The International Tennis Federation (ITF) has officially amended the Rules of Tennis in order to approve the use of two new types of balls in tournament play. The aim of introducing the new balls is to either speed up the game (fast-speed, Type 1 ball), or slow down the game (slow-speed, Type 3 ball), compared to the game when using the regular (medium-speed, Type 2) ball. The physics associated with the balls is predictable, and has been confirmed using the Type 3 ball (Blackwell, et al., 2002, Sports Biomechanics, 1(2), 187-191; Brody, 1987, Philadelphia: University of Philadelphia Press; Haake, et al., 2000, Sports Engineering, 3, 131-143). The effect of the Type 3 ball on the players' physiological responses, however, is in question. Anecdotal evidence suggests that senior players tend to default (quit) during match play at a higher rate than when playing with the medium-speed ball. The ITF web site, however, states players do not fatigue while using the Type 3 ball http://www.itftennis.com/html/rule/framesettst.html). The purpose of this study was to investigate differences in physiological responses of tennis players, and confirm play statistics, using the Type 3, slow-speed ball compared to the regular, Type 2 ball. Twenty skilled tennis players, assigned as opponents by skill level, participated in ten matches, each lasting one hour. Half the time was spent using the Type 3 ball and half the time they played with the regular ball. The order of the ball type was randomized. The mean heart rate for a player while playing with a particular ball was obtained from heart rate monitors (Polar Vantage NV) that collected average heart rates over 5 second time periods. Activity monitors (Stay Healthy RT3) measured motion (acceleration) levels every second with an accelerometer, and these values were averaged for the 30 minute play period. Matches were videotaped to allow for play analysis. Heart rates while playing with the Type 3 ball were 156.8 + 17.8 bpm (mean + SD) and significantly (p<0.05) greater than the heart rates of 152.8 + 17.0 bpm, measured while playing with the regular ball. Statistical significance was also demonstrated for the activity levels (arbitrary units), as Type 3 ball play resulted in 2024.8 + 314.7 units, a higher value than the regular ball result of 1919.7 + 267.1 units. Additional to the physiological variables, significant differences were revealed when looking at play statistics. Using the Type 3 ball, the average percentage of good, first serves, was 75.4 + 10.5%. This is higher than the average using the regular ball, which was 65.3 + 18.6%. The average number of good shots during a rally was also significantly higher while using the Type 3 ball (4.3 + 1.1), compared to the average while using the regular ball (3.6 + 1.0). The development of the Type 3 ball is aimed at reducing the speed of the ball and at the same time making tennis easier to play. This ball is slightly (6%) larger than the regular ball, and the larger size causes additional drag and allows for a greater Magnus effect. This translates into more accuracy and a greater number of balls that stay in the court of play compared to the regular ball. It is logical that players' heart rates and activity levels would increase during Type 3 ball play because the rallies last longer. It is also logical that these results support anecdotal reports that players fatigue more while using the Type 3 ball compared to the regular ball. However, these results seem to contradict the ITF statement that players can play 35% longer while using the Type 3 ball.
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