Ball Accuracy Research Articles

Cold-water immersion and whole-body cryotherapy attenuate muscle soreness during 3 days of match-like tennis protocol.

This study aimed to investigate the effect of whole-body cryotherapy (WBC), cold-water immersion (CWI) and passive recovery (PAS) on tennis recovery. Thirteen competitive male tennis players completed three consecutive match-like tennis protocols, followed by recovery (WBC, CWI, PAS) in a crossover design. Five tennis drills and serves were performed using a ball machine to standardize the fatiguing protocol. Maximal voluntary contraction (MVC) peak torque, creatine kinase activity (CK), muscle soreness, ball accuracy and velocity together with voluntary activation, low- and high-frequency torque and EMG activity were recorded before each protocol and 24h following the third protocol. MVC peak torque (-7.7 ± 11.3%; p = 0.001) and the high- to low-frequency torque ratio (-10.0 ± 25.8%; p < 0.05) decreased on Day 1 but returned to baseline on Day 2, Day 3 and Day 4 (p = 0.052, all p > 0.06). The CK activity slightly increased from 161.0 ± 100.2 to 226.0 ± 106.7 UA L-1 on Day 1 (p = 0.001) and stayed at this level (p = 0.016) across days with no differences between recovery interventions. Muscle soreness increased across days with PAS recovery (p = 0.005), while no main effect of time was neither observed with WBC nor CWI (all p > 0.292). The technical performance was maintained across protocols with WBC and PAS, while it increased for CWI on Day 3 vs Day 1 (p = 0.017). Our 1.5-h tennis protocol led to mild muscle damage, though neither the neuromuscular function nor the tennis performance was altered due to accumulated workload induced by consecutive tennis protocols. The muscle soreness resulting from tennis protocols was similarly alleviated by both CWI and WBC. IRB No. 2017-A02255-48, 12/05/2017.

EFEITOS DO TREINAMENTO FUNCIONAL SOBRE A QUALIDADE DE GOLPE DOS JOGADORES DE TÊNIS

ABSTRACT Introduction: Functional training values the athletes’ physical activity and the integral exercise proper of the practiced sport. Tennis frequently integrates this exercise into regular training, aiming to enrich teaching. Objective: Compare the effects of functional training in daily exercise on the tennis players’ strokes based on the athletes’ performance. Methods: A research sample of 18 young male tennis players in tennis clubs were used. The volunteers were randomly divided into two groups, control and experimental. The control group received traditional physical training methods in their daily training. The experimental group had functional physical training added to their daily training. Before and after training, the ITN and functional movement screening methods were used to study the hitting quality of the tennis players. Finally, a mathematical and statistical analysis of the results ascertained in the tests was performed. Results: After 12 weeks, the mean level and accuracy of the experimental group were significantly higher (P&lt;0.05). The control group showed a slight improvement in the mean level and ball accuracy but without statistical significance (P&gt;0.05). Conclusion: Functional training associated with regular training positively improved the quality of hitting in tennis players. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

On the Use of the Repeated-Sprint Training in Hypoxia in Tennis.

PurposeTo examine physiological and technical responses to repeated-sprint training in normobaric hypoxia at ∼3,000 m (RSH, n = 11) or in normoxia (RSN, n = 11) compared to a control group (CON, n = 8) in well-trained tennis players. Participants were 28.8 ± 5.9 years old without any previous experience of training in hypoxia.MethodsIn addition to maintaining their usual training (CON), both RSH and RSN groups completed five tennis specific repeated-shuttle sprint sessions (4 × 5 × ∼8 s maximal sprints with ∼22 s passive recovery and ∼5 min rest between sets) over 12 days. Before (Pre), the week after (Post-1) and 3 weeks after Post-1 (Post-2), physical/technical performance during Test to Exhaustion Specific to Tennis (TEST), repeated-sprint ability (RSA) (8 × ∼20 m shuttle runs—departing every 20 s) and heart rate variability (HRV) were assessed.ResultsFrom Pre to Post-1 and Post-2, RSH improved TEST time to exhaustion (+18.2 and +17.3%; both P < 0.001), while the “onset of blood lactate accumulation” at 4 mmol L–1 occurred at later stages (+24.4 and +19.8%, both P < 0.01). At the same time points, ball accuracy at 100% V̇O2max increased in RSH only (+38.2%, P = 0.003 and +40.9%, P = 0.007). Markers of TEST performance did not change for both RSN and CON. Compared to Pre, RSA total time increased significantly at Post-1 and Post-2 (−1.9 and −2.5%, P < 0.05) in RSH only and this was accompanied by larger absolute Δ total hemoglobin (+82.5 and +137%, both P < 0.001). HRV did not change either supine or standing positions.ConclusionFive repeated sprint training sessions in hypoxia using tennis specific shuttle runs improve physiological and technical responses to TEST, RSA, and accompanying muscle perfusion responses in well-trained tennis players.

