Reliability of Accuracy and Precision Tests for Elite Para Table Tennis Players

The primary purpose of this study was to adapt selected accuracy and precision tests in table tennis to the specific skills of elite table tennis players with impairment. The study included a sample of 23 Para table tennis players with an average age of 31.8 ± 12.22 years (including 30.4% females) who belonged to the senior Polish Para table tennis team. A battery of six tests evaluating stroke accuracy and serve precision was assessed. The analysis of the reliability of these tests confirmed the legitimacy of using this battery of accuracy and precision tests to assess the skills of Para table tennis players in all three integrated sport classes: players in wheelchairs, in a standing position, and with intellectual impairment. Analysis of the data obtained from the tests could provide coaches with relevant information regarding elite Para table tennis players' level of performance and examine selected accuracy and precision elements of their individual technique.

Sequential Mapping of Game Patterns in Men and Women Professional Padel Players

PURPOSE

This study analyzed the sequences of actions in professional men and women padel players to identify common game patterns.

METHODS

The sample comprised 17,557 stroke-by-stroke actions (N = 1640 rallies) of the championship World Padel Tour. Multistep Markov chains were used to calculate the conditional probabilities of occurrence of actions during the rally.

RESULTS

Results revealed that men's and women's padel is mainly defined by 36 patterns constituting 55% and 63% of all actions in the game, respectively, with the 10 most common sequences accounting for 42% to 45% of the game. There were recurrent technical-tactical actions with specific offensive and defensive functions that were constantly reiterated during the rallies. In men, the use of smash, volley, bandeja, direct, back wall, back-wall lobs, and direct lobs followed a foreseeable pattern up to 8 lags, whereas women described predictable interactions for volley, bandeja, direct, lobs, and direct lobs up to 5 lags and for smash and back wall up to 4 lags.

CONCLUSIONS

The ability of padel players to recall these patterns and enhance their anticipation skills may potentially improve their performance. These findings contribute to a better knowledge of professional padel game dynamics while providing coaches and players with useful information to optimize training and decision-making strategies.

Effects of Acute Physical Fatigue on Gaze Behavior in Expert Badminton Players

Perceptual cognitive skills in real game settings, under conditions of fatigue, such as the ability to gather relevant visual information, are key factors in achieving motor goals in sports. The objectives were to evaluate the effects of acute physical fatigue on gaze behavior during a badminton game (Study 1) and in an unfavorable force ratio situation (Study 2). Six international-level badminton players played two sets and unfavorable force ratio situations while wearing eye-tracking glasses before and after a fatiguing task. During the set, fatiguing physical exercise led to fewer fixations per exchange and more fixations on one area of interest. During unfavorable force ratio situations, fatiguing physical exercise led to shorter fixation durations per exchange, shorter fixation durations on two areas of interest, and longer fixation durations on one area of interest. The results showed that gaze behaviors were adapted in acute physical fatigue conditions to maintain performance.

Stress Fracture of the Trapezoid in a Professional Tennis Player

Background: Repetitive microtrauma can lead to trapezoid and second metacarpal stress fractures in racket sport players. Nontraumatic trapezoid stress fractures are rare and difficult to diagnose. To our knowledge, only 3 cases had been reported as of May 2023. We report the fourth case of a nontraumatic sports-related trapezoid stress fracture and only the second case in a tennis player. Case Report: A 29-year-old professional and right hand-dominant male tennis player presented with right hand and wrist pain for 3 weeks. He complained of dorsal wrist tenderness proximal to the base of the second metacarpal that was exacerbated by extension of the index finger. Initial radiographs were normal, but magnetic resonance imaging of the wrist showed a stress fracture of the trapezoid bone and base of the second metacarpal. The patient was treated conservatively with a wrist brace, cessation of sports activities, and modification of his training routine. The patient was asymptomatic at 1-year follow-up. Conclusion: This case highlights the relationship between trapezoid and second metacarpal stress fractures in athletes. A high index of suspicion for trapezoid stress fractures should be maintained and included in every differential diagnosis for athletes, especially racket sport players presenting with wrist pain. To avoid future injuries, clinicians should not only treat the fracture but also address the risk factors predisposing to this injury.

The Effects of Neuromuscular Training on Sand Versus Hard Surfaces on Physical Fitness in Young Male Tennis Players

PURPOSE

To examine the effects of a neuromuscular training program combining plyometric exercises with acceleration, deceleration, and change-of-direction drills conducted on sand or hard surfaces on the fitness qualities of young male tennis players.

METHODS

Thirty-one young male players were allocated to a training group performing 12 training sessions on sand or hard surfaces, during a 6-week period. Tests included linear sprint (10-m acceleration with 5-m split times), change of direction (modified 5-0-5 test), vertical jumps (countermovement jump and the 10/5 repeated-jump test), isometric hip abduction and adduction strength, and dynamic balance (Y-balance test). Perceived training loads and muscle soreness were assessed during the intervention.

RESULTS

Both training strategies were similarly effective in improving the analyzed fitness components. Group × time interaction effects were noticed, with countermovement jump (P = .032), repeated-jump test (P = .029), and reactive strength index (P = .008) favoring hard surfaces and 5-m sprint (P = .009), dynamic balance (P < .05), adduction strength (P < .05), and abduction strength (P < .001) indices favoring sand. Furthermore, the sand group promoted greater perceived training loads and muscle soreness (P < .05) than the hard group across the intervention period.

CONCLUSION

Neuromuscular training strategies characterized by a relatively low volume (∼35 min), conducted on sand or hard surfaces, promoted similar improvements in the fitness qualities of young tennis players, with selected surface-interaction effects. Training on sand can cause transiently higher training loads and persistently higher muscle soreness, suggesting the need for an adequate familiarization period.

Lower limb muscle activity during first and second tennis serves: a comparison of three surface electromyography normalisation methods

We assessed lower limb muscle activity during the execution of first and second tennis serves, exploring whether the extent of these differences is influenced by the chosen method for normalising surface electromyography (EMG) data. Ten male competitive tennis players first completed three rounds of maximal isometric voluntary contractions (MVC) of knee extensors and plantar flexors for the left (front) and right (back) leg separately, and three squat jumps. Afterward, they executed ten first and ten-second serves. Surface EMG activity of four lower limb muscles (vastus lateralis, rectus femoris, gastrocnemius lateralis, and soleus muscles) on each leg was recorded and normalised in three different ways: to MVC; to peak/maximal activity measured during squat jump; and to the actual serve. For the rectus femoris and soleus muscles of the left leg, and the gastrocnemius lateralis and soleus muscles of the right leg, EMG amplitude differed significantly between normalisation techniques (P ≤ 0.012). All muscles showed greater activity during the first serve, although this difference was only statistically significant for the right vastus lateralis muscle (P = 0.014). In conclusion, the EMG normalisation method selected may offer similar information when comparing first and second serve, at least for leg muscles studied here.

Analysis of Technical-Tactical Actions in High-Level Table Tennis Players: Differences between Sexes

Table tennis is a sport played at a high speed; therefore, the technical-tactical variables are very important. The objective of the research is to analyze the technical and tactical characteristics of high-level TT players according to sex. A total of 48 high-level players (24 women and 24 men) participated in the present study. The investigation was carried out during two championships. The matches were recorded and subsequently analyzed by notational analysis. The results indicate that women stroke the ball more times during the rallies. In the men's competition, the forehand technique predominates over the backhand technique. The flip was the most used in the male sex (p < 0.05). At the tactical level, more winning actions were performed in the men's competition than in the women's, both with the forehand and backhand game. Men performed more losing technical actions when using the forehand and backhand flips. The pivot footwork tactical action was higher in the men's competition. The analysis of the technical-tactical actions highlighted important differences between the sexes. The predominant losing techniques among players are forehand and backhand flip. Female players use more defensive strokes, while male players use more offensive strokes, in particular the flip technique. The potential biomechanical progress of the male player characterized by a larger wingspan biotype could facilitate a better technical-tactical performance. The results obtained are of interest to improve the performance of the players as they must train at a technical-tactical level differently depending on the sex and style of play.

Conditional performance factors in padel players: a mini review

Introduction

Padel's global growth highlights its technical complexity. The first publications focus on the physical aspects of padel, using methods that evaluate players' endurance, strength, speed, and range of motion, while the quantification of load, using internal and external indicators, is crucial for performance optimization, whilst taking into account athletes' profiles and levels. Therefore, the objective entailed analyzing the scientific literature about the conditional demands in competition within padel players from different levels.

