Kinematic Parameters Of Basketball Jump Shots Projected From Varying Distances
AbstractThe purpose of this study was to identify changes in kinematic parameters of jump shots performed by four male and four female intercollegiate basketball players projected from varying distances. Subjects shot their first basket from 10 Et directly in front of the basket and shot until they successfully made three baskets. They then moved back 2 ft for each new distance, until they found a distance from which they could not make 3 succeggful baskets out of 10 attempts. All males reached a distance of 27 ft directly in front of the basket; two females reached 25 ft, one reached 23 ft, and one 19 ft. All attempts were filmed with a Locam camera operating at 100 fps. Nineteen segmental endpoints and ball center of one successful trial from each distance were digitized with a Graf/ Pen sonic digitizer interfaced to an IBM compatible microcomputer with a 486 processor. Raw data were smoothed with a lowpass digital filter using a cutoff frequency individually determined for each point digitized based on a harmonic analysis of the raw data. Mean angle of projection decreased as distance increased (M 10' =53.5 deg, M 27' =42.9 deg; F 10' =54.9 deg, F 23 ' =50 . 2 deg) . Accordingly, mean ball velocity of pro jection increased as distance increased (M 10' = 4.8 m/s, M 27' = 8.2 m/s; F 10' =5.4 m/s, F 23' =8.0 m/s) as did shoulder and elbow angular velocity at release (Shoulder (M 10' =3.2 rad/s, 27' =6.0 rad/s; F 10' =5.0 rad/s, 23' =10.6 rad/s); Elbow (M 10' =7.4 rad/s, M 27' =11.0 rad/s; F 10' =10 rad/s, 23' =15.8 rad/s)]. Mean angle of trunk inclination at release did not change as distance increased for neither males nor females (M = 1. 5 rad, F =1. 6 rad). Ball release occurred at similar vertical positions of center of gravity as distance increased (M 10 ' =1. 4 rn, M 27 ' =1. 5 m; F 10 ' =1. 2 rn, F 23' =1. 2 m). Males released their shots around the peak of their vertical jumps. Females, however, released their shots at the peak of their jump for 10 ' (1 . 2 m), 15 ' (1 . 2 m), and 17 ' (1 . 3 m), but released their shots before reaching the peak of their jump for distances of 19 " 21 " and 23 ' (19 ' peak =1 .4 rn, release =1 .3 m; 21' peak =1.3 rn, release =1.2 m; 23' peak =1.3 rn, release =1.2 m). Therefore, although release height did not change for the females as distance increased, the actual height they jumped did. Mean horizontal displacement of center of gravity increased as distance increased (M 10' =-.02 rn, M 27' = .11 m; F 10' = .02 rn, F 23 ' = .12 m). In general, to accomplish the task of successfully projecting the basketball through the basket from increasing distances directly in front of the basket, the subjects of this investigation decreased their angle of projection, increased velocity of projection, shoulder and elbow angular velocity at release, and increased their vertical and horizontal displacements of their center of gravity.
Coaching and Sports Activities
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