Ball Classification through Object Detection using Deep Learning for Handball

Dynamic gameplay, fast-paced and fast-changing gameplay, where angle shooting (top and bottom corner) has the best chance of a good goal, are the main aspects of handball. When it comes to the narrow-angle area, the goalkeeper has trouble blocked the goal. Therefore, this research discusses image processing to investigate the shooting precision performance analysis to detect the ball's accuracy at high speed. In the handball goal, the participants had to complete 50 successful shots at each of the four target locations. Computer vision will then be implemented through a camera to identify the ball, followed by determining the accuracy of the ball position of floating, net tangle and farthest or smallest using object detection as the accuracy marker. The model will be trained using Deep Learning (DL) models of YOLOv2, YOLOv3, and Faster R-CNN and the best precision models of ball detection accuracy were compared. It was found that the best performance of the accuracy of the classifier Faster R-CNN produces 99% for all ball positions.

Can Eight over Bowling Spell be a Directives of Pace Bowling for Practice Session: An Experimental Study

The purpose of this study was to find out the effect of continuous bowling spell on physical and physiological performance in pace bowling and also to find out how many over a district level pace bowler can bowl at a stretch in practice session. In the present study ten (10) male pace bowlers 18 to 23 years from Paschim Medinipur West Bengal were selected for this study. Data on selected physiological parameters namely pulse rate, blood lactate were measured prior to the first over and Rate of perceived exertion (RPE) and performance variable ball accuracy were measured after the 1st over and immediately after the completion of each 3rd, 5th, and 8th overs, by using digital sphygmomanometer, blood lactate analyser (Accutrend plus) and Borg scale respectively. The basic statistical parameters were calculated for all the data: the mean and standard deviation. One-way, repeated measures ANOVA were performed to determine differences in the respective 8- over spell. The result shows that all the physiological variables were significantly changed during a longduration of bowling spell. And no significant difference was found on bowling Performance variable ball accuracy during the 8-over spell on cricket pace bowling performance. It may be concluded that a district level pace bowler can bowl constant 8- over bowling spell at a stretch in practice session in West Bengal environment conditions.

Improved Muscle Activity Following Motor Training Without Vision of the Throwing Motion in Baseball Pitchers

Throwing motion without vision has the potential as a training method to improve proprioception by concentrating more on joint movements in throwing. Therefore, the purpose of this study was to suggest a method of training motor sense, which can improve ball velocity and the pitchers’ control (target accuracy). The study population consisted of 20 high school and college baseball players. Rotator cuff and elbow joint muscle activation, ball velocity, and ball accuracy in the stride, arm cocking, acceleration, and deceleration phases during throwing the ball with maximum effort (TBME) with or without vision were measured.

Shooting Ball Accuracy with U16 Soccer Players after Preparation Period

Shooting Ball Accuracy with U16 Soccer Players after Preparation Period

The Influence of Machining Conditions on Performance of Diamond Grinding of Silicon Carbide Ceramic Balls

The paper presents some results of an experimental investigation of the influence of machining conditions on the process of diamond grinding of silicon carbide ceramic balls. The process performance parameters are the rate of the ball diameter reduction, the rate of change (decreasing/increasing) of the deviation from spherical form, and the rate of change of the variation of ball lot diameter. To separate the portion due to solely the influence of the machining conditions, the authors have applied a method of graphical approximation of the time behavior of mean value of ball accuracy characteristics per batch. It has been found out that the separated portions can change upwards or downwards depending on the values of the machining conditions, namely: diamond wheel infeed, wheel feed rate, and ball-holder table rotational speed. The full factorial experiments of type 23 have revealed the most effective (for correcting the ball shape) combination of the factors studied, which is different for each of the three ranges of such deviation: above 300 μm, within 150–300 μm, and below 150 μm.