Methods

Data was collected from various databases and after the selection process, the information was analyzed in mini review.

Results

The mini review shows that the conditional demands are categorized into internal and external load to try to obtain reference values that may define the demands of padel based on the competitive level and sex. Regarding the internal load, the heart rate (HR)% of the padel players from different levels is around 70%-80% of the HR Max. Regarding the external load, in femalés categories, a greater number of strokes are made per point which entails a longer duration in the points.

Conclusions

Padel research usually analyses physical demands using internal and external loading. HR% values (70%-80% HR Max) are consistent across studies. There is variation between variables such as strokes per point, and contextual factors affect the metrics. Further exploration is vital to obtain comprehensive benchmarks and understand the demands of this sport.

The Impact of Sex and Biological Maturation on Physical Fitness in Adolescent Badminton Players

The main objective of this study was to examine the impact of maturity status and sex on selected measures of physical fitness in adolescent badminton players. Eighty-one badminton players (39 boys, 42 girls; age: 12.7 ± 1.4 years; body height: 153.5 ± 10.5 cm; body mass: 48.3 ± 13.2 kg) participated in the study and were divided into pre-peak height velocity (PHV, n = 31), circa-PHV (n = 29), and post-PHV (n = 21) groups. The assessment of physical fitness included linear sprint (5-m, 10-m) and change-of-direction (CoD) speed tests using a modified 5-0-5 CoD test (CoD deficit [CoDD%]) and an on-court CoD test, as well as the countermovement jump (CMJ) test as a proxy of lower limbs' muscle power. Pre-PHV players presented lower performance levels (p < 0.001; ES: 1.81-1.21) than post-PHV in CMJ, linear sprint (5, 10-m) speed, and both CoD tests. In addition, compared to circa-PHV, pre-PHV players demonstrated moderately lower performances in the 10 m sprint and CoD tests (p < 0.05; ES: 0.65-1.00). Regarding the CoDD%, no between-group differences were found. Irrespective of the maturity status, boys outperformed girls in CMJ (p = 0.01; ES: 0.71), linear sprint speed (p < 0.05, ES: 0.52-0.77), and the modified 505 test (p = 0.01; ES: 0.71). Findings only showed significant sex-by-maturity interactions for the pre-PHV group. In addition, sex-related performance differences were found in favor of the boys for most measures except for CoDD%. Our results imply that maturity status (i.e., PHV) and not chronological age should be used to design training programs. Female adolescent badminton players should receive specifically targeted exercise interventions based on their fitness status and needs.

Importance of Maintaining Net Position in Men's and Women's Professional Padel

The objective of this research was to analyze the importance of maintaining the net position in men's and women's professional padel. The data sample was drawn from 2,756 padel rallies (n = 1,434 men's and n = 1,322 women's) in matches played during the 2021 season of the World Padel Tour circuit. The results showed that there was no net exchange in 50.7% of the women's rallies, while in 65.9% of men's rallies, the servers kept the net. Due to their physical advantages, men servers had more opportunities to finish the rally at the net than women servers, giving them more opportunities to win the rally. However, when either men or women receivers finished the rally at the net, they had more opportunities to win the rally. In addition, both men and women tended to end the rallies with a winner when they were in the net zone and with an error when they were at the back of the court. These findings suggest that wins in padel are closely related to time spent at the net.

Stroboscopic Eyewear Applied During Warm-Up Does Not Provide Additional Benefits to the Sport-Specific Reaction Speed in Highly Trained Table Tennis Athletes

PURPOSE

While long-term training with stroboscopic eyewear suggests performance-enhancing effects on visuomotor abilities, it remains unclear whether a short-term application, for example, during a warm-up, results in immediate performance gains. This study evaluated potential performance-enhancing effects of stroboscopic eyewear applied during warm-up on reaction speed that may provide athletes an edge in visuomotor-demanding sports.

METHODS

Twenty-eight international-level table tennis athletes participated in this study. Participants performed their individual 10-minute table-tennis-specific warm-up under normal visual conditions and with stroboscopic eyewear. Prior to and after the warm-up, visuomotor reaction time was assessed in a sport-specific reaction test where athletes had to return 30 table tennis balls played by a ball machine at high speed to their backhand side. Reaction time was determined as the interval between ball output and movement onset as triggered by a mechanical switch. Furthermore, the time between ball-table contact and ball-racket contact (hit time) was analyzed as an indicator of how early the athletes intercepted the ball.

RESULTS

Reaction time significantly improved following the warm-up (P < .001, ηp2=.393). However, there was no additional benefit of the stroboscopic eyewear (P = .338, ηp2=.034). No changes after the warm-up were observed for hit time (P = .246, ηp2=.055).

CONCLUSIONS

The results indicate that warm-up facilitated visuomotor reaction speed; however, stroboscopic eyewear did not provide additional positive effects when compared to a warm-up under normal visual conditions. While shutter glasses may be useful for training over longer periods, short-term positive effects were not supported in this study.

Analysis of the spatial distribution of the serve and the type of serve-return in elite table tennis. Sex differences

Serve and return of the serve are among the most critical technical-tactical factors influencing performance in table tennis (TT). The present study aimed to analyse sex differences in the spatial distribution of serve and serve-return in elite TT players. A total of 48 elite TT players (men: n = 24; women: n = 24) participated in the investigation. A total of 24 matches were recorded and examined, analysing 1,177 plays and 5,319 strokes in the men's competition and 950 games and 5,097 strokes in the women's competition. Technical actions were analysed using an observation tool validated by two expert TT coach with a high level of agreement (K > 0.80). Men distributed their serves over zones 1 and 2 of the table, while women more frequently selected zone 5 (p < 0.05). In men, 30.1% of the serves were near the net, 63.6% in the middle zone of the table and 6.2% in the end zone of the table, while in women, these values were 10.9%, 67.2%, and 21.8%, respectively. As for the technique of the serve-return depending on the zone of the service, in men the action of the cut from zone 1 and 2 predominated, while in women this technique was more frequent from zone 5 (p < 0.05). On the other hand, the serve-return with the flip technique in zone 1, 3 and 4 was more frequent in men (p < 0.05). As for the return of the serve with the topspin technique, there were differences in zone 3, being more frequent in men (p < 0.05). Finally, the serve return with cut and defensive serve-return techniques in zones 3, 4, 5, and 6 were more frequent in women (p < 0.05). There are differences between sexes in service and return of serve actions during a match in elite players.

A Comparison of Match Load Between Padel and Singles and Doubles Tennis

PURPOSE

To quantify match load associated with padel and compare responses with both singles and doubles tennis.

METHODS

On separate days, 12 participants (7 men and 5 women) played 60-minute padel (PADEL), singles tennis (SINGLES), and doubles tennis (DOUBLES) simulated games. Participants wore a 10-Hz GPS/100-Hz triaxial accelerometer unit and heart-rate monitor. Exercise-related sensations and blood lactate concentration were monitored every 20 minutes. Match-play characteristics (temporal structure) and shot selection were derived from video analysis. Vertical jump ability was assessed before and after each game.

RESULTS

Heart rate, exercise-related sensations (overall perceived exertion and limb discomfort), and physical load (total distance covered, PlayerLoad, acceleration density and load) for SINGLES were higher compared with DOUBLES and PADEL (all P ≤ .05). Blood lactate concentrations remained low (1-2 mmol·L-1) and did not differ between conditions. Effective playing time (P < .001) was lower in SINGLES and DOUBLES compared with PADEL. The number of forehands (P = .002) and backhands (P < .001) was greater for SINGLES than for DOUBLES and PADEL. The number of volleys/smashes and lobs (P < .05) was greater for PADEL compared with SINGLES and DOUBLES. Performance for squat, countermovement, and multirebound jumps was similarly reduced below baseline after match play (P < .05), independent of condition.

CONCLUSION

Padel imposes a unique match load on players that is different from singles tennis and more closely resembles that of doubles tennis. Cardiovascular stimulation and physical load are highest in singles tennis, while padel sees players hit a larger variety of shots with higher effective playing percentages.

