title: Resultant tennis ball velocity as a function of off-center impact and grip firmness.
abstract: The relationship between resistance to rotation about the longitudinal axis of a tennis racquet and post-impact ball velocity following off-center hits was investigated. Two conditions simulating the extremes of grip firmness (zero vs maximal) were compared. Tennis balls were released manually from a platform onto the racquet face from a height of 5.75 m and impacted at 10.62 m . s-1. Forty-one trials were filmed at 175 frames . s-1 and were digitized electronically. Results were subjected to a multivariate analysis of covariance (MANCOVA) using transverse and longitudinal distances between the point of impact and the geometric center of the racquet face as covariates. MANCOVA results indicated no significant differences between post-impact ball velocity for the two conditions. Therefore, it was concluded that previously reported concepts regarding striking mass and grip rigidity are no longer tenable and that the influence of grip firmness in activities in which hand-held implements are used is important only in terms of post-impact implement control. Potential adverse physiological/anatomical effects related to over-gripping are suggested.
mesh_terms: D004867:Equipment Design; D006225:Hand / Q000502:physiology*; D006801:Humans; D055585:Physical Phenomena; D010825:Physics; D012399:Rotation; D013177:Sports; D013715:Tennis