Effects of Repeated-Sprint Training in Hypoxia on Tennis-Specific Performance in Well-Trained Players.

This study examined the physiological, physical and technical responses to repeated-sprint training in normobaric hypoxia [RSH, inspired fraction of oxygen (FiO 2 ) 14.5%] vs. normoxia (RSN, FiO 2 20.9%). Within 12 days, eighteen well-trained tennis players (RSH, n=9 vs. RSN, n=9) completed five specific repeated-sprint sessions that consisted of four sets of 5 maximal shuttle-run sprints. Testing sessions included repeated-sprint ability and Test to Exhaustion Specific to Tennis (TEST). TEST’s maximal duration to exhaustion and time to attain the ‘onset of blood lactate accumulation’ at 4 mMol.L −1 (OBLA) improvements were significantly higher in RSH compared to RSN. Change in time to attain OBLA was concomitant with observations similar in time to the second ventilatory threshold. Significant interaction (P=0.003) was found for ball accuracy with greater increase in RSH (+13.8%, P=0.013) vs. RSN (–4.6%, P=0.15). A correlation (r=0.59, P<0.001) was observed between change in ball accuracy and TEST’s time to exhaustion. Greater improvement in some tennis-specific physical and technical parameters was observed after only 5 sessions of RSH vs. RSN in well-trained tennis players.

Effects of Point of Aim on the Accuracy and Eye Movement Behavior in Bowling: A Pilot Study

Background: A common research question in far-target aiming has been the importance and significance of the final visual fixation before movement initiation. In rolling tasks, such as 10-pin bowling, location of point of aim needs not be at the final target, the pins, but may be located at any point along the trajectory of the ball. Objective: Specific interest in the present experiment has focused on the relationship between visual point of aim and performance accuracy, and the relationship of visual control strategies utilized by expert performers. Methods: Skilled bowlers (N=7) performed 20 trials per condition concentrating on visual targets in different distances along the bowling lane (20, 40, 60 feet, and self-selected). Ball trajectory was tracked using a video based system and eye movement was measured using an eye tracking system. Results: Deviation of the ball from the visual target increased with visual target distance, while deviation of the ball from the pins was the lowest in the self-selected visual targets, followed by aiming at the pins. The final fixation duration before movement initiation was not associated with ball accuracy regardless of visual target locations. However, results demonstrated the association between final fixation duration task difficulty, that is, longer final fixation duration with increased visual target distance. Conclusion: The results indicate that visual fixations before movement initiation are uncharacteristically long while visual fixations just before the completion of the movement are relatively short.

Technical and tactical skills related to performance levels in tennis: A systematic review

ABSTRACTThe aim of this systematic review is to provide an overview of outcome measures and instruments identified in the literature for examining technical and tactical skills in tennis related to performance levels. Such instruments can be used to identify talent or the specific skill development training needs of particular players. Searches for this review were conducted using the PubMed, Web of Science, and PsycInfo databases. Out of 733 publications identified through these searches, 40 articles were considered relevant and included in this study. They were divided into three categories: (1) technical skills, (2) tactical skills and (3) integrated technical and tactical skills. There was strong evidence that technical skills (ball velocity and to a lesser extent ball accuracy) and tactical skills (decision making, anticipation, tactical knowledge and visual search strategies) differed among players according to their performance levels. However, integrated measurement of these skills is required, because winning a point largely hinges on a tactical decision to perform a particular stroke (i.e., technical execution). Therefore, future research should focus on examining the relationship between these skills and tennis performance and on the development of integrated methods for measuring these skills.

Technical Alterations during an Incremental Field Test in Elite Male Tennis Players.

