematic and kinetic factors as well as the temporal
association of segmental body motions. Optimization of
these parameters allows for efficient and consistent transfer of
energy from proximal to distal components. Understanding
the variables that optimize function may prevent injury by
reducing the forces imparted to the shoulder and elbow joints.
Breakdown of the kinetic chain will reduce its efficiency,
making top velocity more difficult (Table 2).
The Kinetic Chain in Overhand Pitching:
Its Potential Role for Performance
Enhancement and Injury Prevention
ShaneT.Seroyer,MD,*ShaneJ.Nho,MD,BernardR.Bach,MD,CharlesA.Bush-Joseph,MD,
GregoryP.Nicholson,MD,andAnthonyA.Romeo,MD
The overhead throwing motion is a coordinated effort of muscle units from the entire body, culminating with explosive motion
of the upper extremity. The throwing motion occurs at a rapid pace, making analysis difficult in real time. Electromyographic
studies and high-speed video recordings have provided invaluable details regarding the involved musculature, the sequence of
muscle involvement, and associated kinematic variables. The goal of the present article is to provide an overview of the kinetic
chain—that is, a detailed description of the muscular coordination during each phase of pitching—and to describe specific
types of pitches. An enhanced understanding of the components of the kinetic chain and the phases of the throwing motion
can provide important information for rehabilitation, performance enhancement, and injury prevention.
Keywords: pitching, throwing shoulder, kinetic chain, pitching motion, shoulder injuries
[ Athletic Training ]
From the Rush University, Chicago, Illinois
*Address correspondence to Shane T. Seroyer, MD, 515 Mayfield Road, Ste 116, Arlington, TX 76014 (e-mail: sseroyer@gmail.com).
No potential conflict of interest declared.
DOI: 10.1177/1941738110362656
© 2010 The Author(s)