Coefficients of Restitution of Balls Used in Team Sports for the Visually Impaired

in Journal of Applied Biomechanics
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This study examined the coefficients of restitution (e) of selected balls used in team sports for the visually impaired: beep baseball and goal ball. Specifically, a basketball was compared to two men's standard goal balls, and a softball was compared to three different types of beep baseballs. The e for all balls was calculated by dropping each ball five times from heights of 6 ft (1.83 m) and 19.25 ft (5.88 m). A Sony reel-to-reel videotape recorder was used to record rebound heights on a background scale for each ball dropped. Reliability tests of the procedures yielded correlation coefficients (r) of 0.996 and 0.998 for the 6 ft (1.83 m) and 19.25 ft (5.88 m) drops, respectively. Two two-factor analysis of variance (ANOVA) tests yielded significant differences across ball type and height of drop for the basketball and goal balls and for the softball and beep baseballs, respectively (p < 0.001). The es for the more recently developed beep baseballs are close to that of the standard softball, indicating a possible danger to visually impaired participants in beep baseball.

Peter McGrain is with the Division of Physical Therapy, University of North Carolina at Chapel Hill; James Mastro is director of the Braille Sports Foundation, Minneapolis; and James Van Dyke is a director for Rem-Indiana, Inc., Lafayette, IN.

Direct all correspondence to Peter McGrain, Division of Physical Therapy, Medical School Wing E 222H, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514.

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