No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Abstract
The primary aim of this study was to determine whether variations in rebound speed and accuracy of a tennis ball could be detected during game-simulated conditions when using three rackets strung with three string tensions. Tennis balls were projected from a ball machine towards participants who attempted to stroke the ball cross-court into the opposing singles court. The rebound speed of each impact was measured using a radar gun located behind the baseline of the court. An observer also recorded the number of balls landing in, long, wide and in the net. It was found that rebound speeds for males (110.1+/-10.2 km.h-1; mean+/-s) were slightly higher than those of females (103.6+/-8.6 km.h-1; P<0.05) and that low string tensions (180 N) produced greater rebound speeds (108.1+/-9.9 km.h-1) than high string tensions (280 N, 105.3+/-9.6 km.h-1; P<0.05). This finding is in line with laboratory results and theoretical predictions of other researchers. With respect to accuracy, the type of error made was significantly influenced by the string tension (P<0.05). This was particularly evident when considering whether the ball travelled long or landed in the net. High string tension was more likely to result in a net error, whereas low string tension was more likely to result in the ball travelling long. It was concluded that both gender and the string tension influence the speed and accuracy of the tennis ball.
... It is likely that the advanced recreational performers noticed the change in rebound angle, but on a whole were not able to relate this back to the string tension of the racket. Interestingly, the effect of string tension on the type of error is statistically measurable, and it is clear that more net errors occur with tightly strung rackets and more long errors occur with loosely strung rackets [2]. These results may be attributed to both the velocity and angle of rebound changes associated with variable string tensions as described earlier. ...
... Advanced male recreational players undertaking a similar experiment impact the ball at approximately 110 km h -1 [2]. Mean rebound speed for the current study of elite male performers was approximately 6% higher. ...
... When it comes to ball placement, long errors were twice as likely as net errors and three times more likely than wide errors ( Table 2). The ratio of long errors to wide errors is comparable to previous research with advanced recreation players [2], but the ratio of long errors to net errors is far greater. The greater percentage of long errors compared to a net errors suggests that elite players are more likely to be pressing for deep strokes than strokes that just go in. ...
Eighteen elite male tennis players were tested to determine their ability to identify string tension differences between rackets
strung from 210N (47lb) to 285N (64lb). Each player impacted four tennis balls projected from a ball machine before changing
rackets and repeating the test. Eleven participants (61%) could not correctly detect a 75N (17lb) difference between rackets.
Only two participants (11%) could correctly detect a 25N (6lb) difference. To establish whether varying string tensions
affected ball rebound dynamics, the ball’s rebound speed and landing position were analysed. The mean rebound ball speed was
117kmh−1, with only the trials from the 210N racket producing significantly lower (P<0.05) rebound speeds than the 235N and 260N rackets. This is contrary to previous laboratory-based tests where higher
rebound speeds are typically associated with low-string tensions. The anomaly may be attributable to lower swing speeds from
participants as they were not familiar with such a low string tension. Ball placement did not appear related to string tension,
with the exception of more long errors for the 235N racket and fewer long errors for the 285N racket. It was concluded that
elite male tennis players display limited ability to detect changes in string tension, impact the ball approximately 6% faster
than advanced recreational tennis players during a typical rallying stroke, and that ball placement is predominantly unrelated
to string tension for elite performers.
... Before testing, the participants performed a 20-minute standardized warm-up led by a strength and conditioning coach. 9 All tests were performed on the same court surface. ...
... Junior tennis players (N = 12; height = 1.73 [0.1] m; weight = 62 [9] kg; body mass index = 20.7 [2] kg/m 2 ) were classified as n = 7 neutrals, n = 4 moderate morning types, and n = 1 moderate evening type. At baseline, PSQI mean score was 2.7 (0.9), indicating no self-reported sleep complaints. ...
Purpose:
Little is known about the effect of sleep restriction (SR) on different domains of athletes' physical performance. Therefore, the aim of this randomized, counterbalanced, and crossover study was to evaluate the effect of acute SR on sport-specific technical and athletic performance in male junior tennis players.
Methods:
Tennis players (N = 12; age 15.4 ± 2.6 y) were randomly allocated to either a sleep-restriction condition (SR, n = 6), where they experienced acute sleep restriction the night before the test session (≤5 h of sleep), or to a control condition (CON, n = 6), where they followed their habitual sleep-wake routines. Testing procedures included 20 left and right serves, 15 forehand and backhand crosscourt shots, and a repeated-sprint-ability test (RSA). The accuracy of serves and shots was considered for further analysis. One week later, players of SR joined CON, and players of CON experienced SR, and all test procedures were repeated.
Results:
Significant decrease in the accuracy of right (-17.5%, P = .010, effect size [ES] = 1.0, moderate) and left serve (-14.1%, P = .014, ES = 1.2, large), crosscourt backhand (-23.9%, P = .003, ES ≥ 2.0, very large), and forehand shot (-15.6%, P = .014, ES = 1.1, moderate) were observed in SR compared to CON, while RSA was similar in both conditions.
Conclusion:
Coaches and athletes at the team and individual level should be aware that 1 night of SR affects sport-specific but not athletic performance in tennis players.
... Ball Larger peak Rx impact force estimates (normal to the racket surface) compared to peak Ry impact force estimates (parallel to the racket surface and close to vertical direction of the racket movement at the impact) suggests that Rx forces contribute to ball speeds and the topspin whereas Ry forces may be more related to generating topspin. Difference in magnitude between string tensions may be due to the more control the higher string tension racket gives at impact [4]. The peak impact resultant force estimates were similar to those reported in the literature. ...
... The peak resultant impact force for 258N string tension were 40% larger than the 214N string tension possibly due to differences in coefficient of restitution of the different string tensions. Higher string tension rackets have lower coefficient of restitution resulting in a slower rebound velocity whereas lower string tension rackets have higher coefficient of restitution resulting in faster rebound velocities [2,4]. With almost similar acceleration at impact (1.23 vs. 1.33 m•s -1 ) and larger ball velocity (36.6 vs. 16.8 m•s -1 ), it may be that with higher string tension, the string deforms less and the impact duration may be shorter which, in turn, may explain for the larger peak resultant impact force for the 258N (higher string tension) string tension than the 214N (lower string tension) string tension. ...
Abstract. The purpose of this study was to establish a method to estimate impact force in tennis forehand stroke to determine if differences in string tension would affect impact force. This is a preliminary study using only one participant. Estimates were determined using kinematic data and data obtained from strain gauges. Preliminary data on peak resultant impact force estimates were within the range of those reported in the literature. Peak resultant force estimates were larger for higher string tension rackets and lower string tension in the racquets possibly due to differences in coefficient of restitution. Data estimated from this study, regardless of string tension, may give a better representative of peak resultant impact force as the data were not filtered.
... This could be done performing exercises were the player has to hit at different part of the courts, dividing it in areas in a longitudinal direction or practising strokes modifying some parameters that could affect the flight of the ball such as the hitting speed, heights of the ball over the net (ropes could be used) or the ball spin. A modification of the racket parameters could also be considered, such as the swing-weight or tension of the string since they influence the accuracy (Allen et al., 2016;Bower & Cross, 2005). Player one could be advised to work his backhand both laterally and longitudinally (his ellipse is less eccentric, has a shape more similar to a circle). ...