We investigated technical and physiological responses along with their relationships during an incremental field test to exhaustion specific to tennis (TEST) in elite players. Twenty male elite tennis players completed TEST, which consisted of hitting alternatively forehand and backhand strokes at increasing ball frequency (ball machine) every minute. Ball accuracy (BA), ball velocity (BV), and tennis performance (TP) index (TP = BA × BV) were determined by radar and video analysis for each stroke, in addition to cardiorespiratory responses and blood lactate concentrations. At low intensities (less than 80% of maximal oxygen uptake [V˙O2max]), technical performance was steady. From 80% to 100% of V˙O2max, significant and steady decreases in BV (-9.0% and -13.3%; P = 0.02 and P = 0.002), BA (-19.4% and -18.4%; both P < 0.001), and TP (-27.4% and -29.15%; both P = 0.002) occurred for forehands and backhands, respectively. Changes in TP and blood lactate concentration from 60% to 100% of V˙O2max were inversely correlated (r = -0.51, P = 0.008). BV was 5.2% higher (P = 0.042) for forehand versus backhand, and there was no difference between strokes for both BA (P = 0.930) and TP (P = 0.536). Technical alterations (i.e., decrease in BV, BA, and TP) in elite players undergoing TEST only occurred at high intensity (>80% of V˙O2max), presumably because of the use of compensatory strategies to overcome fatigue. Above this intensity, all technical indices decreased steadily until exhaustion, independently of the stroke nature.

Does stride length play a role in cricket fast bowling performance outcomes? An observational, cross-sectional study

The aim of this study was to determine the effect of delivery stride length on the performance outcomes of ball release speed, accuracy and ball release height within a large cohort of elite male cricket fast bowlers. Data for this observational, cross-sectional study were collected from national under 19, senior state and international level players over a four-year period. No statistically significant differences were found between the three stride length groups (short, medium and long). However, a functional difference in accuracy was evident between short and long stride length groups, with the long stride length group being less accurate (effect size (ES) = 0.8; ES confidence interval (CI) = 0.2–1.4). Therefore, it can be concluded, given the results of the current study and previous injury-related research, that in no way is it advantageous for bowlers to have a stride length that exceeds the recommended 75–85% of standing height.

Gluteus medius kinesio-taping: the effect on torso-pelvic separation, ball flight distance and accuracy during the golf swing

Background. The kinesio-taping method, which is becoming increasingly popular, may provide support and stability to joints and muscles without inhibiting range of motion. Objective. The aim of the study was to determine the effect of kinesio-taping of the gluteus medius muscle on x-factor (torsopelvic separation), ball flight distance and accuracy (smash factor ratio). A specific aim was to determine whether a correlation exists between hip abduction strength and x-factor, ball distance and accuracy. Methods. This study is a one group pretest-posttest quasiexperimental design which took place at a golf facility. Twentynine amateur golfers with handicap of scratch ±2, who were between the ages of 18- and 25-years, participated in this study. Biomechanical outcomes were recorded with and without kinesio-tape applied on the gluteus medius muscle of the trail leg. Biomechanical golf swing analysis with the iClub™ Body Motion System determined the x-factor at the top of the backswing. Ball flight distance and accuracy were measured with FlightScope® and dominant hip abduction strength was measured with the MicroFET Hand-held Dynamometer. Results. Kinesio-tape is effective in improving the relative hip abduction strength (p&lt;0.001), although the effect size was small (Cohen’s d=0.24). With regard to the biomechanical outcome measures, namely x-factor (p=0.28), ball flight distance (p=0.53) and accuracy (p=0.1), there was no significant improvement. Conclusion: Even though the relative hip abduction strength was improved, there was no effect on golf swing biomechanics. This can be explained due to the fact that x-factor, ball flight distance and accuracy are dependent on a combination of body movements to produce the golf swing. Keywords. Golf, X-factor, pelvic stability, taping

Research on Material Features in Design Technique of Tennis Materials

Tennis is being loved by more and more people now. Moreover, it is gradually becoming an important leisure and recreation activity. As for this, material features involved with tennis design is currently widely studied and noticed by scholars domestic and overseas. Based on the positive results obtained by researchers domestic and overseas, the paper further summarized and generalized the development process of tennis racket frame and the material features of tennis racket string. Besides, the technical process of tennis racket design is also analyzed. Eventually, by integrating the pressure carrying feature of tennis racket, by taking carbon fiber tennis racket as the example, the paper has calculated related mechanical indexes, so as to high-lighten its excellent performance. In addition, racket string also has significant influence on ball speed and accuracy rate. By looking up related literatures, the intrinsic relationship is also revealed.

