Movement characteristics of the tennis volley

Purpose: The purpose of this study was to examine selected movement charact eristics of the tennis volley by evaluating temporal and ground reaction fo rce (GRF) parameters. Methods: Seven skilled tennis players performed volle y strokes under 18 experimental conditions including variations in lateral contact location (forehand (FH) and backhand (BH)), ball contact height thi gh, middle, low), and ball speed (fast, medium, slow). A ball machine was m odified so that the subjects could not predict the ball trajectory before i t was released from the machine. The GRF and temporal parameters were deter mined using two force platforms and two high-speed (120 Hz) video cameras, respectively. Average and maximum values of each measured parameter were co mputed for different phases of the volley. Results: The average reaction ti mes (from ball release to initial racquet movement (IRM)) for FH and BH tri als were 226 and 205 ms, respectively, and the difference was statistically significant. The average stroke time (from IRM to ball impact) ranged from 381 ms in fast speed trials to 803 ms in slow speed trials. A distinct rac quet forward motion immediately before ball impact occurred in 75% of the t rials and they were evenly distributed between FH and BH trials. An ipsilat eral side step (a side step of the foot on the same side of the oncoming ba ll before the crossover step of the other foot) occurred more often in FH ( 45%) than in BH (34%) trials. Conclusions: The GRF during the stroke phase suggest that the subjects initiated lateral movement by leaning sideward wh en ball velocity was low and by a vigorous pushoff of the contralateral foo t when ball velocity was high.