... The test proposed in this work and the Excel tool that accompanies it is expected to be valuable for scientists who want to study accuracy. In our opinion, there are still a large number of factors that can affect accuracy during play and their impact should be studied in greater depth than what has been done so far, such as: fatigue (Lyons et al., 2013), racket characteristics (Bower & Cross, 2005), mental aspects (Robin et al., 2007), variables related to the ball that approaches the player (Bower & Sinclair, 2007) or with the ball that leaves the racket (Knudson & Blackwell, 2005). Since the test does not require complex technical knowledge or setting-up, it is also expected that coaches with limited access to high end technologies can use it. ...
Stroke accuracy is highly related with tennis performance and has traditionally been quantified using general areas of scoring. Hence there is a need to develop methods that allow accuracy to be measured with higher resolution. The aim of the work is to develop a field test and an Excel spreadsheet associated that allows to evaluate
the accuracy of the strokes with a resolution up to centimetres and to study how shots landings are distributed. The test consists of 4 series of 20 groundstrokes performed in the down the line or cross-court direction (this is modifiable). The 2D coordinates of bounce of the ball is recorded with a camera, digitalized using a specialized software and introduced in the Excel spreadsheet. Then it computes a series of parameters that describe the 95% confidence ellipse of the shot landing on the court. A real example of the test outcomes of two advanced players-performing forehands and backhands down the line- is shown. Consistent with previous literature both players obtained a better accuracy in the mediolateral direction than in the longitudinal direction and ellipses were oriented almost parallel to the sideline (ellipse tilts were below 12 degrees in all cases). Ellipse area was considerably greater for the backhand than for the forehand in player two (38.8 vs. 55.5m2) but not in player one (51.5 vs. 50.8 m2). Finally, the centre location of the ellipse in the longitudinal axis was positive in all cases (near 200 cm) which suggest that both players preferred to make short shots rather than send the ball out of the limits of the baseline. We conclude that this methodology can be used by researchers that want to assess accuracy with high resolution and by coaches that want to evaluate -with high sensibility- the player progression after a training program.
... It has also been shown that lower string-tensions enable greater rebound velocity, although higher string-tensions produce lower rebound angles, greater accuracy, and greater control of shot. 23,24 The present study aimed to determine the effect of racket string-tension on the amount of force transmitted to the elbow during backhand tennis strokes using tennis players as volunteers, with a practical, demonstrable, consistent methodology allowing control of almost all other variables involved in the backhand stroke. The clinical significance of this was to assess how string-tension can modulate forces dissipated at the elbow, a known factor in the risk of development of LE. ...
... In some studies, trial selections were based on whether the player was able to strike the ball and make it land on a target area. 13,24 This method of trial selection need not necessarily mean that the ball-racket interaction was constantly in the middle of the racket in all trials. By these methods, consistency of impact location cannot be ensured. ...
Background:
Lateral epicondylitis (LE) occurs in almost half of all tennis players. Racket-string tension is considered to be an important factor influencing the development of LE. No literature yet exists that substantiates how string-tension affects force transmission to the elbow, as implicated in LE development. We establish a quantitative relationship between string-tension and elbow loading, analyzing tennis strokes using rackets with varying string-tensions.
Methods:
Twenty recreational tennis players simulated backhand tennis strokes using three rackets strung at tensions of 200 N, 222 N and 245 N. Accelerometers recorded accelerations at the elbow, wrist and racket handle. Average peak acceleration was determined to correlate string-tension with elbow loading.
Results:
Statistically significant differences (p < 0.05) were observed when average peak acceleration at the elbow at 200 N string-tension (acceleration of 5.58 m/s(2)) was compared with that at 222 N tension (acceleration of 6.83 m/s(2)) and 245 N tension (acceleration of 7.45 m/s(2)). The 200 N racket induced the least acceleration at the elbow.
Conclusions:
Although parameters determining force transmission to the elbow during a tennis stroke are complex, the present study was able to control these parameters, isolating the effect of string-tension. Lower string-tensions transmit less force to the elbow in backhand strokes. Reducing string-tension should be considered favourably with respect to reducing the risk of developing LE.
... Machines such as tennis ball launchers and baseball pitchers are used from recreational to professional levels yet no previously published studies exist as far as the authors are aware on their accuracy and consistency, however numerous studies have used these machines and reported these data. For example in tennis, the CV for ball projection speeds typically ranges from 2- 10 percent (Knudson, 1991;Bower & Cross, 2005;Cooke & Davey, 2005) and angles of projection with 7 percent variation (Knudson, 1991). While some are designed to vary projection to simulate a tennis rally many professional players and coaches encourage the use of tennis ball launchers (TBL) in practice as they "can be programmed to serve the exact ball required in terms of length, trajectory, angle and spin for both tennis and table tennis" (Launder, 2001 p.122). ...
... As advertised the TBL's maximum velocity is 22.4m/s (50mph). It also found similar results of projectile velocity variance as those found by Bower (2005) and Cooke and Davey (2005) perhaps indicating that advances in technology have not decreased velocity variability. However, this could also be due to the reflective tape on the balls reducing grip (therefore decreasing ball speed) when in contact with the TBL's rotating wheels. ...
