The effects of ball impact location and grip tightness on the arm, racquet and ball for one-handed tennis backhand groundstrokes.
A torque-driven, 3D computer simulation model of an arm-racquet system was used to investigate the effects of ball impact location and grip tightness on the arm, racquet and ball during one-handed tennis backhand groundstrokes. The stringbed was represented by nine point masses connected to each other and the racquet frame with elastic springs and three torsional spring-dampers between the hand and the racquet were used to represent grip tightness. For each perturbation of nine impact locations and grip tightness, simulations were run for a 50 ms period starting with ball-racquet impact. Simulations showed that during off-centre impacts below the longitudinal axis of the racquet, the wrist was forced to flex up to 16° more with up to six times more wrist extension torque when compared to a centre impact simulation. Perturbing grip tightness had no substantial effect on centre impact simulations. However, for off-centre impacts (below the longitudinal axis of the racquet) a tight grip condition resulted in a substantial decrease in racquet rotation within the hand (less than 2°) and an increase of 6° in wrist flexion angle when compared to the equivalent simulation with a normal grip. In addition there was approximately 20% more wrist extension torque when compared with equivalent off-centre impact simulation with a normal grip. Consequently off-centre impacts below the longitudinal axis of the racquet may be a substantial contributing factor for tennis elbow injuries with a tight grip aggravating the effect due to high eccentric wrist extension torques and forced wrist flexion.
School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire LE11 3TU, UK. M.A.King@lboro.ac.uk
Mark A
MA
King
Behzat B
BB
Kentel
Sean R
SR
Mitchell
D001132:Arm / Q000502:physiology*; D003198:Computer Simulation; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D013715:Tennis; D014953:Wrist / Q000502:physiology*