Laura Miller - Dissertation Proposal Defense
Thursday, February 3rd;
10:30-11:30am
233 Townsend Hall
Title: Biomechanical variability in high school and collegiate softball pitchers: a withinand between-pitch comparison
Advisor: Thomas W. Kaminski, PhD, ATC, FNATA, FACSM
Committee:
James Richards, PhD
Todd Royer, PhD
Sherry Werner, PhD
John McDonald, PhD
Kurt Manal, PhD
ABSTRACT
Background: Fastpitch softball has become of the fastest growing sports in the country
but despite its increasing popularity, baseball and softball athletes are often grouped
together as “overhand athletes”. The pitching position and more specifically, pitch
selection differ between the two sports. Baseball pitchers focus on using a fastball to
dominate batters, choosing speed over movement. Softball pitchers generally utilize a
repertoire of five to six pitches with fastball not relied upon heavily, choosing movement
over speed. Current research in baseball pitching has suggested that variability, which has
begun to emerge as a quantifiable and functional characteristic of sport-specific
movements, in pitching mechanics decreases as playing level increases. It is logical that
softball pitchers would exhibit this same trend of decreasing variability within the same
pitch. Where the two sports potentially diverge however, is between-pitch variability. It is
possible that as a softball pitcher matures into her pitch repertoire and enters a higher
level of competition and skill, variability is necessary in order to perfect and maintain her
ability to selectively throw different pitches, deemphasizing the fastball. A younger and
less skilled pitcher would then demonstrate decreased variability between pitches due to
her still developing ability to deviate away from fundamental (fastball) mechanics.
Purpose: The purposes of this study are: (1) to explore within-pitch variability differences
between high school and collegiate softball pitchers, (2) to explore the relationship of
within-pitch variability and skill among high school and collegiate softball pitchers, (3) to
explore between-pitch variability differences between high school and collegiate softball
pitchers and (4) to explore the relationship of between-pitch variability and skill among
high school and collegiate softball pitchers. Methods: Two equal groups of twenty-five
female softball pitchers will be recruited at the high school and collegiate level for upper
extremity biomechanical analysis. Subjects will be asked to pitch a minimum of ten trials
for each type of pitch in their repertoire. In order to reflect more a game-like pitch order,
each of the subject’s pitches will be drawn at random. Standard inverse dynamics
calculations will be utilized to determine peak shoulder compression forces, peak
shoulder internal rotation moments and peak elbow flexion moments during pitch
delivery phase. For statistical analyses, Student’s t-tests will be used to asses variability
differences for the dependent variables between playing level and Pearson productmoment correlations coefficients will be used to establish relationships for between
pitching experience and variability. Significance: Establishing movement variability
differences between collegiate and high school softball opens the door for future research
using longitudinal and a prospective research design to investigate whether pitchers with
lower movement variability sustain higher rates of injury. Movement variability as a
protective mechanism from injury during pitcher development has never been considered
in this population, and becomes even more important as emerging literature implicates
the anterior shoulder as a suspect with regard to injury in softball pitchers. From a
training perspective, developing softball pitchers may benefit from inducing variability
into their training regimens by being introduced to different pitches at one time and by
being encouraged to practice these pitches in equal amounts. This challenges the current
instructional paradigm of waiting until a young pitcher has developed proper fastball
mechanics before introducing another pitch. Constant repetition of not just inefficient
mechanics, but the motion in general without induced variability, may contribute to a
reduced movement variability state and increase injury potential. Movement variability
may serve as a natural selection model for determining which athletes will be able to
withstand elite training to achieve higher levels of performance.