Relative contribution of the internal rotators of the shoulder to speed of the fastball in college baseball pitchers

<p>The problem of this study was to determine the relative contribution of the strength of shoulder internal rotators among various muscle groups to ball speed in the fastball pitch as exhibited by college pitchers. An objective of the study was to explain at least 40% of the contribution of ball speed. The literature appears to be somewhat inconclusive as to the quantification of component contributors of muscle groups m the upper extremity to ball speed. It appears in the literature that variables other than upper extremity strength account for approximately 50% of ball speed. Some research has indicated that strength of the shoulder internal rotators is a major contributor while most research of this type has either been inconclusive or qualitative m nature. Eighteen college pitchers were tested for upper extremity peak torque production on the Cybex II Isokinetic Dynamometer at speeds of 90 and 240 degrees/second. Fastball speed was measured with a hand held radar gun. Results of regression analyses performed on the data indicate a strong correlation between the internal rotators of the upper extremity and fastball speed. A regression equation using a hierarchical strategy to maximize R² accounted for 40% of contribution to ball speed using independent variables of shoulder internal rotation at 90° /sec. (X₁) and elbow flexion at 240°/sec. (X₂); ie, Speed=62.861+245X₁ +.39X₂. The standardized beta weights for this equation indicate that the greater contributor to ball speed was Sho/Int/Rot-90 when the effects of Elb/Fl-240 are controlled. When elbow extension at 90° /sec. was added to the equation as X₃ approximately 59% of ball speed is explained; ie, Speed=68.605 + 268X₁ + 807 X₂- .430X₃.</p>

Name thesis:degree_name

Master of Arts (M.A.)

Level thesis:degree_level

Thesis - Pacific Access Restricted

Discipline thesis:degree_discipline

Physical Education

Year dc:date.available

1989

Author dc:creator

• Thornton, James Leland

Contributors dc:contributor

• John G. Boelter

• Baseball Physiological aspects
• Pitching (Baseball)
• Shoulder Muscles
• Sports Sciences
• Sports Studies

Licence

• http://rightsstatements.org/vocab/InC/1.0/

Repository record dc:identifier

https://scholarlycommons.pacific.edu/uop_etds/506

OAI identifier oai:identifier

oai:scholarlycommons.pacific.edu:uop_etds-1505