Changes in Overhand Throwing Patterns as a Function of Ball Size

Ten males and 10 females in each of four grade/age groups threw styrofoam balls of six different diameters as hard as possible at a wall 6.7 m away. Each ball size was thrown four times. The first hypothesis, that the levels of the five components of the one-hand overhand throw would be quite stable for individuals for throws of a particular ball size, was supported. Ball sizes at which the component levels were unstable marked the beginning of a transition to a new component level 70.6% of the time. The second hypothesis, that five components would change from higher to lower levels for most of the subjects as ball size was scaled up, was supported only for the backswing and forearm components. These components were more likely to be affected by increasing ball size because the higher level components required a firm, one-hand grip on the ball, which became more difficult as ball diameters exceeded the subjects' hand widths. The results indicate that practitioners need to recognize that different ball sizes may elicit different throwing patterns, and specifically that a critical ball diameter may be reached when it is equal to hand width.