Influence of Successive Wheelchair Tennis Matches on Handgrip Strength in High-Level Male Players

The purpose of this study was to examine the effects on upper strength in high-level male players playing four successive wheelchair tennis (WT) matches. Eight international WT players took part in a competition, playing one match per day over four consecutive tournament days. Before and after the match, the maximal isometric handgrip strength was measured on the dominant and non-dominant hand. Additionally, each player was equipped with one radiofrequency and IMU device on their wheelchair to control his activity profile (distance). The results showed significant differences between successive matches, with decreasing dominant handgrip strength (p = 0.02, η² = 0.043), and there was a significant interaction between successive matches and the accumulated distance (p = 0.013, η² = 0.049). The pre- and post-match strength values of the dominant hand decreased throughout the matches over a number of days, and post hoc analysis showed differences between the first and fourth matches only in pre-match strength (49.06 ± 6.96 vs. 45.94 ± 7.1; p = 0.045; ES: 1.04) but not in the non-dominant hand. Successive matches caused a decrease in the strength values of the WT players, mainly in the dominant hand. These results should be taken into account in the recovery and prevention of injuries in competitions with successive matches.

Auditory Information Reduces Response Time for Ball Rotation Perception, Increasing Counterattack Performance in Table Tennis

Purpose: Identifying the magnitude of ball rotation is critical to reduce response time, aiming to improve table tennis performance. This study analyzed the influence of auditory and visual information on the perception accuracy and counterattack performance of table tennis players. Methods: Twenty-two high-level table tennis players (22.5 ± 6.1 years, 71.2 ± 9.8 kg, 173.5 ± 7.7 cm) performed two tasks. In the first task, the athletes analyzed audio and video files of the forehand movement on a computer screen with auditory, visual, and combined information and, as soon as possible, chose the ball spin type on a keyboard: fast (spinning ball forward at 140 rotations per second (rotations/s); medium (105 rotations/s); slow (84 rotations/s); or flat hit (70 rotations/s). In the second task, the athletes performed 80 counterattacks (forehand movement) at the table on a target (68x38 cm) with and without auditory information. Results: Friedman's ANOVA revealed a significant effect of condition for perception accuracy (p < .001). Post hoc tests showed higher perception accuracy in the combined and visual conditions. ANOVA also revealed a significant effect of condition for response time to perceive ball rotation (p < .001). The response time was shorter in the combined condition than the other conditions for all spin types. Kendall's analyses showed no significant correlations between perception accuracy and response time in any ball spin type. Regarding the counterattack performance, the Wilcoxon signed-rank test indicated higher performance when auditory information was available (p = .022). Conclusions: As auditory information influences the response time and counterattack performance, it seems crucial for trainers and athletes to explore and include auditory perception training methods.

Performance Outcomes Following Isoinertial or Machine-Based Training Interventions in Female Junior Tennis Players

PURPOSE

To evaluate changes in physical performance indicators after executing a flywheel or machine-based neuromuscular training program in young female tennis players.

METHODS

Twenty-four players were divided into a machine-based  group (MG), flywheel  group (FG), and control group. Countermovement jump (CMJ), sprint time (5, 10, and 15 m), change-of-direction (COD) performance (right and left), medicine-ball throws (overhead, forehand, and backhand), and serve velocity were included as tests at baseline, week 4, and week 8.

RESULTS

Both MG and FG largely improved from baseline to weeks 4 and 8 of training in CMJ (11.6, 10.6%; effect size [ES] = 1.24, 1.95). Also, sprint time 5 m and 10 m, COD performance-right, and COD performance-left improved moderately to very largely at week 4 in MG (-5.0% to -6.2%; ES = -1.79 to -4.19) and FG (-2.9% to -5.1%; ES = -1.13 to -1.64), respectively. Regarding medicine-ball throw, only FG improved moderately to very largely from weeks 4 to 8 in overhead (9.3%; ES = 1.46), forehand (8.0%; ES = 1.08), and backhand (6.1%; ES = 1.15). Serve velocity improved moderately from weeks 4 to 8 in MG (5.8%; ES = 0.87).

CONCLUSIONS

Four weeks of the tested programs seem sufficient to improve physical determinants in young female participants. Greater improvements in CMJ and medicine-ball throw following flywheel neuromuscular training indicate the importance of including exercises that emphasize the stretch-shortening cycle and involve the entire kinetic chain. Performing the same intervention with no load adjustments may stall or even decrease performance in some parameters from weeks 4 to 8.

A Multiday Professional Padel Tournament Impairs Sleep, Mental Toughness, and Reaction Time: A World Padel Tour Field Study

This study aimed to assess, for the first time, how self-reported sleep, mental toughness, and reaction time are impacted by a professional padel tournament. In addition, we evaluated whether sex, age, and/or ranking play a role in this possible effect of a tournament on these variables. Twenty-three professional players (15 men, Mage = 24 ± 6 years; eight women, Mage = 21 ± 5 years) were evaluated on two occasions: (a) baseline, in a noncompetitive week and (b) postmeasure, the morning after an individual was eliminated from the tournament. The Pittsburgh Sleep Quality Index, the Mental Toughness Questionnaire, and the psychomotor vigilance task were used to evaluate the dependent variables. Wilcoxon tests or paired samples t tests were employed to assess the effect of participating in the tournament. To test correlations between variables, Pearson correlation coefficients (quantitative variables) or chi-square distributions (qualitative variables) were employed. Results showed that self-reported sleep (p < .01), mental toughness (p = .01), and reaction time (p = .04) were significantly impaired by the tournament. Exploring moderating variables, results showed that mental toughness did not correlate with sleep impairments (p > .05). In contrast, a nearly significant correlation between sleep impairments and higher reaction times was found (p = .066). No significant effects of age, sex, and ranking were observed. In conclusion, participating in a padel competition impairs the self-reported sleep, mental toughness, and reaction time of professional padel players. A trend toward a significant correlation between the competition-related impairment in sleep and reaction time was observed, whereas age, ranking, and sex were not found to be moderators of any of these impairments.

Technical skills in complex tennis situations: Dutch talented players U15 compared to players U17

Introduction

Technical skills in complex situations appear crucial for progress towards elite tennis performance. However, it is unknown how these skills develop in different age categories in a group of talented youth players. The aim of this study is to evaluate possible differences in technical skills among Dutch talented youth tennis players U15 compared to U17.

Methods

A total of 19 players (12 males, 7 females; age 14.6 ± 1.4 years) were tested on ball speed, accuracy, percentage errors and spin rate using the on-court Dutch Technical-Tactical Tennis Test. With a ball machine, four games were simulated which were either fixed (game 1 and game 2) or variable (game 3 and game 4), depending on the complexity of the task. Each game consisted of two offensive, two neutral and two defensive rallies, representing different tactical situations.

Results

A two-way ANOVA revealed a statistically significant interaction between the effects of age category and sex for ball speed (F(1,15) = 5.472, p = 0.034, η ² = 0.267), indicating that males U17 produced higher ball speed compared to males U15, whereas no differences were found between females U15 and U17. A one-way ANCOVA showed that, regardless of sex, players U17 scored significantly higher on accuracy than players U15 (F(1,16) = 5.021, p = 0.040, η ² = 0.239). No differences were found between players U15 and U17 for spin rate and percentage errors (p > .05), although there was a medium to large effect size for males U17 to produce higher spin rates compared to males U15. A closer examination of accuracy revealed that players U17 scored significantly higher compared to players U15 in game 4 (F(1,17) = 6.358, p = .022, η ² = .272) and in defensive situations (F(1,17) = 9.602, p = .007, η ² = .361).

Discussion

In conclusion, the results of the current study suggest that technical skills, especially ball speed for males and accuracy in complex situations for both males and females, continue to develop in adolescence in talented tennis players. There is an increased understanding about underlying technical skills that contribute to progress towards elite tennis performance. To effectively develop technical skills, coaches are encouraged to design specific practices where these skills are performed in complex situations under high cognitive and temporal pressure.

Relationships between selected indices of postural stability and sports performance in elite badminton players: Pilot study

The main aim of this study was to determine the relationships between postural stability and the place in the ranking of badminton players. The study examined 10 elite players from Polish national badminton team. The scope of the study included basic somatic characteristics, such as body height, body weight, BMI, and training experience. A Microgate GYKO inertial sensor system was used to assess the postural stability of athletes. Using Spearman's rank correlation, cause-and-effect relationships between the place in the sports ranking and the analyzed variables characterizing postural stability were recognized. Depending on the distribution and homogeneity of variance, the significance of differences in variables that characterize postural stability between players of different sports skill levels (two groups) was calculated. The Student's t-test or Mann-Whitney's U-test was used for this purpose. In general, the athletes with higher positions on the ranking list presented a higher level of postural stability in both tests, which is also confirmed by the normalized values. However, for all variables of postural stability, no statistically significant correlations with sports ranking were observed. Higher values of Spearman's rank correlation coefficients were found for the test performed in the one-foot standing test compared to the two-foot test. The results obtained indicate that particular attention in badminton training should be paid to the development of the level of postural stability in order to improve sports performance.

