PELVIS-SHOULDER MOVEMENT VARIABILITY AND CUETIP MOTION DURING THE WARM-UP AND FINAL STROKES IN POOL

The purpose of this study was to investigate the variation and variability of cuetip, shoulder and pelvis on stop shot, push shot and draw shot during warm-up strokes (W3, W2, W1) and final stroke (FS). Eight cameras were used to determine three-dimensional motions of cue, shoulder and pelvis for a pool world cup championships winner. The results showed that the largest variation was presented in the final stroke as well as the greatest consistence through trials. Variation of shoulder and pelvis was supposed an essential factor for a pool shoot. The cuetip, shoulder, and pelvis all demonstrate the similar pattern with greatest variability in first warm stoke and greatest consistence on the final stroke. The variability will converge to from the warm-up strokes to the final stroke

LOWER LIMB STABILIZATION STRATEGIES OF DART ATHLETES AT DIFFERENT LEVELS

The purpose of the study was to understand lower limb stabilization strategies during the acceleration phase of dart throwing in athletes at different levels. Multi-Axis Force Plates and 3D Motion Capture were adopted to collect data. Six male darts athletes, including three elite athletes and three sub elite athletes, throw darts to hit Bull\u27s Eye abiding the rules of the World Darts Federation. The study shows that during acceleration phase, the ground reaction force of elite athletes changes substantially, while the change of ground reaction force of sub elite athletes was relatively small. Significant difference of the change in the front foot ground reaction force (GRF) on a vertical axis is reached (p\u3c0.05). The cause may be because the elite players use greater GRF transition from rear foot and front foot than sub elite players. On the contrast, sub elite athletes are still in the stage of integration, thus lower limb movement is minimized in order to stabilize the throw

Ground Reaction Forces of Dart-Throwing at Different Target Heights

The purpose of the study was to explore whether dart players produce different lower limb control strategies when throwing darts at spatially separated targets in the vertical direction. Eight experienced darts players (height 1.75±0.04 m, mass 83.4±19.3 kg) participated in this research. Two Multi-Axis Force Plates were used to collect GRF data on both legs and synchronized with a Motion Capture System. The participants threw darts at three targets at different heights, which were the upper section of the 20 point area, bullseye and lower section of the 3 point area. The results showed that the amplitude of anterior-posterior GRF of their front legs were significantly different when darts was thrown at the 20 zone, bullseye and 3 zone respectively. Our study found that the braking forces of the front legs were greater when a dart was being thrown at the highest target (20 points) than when it was being thrown at the lowest target (3 points)

KINETIC PROPERTIES AND EMG ACTIVITY OF NORMAL AND OVER-SPEED PEDALING IN TRACK SPRINT CYCLISTS: A CASE STUDY

Track sprint cycling requires unique skills. We investigate the pedaling kinetics and muscle coordination of a male track sprinter (170cm, 65kg, peak power 1513W) to see if they differ from that of a non-sprinter, and if the subject’s own technique vary from normal riding to an under-load maximal cadence sprint. Two trials were collected using 3D motion capture technology. EMG signals of 8 leg muscles were recorded. Joint torque and power of each trial were calculated using a subject specific musculoskeletal model, with realistic pedal forces as input to our dynamic simulation. Flexion torque appears at the knee during its extension, different from the non-sprinters. Joint torque and power appears similar for both trials, but 6 of the 8 muscles showed differences in EMG patterns. These findings could potentially benefit the evolvement of training methods

THE CORRELATION OF GOLF PUTTING CLUB HEAD VELOCITY AND GRIP FORCE FOR EACH PHASE

We investigate the correlation of golf putting club head velocity and grip force in different phases during the putting stroke. Five elite college players (handicap: 2~8) executed a putt as accurately as possible to reach a target distance of 12ft. The Novel System and were used to measure the grip force and club head velocity. The lowest club head velocity and grip force both occurred at address up to the top of backswing (phase I). The club head velocity and grip force started increasing during the downswing and reached its peak before impact (phase II), and decreased after impact to finish (phase III). The mean club head velocity and grip force for Phase I, II, III in order are 0.33m/s, 0.92m/s, 0.87m/s; 28.09N, 54.77N, 50.76N. Club head velocity was significantly correlated to grip force in phase II and III (r=0.937; r=0.866). The similar variation pattern of club head speed and grip force may give better control to the putter during the impact and produce more consistent putting stroke

The Influence of Court Surfaces on Lower Limb Muscle Activation of Tennis Run-and-Stroke

This study aimed to examine the characteristics of lower extremity muscle activity between different tennis court surfaces. Six male right-handed elite tennis players were recruited, and their electromyography activity (EMG) during open stance running forehand were collected. Average activity level of rectus femoris (RF), biceps femoris (BF), gastrocnemius (GAS), tibialis anterior (TA) from the lead leg, which normalized by maximal voluntary isometric contractions (MVC) was recorded under different situation (hard court, grass court, clay court). Our study demonstrates that GAS was significantly different and the activation level was greater on a hard court than on clay (p = .005). Tennis players should enhance their gastrocnemius muscle performance when matching from clay to hard court to avoid a higher level of gastrocnemius activation when adapting to a different court, which could lead to an injury. KEYWORDS: Grand Slam, training, EMG, performanc

DISTRIBUTION OF GRIP PRESSURE THROUGHOUT THE PHASES OF PUTTING IN ELITE GOLF COLLEGE PLAYERS

The purpose of this study is to investigate the distribution of grip pressure, force and the peak pressure of different phases during the putting stroke. Five elite college players with handicaps of 2-8 participated in the study. The Novel Pliance-x System and 150Hz 8- camera Motion Analysis Corporation System were used to collect grip pressure and identify each phase of the putting stroke. At each phase of the putting stroke, average grip pressure, peak pressure and grip force were investigated. Results indicated that lowest grip pressure occurred at address up to the top of backswing (2.41±1.36 Kpa). Grip pressure started to increase during the downswing and reached its peak, 0.02±0.05s, before impact (4.70±1.97 Kpa). The pressure reduced again after impact (4.36±2.06 Kpa). Results indicate that grip pressure does not remain the same throughout the stroke

KINEMATICS ANALYSIS OF THE UPPER EXTREMITY DURING THE TWOHANDED BACKHAND DRIVE VOLLEY FOR FEMALE TENNIS PLAYERS

The purpose of this study was to discuss the motion characteristics of the arms in the two-handed backhand drive volley. Five elite female tennis players participated in this study, their two-handed backhand drive volley strokes were analysed, and all participants are right handed. Motion Analysis System with 10 Eagle Digital inferred high speed cameras at 200Hz were used for this study. The results show a similar elbow and wrist speed strategy in x-axis between two-handed ground stroke and drive volley, our study also found that the rear arm dominates the stroke and mainly provide the topspin that is required for the skill of the drive volley. In order to create better stroke efficiency, the right elbow reached peak velocity first, followed by the right wrist before racket impact with the ball