Mixed-method pre-cooling reduces physiological demand without improving performance of medium-fast bowling in the heat

This study examined physiological and performance effects of pre-cooling on medium-fast bowling in the heat. Ten, medium-fast bowlers completed two randomised trials involving either cooling (mixed-methods) or control (no cooling) interventions before a 6-over bowling spell in 31.9±2.1°C and 63.5±9.3% relative humidity. Measures included bowling performance (ball speed, accuracy and run-up speeds), physical characteristics (global positioning system monitoring and counter-movement jump height), physiological (heart rate, core temperature, skin temperature and sweat loss), biochemical (serum concentrations of damage, stress and inflammation) and perceptual variables (perceived exertion and thermal sensation). Mean ball speed (114.5±7.1 vs. 114.1±7.2 km · h−1; P = 0.63; d = 0.09), accuracy (43.1±10.6 vs. 44.2±12.5 AU; P = 0.76; d = 0.14) and total run-up speed (19.1±4.1 vs. 19.3±3.8 km · h−1; P = 0.66; d = 0.06) did not differ between pre-cooling and control respectively; however 20-m sprint speed between overs was 5.9±7.3% greater at Over 4 after pre-cooling (P = 0.03; d = 0.75). Pre-cooling reduced skin temperature after the intervention period (P = 0.006; d = 2.28), core temperature and pre-over heart rates throughout (P = 0.01−0.04; d = 0.96−1.74) and sweat loss by 0.4±0.3 kg (P = 0.01; d = 0.34). Mean rating of perceived exertion and thermal sensation were lower during pre-cooling trials (P = 0.004−0.03; d = 0.77−3.13). Despite no observed improvement in bowling performance, pre-cooling maintained between-over sprint speeds and blunted physiological and perceptual demands to ease the thermoregulatory demands of medium-fast bowling in hot conditions.

Skilled throwers use physics to time ball release to the nearest millisecond

Skilled throwers achieve accuracy in overarm throwing by releasing the ball on the handpath with a timing precision as low as 1 ms. It is generally believed that this remarkable ability results from a precisely timed command from the brain that opens the fingers. Alternatively, precise timing of ball release could result from a backforce from the ball that pushes the fingers open. The objective was to test these hypotheses in skilled throwers. Angular positions of the hand and phalanges of the middle finger were recorded with the search-coil technique. In support of the backforce hypothesis, we found that when subjects made a throwing motion without a ball in the hand (i.e., without a backforce), they could not open the fingers rapidly, and they had lost the ability to time finger opening in the 1- to 2-ms range. In addition, relationships were found between the magnitude and timing of hand angular acceleration and finger (joint) extension acceleration. The results indicate that although a central command produced initial hand opening, precise timing of ball release came from a mechanism involving Newtonian mechanics, i.e., hand acceleration produced a backforce from the ball on the fingers that pushed the fingers open. In this mechanism, given the appropriate finger force/stiffness, correction for errors in hand acceleration occurs automatically because hand motion causes finger motion. We propose that skilled throwers achieve ball accuracy by computing finger force/stiffness based on state estimation of hand acceleration and that ball inaccuracy occurs when this computation is imprecise.