The purpose of this study was to investigate the reliability and consistency of the Sports Tutor Tennis Cube TM ball launcher. Five identical (mass, diameter) competition standard tennis balls were each launched twenty-five times and flight was assessed using 3D infra red motion analysis. 3D resultant velocity was found to be 18.9 ± 0.89 m/s, landing points had a coefficient of variation in the lateral direction of 8.28% and 18.4% in the vertical direction Trajectory was also projected to estimate ball carry showing ball flight range (horizontal spread) of 14.9 ± 3.71 m. Results showed that whilst the commercially popular tennis ball launcher was stroke specific, it exhibited a level of variability This could be seen to bring variance to tennis players' practice that they once thought did not occur with the use of tennis ball machines. INTRODUCTION: The purpose of this study was to investigate the variability of outcome of commonly used projectile launchers. Machines such as tennis ball launchers and baseball pitchers are used from recreational to professional levels yet no previously published studies exist as far as the authors are aware on their accuracy and consistency, however numerous studies have used these machines and reported these data. For example in tennis, the CV for ball projection speeds typically ranges from 2-10 percent (Knudson, 1991; Bower & Cross, 2005; Cooke & Davey, 2005) and angles of projection with 7 percent variation (Knudson, 1991). While some are designed to vary projection to simulate a tennis rally many professional players and coaches encourage the use of tennis ball launchers (TBL) in practice as they "can be programmed to serve the exact ball required in terms of length, trajectory, angle and spin for both tennis and table tennis" (Launder, 2001 p.122). However, it is unclear if recently manufactured TBL's have improved upon the consistency of ball projection variables and so for this study a popular commonly used TBL, the Sports Tutor Tennis Cube TM was investigated. METHODS: For the relatively slow tennis ball launch velocity selected (15-25 ms -1) three-dimensional high speed motion analysis was deemed our laboratory's most accurate method of assessing ball flight. Thus pilot trials were conducted using two tennis balls wrapped with 3M TM reflective tape to examine the robustness of the tape wrapping. Trials showed that taping remained intact on ball one up to trial thirty-four and ball two up to trial twenty-five. It was therefore decided that to perform one hundred trials five balls would be needed, twenty trials each. Equipment & Materials: The Sports Tutor Tennis Cube TM launcher was used. Five new premium competition-standard tennis balls (Wilson Trainer TM) were each labelled A-E and wrapped with five pieces of retro-reflective tape (5 cm diameter, 21 cm length) so that they were fully covered. Wrapping followed standard retro-reflective marker covering protocol indicated by leading motion analysis system manufacturers (Motion Lab Systems 2011). For the current study the TBL was placed 3.58 m back from a target wall, at a height of 0.79 m and surrounded by a semi circle arrangement of 6 Eagle digital cameras (Motion Analysis Corporation Ltd., Santa Rosa, California) operating at 400-Hz. The TBL was set to Speed 10 and the trajectory was at its lowest, nearly horizontal trajectory 1. These settings remained constant throughout the experiment. Protocols: Data collection was triggered via manual start. The five tennis balls were then fired twenty times each at the wall and 3D data was collected for each trial. The tennis balls were tracked from TBL projection to wall impact and rebound. Data were filtered using Cortex at 6-Hz. Data Analysis: Variables examined were horizontal velocity, projected trajectory and landing points. Descriptive statistics (mean, standard deviation, range and quartiles) were calculated. Variability analysis was performed by applying a coefficient of variation test to all data. The coefficient of variation was calculated as the standard deviation divided by the mean and expressed as a percentage. 95% confidence ellipse was also calculated for the landing points (mean ±SD) (Ennos, 2007). Projected trajectory was calculated using initial velocity, angle of release and height of release taken 3 frames after TBL ball projection to allow clearance from the machine.
... Although the forehand groundstroke has been previously investigated (Bower & Cross, 2005, 2008, the present study is the first to provide information on both ball speed and accuracy in the cross-court and down-the-line groundstrokes of elite and highperformance players. The main findings of the present study are as follows: (1) the total number of strokes that landed inside the target area (general consistency) did not differ between elite and highperformance players; (2) the ball speed of the forehand and the backhand groundstroke was higher for the elite group when analysing all successful shots, the six fastest shots, and the six most accurate shots; ...
... The mean rebound ball speed of the elite players (34.6 m × s Á1 ) was higher than the 32.5 m × s Á1 reported by Bower and Cross (2008). Moreover, the participants in the high-performance group demonstrated slightly higher ball rebound speeds than the male participants of a previous study that focused on string tension effects (Bower & Cross, 2005). Generally, the ball speeds generated were higher than the racquet speeds in the forehand (Bahamonde & Knudson, 1998;Elliott & Marsh, 1989;Elliott et al., 1997;Iino & Kojima, 2001) Ball speed and hitting accuracy in tennis 5 2002) reported previously. ...
The main aim of this study was to identify and compare ball speed and hitting accuracy of forehand and backhand groundstrokes between ATP professionals (elite) and high-performance youth players when shots were played cross-court and down the line to a target square. Six elite and seven high-performance tennis players volunteered to participate in the study. A Doppler-radar device and a digital video camera, operating at 120 frames per second, were used to measure ball speed and accuracy of forehand and backhand groundstrokes in the respective situation (cross-court and down the line). The results of 1040 measured groundstrokes indicate that the ball speed of the forehand and the backhand ground stroke was higher in the elite group when analysing (1) all valid shots, (2) the six fastest shots, and (3) the six most accurate shots (all P < 0.05). In addition, all players achieved a higher forehand speed compared with their backhand when balls were directed cross-court (P < 0.01). The participants demonstrated similar ability when considering accuracy of their groundstrokes (P > 0.05). However, a group difference for accuracy was identified when considering the six fastest forehand shots (P<0.05), and the forehand cross-court stroke was played more accurately than the backhand cross-court stroke by both groups (valid shots and six most accurate shots, P<0.05). Moreover, there was no evidence that players who impacted the ball faster were any less accurate than those who impacted the ball more slowly. Analyses for participants actually revealed a negative correlation between ball speed and mean radial error (accuracy) for the backhand down the line (r= - 0.77, P<0.01). According to the results of this study, ball speed seems to be the determining factor that separates elite from sub-elite tennis players.
... In order to achieve successful performance in tennis, female tennis players must develop many interrelated tennis skills to reach high level of success in a tennis match. Success or failure of any type of stroke in tennis can be a matter of precision in terms of only several centimetres (Bower & Cross, 2005). To win a match, the number of errors must be reduced to a minimum, thus players with a higher percentage of accuracy of strokes are usually more successful. ...
Several studies investigated the situational efficiency parameters at tennis matches in the men's and women's competition at previous Rolland Garros tournaments. The aim of this study was to determine if there are differences in the situational efficiency parameters between winners and losers in the women's main draw competition at Roland Garros 2022. This study included 125 main draw matches. Differences in performance were analysed across 7 situational efficiency variables: aces, double faults, 1st serve average speed, 2nd serve average speed, winners, unforced errors and forced errors. The results showed significant differences between winners and losers with the following parameters on the winners’ side: number of aces per match (2.40/1.63; p = 0.03), winners (24.83/19.37; p = 0.00), unforced errors (23.80/29.13; p = 0.00) and forced errors (19.71/23.64; p = 0.00). The results demonstrated that there were no significant differences in double faults, 1st serve average speed and 2nd serve average speed. More aces of winners can indicate better service accuracy and variability, as there is no significant difference in service speed. Also, a more successful start of a point can positively affect the early dominance in the point rally and easier achieving of winners. In addition to all the above, it is notable that more successful tennis players, as well as having more winners, record less unforced and forced errors. The information obtained should be used by tennis coaches in planning trainings and preparing matches in order for their tennis players to achieve maximum results. Keywords: tennis, efficiency, match statistics
... Generally, ensuring the fewest unforced errors during a tennis match will contribute to improved competitive tennis performance. This indicated a need tominimize the number of unforced technical errors during a tennis match (8). When reliable data are obtained, the percentage of unforced errors is a valid indicator of tennis performance (30). ...
The control and quantification of internal and external training load is essential to the correct design of training programs. In tennis, along with anaerobic, psychological and tactical abilities, technical skills and endurance conditioning are key to competitive performance. Therefore, it could be useful to use testing and training loads and methods that include physiological and technical parameters at the same time. The aim of this review was to identify a new training load parameter, suitable for on-court use in tennis, based on technical and physiological skill, to allow control of internal and external loads.
... The serve speed in tennis is influenced by numerous factors, including the technique and biomechanics of the serve (Brody, 1987;Elliott, Reid, & Crespo, 2003, 2009Knudson, 2006), the motor precondition (Grosser, Kraft, & Schönborn, 2000), body dimensions (Vaverka & Cernošek, 2013), physical qualities of the racket and string tension (Brody, Cross, & Lindsey, 2007) and the balls (Blackwell & Knudson, 2002;Bower & Cross, 2005;Haake, Allen, Choppin, & Goodwill, 2007). Also, environmental conditions affect serve execution, such as light levels (i.e. ...