A Query Language for Exploratory Analysis of Video-Based Tracking Data in Padel Matches

Recent advances in sensor technologies, in particular video-based human detection, object tracking and pose estimation, have opened new possibilities for the automatic or semi-automatic per-frame annotation of sport videos. In the case of racket sports such as tennis and padel, state-of-the-art deep learning methods allow the robust detection and tracking of the players from a single video, which can be combined with ball tracking and shot recognition techniques to obtain a precise description of the play state at every frame. These data, which might include the court-space position of the players, their speeds, accelerations, shots and ball trajectories, can be exported in tabular format for further analysis. Unfortunately, the limitations of traditional table-based methods for analyzing such sport data are twofold. On the one hand, these methods cannot represent complex spatio-temporal queries in a compact, readable way, usable by sport analysts. On the other hand, traditional data visualization tools often fail to convey all the information available in the video (such as the precise body motion before, during and after the execution of a shot) and resulting plots only show a small portion of the available data. In this paper we address these two limitations by focusing on the analysis of video-based tracking data of padel matches. In particular, we propose a domain-specific query language to facilitate coaches and sport analysts to write queries in a very compact form. Additionally, we enrich the data visualization plots by linking each data item to a specific segment of the video so that analysts have full access to all the details related to the query. We demonstrate the flexibility of our system by collecting and converting into readable queries multiple tips and hypotheses on padel strategies extracted from the literature.

Incidence of Upper Body Injuries in Amateur Padel Players

The objectives of this study were to analyze the injuries suffered during the previous year by amateur padel players according to the characteristics of the racket, their usual volume of practice and their experience in padel. A total of 950 amateur players (X age: 31.68 years; X weight: 70.84 kg; X height: 170.9 cm) participated voluntarily, completing an ad-hoc questionnaire. The results indicated that the appearance of the injuries and their location was different according to the sex of the amateur padel players. Men had a higher incidence of muscle and ligament injuries in the shoulder, and tendon injuries in the elbow. On the other hand, women had a greater probability of having muscle injuries in the shoulder and arm, ligament injuries in the elbow and bone injuries in the wrist and elbow. In general, tendon injuries were the most common injury in padel and the shoulder and elbow were the most affected areas. Moreover, men tend to use heavy (CSR = 6.0), fiberglass or carbon (CSR = 2.1), diamond-shaped rackets (CSR = 3.2), with a hard core (CSR = 4.4) and with two or more over grips (CSR = 2.7). Women usually use less heavy (CSR = 6.0), round-shaped rackets (CSR = 4.9), with a soft core (CSR = 4.4) and with one or no over grips (CSR = 2.7). In addition, men tend to play padel more often and have been practicing for longer. In conclusion, although the risk of injury depends on many factors, we identified that the characteristics of the racket, the volume of weekly practice, the experience of the player and the gender of the player are fundamental aspects to take into account for the prevention of injuries in amateur padel players.

Heart rate, oxygen uptake, and energy expenditure response of an SL3 class parabadminton athlete to a progressive test and simulated training session: a case study

This investigation demonstrated a routine of evaluation and training of an athlete of the SL3 class of parabadminton for 2 days continuously monitored by a metabolic analyzer with measurements of oxygen consumption (V̇O₂), carbon dioxide production, and heart rate (HR). The results showed HR and V̇O₂ responses varying between 50% and 99.54% of HRmax (mean HR 80.92 bpm), and 6% and 104% (mean V̇O₂ 35.25 mL/kg/min) of V̇O₂max, during the simulated game. The exercise test and the simulated training session showed significant changes in HR and V̇O₂, reinforcing the need for considerable energy input to training and assessment.

Design and Validation of a New Tennis-Specific Reactive Agility Test-A Pilot Study

Agility is an important ability for tennis players, but there is an evident lack of studies focusing on the applicability of tennis-specific agility tests that capture a combination of the physical and cognitive agility performance. Therefore, the main aim of this study was to design and test measurement properties of the tennis-specific reactive agility test that would be feasible and practical for regular implementation. A total of 32 youth tennis players (21 males and 11 females; 10.85 ± 1.50 years) participated in this study. The measurement characteristics of the newly designed reactive agility tennis-specific (TS-RAN) test have been established by comparing it with two generic agility tests and with two tennis-specific pre-planned agility tests. The overall reliability of the new TS-RAN test can only be considered "moderate to good", as although the results of participants showed good internal consistency, the within-subject reliability of the test proved to be unsatisfactory, since the participants showed a lack of performance consistency. This is not unexpected considering the very young age of the participants who performed the test for the very first time. The new TS-RAN test was highly projected (0.91) on the same single latent dimension, with the variance predominately explained by the tennis-specific agility tests. The test's greatest strength is its high feasibility, since the test does not require any special set-up nor technical equipment, and that makes it practical for regular implementation in a practical setting. Further research studies are needed in order to confirm the test's potential to be widely accepted and used.

Physical Fitness and Upper Limb Asymmetry in Young Padel Players: Differences between Genders and Categories

This study aimed to assess the physical fitness and upper body asymmetries of young padel players aged between 13 and 16 years and to determine the possible differences between genders and categories. A total of 60 padel players were divided into four groups: under-14 male (n = 15; age: 13.75 ± 0.45 years; height: 1.64 ± 0.07 m; weight: 54.7 ± 8.3 kg), under-14 female (n = 15; age: 13.75 ± 0.44 years; height: 1.60 ± 0.05 m; weight: 51.5 ± 6.0 kg), under-16 male (n = 15; age: 15.44 ± 0.51 years; height:1.71 ± 0.04 m; weight: 63.88 ± 6.2 kg) and under-16 female (n = 15; age:15.46 ± 0.52 years; height:1.63 ± 0.05 m; weight: 55.08 ± 3.6 kg). Handgrip strength, ischiosural flexibility, gestural speed of the dominant arm, vertical jump, cardiorespiratory capacity, lateral movement, lateral acceleration and reaction time were measured. Male players showed better results in manual grip strength, vertical jump power, cardiorespiratory capacity and lateral movement (p < 0.05). Moreover, males presented a higher percentage of asymmetry in upper limb strength. Female players showed better reaction time and greater flexibility (p < 0.05). Regarding the differences between categories, the under-16 players showed greater flexibility, gestural speed, vertical jump power, cardiorespiratory capacity and lateral movement compared to the under-14 players. These results can be used as reference values for coaches/physical trainers of younger categories to improve health control and physical performance planning.

Quiet Eye as a Mechanism for Table Tennis Performance under Fatigue and Complexity

QE is the final ocular fixation that precedes critical athletic movements and that enables athletes to gather relevant information and organize their subsequent movement. Although little is known about the factors sustaining performance in table tennis, to date there has been no investigation to assess QE as a contributor to table tennis performance. Furthermore, there is limited research regarding the influence on QE of factors that are known to impact performance, such as task complexity and fatigue. In a within-subjects experimental design, we manipulated fatigue (high vs low) and task complexity (high vs low). Eleven elite table tennis players (m_age =14.72 years, m_experience = 7.27 years) underwent each of the four resulting conditions. Athletes made longer QE before hit versus missed shots (p <.001, η²p = .795) and QE and performance decreased under fatigue (p = 0.02, η²_p = .628; p = .002, η²_p = .62), but we did not detect a significant effect of complexity on QE (p = .352, η²_p = .087). This study is one of the first to show that QE sustains performance in a dynamic sport, that is table tennis, and that QE is affected by fatigue.