Shoe influence on actual and perceived ball handling performance in soccer

Purpose: Ball handling, the interaction between foot and ball, is the defining component of soccer. Soccer footwear was shown to influence ball velocity and ball accuracy during standardized kicking techniques. However, ball handling comprises all sorts of foot and ball interaction. Therefore, this research quantified general ball handling performance of soccer players wearing different footwear. Methods: Nineteen experienced soccer players performed a subjective and objective ball handling test. It included dribbling, juggling, lofted passing of stationary ball, one touch passing of rolling ball and one touch passing from aerial. Different footwear conditions included two soccer shoe models, a non soccer specific indoor court shoe and barefoot. Shoe performance was analyzed using repeated measures ANOVA and Bonferroni post-hoc tests (P < 0.05). Results: Objective performance measurements revealed only few statistically significant differences between footwear. In contrast, subjective perception measurements showed statistical differences between footwear. Subjects generally perceived soccer specific footwear as suited protective devices during ball handling and to be better suited for ball handling performance than non soccer specific footwear. Additionally, subjects tended to judge ball handling between the two soccer shoes to be different. However, subjective ball handling perception did not generally reflect objective performance of players. Conclusion: Footwear changes perception of ball handling performance. It may also alter actually measurable performance. Specific mechanisms allowing players to exhibit increased ball handling performance by use of footwear have not been identified yet. Thus, soccer research should also aim to establish suited biomechanical and mechanical protocols for the analysis of interface characteristics of foot and ball.

Physiological responses and bowling performance during repeated spells of medium-fast bowling

The aim of the present study was to investigate the relationship between physiological and performance responses during repeated 6-over fast-bowling spells. Six, first-class, medium-fast bowlers performed 2 × 6-over spells separated by 45 min of light activity. The 6-over spells were based on the Cricket Australia fast bowling skills test that is a set order of deliveries at a grid-based target. Ball speed, accuracy and full and final 5-m run-up speed were measured on each ball. Nude mass, heart rate, core temperature, capillary blood lactate, pH and glucose, perceptual measures of RPE and muscle soreness (MS) and repeated vertical jump efforts were measured prior to, during and following each spell. Results indicated no decrement (P = 0.41) and small effect sizes (d < 0.2) in bowling speed (125.7 ± 5.1 and 125.4 ± 4.5 km · h−1) or accuracy (40.4 ± 16.1 and 41.6 ± 18.0 AU) between spells 1 and 2. No differences (P = 0.6 − 0.8) were present between spells for heart rate, core temperature, lactate, pH, glucose, RPE, MS or vertical jump. Only final 5-m run-up speed showed a large correlation with ball speed (r = 0.70), while accuracy and speed were not correlated (r = 0.05). In conclusion, repeated 6-over spells in well-trained bowlers results in minimal performance decrement in mild conditions (22°C). As faster bowlers had faster final 5-m run-up speeds, the maintenance of high final 5-m run-up speeds might be important to maintaining bowling speed. Future research should also include a third bowling spell and warmer environmental conditions.

The effect of altered pitch length on performance and technique in junior fast bowlers

The aim of this study was to assess the effect of pitch length (20.12 m [full length], 18 m and 16 m) on the fast bowling performance and technique of junior cricketers. Performance measures included ball release speed and accuracy, while technique variables evaluated were those shown to be related to the aetiology of lower back injury. Thirty-seven fast bowlers from the under-11 (n = 14), under-13 (n = 11) and under-15 (n = 12) age groups were filmed bowling five deliveries at each of the above pitch lengths. Two synchronized NAC video cameras operating at 200 Hz permitted three-dimensional reconstruction of the hip and shoulder alignments, while a standard digital video camera operating at 50 Hz (positioned perpendicular to the bowling action) was used to measure front knee angle and ball release speed. Accuracy scores were taken from a zoned target at the batsman's stumps. A two-way analysis of variance with repeated measures (with age and pitch length as the between- and within-participant variables, respectively) was used to compare each age group at the 0.05 significance level. Results showed that accuracy improved in all age groups at shorter pitch lengths, although ball velocity remained constant throughout all trials. Shoulder counter-rotation increased significantly for the under-13 bowlers when bowling on the full-length pitch in comparison with the two shorter lengths. Counter-rotation also increased on the full-length pitch in the under-11 age group, although this increase was not significant. The under-15 bowlers' techniques did not change as pitch length increased. As under-11 and under-13 bowlers adopted a “safer” bowling action with superior accuracy on the 18 m compared with the full length pitch, it was concluded that these age groups should bowl on an 18 m pitch to reduce the likelihood of lower back injuries and improve accuracy.