Date of Award

2008

Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

First Advisor

David Relling

Keywords

Baseball; Biomechanics; Elbow Joint; Range of Motion, Articular; Shoulder Joint

Abstract

Purpose: There are a large number of fast pitch softball participants including high school, college, Olympic, professional and recreational leagues. While a large number of studies describe the baseball pitch, there is a shortage of studies describing the windmill softball pitch. Therefore, the purpose of this study is to utilize electromyography (EMG) and motion analysis to determine the biomechanical factors of muscle recruitment, shoulder and elbow range of motion and joint velocities during the windmill softball pitch.

Subjects: Five Division II women's fast pitch softball pitchers, mean age 19 years, were included in the study. The player's pitching experience averaged 9.5 years.

Instrumentation: A ViconPeak motion analysis system using 8 MX40 cameras at a capture rate of 250 frames per second was used to collect the complete pitch. ViconPeak Workstation® software was used to label, reconstruct, and process the raw data. EMG data was collected at a frequency of 1000 Hz using bipolar, self-adhesive, pre-geled EMG surface electrodes. The data was rectified, normalized to the fast pitch EMG for each phase, and smoothed using RMS 50 with.Noraxon MyoResearch XP software.

Procedure: The procedure and methods were explained to the subjects prior to informed consent. After informed consent, the subjects were instrumented with EMG electrodes and reflective markers. Subjects completed a self-selected warm-up similar to a practice or game. Pitchers performed five repetitions of each randomly assigned set of pitches.

Data Analysis: A repeated measures ANOVA was used to analyze all data. Statistical significance was set a priori at 0.<.05

Results: No significant difference was identified for EMG activity between the type or phase of pitch. Kinematic data revealed significantly faster ball speed for the fastball and riseball compared to the dropball. The fastball and riseball demonstrated significantly higher shoulder internal rotation angular velocities compared to the changeup.

Conclusion and Clinical Implication: Pitch type and phase did not influence muscle recruitment as displayed by EMG, therefore a general training program is warranted. The fastball and riseball demonstrated significantly higher angular velocities for shoulder internal rotation which could explain the higher ball velocity. At the same time, lower softball angular velocities compared to baseball pitching may be offset by the increased pitch volume. This is often observed in softball pitchers which may be the primary impetus for injury. Future studies are recommended to investigate the effect of pitch release on forearm and wrist kinematics.

Download
COinS