How do athletes cause ball flight path deviation in high-performance interceptive ball sports? A systematic review

Athletes alter ball flight trajectory in interceptive ball sports to change task constraints that their opponents must overcome to successfully meet the ball in flight. This systematic review identified how athletes change their techniques to alter the ball flight trajectory in high-performance interceptive sports where the ball is projected by the hand towards an opponent. Studies that reported the kinematics or ball flight characteristics of these movements were searched for using SportsDiscus, Scopus, MEDLINE and CINAHL Plus databases up to 27 April 2021. Forty-eight articles met the inclusion criteria, including 19 baseball, 12 cricket, five handball, four softball, three volleyball and five water polo studies. Extracted data were presented as ranges and descriptively analysed to report athlete sporting actions. Trajectory deviation can be caused by imparting an altered seam orientation or spin rate and axis of rotation on the ball. Athletes impart sidespin or manipulate seam orientation to cause lateral deviation while topspin and backspin are used to create vertical changes in the flight path. Adjusting the shoulder, forearm, wrist, hand and fingers of the throwing or striking arm can be used to impart an altered seam orientation or spin rate and axis of rotation on the ball. The findings of this review could assist coaches and athletes across a variety of sports to improve the ability to deviate the ball during flight.

Robot Anticipation Learning System for Ball Catching

Catching flying objects is a challenging task in human–robot interaction. Traditional techniques predict the intersection position and time using the information obtained during the free-flying ball motion. A common pain point in these systems is the short ball flight time and uncertainties in the ball’s trajectory estimation. In this paper, we present the Robot Anticipation Learning System (RALS) that accounts for the information obtained from observation of the thrower’s hand motion before the ball is released. RALS takes extra time for the robot to start moving in the direction of the target before the opponent finishes throwing. To the best of our knowledge, this is the first robot control system for ball-catching with anticipation skills. Our results show that the information fused from both throwing and flying motions improves the ball-catching rate by up to 20% compared to the baseline approach, with the predictions relying only on the information acquired during the flight phase.

Clustering Golfers through Force Plate Analysis

Golf is a sport which requires players to use ground interaction to generate clubhead speed in order to propel the ball towards the target. Force platforms are a technology which can be used to measure these ground reaction forces. Golfers generate force through a combination of jumping, sliding or twisting actions during the swing. Understanding how golfers generate these forces and if there are any groups which golfers could be clustered into could be used to enhance golf instruction as well as clubhead design or fitting practices for golf equipment. A total of 105 right-handed experienced golfers (handicap mean = 8.32 ± 8.31) consented to participate in the study of different swing speeds (31 below 95 mph, 41 over 105 mph and 33 between 95 and 105 mph). A calibrated single force plate was used for the test which sampled at 1000 Hz and recorded force and moment data in three axes. After a self-guided warm up, the players were instructed to hit five 7-iron shots and five drives to the best of their ability in an indoor hitting bay which used a launch monitor to record the club delivery and ball flight information. It was found that handicap or swing speed did not dictate the primary force production mechanism (sliding, jumping or twisting/spinning). This knowledge could aid engineers to design equipment better suited to the individual and help coaches build individualized programs to create power and clubhead speed in all players.

Influence of Grip Mass on Driving Performance

The purpose of the study was to determine the influence of grip mass on driver clubhead kinematics at impact as well as the resulting kinematics of the golf ball. Three club mass conditions (275, 325, and 375 g) were tested by 40 experienced golfers (handicap = 7.5 ± 5.3) representing a range of clubhead speeds (36 to 54 m/s). Each participant executed 12 drives per condition using matched grips and shafts and a single clubhead. Club mass was modified by inserting 50 g and 100 g into the grips of the two heavier conditions. The heaviest condition was associated with the slowest clubhead speed (p = 0.018) and highest vertical launch (p = 0.002), which resulted in no net influence on driving distance (p = 0.91). Lateral dispersion was greatest with the 325 g condition (p = 0.017), as was horizontal impact spot variability on the driver face (p = 0.031). Findings at the individual golfer level were not reliable enough to suggest that grip mass could be effectively used in a fitting environment to either shift ball flight tendencies or improve consistency.

THE EFFECTS OF A SPECIFIC TRAINING PROGRAM ON THE KINEMATIC PARAMETERS OF THE JUMP SHOT AMONG ELITE FEMALE HANDBALL PLAYERS

The aim of this research was to determine the effects of an eight-week specific training program on the kinematic parameters of the jump shot at 9m from the goal, among elite female handball players. The sample of participants consisted of 30 female handball players (height: 1.73±0.08 m; mass: 69±8.9 kg; body mass index-BMI 22.9±2 kg/m2; training experience: 12.3±6.2 yrs), competing in the first national handball league of the Republic of Serbia. The research was longitudinal in nature, with an initial and final measuring. The experimental treatment included a 30 min replication of the regular training session, with specifically designed exercises (work with medicine balls, stabilizer training, and strength training in a gym). 12 kinematic variables of the jump shop were analyzed using the Kinovea software program, ver. 0.8.2. The analysis of covariance and the effect size (ES) determined a positive effect of the specific program on the kinematic parameters of the jump shot, especially on the variables of height and maximal ball flight velocity.

Studies and simulations on the flight trajectories of spinning table tennis ball via high-speed camera vision tracking system

When a table tennis ball is hit by a racket, the ball spins and undergoes a complex trajectory in the air. In this article, a model of a spinning ball is proposed for simulating and predicting the ball flight trajectory including the topspin, backspin, rightward spin, leftward spin, and combined spin. The actual trajectory and rotational motion of a flying ball are captured by three high-speed cameras and then reconstructed using a modified vision tracking algorithm. For the purpose of model validation, the simulated trajectory is compared to the reconstructed trajectory, resulting in a deviation of only 2.42%. Such high modeling accuracy makes this proposed method an ideal tool for developing the virtual vision systems emulating the games that can be used to train table tennis players efficiently.