What causes tennis ball wear?

Very rarely do we ever see a tennis player approach a serve before studying the ball's appearance and feel intently. Is ball wear part of the game or should manufacturers aim to maintain ball performance throughout match-play, like in so many other sports?

Steele (2006) established a framework for identifying the key areas that contribute to wear. In brief, racket impact conditions, repeated impacts, precipitation, cloth construction and natural pressure loss are some of the major causes. Wear is primarily associated with a reduction in the coefficient of restitution and altered flight aerodynamics. However important differences in appearance, feel, rebound angles, friction-ball-turf interaction, ball mass, centre of mass and carcass stiffness, should also be considered and have yet to be investigated in full. Current optimisation techniques include changes in fibre type, fibre thickness, rubber stiffness, and porosity.

Following extensive interviews with players, a literature review and analysis of ball characteristics in play, Steele (2006) captured the effects of each of the characteristics named above on ball properties, particularly ball mass lost and coefficient of restitution. Improvements in racket technology offer customisation and a tailored product. Elite players often use high stringing tensions to promote increased control over power. Also, better understanding of conditioning programmes have improved fitness and strength increasing impact force and speed from the racket head. However, this is to the determent of ball performance; an increase in ball speed also increases the rate of ball mass lost causing wear.

String type and ball weave are further racket and ball properties that can affect the rate of ball mass lost. Natural gut induces wear significantly quicker than monofilament polyester whilst needle felt weave increases mass lost compared to sateen weave. Water resistant dyes, used to reduce ball water retention, significantly decrease initial mass losses whilst the rate of mass lost is unchanged. Finally a drop in internal pressure was shown to reduce the coefficient of restitution.

Ball wear as an area of research is still in its infancy; however with further understanding players can have the confidence to select any ball to achieve the appropriate response.

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