The effect of baseball and wiffle ball pitching on the change in hardness of forearm flexor-pronator muscles

BACKGROUND: Pitching in baseball with maximal effort has been thought to induce excessive stress on the elbow. Wiffle ball is a recreational substitute for baseball. Its substantially lighter weight ball may reduce elbow stress during pitching. In this study, we aimed to clarify the differences in muscle hardness of the forearm flexor-pronator muscles after pitching the regular baseball and the lightweight ball used for wiffle ball using shear wave elastography, a non-invasive imaging technique.METHODS: Eight adult males were recruited and asked to throw 50 fastballs using a regular baseball and a lightweight ball used in wiffle ball with maximum effort towards a net placed 3 m ahead. The hardness of the muscles was detected as the shear wave speed using shear wave elastography before and after pitching.RESULTS: The difference in shear wave speed differed significantly for the pronator teres after pitching the regular baseball (0.57±0.26 m/s, P<0.001, d=1.890), while there was no change after pitching the lightweight ball (0.03±0.19 m/s, P=0.709, d=0.092).CONCLUSIONS: The result suggested that pitching with the lightweight ball used in Wiffle ball is less physically demanding, especially on the pronator teres, than regular baseball, suggesting a likeable potential of the Wiffle ball game as a lifelong sport with lower injury risk.