The aim of the study was to determine whether the serve speed differs between Grand Slam tournaments (GSTs) played on different court surfaces. The study was carried out for both men and women (n = 70–98) who participated in four of the GSTs in 2008, 2012 and 2016 (Australian Open, French Open, Wimbledon and US Open). The following serve-speed parameters were obtained from the official GST websites: the speed of the fastest serve (FS), the average speed of the first serve in a given match (S1) and the average speed of the second serve in a given match (S2). Statistical analysis was performed using a mixed linear model procedure (NCSS 2007, Keysville, UT). FS varied irregularly, but it did not differ significantly between GSTs in the three observed years. The values of S1 and S2 for both men and women were highest in WIM in all three years, and were significantly higher than the other variables measured at the other GSTs. An association between serve speed and tennis court surface was confirmed only for S1 and S2 at fast grass court surfaces at WIM in the period 2008–2016.
... By using variations of the pull of the strings 22 lbs, 24 lbs, 26 lbs, 28 lbs, 30 lbs is produced that the higher the pull of the strings, the lower the velocity of the shuttlecock [3,4]. These results confirmed research that influences pull the strings high will produce a velocity bounce lower than the pull of the strings low [3,5]. ...
p style="text-align: justify;">Racket and strings is an important factor in the badminton sport. The aim of this study to analyze the pull and the diameter racket string based on restitution coefficient of shuttlecock. The variation of pull was measured used racket Vinlux Miotex Power 007. Six variation of racket string are (22, 23, 24, 25, 26, and 27) lbs. The diameter of the strings has kept constant of 0.66 mm. The other variable is the diameter variation of the strings are (0.62, 0.64, 0.66, 0.68, and 0.70) mm, respectively and the pull of the strings are kept constant of 24 lbs. Based on the result, the increasing of the pull was decreased the COR value, from 0.541 to 0.374 for 22 lbs to 27 lbs, respectively. Furthermore, the similar trend for the diameter variation with the pull variation, the COR value was decreases with the increasing of the diameter, from 0.529 to 0.447 for (0.62 to 0.70) mm. We can conclude, the increases of the pull and diameter variation was decresed COR value of shuttlecock. ©2016 JNSMR UIN Walisongo. All rights reserved.</p
... 10 Experiments and theoretical models confirm that string bed stiffness affects ball impact duration, rebound speed, rebound angle, and thus unforced stroke errors from the subsequent ball flight. [11][12][13][14] For example, a lumped parameter model is presented 13 in which the ball is represented by a parallel spring and damper and the string bed is represented by a linear spring attached to a rigid frame. A similar lumped parameter model developed 14 represents the string bed by a (cubically) nonlinear spring that captures the hardening behaviour of the string bed as it stiffens under larger deflections. ...
The overall stiffness of the string bed of a tennis racquet depends on numerous factors including the size and shape of the string bed, initial string tension, string spacing, and string geometric and material properties. This article contributes an analytical model of the string bed that employs nonlinear membrane theory to estimate static stiffness. The partial differential equation governing string bed deformation is discretized using a one-term Galerkin approximation that employs a logarithmic shape function for the string bed deflection. The resulting force–displacement relation at the centre of the string bed yields the string bed stiffness as a function of the major design parameters, including the shape and size of the frame, string tension used during stringing, and string spacing, diameter, and elastic modulus. To assess the accuracy of this model, the predicted force–displacement relation was compared to that measured from experiments on a string bed instrumented with a load cell and photoelectric (laser) displacement sensor. Experimental results confirm that the analytical model yields accurate estimates of the string bed load–displacement characteristics, especially for displacements of 5 mm or less.
... Second, isometric testing was conducted using static positions and this method cannot replicate all joint angles, specific tennis movements and the rotation velocities of segments in stroke production (Murphy and Wilson, 1997). Moreover, interference of uncontrolled variables such as different service techniques used (i.e., foot-up and foot-back), the type of a racket and the type and tension of strings on the rackets used by players, could have a direct impact on serve velocity (Bower and Cross, 2005;Lees, 2003). Finally, the effectiveness of tennis serve is not only determined by the ball © Editorial Committee of Journal of Human Kinetics speed, there are important additional performance indicators such as the ball rotation or spin (topspin or slice serves) and accuracy (Abrams et al., 2011;Elliot et al., 1995). ...
The aims of this study were to analyze the relationship between maximum isometric strength levels in different upper and lower limb joints and serve velocity in competitive tennis players as well as to develop a prediction model based on this information. Twelve male competitive tennis players (mean ± SD; age: 17.2 ± 1.0 years; body height: 180.1 ± 6.2 cm; body mass: 71.9 ± 5.6 kg) were tested using maximum isometric strength levels (i.e., wrist, elbow and shoulder flexion and extension; leg and back extension; shoulder external and internal rotation). Serve velocity was measured using a radar gun. Results showed a strong positive relationship between serve velocity and shoulder internal rotation (r = 0.67; p < 0.05). Low to moderate correlations were also found between serve velocity and wrist, elbow and shoulder flexion - extension, leg and back extension and shoulder external rotation (r = 0.36 - 0.53; p = 0.377 - 0.054). Bivariate and multivariate models for predicting serve velocity were developed, with shoulder flexion and internal rotation explaining 55% of the variance in serve velocity (r = 0.74; p < 0.001). The maximum isometric strength level in shoulder internal rotation was strongly related to serve velocity, and a large part of the variability in serve velocity was explained by the maximum isometric strength levels in shoulder internal rotation and shoulder flexion.
... The technical skill of a tennis player can have a direct influence on the final outcome of a match. For example, the player with the fewest unforced errors has a higher probability of winning a match (15). In this regard, different studies have found relationships between technical skill and competitive performance at a range of competitive levels (4, [34][35][36]. ...
This study aimed (i) to evaluate a new training load parameter in tennis based on the ball-hitting frequency (Ballf) at VO2max occurs (maximal aerobic frequency of ball hitting, MAF) and (ii) to assess the accuracy of a specific endurance tennis test (SET-Test) for predicting MAF. Thirty-five male competitive tennis players performed the SET-Test and selected physiological and performance parameters at maximal workload (MAX), last completed stage (LS) and MAF were compared. Performance parameters (Ballf, time, stage and hits per test) at LS were higher than at MAF (20.2+/-1.7 vs. 18.1+/-1.5 shots[middle dot]min-1, 6.6+/-0.8 vs. 5.6+/-0.8 stages, and 189+/-33 vs. 147+/-27 hits; p<0.001), and highly correlated (r=0.72-0.77; p<0.001). The mean difference between Ballf and Stage at MAF and LS were 2.1+/-1.1 shots[middle dot]min-1 and 1.1+/-0.6 stages, respectively. The main physiological parameters (heart rate, VO2 and VCO2 at LS were higher than at MAF (191+/-9 vs. 186+/-8 beats[middle dot]min-1, 55.5+/-5.9 vs. 55.0+/-6.0 ml[middle dot]kg-1[middle dot]min-1 and 4724+/-880 vs. 4253+/-739 ml[middle dot]min-1; p<0.005), and were very strongly correlated (r=0.93-0.99; p<0.001). We conclude that MAF can be used as a practical performance parameter to prescribe tennis-specific training, and that the SET-Test is a valid method for assessing MAF. Gas exchange measurements not being available, as a rule of thumb, most players reach their MAF at ~1 stage (95% CI 0.9-1.2) and ~2 shots[middle dot]min-1 (95% CI 1.7-2.5) less than their completed LS. A model for specific on-court training protocols for optimizing aerobic fitness in competitive tennis player is proposed. Copyright (C) 2016 by the National Strength & Conditioning Association.