A Binary-Entropy Analysis of the Relationship Between Scoring Structure and Match Outcome in Badminton

This study explores the relationship between the scoring structure and the win or loss of a badminton match, while providing quantitative analytic data using binary entropy to determine the uncertainty of said win or loss. Scoring structure data were collected from the official match records of the top 16 events of the World Badminton Championships from 2006 to 2020 (a total of 10 editions) as collection objects (745 matches and 1,734 sets in all) and were analyzed by means of notational analysis. Our entropy analysis showed that the main factor affecting the certainty of win or loss in men's singles, men's doubles and mixed doubles comes from the number of leading points, and in women's singles and women's doubles from whether the current point is closer to the match point. Our binary-entropy analysis based on scoring structure showed that, to maintain high uncertainty so that players stay competitive, the scoring points of two sides should differ in less than 5; in addition, the decisive factors for victory strongly depend on gender, also justifying research results of previous studies.

Analysis of the Actions of Net Zone Approach in Padel: Validation of the NAPOA Instrument

To carry out research that analyzes performance indicators through observational methodology, it is necessary to have validated tools. The purpose of this study was to design and validate a tool to ascertain the characteristics of the strokes that padel pairs use to reach the net and their consequences in the two subsequent shots of the game. Eleven experts, who had to meet four of the five inclusion criteria established by the researchers, participated in the process. Aiken’s V coefficient and confidence intervals were used to analyze content validity and Cronbach’s α coefficient to calculate reliability. The adequacy and wording of the sixteen variables initially designed were evaluated. Four variables were eliminated due to obtaining values <0.90 in Aiken’s V coefficient in adequacy. The rest of the variables were modified in their wording, according to the qualitative evaluations of the experts, or were considered correct. The reliability of the instrument was acceptable (α = 0.89). The NAPOA instrument is novel, as it is of interest to analyze the characteristics of the strokes that padel players use to achieve the offensive position.

Effects of Acute Physical Fatigue on Gaze Behavior and Performance During a Badminton Game

In badminton, the ability to quickly gather relevant visual information is one of the most important determinants of performance. However, gaze behavior has never been investigated in a real-game setting (with fatigue), nor related to performance. The aim of this study was to evaluate the effect of fatigue on gaze behavior during a badminton game setting, and to determine the relationship between fatigue, performance and gaze behavior. Nineteen novice badminton players equipped with eye-tracking glasses played two badminton sets: one before and one after a fatiguing task. The duration and number of fixations for each exchange were evaluated for nine areas of interest. Performance in terms of points won or lost and successful strokes was not impacted by fatigue, however fatigue induced more fixations per exchange on two areas of interest (shuttlecock and empty area after the opponent's stroke). Furthermore, two distinct gaze behaviors were found for successful and unsuccessful performance: points won were associated with fixations on the boundary lines and few fixation durations on empty area before the participant's stroke; successful strokes were related to long fixation durations, few fixation durations on empty area and a large number of fixations on the shuttlecock, racket, opponent's upper body and anticipation area. This is the first study to use a mobile eye-tracking system to capture gaze behavior during a real badminton game setting: fatigue induced changes in gaze behavior, and successful and unsuccessful performance were associated with two distinct gaze behaviors.

Physical Fitness Profiling of National Category Table Tennis Players: Implication for Health and Performance

The aims of this study were to: (1) analyze table tennis players' physical profiles considering and comparing players age categories (i.e., under U12, U14, U16, U20, Senior and Older); and (2) to quantify the correlations among the variables measured by each test. Seventy-one table tennis players (61 men and 10 women, 19.7 ± 11.23 years, 1.65 ± 0.13 m, 59.71 ± 17.72 kg and 21.60 ± 4.22 kg/m²) divided into six age groups, performed a sprint test, forearm isometric strength test, countermovement vertical test, countermovement horizontal test, change of direction ability (CODA) test and flexibility test. U14 players performed better than U12 in all tests (ES = -0.70 to 1.98, moderate to large) except in Sit and Reach (SAR) test (ES = 0.19, trivial). The U16 group also obtained better results than U14 in all tests (ES = 0.77 to -2.31, moderate to large) except for the SAR test (ES = 0.19, trivial). The U20 group performed better than U16 in all the tests (ES = 0.73 to -1.53, moderate to large) except for the 5 m sprint test (ES = -0.02, trivial), 10 m sprint test (ES = -0.51, moderate) and SAR (ES = 0.11, trivial). Differences between Senior and U20 were only found in the arm swing counter movement jump (CMJAS) (ES = -0.82, large) and modified agility test (MAT) (ES = 1.19, large), with the U20 group being better in both variables. The senior group performed better in the MAT test than the older group (ES = 0.94, large). The relation found between forearm isometric strength, vertical jump, horizontal jump, sprint and CODA ability (r = -0.53; ±0.14, 0/0/100, most likely to r = 0.83; ±0.06, 100/0/0, most likely) indicates that these capacities are related in table tennis players. Nevertheless, the lack of association between the sit and reach test with the other capacities may indicate that flexibility is an independent capacity.

How Mentally Fatiguing Are Consecutive World Padel Tour Matches?

It is currently unknown whether mental fatigue occurs throughout a WPT competition and whether consecutive matches affect how mentally fatiguing a match is perceived to be. The objective was to quantify the effects of successive professional matches on mental fatigue. A total of 14 professional players (9 males, Mage = 25, 5 females, Mage = 21) participated during qualified rounds of a WPT with three eliminatory matches: Match 1 (morning) and 2 (afternoon) on day 1 (n = 14), Match 3 (morning) on day 2 (n = 6). Mental fatigue and motivation, with scales, and reaction time, with a 3-min Psychomotor Vigilance Test, were measured at two time intervals (pre and post matches (<30 min)). To analyze the evolution of these variables, a two-way repeated measures MANOVA was performed. An increase in mental fatigue from pre- to post-matches was observed (p < 0.01), with an accumulation of mental fatigue between matches played on day 1 (p < 0.01), maximizing the mental fatigue perceived during Match 2. Padel matches impair motivation and reaction time (p = 0.04), without effects between successive matches, which reinforced the idea that mental fatigue may impair padel performance (i.e., reaction time). Coaches should use training interventions and recovery strategies to counteract/avoid the accumulation of mental fatigue during professional tournaments.

Evaluation of Open-Source and Pre-Trained Deep Convolutional Neural Networks Suitable for Player Detection and Motion Analysis in Squash

In sport science, athlete tracking and motion analysis are essential for monitoring and optimizing training programs, with the goal of increasing success in competition and preventing injury. At present, contact-free, camera-based, multi-athlete detection and tracking have become a reality, mainly due to the advances in machine learning regarding computer vision and, specifically, advances in artificial convolutional neural networks (CNN), used for human pose estimation (HPE-CNN) in image sequences. Sport science in general, as well as coaches and athletes in particular, would greatly benefit from HPE-CNN-based tracking, but the sheer amount of HPE-CNNs available, as well as their complexity, pose a hurdle to the adoption of this new technology. It is unclear how many HPE-CNNs which are available at present are ready to use in out-of-the-box inference to squash, to what extent they allow motion analysis and if detections can easily be used to provide insight to coaches and athletes. Therefore, we conducted a systematic investigation of more than 250 HPE-CNNs. After applying our selection criteria of open-source, pre-trained, state-of-the-art and ready-to-use, five variants of three HPE-CNNs remained, and were evaluated in the context of motion analysis for the racket sport of squash. Specifically, we are interested in detecting player's feet in videos from a single camera and investigated the detection accuracy of all HPE-CNNs. To that end, we created a ground-truth dataset from publicly available squash videos by developing our own annotation tool and manually labeling frames and events. We present heatmaps, which depict the court floor using a color scale and highlight areas according to the relative time for which a player occupied that location during matchplay. These are used to provide insight into detections. Finally, we created a decision flow chart to help sport scientists, coaches and athletes to decide which HPE-CNN is best for player detection and tracking in a given application scenario.

Entropy of Badminton Strike Positions

The aim of the current study was twofold: (i) to investigate the distribution of the strike positions of badminton players while quantifying the corresponding standard entropy and using an alternative metric (spatial entropy) related to winning and losing points and random positions; and (ii) to evaluate the standard entropy of the receiving positions. With the datasets of 259 badminton matches, we focused on the positions of players’ strokes and the outcome of each point. First, we identified those regions of the court from which hits were most likely to be struck. Second, we computed the standard entropy of stroke positions, and then the spatial entropy, which also considers the order and clustering of the hitting locations in a two-dimensional Euclidean space. Both entropy quantifiers revealed high uncertainty in the striking position; however, specific court locations (i.e., the four corners) are preferred over the rest. When the outcome of each point was taken into account, we observed that the hitting patterns with lower entropy were associated with higher probabilities of winning points. On the contrary, players striking from more random positions were more prone to losing the points.

