IMPORTANCE OF DISGUISING STROKES IN A GAME BETWEEN TWO TENNIS EXPERTS (FEDERER AND DJOKOVIC) [265]

Author(s): DIMIC M., Institution: WASEDA UNIVERSITY, Country: JAPAN

INTRODUCTION:
Tennis games, especially those of high levels, are not just the matter of ball speed and placement but tactics as well. In order to create tactical advantages, players try to “disguise” their intentions and confuse opponents. Williams et al. (2009) showed that due to manipulated (misleading) dynamics of the movement in hips, shoulders, and arm/racket regions, anticipation accuracy of the stroke direction can significantly decrease in skilled players. Hitters could influence point dynamics by mimicking elements of the genuine movement (Panten et al., 2019), to trigger opponents’ incorrect anticipatory movement (Pollick et al., 2001). We tried to answer how frequently and how effective disguising can be used by analyzing highest ranking game, the 2019 Wimbledon final, played by two tennis greats. Our hypothesis was that disguised strokes can be efficient enough to make the opponent move initially to the opposite direction of the ball, creating advantageous point dynamics (APD)
METHODS:
Analysis was based on video footage of two sets (second and third of the match) with contrasting scores (6-1 and 6-7), taken from the official Wimbledon YouTube channel. Frame by frame analysis of only ground strokes was done. For each groundstroke, we determined whether it was with disguised intention or not. A disguised stroke was defined as the one containing cues indicating initial stroke intention (ISI) of the ball direction in the pre contact phase, but with the actual post-contact trajectory being different (Helm et al., 2017). To judge the ISI, we analyzed (1) hitter’s pre-contact movement time efficiency, direction and mechanics from the split step to the deceleration and set up (Murphy et al., 2016; Lofting and Hagemann, 2014) and (2) hitter’s pre-contact mechanics from the moment of posting the loading foot to the zone of impact (Landlinger, 2010 (forehand); Reid and Elliott, 2002 (backhand)). Based on the data on how receivers predict the ISI of the hitters (Ward et al. (2002); Singer et al. (1996)), we were attentive to the loading foot position, hip and shoulder external rotations in judging the hitter’s ISI. To investigate the effectiveness of disguising stroke, we analyzed receiver’s anticipatory movement (correct or wrong), and point dynamics following the disguised stroke
RESULTS:
In the 1st set analyzed, 38.8% of all ground strokes made by two players were with disguised intention. For the 2nd set, disguised stroke frequency was 26.2% of all 214 ground strokes. Winners of both sets made opponents move more frequently to the opposite direction of the ball following their disguised strokes than the undisguised strokes. 51% of disguised strokes created an advantageous point dynamics (winners or advantage), significantly higher that for the undisguised strokes (40%).
CONCLUSION:
Two expert players showed that with disguising ISI they could impose tactical superiority and create advantageous point dynamics. Suitable training program of disguised shots should have competitive utility