... Goodwill and Haake [32] showed normal rebound speed to increase as string tension decreased for oblique impacts in a laboratory experiment, although rebound spin was reported to be independent of string material, diameter and tension. Bower and Cross [79] showed rebound ball speeds to be inversely related to string tension for actual tennis strokes, in line with the laboratory results and theoretical predictions of other authors [54,78,80]. ...
The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and biomechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swingweights of around 0.030–0.035 kg/m2 are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions.
... One of the purposes of this study was to determine reliability of kicking performance test measured by a radar gun. Authors found only a small number of scientific articles in which a radar gun was used and none of them dealing with soccer situations (Pugh et al., 2001(Pugh et al., , 2003Peterson et al., 2004;di Pramero et al., 2005;Frothomme et al., 2005;Gander et al., 1994;Jegede et al., 2005;Bower & Cross, 2005;Signorile et al., 2005;). Reliability analysis (Alpha) performed on three items of the kicking performance test was 0.96. ...
Kicking is one of the most vital skills in soccer and strength and power share importance in the explosive movement of top level play. The full instep – kick is one of the kicks typically used to generate fastball speed. Twenty-seven Croatian national football team members (U-15) (mean (SD) age 15.8 (2.9) years, height 173.5 (5.5) cm, weight 62.1 (5.4) kg took part in the study, and performed sprint tests and kicking performance test (measured by radar gun, Stalker-Pro, Texas). The purpose of this study was to investigate the relationship between kicking performance and sprinting performance, using field performance tests. Kicking performance correlated with sprinting performance in all four sprinting variables (r = 0.49 to 0.54; p Keywords: KICKING PERFORMANCE; SOCCER PLAYERS; SPRINTING PERFORMANCE Document Type: Research Article Publication date: May 1, 2007 More about this publication? Editorial Board Information for Authors Subscribe to this Title Terms & Conditions ingentaconnect is not responsible for the content or availability of external websites $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher In this Subject: Internal Medicine By this author: Sporiš, Goran ; Vučetić, Vlatko ; Jerković, Marjan GA_googleFillSlot("Horizontal_banner_bottom");
... The question is whether the effects of string tension found in the laboratory would be seen in the field during play. Bower and Cross (2005) investigated this using a ball projection machine. Tennis players at competitive level were asked to return balls with three differently strung racquets. ...
Abstract Affordances mean opportunities for action. These affordances are important for sports performance and relevant to the abilities developed by skilled athletes. In racquet sports such as badminton, different players prefer widely different string tension because it is believed to provide opportunities for effective strokes. The current study examined whether badminton players can perceive the affordance of string tension for power strokes and whether the perception of affordance itself changed as a function of skill level. The results showed that string tension constrained the striking performance of both novice and recreational players, but not of expert players. When perceptual capability was assessed, perceptual mode did not affect perception of the optimal string tension. Skilled players successfully perceived the affordance of string tension, but only experts were concerned about saving energy. Our findings demonstrated that perception of the affordance of string tension in badminton was determined by action abilities. Furthermore, experts could adjust the action to maintain a superior level of performance based on the perception of affordance.
... He feels worse if the impact point is either the free-supported racket COP or the hand-held racket COP. Moreover, Bower, [7,8] showed in their study of string tension effect under laboratory conditions that high string tension produced lower rebound angles and could contribute to the greater number of net errors, whereas low string tension was more likely to provide greater rebound velocity and allow longer traveling of the ball. Zhuang and Chen [9] studied the effects of boundary condition (hand-grasp, free-free, fixed-free) on the vibration of a racket. ...
Finite element impact simulations were performed to observe the vibration of a tennis racket and its strings, as well as the
effects of string tension and impact location on a player’s hand and his chances of getting an injury. Studies using the finite
element method [FEM] revealed that decreasing the string tension lowers the coefficient of restitution. The ratio of speed
to angle change increases with a decrease in string tension. Moreover, the resultant force on the player’s hand is stronger
if the tennis ball hits the dead spot than if it hits the sweet spot. For instance, as a tennis ball hits the dead spot with
a speed of 10.05m/s, an angle of 15°, and a string tension of 222N, the player’s hand feels a maximum resultant force of almost
424N, which is 1.61 times higher than if the ball hits the sweet spot, at t=0.081 and t=0.0149. Moreover, the force exerted
on the player’s hand if the ball hits either the best-bounce spot or the off-center spot is 1.4 times higher than if the ball
hits the sweet spot.
... He also showed that a significant increase in racket power can be achieved by increasing the stiffness of the racket frame, at least for impacts near the tip or throat of the racket. Bower and Cross [4] conducted an experimental study on string tension effects on the rebound speed and accuracy of a tennis ball. They found that the increase in the string tension allows the ball's rebound to become lower and slower. ...
The structural behavior of string bed of tennis rackets was investigated subjected to transverse force perpendicular to the
string bed. The mathematical model developed for the string bed was implemented into a computer programming code. This code
was used to conduct extensive parametric studies on the structural behavior of the string bed for various parameters, including
string tension, axial rigidity of the string, string spacing and head size. The analysis results showed that while the transverse
stiffness of the string bed is proportional to the string tension, the transverse stiffness of the string bed is inversely
proportional to string spacing and head size. In addition, the axial rigidity of the string significantly amplifies the transverse
stiffness of the string bed for relatively large transverse deflection of the string bed.
KeywordsString–String bed–Tennis racket–Transverse stiffness
... Few studies have reported the relationship between ball speed and its impact on performance in different sports, including golf, baseball, tennis and volleyball. For instance, ball speed, ball control and sensitivity to string tension were assessed using a radar gun in tennis (Bower & Cross, 2005). Similarly, throwing speed was used to explain the relationship between body elevation and lower limbs' performance in water polo (McCluskey et al., 2010) and club head speed was directly correlated with golf handicap as an indicator of a player's performance (Fradkin, Sherman, & Finch, 2004). ...
The precise influence of serve type and serve ball speed on beach volleyball performance is unclear. We examined the relationship between serve type and speed and their effectiveness during the 2008 Men's and Women's Open World Tour Tournament. Three hundred and seventy-eight and 375 serves performed by men and women respectively from the main draw tournament were analysed. Serve speed was recorded using a radar gun. Two expert observers recorded serve speed, serve mode, serve effectiveness and rally outcome. There was no relationship between serve speed and its effectiveness for men (r = -0.047, P > 0.05) and for women (r = -0.048, P > 0.05). However, there was a relationship between serve ball speed and its effectiveness both for men and women, when speed was categorised into three groups. There was a better balance between negative and positive outcomes at medium speeds for men and at low and high speeds for women. There was a relationship between ranking and serve ball speed only for women and between ranking and type of serve for both genders. There was no relationship between rally outcome and serve effectiveness. The combination of high ball speed and jump serve is characteristic of high ranking women but not of men.