Recovery during and after a simulated multi-day tennis tournament: Combining active recovery, stretching, cold-water immersion, and massage interventions

The aim of this study was to investigate the effects of a mixed-method recovery intervention (MMR) consisting of active recovery, stretching, cold-water immersion, and massage on physical, technical, physiological, and perceptual recovery during and after a five-day simulated tennis tournament. Nine competitive male tennis players (age, 24.6±4.2 years) with national ranking positions (German Tennis Federation) and Universal Tennis Ratings between approximately 11-13 participated in two singles tennis tournaments, which were separated by a three-month washout period. During the tournaments, participants played five two-and-a-half-hour competitive singles tennis match on five consecutive days. For the assignment to one of two groups, athletes were matched into homogeneous pairs according to their ranking. Then, within each pair, the players were randomly assigned to one of two groups. The first group performed MMR during the first tournament, whereas the other group used passive recovery (PAS). During the second tournament, recovery conditions were interchanged. Measures of physical and technical performance as well as physiological and perceptual responses (heart rate, blood lactate concentration, perceived exertion) were recorded during match-play sessions. Furthermore, muscle soreness, perceived recovery state, blood markers, countermovement jump height (CMJ), and repeated sprint ability (RSA) were determined before, during, and after the five-day tournament periods. Results showed significant changes over time (P < 0.05) in muscle soreness, perceived recovery state, creatine kinase, c-reactive protein, insulin-like growth factor 1, and countermovement jump height. However, no significant differences or recovery strategy x time interactions were noted either for tennis-specific performance (e.g. number of total points won) or any other of the measured parameters between MMR and PAS (P > 0.05). In conclusion, the repeated use of MMR during and after a five-day tennis tournament did not affect match performance, match load, or recovery from repeated days of tennis match play.

Gender Differences in Neuromuscular, Haematological and Urinary Responses during Padel Matches

Research on the acute physiological response to a padel match is limited. The present study aimed to: (a) evaluate neuromuscular, urinary, and hematological responses after simulated padel competition (SC) and (b) analyze possible gender differences. In this study, 28 high-level padel players participated (men = 13, age = 26.83 ± 6.57 years; women = 15, age = 30.07 ± 4.36 years). The following parameters were analyzed before and after SC: neuromuscular (hand grip strength, squat jump (SJ), countermovement jump (CMJ), and Abalakov jump (ABK)), hematological (red blood cells, hemoglobin, and hematocrit), and urinary (pH, specific gravity, microalbuminuria, and red blood cells). Significant gender differences were found in neuromuscular and hematological responses, with men obtaining higher values (p < 0.05). For the SC influence, changes were noted in ABK and microalbuminuria (p < 0.05). The percentages of change in hand grip strength, SJ (height and watts), CMJ (height), and ABK (height) were higher for men than women (p < 0.05). SC negatively influenced the neuromuscular parameters to a greater extent in women. Our results could be related to gender differences in game actions, the temporal structure, and anthropometric and physiological characteristics. Game dynamics and a different organic response between male and female padel playing were confirmed.

Estimating Player Positions from Padel High-Angle Videos: Accuracy Comparison of Recent Computer Vision Methods

The estimation of player positions is key for performance analysis in sport. In this paper, we focus on image-based, single-angle, player position estimation in padel. Unlike tennis, the primary camera view in professional padel videos follows a de facto standard, consisting of a high-angle shot at about 7.6 m above the court floor. This camera angle reduces the occlusion impact of the mesh that stands over the glass walls, and offers a convenient view for judging the depth of the ball and the player positions and poses. We evaluate and compare the accuracy of state-of-the-art computer vision methods on a large set of images from both amateur videos and publicly available videos from the major international padel circuit. The methods we analyze include object detection, image segmentation and pose estimation techniques, all of them based on deep convolutional neural networks. We report accuracy and average precision with respect to manually-annotated video frames. The best results are obtained by top-down pose estimation methods, which offer a detection rate of 99.8% and a RMSE below 5 and 12 cm for horizontal/vertical court-space coordinates (deviations from predicted and ground-truth player positions). These results demonstrate the suitability of pose estimation methods based on deep convolutional neural networks for estimating player positions from single-angle padel videos. Immediate applications of this work include the player and team analysis of the large collection of publicly available videos from international circuits, as well as an inexpensive method to get player positional data in amateur padel clubs.

Analysis of Game Performance Indicators during 2015-2019 World Padel Tour Seasons and Their Influence on Match Outcome

A better understanding of the demands of in-game competition demands may improve coaching strategies, training designs, and injury prevention programs. However, there is limited information regarding performance analysis in professional padel. This study aimed to analyse performance indicators and their influence on match outcomes regarding sex, tournament round, and set number. The sample contained 1070 sets from 532 matches of the 2016 to 2019 World Padel Tour seasons. Variables including sex, round, game result, stroke effectiveness, and break points were registered through systematic observation. A non-parametric approach was applied to evaluate differences between sex, match outcome, and tournament round. The results showed significant differences between winners and losers regarding sex in break points (male d = 2.13, p = 0.00; female d = 2.22, p = 0.00), smash winners (male d = 0.85, p = 0.00; female d = 0.69, p = 0.00), groundstroke winners (male d = 1.01, p = 0.00; female d = 1.18, p = 0.00), volley winners (male d = 1.08, p = 0.00; female d = 0.91, p = 0.00), and errors (male d = 0.76, p = 0.00; female d = 0.65, p = 0.00). Furthermore, differences in shot effectiveness between winners and errors increased in the last set of the match and in the last round of the tournament (p < 0.05). Therefore, shot effectiveness seems to be a key factor in professional padel that distinguishes between winning and losing players. Such knowledge may have implications in the design of appropriate game strategies and specific training sessions to improve performance and to prevent sport injuries.

Handedness and Relative Age in International Elite Interactive Individual Sports Revisited

Relative age effects (RAE) describe the unintended side effect of annual age grouping such that athletes born close to a specific cutoff date are more likely to be associated with attaining higher performance status than athletes born later. One factor suggested to override the RAE is handedness. Given the left-handers' rarity and their proposed performance advantage in interactive sports, left-handedness may be associated with a lower likelihood of suffering from selection inequalities like RAE in those sports compared with right-handedness. Here, in a two-study approach, we tested that hypothesis by examining male and female athletes from various interactive individual sports sampled over a 10-year period from 2007 to 2016. Study 1 investigated distributions of birth and handedness of senior athletes listed in the top 200 of year-end world rankings in table tennis, tennis, squash, and fencing (épée, foil, and saber). Study 2 followed a similar design but focused on junior athletes in the fencing disciplines and tennis. Unlike the above prediction, in both studies, birth distribution was not found to be reliably associated with handedness in any of the sports or disciplines considered. Left-handers were consistently overrepresented in épée, foil, and table tennis, occasionally in saber and tennis, and not at all in squash. Birth frequencies decreased from quartile Q1 (January to March) to Q4 in almost any sporting domain at the junior level, whereas such trend was rarely found at the senior level. In conclusion, while providing novel insight on the role handedness may play at the junior level, our findings do not support the hypothesis that left-handedness helps override birth-related inequalities in high sporting achievement in elite interactive individual sports.

Physical Fitness in Young Padel Players: A Cross-Sectional Study

This study aimed to examine the fitness characteristics and to identify the influence of gender and practice experience between young amateur padel players. A total of thirty-four padel players (n = 19 boys and 15 girls) aged 13 to 17 years old (age 14.6 ± 1.5 years; body mass 63.4 ± 14.5 kg; height 166.6 ± 9.8 cm; 6.2 ± 2.5 padel experience) volunteered to participate. Body composition was assessed by bioimpedance. Change of direction and agility were evaluated by two padel-adapted tests. Upper-limb strength measurement included overhead and side medicine ball throws with dominant and non-dominant hands. One-way ANCOVA was used to determine whether there were significant differences between gender and experience on fitness variables adjusting for age as a covariate. Male and female young padel players presented an apparently healthy body composition and exhibited similar performance in all fitness tests except for jumping ability. Practice experience seemed to influence upper-limb throwing strength, however, sub-analyses revealed no conclusive results. These results contribute to the existing knowledge in padel by providing new data about the fitness status of amateur young players aged 13 to 17 years old and open a window for future interventions using padel as a health promotion tool among youths.