The ultimate goal of this Dissertation was to identify some critical aspects of the use of service in high-level volleyball and beach volleyball. To address this purpose and to achieve a more contextualized approach, four studies on different aspects of service performance in both sports were conducted. The first study, car- rying out an analysis between service mode, speed and effectiveness in high-level volleyball, highlighted the importance of the use of jump service abilities. Although no significant relationship was found between service velocity and a better direct outcome related to effectiveness, jump services were revealed as the perfect weapon to avoid first-tempo and quick outside attacks from the opponents.
Our second study was intended to verify the relationship between service speed and its effectiveness in a high-level beach volleyball tournament. In this new research, the sample included men and women’s teams and incorporated two inter- esting additional performance factors: rally outcome and the ranking of the teams. The results showed that the proportion of jump float services used by men and women in beach volleyball is similar, while the differences are greater in the use of jump topspin service and standing float service. Despite finding no relationship between service speed and effectiveness in either gender, a relationship was found when service was categorized into three groups of speed. Greater percentages of perfect receptions were found when facing low speed services, with the opposite occurring at higher speed services. However, no correlation between service speeds, reception outcome, final rally outcome and service effectiveness was found for ei- ther gender in our final results.
Later, a third study aimed at clarifying if the peak velocity was an accurate value to understand how the service affects the reception in volleyball, was con- ducted. To register the speed of the ball while contacting with the receiver seemed a more contextualized and efficient value assessing service action, but a linear rela- tionship between peak and final speed was found in the services registered during a
high-level volleyball tournament. Speed proved not to be the only factor affecting the quality of the reception, as we were unable to find any of the fastest services record- ed among the ones from the winning team, and no significant differences were found between finalists and non-finalists in terms of average service speeds.
Our final research, framed within the field of analytics in sport, was an anal- ysis to determine which of the skills and performance factors has the strongest ef- fect on the result of a volleyball match, and used inferential statistics to obtain the results. Our main findings were that the result of a volleyball match could not be explained by just one performance factor. In our analysis the category of the team was the principal explanatory factor of performance, while the secondary factors identified as those increasing the possibility of winning were the transition phase production and the reduction of the number of reception errors and blocked attacks.
We can conclude that service is a very important element of performance in volleyball and beach volleyball. Although it cannot explain by itself the result of a match in high-level competitions, it is a key element in preventing an effective at- tack performance from the opponent. Service behavior and its ability to impair the opponent’s game is not only based on speed, but is clearly influenced by the use of jump abilities. The successful execution of the service is a complex issue, and like the other skills in the game has a physical, technical, strategic and tactical compo- nent. Nevertheless, proper use of this technical skill is capital in making the result of a high-level match uneven. The contribution of the service skill to the production of the transition phase is clearly related to the achievement of a positive outcome. However, some other aspects have been identified as relevant to success in a volley- ball or beach volleyball match.
This book presents the results of research into a range of objects found in thriftshops, from cassettes and cameras, to tennis racquets and binoculars. The common theme that unites them all is that they have been used and discarded, before finding a new owner through a thriftshop-in effect, they're all loveable.
The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and bio-mechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swing-weights of around 0.030–0.035 kg/m 2 are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions.
Introduction
The tennis serve is a highly complex stroke because of the reliance on multiple body segments to produce power through properly timed rotations and complex coordinated muscular activations, as well as the most important from a strategic standpoint (Girard et al., 2007; Elliot, 2003). Therefore, strength levels in muscles related to the serve performance seem to be an important issue. The aim of this study was to analyse the relationship between isometric strength levels in different upper and lower limb movements and serve velocity in competitive tennis players.
Methods
Twelve male competitive tennis players (mean ± SD; age: 17.2 ± 1.0 years; height: 180.1 ± 6.2 cm; weight: 71.9 ± 5.6 kg) participated in the study. Measurements were conducted using a strain gauge (500N) connected to a portable MuscleLabTM system, and included maximal isometric voluntary contraction (100 Hz) of the wrist flexion/extension, elbow flexion/extension, and shoulder internal/external rotation, in the dominant side, as well as leg and back extension. A radar gun (Stalker ATS 4.02, EUA) was used to measure serve velocity (i.e., best of twelve serves (six to each side)). The relationship between quantitative variables was established with a linear correlation analysis, by calculating the Pearson’s linear correlation coefficient (r). A multivariate analysis was carried out using a multiple regression model (stepwise method).
Results
None of individual quantitative variables analysed was significantly correlated with serve velocity in any of the analysed movements. Individual correlations were found for wrist (p=0.076) and elbow (p=0.08) flexion/extension. Results obtained from the multivariate analysis showed that the highest relationship (R2=0.484) was established between serve velocity and wrist flexion/extension, shoulder flexion and internal rotation, and knee extension.
Discussion
The lack of relationship between strength variables analysed and serve velocity could be due to the complexity of the tennis serve motion. The serve requires a combination of limb and joint movements in order to summate and transfer forces from the ground up through the kinetic chain and out into the ball (Pugh et al., 2003). Multivariate correlation suggests that in order to be efficient in the tennis serve, isolated strength is not the only determinant factor, and the total body perspective is just as important as the individual segments alone (Kovacs & Ellenbecker, 2011). Effective servers maximally utilize their entire kinetic chain via the synchronous use of selective muscle groups, segmental rotations, and coordinated lower extremity muscle activation.
References
Elliot, B., Fleisig, G., Nicholls, R. & Escamilla, R. (2003). J Sci Med Sport, 6, 87. Girard, O., Micallef, J.P., & Millet, G.P. (2007). J Strength Cond Res, 21, 3.
Kovacs, M. & Ellenbecker, T.S. (2011). Sports Phys Ther, 12:504-513.
Pugh, S., Kovaleski, J., Heitman, R. & Gilley, W. (2003). Percept Mot Skills, 97, 867-72.
Aim:
This study aims at investigating the possible relationships between anthropometric and functional parameters and maximal serve speed in professional tennis players.
Methods:
Eight professional male tennis players (age 23±4 [mean±SD] years;; height 181±4 cm; body mass 80±4 kg;; playing experience 14±4 years;; weekly training practice 29±6 hours) were recruited. Anthropometric parameters (height, body mass, arm--racquet length, arm muscle area), jump performance (Squat Jump, Counter Movement Jump;; Counter Movement Jump Free), handgrip strength and first and second maximal serve speed were assessed.
Results:
Pearson's correlation coefficient showed significant (p<0.05) positive relationships between height and ball speed in both the first (r=0.78;; p=0.02) and second (r=0.80;; p=0.017) serve, and a significant negative correlation between serve speed and arm muscle area in first serve only (r=--0.78; p=0.03). In addition, a trend towards a positive correlation was observed between string tensions and serves speed for both first and second serves (r=0.54;; p=0.16 and r=0.60;; p=0.11, respectively). No significant relationship was found between serve speed and the other variables considered, including jumping performance parameters.