Ball Impact Position in Recreational Male Padel Players: Implications for Training and Injury Management

Racket sports such as padel are characterized by the repetition of unilateral gestures, which can lead to negative adaptations like asymmetries or overuse musculoskeletal injuries. The purpose of this study was to determine the differences in ball impact positions (i.e., forward or backward of the center of gravity) in nine stroke types in a sample of forty-eight recreational male padel players. The sample included 14,478 shots corresponding to 18 matches from six tournaments. Forty-eight male padel players were classified into two groups according to their level: trained (n = 24) and novice (n = 24). Type of stroke and ball impact position were registered using a computerized motion tracking video system. The ball impact position was computed from the distance (cm) between the coordinates of the ball and the player’s center of gravity. Results show that trained players hit the ball in a more backward position (from 11 to 25 cm, compared to novice) in serve and offensive strokes (volleys, trays, and smashes) but used more forward strokes (from 7 to 32 cm, compared to novice) in defensive shots (groundstrokes, wall strokes, and lobs). Because the current differential variables are trainable and demonstrated to be of relevance for performance, the findings of this study may assist padel coaches in designing proper training plans to improve effectiveness and to prevent musculoskeletal injuries regarding the type of stroke and ball impact position. Such knowledge may constitute a very important factor affecting technique, biomechanics, and injury management in padel players of different competitive levels.

Design, Validation, and Reliability of an Observational Instrument for Technical and Tactical Actions in Singles Badminton

Technical and tactical actions are decisive in terms of badminton player competitive performance. The main objective of this research was to design, validate, and estimate the reliability of an observational instrument for the analysis of the tactical and technical actions in individual badminton. The process was carried out in four different steps: first, there was a review of the scientific literature and a preliminary list of variables was made; second, a qualitative and quantitative assessment was completed by 10 badminton expert judges; in the third step, the content validity was estimated using Aiken’s V coefficient; finally, intra-observer reliability and interobserver reliability were tested by two observers specialized in badminton using the Cohen’s Kappa coefficient and the intraclass correlation coefficient. Strokes were used as the unit of measure by our observational instrument; every time badminton players hit the shuttlecock, 22 variables (eight contextual variables, seven variables related to the result of the match, and seven variables related to the game) are observed. The minimum Aiken’s value was 0.58, and reliability was 0.63. In spite of these values, none of the variables had to be removed, but there were modifications in terms of drafting in some of them. The main findings confirmed the validity and the usefulness of this instrument.

Analysis of Performance Parameters of the Smash in Male and Female Professional Padel

The aim of this study was to analyze the distribution and effectiveness of the different types of smash in professional padel according to the area and direction of the strokes and the gender. Through systematic observation, 1.015 smashes from eight finals (four men's and four women's) of the professional matches were analyzed. The smashes were categorized into four types of smash: tray, flat, topspin and off the wall. The results showed both men's and women's that the tray is the most used smash by padel players, presenting a percentage of point continuity of almost 90%. The flat and topspin smashes are the strokes that achieve the highest percentage of winning points (near 60%), although this efficiency decreases significantly when the players move away from the net area (p < 0.05), especially in the flat smash. Men perform a higher percentage of winning smashes than women, mainly in the flat smash (p = 0.02). Furthermore, with regards to direction, flat and off the wall smashes are predominantly down the line strokes and women perform significantly more cross court topspin smashes than men (p = 0.005). The results shown could be used to design tasks and exercises by padel coaches at professional players.

Effects of Beetroot Juice Ingestion on Physical Performance in Highly Competitive Tennis Players

Beetroot juice (BJ) contains high levels of inorganic nitrate (NO₃⁻) and its intake has good evidence in increasing blood nitrate/nitrite concentrations. The ingestion of BJ has been associated with improvements in physical performance of endurance sports, however the literature in intermittent sports is scarce. The aim of this study was to investigate whether BJ could improve physical performance in tennis players. Thirteen well-trained tennis players (25.4 ± 5.1 years) participated in the study during their preparatory period for the tennis season. Subjects were randomly divided into two groups and performed a neuromuscular test battery after either BJ or placebo (PLA) consumption. Both trials were executed on two separate days, in randomized order, with one week of wash out period. The test battery consisted of serve velocity test (SVT), countermovement jump (CMJ), isometric handgrip strength (IHS), 5-0-5 agility test (5-0-5), and 10 m sprint (10-m). No significant differences were found in SVT (1.19%; p = 0.536), CMJ (0.96%; p = 0.327), IHS (4.06%; p = 0.069), 5-0-5 dominant and nondominant side (1.11–2.02%; p = 0.071–0.191) and 10-m (1.05%; p = 0.277) when comparing BJ and PLA ingestion. Thus, our data suggest that low doses of BJ (70 mL) consumption do not enhance tennis physical performance.

Serving Patterns of Women's Badminton Medalists in the Rio 2016 Olympic Games

The aim of the present study was to describe and identify the serving performance profiles of medalists during an elite women’s badminton tournament taking notational and temporal variables into account. The sample was composed of the 14 matches (n = 1,052 rallies) played by the three medalists during the 2016 women’s singles Olympic Games badminton event (Rio, Brazil). The independent variable studied was serving player (medalist/opponent); while the dependent variables were related to notational analysis: serve type, set, and point won by the server/receiver; and the time-related variables: number of strokes per rally, rally time, rest time, and frequency of strokes. The main results showed that: (i) temporal parameters were similar for total match duration but shorter for rally time, and longer for rest time and with more strokes per rally than found in previous research; (ii) the serve effectiveness showed neutral values when analyzing serving by all the players, medalists, and opponents (around 50%); (iii) the two-step cluster analysis identified how successful players used the serve when playing short rallies with backhand short and flick serves (cluster 1), and forehand long serves (cluster 2); and during long rallies with the use of the backhand short serve, forehand short serve and forehand long serve (cluster 3). On the other hand, medalists and their opponents used forehand long serves during set 1 with durations of 8.80 s (cluster 5); and the opponents showed an independent performance using the forehand short serve during sets 1 and 2 (cluster 4); and (iv) the classification tree analysis (Exhaustive CHAID) identified the importance of different serving patterns with the gold medal player using more backhand and forehand flick serves, and the main use of backhand short serves during sets 1 and 2 in all the tournament stages. The bronze medalist used more forehand long serves during all sets, and the silver medalist showed a mixed performance of serves using the forehand short serve, the backhand short serve and the forehand long serve. The current findings may help coaches and players to manage different serving and playing patterns during training and matches according to the serve and rally requirements.

Impaired Performance of the Smash Stroke in Badminton Induced by Muscle Fatigue

PURPOSE

To evaluate the effects of muscle fatigue on badminton performance during a smash stroke.

METHODS

In total, 17 young, well-trained players completed 20 forehand smashes twice (prefatigue and postfatigue protocol), and both speed and precision of the strokes were measured. The fatigue protocol consisted of 10 series of 10 maximal countermovement jumps (3-s rest in between) followed by 8 lunges. Perception of effort and countermovement-jump performance during each series were also measured to assess fatigue.

RESULTS

Shuttlecock speed decreased moderately (-3.3%) but significantly after the fatigue protocol (P < .001, ηp2=.671). Precision significantly decreased after the fatigue protocol (-10.3%, P = .001, ηp2=.473). The decrease in precision was mainly due to an increased number of faults (P = .006, ηp2=.378, dz = 0.756) and to a decrease in accuracy (P = .066, ηp2=.195, dz = 0.478).

CONCLUSION

The present study showed that fatigue impairs performance during specific badminton skills. Moreover, by showing a slight decrease in speed and a large decrease in accuracy of the shuttlecock when fatigue is experienced, the present study suggested that, as previously observed in other racket sports, the speed of the missile appears to be the key factor used by the players to win the rally. Coaches and physical trainers should therefore develop interventions aiming to limit the negative impact of fatigue on badminton strokes.