Conclusions:
Height was confirmed to be the main anthropometric determinant of serves speed in professional tennis players.
Athletes often lose sleep on the night before a competition. Whilst it is unlikely that sleep loss will impair sports mostly relying on strength and endurance, little is known about potential effects on sports involving psychomotor performance necessitating judgement and accuracy, rather than speed, as in tennis for example, and where caffeine is 'permitted'. Two studies were undertaken, on 5h sleep (33%) restriction versus normal sleep, on serving accuracy in semi-professional tennis players. Testing (14:00h-16:00h) comprised 40 serves into a (1.8m×1.1m) 'service box' diagonally, over the net. Study 1 (8m;8f) was within-Ss, counterbalanced (normal versus sleep restriction). Study 2 (6m;6f -different Ss) comprised three conditions (latin square), identical to Study 1, except for an extra sleep restriction condition with 80mg caffeine vs placebo in a sugar-free drink, given (double blind), 30min before testing. Both studies showed significant impairments to serving accuracy after sleep restriction. Caffeine at this dose had no beneficial effect. Study 1 also assessed gender differences, with women significantly poorer under all conditions, and non-significant indications that women were more impaired by sleep restriction (also seen in Study 2). We conclude that adequate sleep is essential for best performance this type of skill in tennis players and that caffeine is no substitute for 'lost sleep'. 210.
This study carries out a comparative analysis between serve mode and speed and its effectiveness at the 2004 Men's Olympic Qualification Tournament.
A total of 377 serves were analysed, 124 of which belonged to Cuba vs Holland, 63 to Spain vs Cameroon, 100 to Spain vs Cuba, and 91 to Holland vs Cameroon. Serve were recorded using a tripod mounted radar gun.
The analysis has shown the predominance of jump serve (JUMP, 84.9%) compared with float serve with jump (FLOAT JUMP, 5.6%) and float serve (FLOAT, 9.5%). Only 25.3% of the total jump serves analysed was successfully stricken back making the first tempo attack possible. The respective percentages for FLOAT JUMP and FLOAT were 42.9% and 55.6%. Ball speed in JUMP (23.03+/-3.94 m.s(-1)) was markedly higher compared with FLOAT JUMP and FLOAT (12.05+/-3.44 m.s(-1) and 11.47+/-4.22 m.s(-1)). While negative outcomes (66.7%) in FLOAT stand out, a better balance between negative and positive outcomes were found in both JUMP (50%) and FLOAT JUMP (42.9%). However, no relationship was found between serve speed and its effectiveness outcome (R2=0 in the overall sample and R2=0.005, when pooling the five serve effectiveness categories into negative and positive outcomes. In fact, JUMP was mainly performed in the span of velocities between 23.06 and 28.06 m.s(-1) in both error and direct point categories.
We found no significant relationship between serve velocity and a better outcome related to effectiveness. In addition, JUMP and FLOAT JUMP present a better balance between negative and positive outcomes compared with FLOAT.
The effects of string tension and longitudinal racket flexibility on post-impact ball velocity were investigated in tennis. Six wooden rackets, two with flexible shafts, two with medium and two with stiff shafts were strung with synthetic gut at tensions of 245N (55 lb), 289N (65 lb) and 334N (75 lb).A pneumatically driven racket-arm was triggered by a stimulus from a photo-electric cell positioned at the exit nozzle of a ball machine so that impact occurred with the racket perpendicular to the path of the ball. New tennis balls were fired to impact each racket at the geometric center of the strings and 5 cm above the geometric center. The average horizontal velocity of the ball, both before and after impact, was determined using stroboscope photography.A significant interaction between racket stiffness and string tension was recorded for an inward ball velocity of 22.7 m/s and a racket velocity of approximately 6.8 m/s. String tension had no significant influence on rebound velocity for a stiff racket following impact with a moving racket. Medium and flexible rackets produced the highest coefficients of restitution when strung at 245N (55 lb) compared to 289N (65 lb) and 334N (75 lb).
The rebound accuracy of tennis impacts was studied by measuring the vertical angles of approach and rebound of tennis balls projected in a vertical plane at a clamped racket. Three identical oversized tennis rackets were strung with nylon at 200, 267, and 334 N of tension. Ten impacts were filmed at 200 Hz for each string tension with the ball impacting the strings centrally and 8 cm off-center. A two-way ANOVA revealed significant (p < .01) main effects for string tension, impact location, and the interaction of string tension and impact location. Treatment-Contrast Interactions demonstrated one significant (p < .01) difference: The decrease in rebound accuracy from a string tension of 200 to 334 N was significantly different for central versus off-center impacts.
The pull tension in a tennis string is always monitored while a racket is being strung, but it is difficult to measure the string tension in a racket after it has been strung. In this paper, a simple technique is described based on measurements of the vibration frequency of the string plane. The key to this measurement is the fact that the vibration frequency depends primarily on the area of the string plane and not its shape. It is shown that there is a small loss in tension with time after a racket is strung but there is a large decrease in tension during the stringing process. The tension immediately after stringing is typically about 30% lower than the pull tension. Additional experiments are described, showing that the large drop in tension is due to a combination of factors including stress relaxation, frame distortion and friction between the strings.
Measurements are presented on the behaviour of a hand-held tennis racquet when it impacts with a tennis ball. It is shown that an impulse is transmitted through the racquet to the hand in about 1.5 ms, with the result that the hand and the forearm both have a strong influence on the behaviour of the racquet even while the ball is still in contact with the strings. Regardless of the impact point, the racquet head recoils as a result of the impact and an impulsive torque is applied to the hand, causing the hand to rotate about an axis through the wrist. The impulsive forces on the hand, arising from this torque, do not drop to zero for any impact point, even for an impact at either of the two sweet spots of the racquet. Forces on the hand arise from rotation, translation and vibration of the handle. For an impact at the vibration node, only the vibrational component is zero. For an impact at the centre of percussion, the net force on the hand or forearm is zero since the forces acting on the upper and lower parts of the hand are then equal and opposite.
Most tennis strings have a performance rating of almost 10 out of 10 if one can believe the manufacturers’ claims. Laboratory tests of tennis strings provide a different picture. The test methods and the results of testing 90 different strings are described. This type of information is needed if players, coaches and stringers wish to make an informed comparison between different strings, and it is also needed if one wishes to model the interaction between a tennis racket and a tennis ball.
In this paper, we describe an experimental investigation of the oblique impact between a tennis ball and head clamped tennis
racket. It was found that the magnitude of the ball rebound spin was not a function of the material, gage or tension of the
string used in the tennis racket. Furthermore, it was concluded that all strings exhibit a sufficiently large friction coefficient
that the ball begins to roll during impact. There is anecdotal evidence from tennis players that suggests that a high string
tension or a rough string surface enable them to impart more spin to the ball. For example, players have been quoted as saying
that a high string tension makes the strings “bite” into the ball, giving more spin. The data reported in this study do not
support these observations. Analysis of the experimental data has shown that the balls are rebounding from the surface with
more spin than would typically be associated with rolling. A second experiment showed that the balls commenced rolling at
the mid-point of the impact. This information was used in a theoretical model to show that the spin that acts on the ball
during the impact can be higher than the value of the rolling spin at the end of the impact.