Performance Differences of Temporal Parameters and Point Outcome between Elite Men's and Women's Badminton Players According to Match-Related Contexts

Background: the aim of the present study was to identify the temporal and notational performance differences between elite men’s and women’s badminton players according to match type and set. Methods: the sample was composed of 60 men’s and 60 women’s matches classified by match type or duration: short (lower quartile), long (upper quartile) and regular matches (interquartile range). Temporal and notational variables were analysed for each match and compared between sexes accounting for match duration. Results: greater intensity for most variables (i.e., rally time, rest time, density, and strokes per match/rally) was exhibited in men’s matches compared with women’s matches (i.e., higher frequency between strokes). In addition, the greater intensity for men compared to women was more pertinent during long matches (13 significant variables) and less evident during short matches (six significant variables). Point outcome displayed similar trends for each sex during matches with more winners for men’s players when serving and more unforced errors for women’s players. Lastly, based on each match type, fewer sex differences were noted during sets 2 and 3, as the match progressed. Conclusion: men’s players performed at a greater intensity than women’s players for different match and set contexts, with this sex difference enhanced when controlling for match type and set. The development of sex- and match-specific scenarios will assist coaches and trainers in the design of specific training drills to enhance the athletic performance of elite badminton players.

Acute Responses to On-Court Repeated-Sprint Training Performed With Blood Flow Restriction Versus Systemic Hypoxia in Elite Badminton Athletes

PURPOSE

Repeated-sprint training (RS) is commonly conducted in normoxia, but its completion with localized (blood-flow restriction [BFR]) or systemic hypoxia has been proven effective for performance enhancement. Yet, few studies have applied these types of RS sessions in racket sports. The authors aimed to determine the acute responses to these types of training in elite badminton players.

METHODS

Eight male elite badminton players participated in this randomized crossover study. They performed 3 on-court RS sessions, each consisting of 3 sets of 10 repetitions of 10-s badminton-specific movements in normoxia (RSN), systemic normobaric hypoxia (RSH, FiO2 = 14%), or with BFR (RS-BFR, 40% arterial occlusion pressure). Performance, perceptual (ie, rating of perceived exertion), and physiological (ie, pulse saturation, muscle oxygenation, blood lactate, creatine kinase, heart-rate variability) responses were measured after each set and up to 48 h postsession.

RESULTS

RS-BFR induced a greater performance impairment (lower distance and accelerations) and a higher local perceived exertion in the legs than RSN and RSH (P < .05), whereas greater overall fatigue was reported with RSH (P < .05). RSH induced a lower saturation (P < .001), but no differences were observed in muscle oxygenation between conditions. No differences in creatine kinase or heart-rate variability were observed at any time point (from baseline up to 48 h after the session).

CONCLUSIONS

RS-BFR-and, to a lower extent, RSH-resulted in impaired performance and a higher perceived strain than RSN. However, these 2 hypoxic methods do not seem to induce a long-lasting (post 24-48 h) physiological stress in elite badminton players.

Statistical Differences in Set Analysis in Badminton at the RIO 2016 Olympic Games

The aim of the present study was to determine statistical differences in a set of badminton competition matches in five different modalities with regard to competition level (Group Phase vs. Eliminatory Phase). Data from 453 sets (125 in men’s singles; 108 sets in women’s singles; 77 sets in men’s doubles; 73 in women’s doubles and 70 in mixed doubles) from the RIO 2016 Olympics Games were recorded and classified in two groups of variables to analyze variables related to match (5) and set (15). A descriptive analysis and univariate test (Mann–Whitney U) for non-parametric data were conducted. The results show in men’s and women’s singles all the variables related to match were higher in the Elimination Phase than in the Group Phase (p < 0.01). In Sets 1 and 3, the longest set duration, rally and average rally were found in the Elimination Phase than Group Stage (p < 0.05). In women’s singles, these differences were also recorded in Set 2. For doubles, the results are more stable among groups. Men’s doubles had a longer duration of the match and set (sets 1 and set 2) (p < 0.01), and also scored highest for average rally strokes (sets 1 3) (p < 0.05) and shuttles used in the Elimination Phase vs. the Group Phase along the match (p < 0.01). In women’s doubles, more shuttles were used in a match in the Elimination than in the Group Phase. Moreover, the same results are established for Set 2, including for average rally. Mixed doubles saw no match going to three sets. However, the greatest differences showed a longer rally and average rally being registered in the Elimination than in the Group Phase. In conclusion, the timing factors of the badminton singles and doubles games were different in the Elimination and Group Phases. This information may help players and coaches prepare and administer different types of workouts or, more specifically, competition schedules adapted to the characteristics of modern badminton.

Reproducibility and Validity of a Stroke Effectiveness Test in Table Tennis Based on the Temporal Game Structure

Purpose: This study aimed to develop a stroke effectiveness test in table tennis based on the temporal game structure to assess the ball speed and ball placement of the players, with a purpose to analyze its reproducibility and validity.

Methods: Nineteen male table tennis players participated in this study. The test was performed twice during the first session and once during the second session to assess the intrasession and intersession reproducibility, respectively. Moreover, the test was examined on its ability to discriminate between regional (n = 10) and local performance-level (n = 9) players and on the relationship between the test results and the table tennis performance to assess the discriminant and concurrent validity, respectively. In general, the test consisted of 11 simulated rallies of 2–5 balls with the effort and rest ratio of 0.5, and focused on attack with offensive strokes at defensive balls delivered by a robot randomly between the left and right positions on the table.

Results: Ball speed, ball placement, and ball speed-ball placement index showed satisfactory reliability (ICC range 0.78–0.96, P < 0.05) and agreement (CV range 2.7–16.2%) outcomes. Additionally, the Bland–Altman plots show the systematic error of the analyses closer to 0, and that most values were within the limits of agreements. Concerning validity analyses, regional players had higher scores of ball placement (+51.3%; P = 0.01, ES = 1.33) and ball speed-ball placement index (+56.1%; P = 0.0009, ES = 1.87) as well as made fewer errors (-25.4%; P = 0.017, ES = 1.20) than local players. Moreover, ball placement (r = -0.79, P = 0.04), ball speed-ball placement index (r = -0.78, P = 0.04), and percentage error (r = 0.88, P = 0.01) presented a strong and significant correlation with table tennis performance. However, ball speed was slightly different between the regional than local players (+1.7%; P = 0.78, ES = 0.13) and this variable was not related to table tennis performance (r = 0.32, P = 0.49).

Conclusion: Our findings show evidences that the test is reproducible. Moreover, discriminant and concurrent validity are confirmed for ball placement and ball speed-ball placement index.

Balance control, agility, eye-hand coordination, and sport performance of amateur badminton players: A cross-sectional study

In this study, balance performance, agility, eye-hand coordination, and sports performance were compared between amateur badminton players and active controls.Thirty young adult badminton players and 33 active controls participated in the study. Static single-leg standing balance (with eyes closed) was measured using a force platform, and dynamic balance was measured using the Y Balance Test (lower quarter). Agility was measured using a hexagon agility test, and eye-hand coordination was measured using a computerized finger-pointing task. Sports performance was quantified by the number of times a shuttlecock fell in a designated area following a badminton serve.The badminton players had superior accuracy in badminton serving (P < .001) relative to the active controls. However, no significant between-group differences were noted in all other outcome variables (P > .05).Amateur badminton players had more favorable sports performance, but not balance performance, agility, or eye-hand coordination, than controls.

Quantifying hitting activity in tennis with racket sensors: new dawn or false dawn?

The non-invasive measurement of movement through sensor technologies is common in elite sport, yet only recently become possible in tennis. This study validated two commercial tennis racquet sensors compared to gold standards in VICON and expert notational analysis. One national-level male tennis player hit 24 shots (9 forehands and 9 backhands, hit with heavy topspin, flat and slice; 6 serves) using a Babolat Play racket with a Zepp sensor. Measures of shot type, impact location and racket speed were compared against those captured by a 500-Hz 12 camera VICON system. Cohen's kappa (κ) and a weighted kappa (κ _w) assessed the accuracy of stroke classification and impact location, respectively, and intraclass correlation coefficients (ICC) validated sensor-derived racket speed. Both sensors recorded the same total stroke volume as VICON, while Zepp racket speed displayed near perfect agreement with VICON (ICC = 0.983; p < 0.001). They exhibited moderate agreement with true stroke classification (Babolat: κ = 0.730; Zepp: κ = 0.612) and minimal agreement with true impact location (Babolat: κ _w = 0.412; Zepp: κ _w = 0.217). During match play, both sensors achieved near perfect accuracy for stroke volume but experienced difficulty discriminating the different stroke types. In sum, the Babolat Play and Zepp determined stroke volume and intensity accurately but were less effective in identifying specific strokes and impact locations.