By constructing a mathematical model, we consider the dynamics of a tennis racket hit by a ball. Using this model, known experimental results can be simulated on the computer, and it becomes possible to make a parametric study of a racket. Such a simulation is essential in the study of two important problems related to tennis: computation of the resulting forces and moments transferred to the hand should assist understanding of the medical problem 'tennis elbow'; secondly, simulation will enable a study to be made of the relationships between the impact time, tension in the strings, forces transmitted to the rim and return velocity of the ball, all of which can lead to the optimal design of rackets.
The relationship is investigated between the apparent coefficient of restitution and the losses in preimpact kinetic energy of the ball for tennis rackets whose handles are constrained by various clamping modes. The complete energy balance equation of the racket-ball system is derived, and experimental results involving four test rackets are then used to evaluate the various components of the total energy loss for the standardized hand-held mode and the vice-clamping mode. Results demonstrate that the apparent coefficient of restitution is not, as previously thought, independent of the clamping mode but varies significantly with the constraining condition applied to the handle, and with the preimpact velocity of the ball. The relative energy losses in the strings are comparatively small, whereas the losses in the ball increase exponentially with the magnitude of the impulse. The major part of the total loss in kinetic energy of the impacting ball is due to the spatial postimpact recoil motion and internal...
This study explored the effects of string type and tension on various factors involved with tennis ball–racquet impact in midsized and oversized racquets. String and racquet material, racquet flexibility, and grip firmness were held constant for each test condition. The dependent variables included postimpact and preimpact ball velocity ratio, racquet head displacement, maximum ball compression, and ball contact duration. It was found that racquet size and string material have varying effects on impact. Although changes in string tension do affect the impact, it is not in a linear fashion. Various string tensions change a racquet's flexibility, thus affecting ball velocity and other factors associated with impact. The results of this study demonstrate the complexity of string and frame interaction.
The rebound angle and velocity of tennis balls impacting a tennis racquet were measured from photographic images during an oblique impact. Tennis balls were projected at three velocities toward a clamped racquet simulating three levels of stiffness and strung at three string tensions. A Kruskal-Wallis ANOVA revealed significant (p<0.01) differences between levels of string tension and levels of racquet stiffness for both apparent coefficient of restitution for an oblique impact and rebound angle to the normal. It was noted that racquet parameters generating greater rebound velocities produced rebound angles closer to the normal.
Several parameters concerning the performance of tennis rackets are examined both theoretically and experimentally. Information is obtained about the location of the center of percussion, the time a ball spends in contact with the strings, the period of oscillation of a tennis racket, and the coefficient of restitution of a tennis ball. From these data it may be possible to design a racket with improved playing characteristics.
It is generally accepted that a decrease in string tension leads to greater racket power and an increase in tension improves racket control. The increase in power at low string tension can be attributed partly to a decrease in energy loss in the ball and partly to a decrease in the vibrational energy transferred to the racket. Racket control is affected if the ball strikes the strings towards one edge of the frame, in which case the racket will rotate about the long axis through the handle. The angle of rotation is decreased when the string tension is increased. Quantitative estimates of the magnitude of these effects are presented, using a one dimensional flexible beam model to describe the racket and springs to model the ball and strings. For tensions in the range 50–60 lb (220–270 N), commonly used in tennis rackets, and for a ball incident at right angles to the string plane, changes in racket power and control are essentially negligible. However, a significant increase in racket power can be achieved by increasing the stiffness of the racket frame.
This study was undertaken to determine influences of string tension and longitudinal flexibility on ball velocity after impact. Three rackets, each of three types classed as Stiff, Average, and Flexible by their manufacturers, were strung with nylon at 40-, 50-, and 60-pound string tensions and subjected to 16 ball/racket impacts. Impact was photographed through a rotating slit disc. Racket head deflection and ball displacement were measured using a Vanguard Analyzer and Digitizer system. Differences in racket head deflection and ball velocity ratio between racket types were investigated using an analysis of variance and Newman-Keuls' post hoc test. Differences in racket head displacement and ball velocity ratio caused by changes in string tension were not independent of differences in longitudinal flexibility. Average flexibility rackets gave significantly less head displacement than Flexible rackets at string tensions of 50 and 60 pounds. Average rackets at 60-pound tension gave significantly less head displacement than in all other test conditions. Stiff, Average, and Flexible rackets behaved differently under dynamic and static conditions. Average and Flexible rackets at 50-pound tension gave significantly higher ball velocity ratios than at other tensions.
In this study, we evaluated the effect of the use of tennis racket string vibration dampers on racket handle vibrations, and perceptions of hand and arm discomfort experienced by tennis players owing to stationary racket impacts. Twenty tennis players (10 males, 10 females) aged 18-29 years volunteered for the study. Two different racket models were impacted at the geometric centre of the racket face and 100 mm distal to the centre both with and without string vibration dampers in place. The participants could neither see nor hear the impacts, and they indicated their discomfort immediately after each impact using a visual analogue scale. An analysis of variance (2 x 2 x 2 factorial) was performed on the scaled discomfort ratings with the factors damping condition, racket type and impact location. No significant differences in discomfort ratings between damped and undamped impacts or between the two racket types were found. Also, central impacts were found to be more comfortable than impacts 100 mm distal to the centre (P< 0.05). There were no significant interaction effects. Vibration traces from an accelerometer mounted on the racket handle revealed that string vibration dampers quickly absorbed high-frequency string vibration without attenuating the lower-frequency frame vibration. In conclusion, we found no evidence to support the contention that string vibration dampers reduce hand and arm impact discomfort.
Forty-one advanced recreational tennis players were tested to determine their ability to detect differences in string tension in a tennis racket. Subjects were given pairs of rackets that varied in tension by up to 98 N (10 kg) and were asked whether they noticed a difference in tension and if so, which racket was strung at a higher tension. Only 11 (27%) of those tested could correctly identify a tension difference of 5 kg (11 lb) or less. Fifteen (37%) could not pick a difference of 10 kg (22 lb). To examine the importance of sound as a means of discrimination, an additional test was undertaken where participants wore earplugs. Of the 26 subjects undertaking this additional test, only 6 (23%) were successful. It was concluded that advanced recreational tennis players demonstrated limited ability to correctly identify differences in string tension and that impact sound was an important factor for those participants who were successful at various levels of discrimination.
The physics and technology of tennis United States Racket Stringers Association A model of tennis stroke accuracy relative to string tension
- H Brody
- R Cross
- C Lindsey
Brody, H., Cross, R., & Lindsey, C. (2002). The physics and technology of tennis. Solana Beach, CA: Racquet Tech Publish-ing, United States Racket Stringers Association. Brody, H., & Knudson, D. (2000). A model of tennis stroke accuracy relative to string tension. International Sports Journal, 4, 38 – 45.