75 Hz for GRFs 12 and 10 Hz for marker trajectories. 13 According to a previous study, 14 the timing of foot-ground contacts was determined using a threshold greater than 16 N of vertical GRF. The GRF variables analyzed were the peak vertical forces, peak braking (posterior direction
Atsushi Makimoto, Yoko Sano, Satoru Hashizume, Akihiko Murai, Yoshiyuki Kobayashi, Hiroshi Takemura and Hiroaki Hobara
Javier Yanci, Daniel Castillo, Aitor Iturricastillo, Tomás Urbán and Raúl Reina
high international repercussion, footballers with CP deserve special attention. Most research has investigated the physical characteristics of footballers with CP, such as cardiovascular capacity, running economy, 4 changes of direction (CODs) ability, 5 jump capacity, muscle strength, and anaerobic
Wim H. van Lier, John van der Kamp and Geert J.P. Savelsbergh
We assessed how golfers cope with the commonly observed systematic overshoot errors in the perception of the direction between the ball and the hole. Experiments 1 and 2, in which participants were required to rotate a pointer such that it pointed to the center of the hole, showed that errors in perceived direction (in degrees of deviation from the perfect aiming line) are destroyed when the head is constrained to move within a plane perpendicular to the green. Experiment 3 compared the errors in perceived direction and putting errors of novice and skilled players. Unlike the perceived direction, putting accuracy (in degrees of deviation from the perfect aiming line) was not affected by head position. Novices did show a rightward putting error, while skilled players did not. We argue that the skill-related differences in putting accuracy reflect a process of recalibration. Implications for aiming in golf are discussed.
Uta Sailer, Florian Güldenpfennig and Thomas Eggert
This study investigated the effect of hand movements on behavioral and electro-physiological parameters of saccade preparation. While event-related potentials were recorded in 17 subjects, they performed saccades to a visual target either together with a hand movement in the same direction, a hand movement in the opposite direction, a hand movement to a third, independent direction, or without any accompanying hand movements. Saccade latencies increased with any kind of accompanying hand movement. Both saccade and manual latencies were largest when both movements aimed at opposite directions. In contrast, saccade-related potentials indicating preparatory activity were mainly affected by hand movements in the same direction. The data suggest that concomitant hand movements interfere with saccade preparation, particularly when the two movements involve motor preparations that access the same visual stimulus. This indicates that saccade preparation is continually informed about hand movement preparation.
Florian Loffing and Norbert Hagemann
When anticipating future events like an opponent’s stroke direction in tennis, players are assumed to rely on both kinematic and contextual cues such as an opponent’s on-court position. However, knowledge of position dependency in shot-direction probabilities and experimental evidence of the effect of on-court position on action-outcome anticipation is missing. Here we show that shot-direction probabilities vary as a function of a hitting player’s on-court position in professional tennis. Moreover, unlike novices, skilled players in particular relied on information about an opponent’s position when anticipating forehand baseline shot direction in a video-based experiment. The position dependency in skilled players’ prediction behavior was most evident when little information on an opponent’s stroke kinematics was available. Findings suggest that skilled players consider the reliability of different information sources by weighting the available contextual and kinematic cues differently in the course of an opponent’s unfolding action.
Roya Khanmohammadi, Saeed Talebian, Mohammad Reza Hadian, Gholamreza Olyaei and Hossein Bagheri
The purpose of study was to demonstrate age-related changes during gait initiation (GI). Therefore, displacement, velocity, total power, mean and median frequency of COP trajectories were measured during phases of GI in anteroposterior (AP) and mediolateral (ML) directions. The older group demonstrated the slower and lesser displacement in comparison with the younger group during anticipatory phase in AP direction and during locomotor phase in AP and ML directions. In addition, the median and mean frequency were greater in the older relative to the younger group during anticipatory phase in AP direction, while these were lesser in older than younger group during locomotor phase in AP and ML directions. Moreover, total power was greater among older than younger adults during the anticipatory phase in ML direction and during all phases in AP direction. This study suggests that COP-related parameters extracted from time and frequency domains have the ability to demonstrate age-related changes.
Moataz Eltoukhy, Christopher Kuenze, Jeonghoon Oh, Eryn Apanovitch, Lauren Butler and Joseph F. Signorile
mechanisms, like pivoting, sudden deceleration, and direction change without player contact. 4 Noncontact ACL injury occurs frequently in sports that involve cutting maneuverers, 5 causing short- 6 , 7 and long-term morbidity. 8 Specifically, young females have been consistently shown to experience
Cornelius John, Andreas Stotz, Julian Gmachowski, Anna Lina Rahlf, Daniel Hamacher, Karsten Hollander and Astrid Zech
their shoes on and jump off the box with both feet in the direction of the landing line. Immediately after landing, the participant had to rebound for a maximal vertical jump. To assure that the participants understood the task and to avoid any incorrect trials, participants were asked to conduct some
Nick Dobbin, Jamie Highton, Samantha L. Moss and Craig Twist
.3) 42.5 (5.2) 0.63 (0.12) Most likely ↑ 1.12 (0.12) Most likely ↑ 0.70 (0.14) Most likely ↑ Change of direction, s 20.31 (1.22) 20.44 (1.30) 19.68 (0.84) 0.10 (0.13) Likely trivial −0.46 (0.14) Most likely ↓ −0.60 (0.13) Most likely ↓ Medicine-ball throw, m 6.3 (0.9) 7.1 (0.8) 8.1 (0.8) 1.00 (0.14) Most
Gretchen D. Oliver, Jessica K. Washington, Sarah S. Gascon, Hillary A. Plummer, Rafael F. Escamilla and James R. Andrews
major contributor in pelvic stability. The independent variables in this study were time and event of the throwing motion for each kinematic variable, and time, side, and direction for each pROM variable. The dependent variables were shoulder horizontal abduction, shoulder elevation, shoulder rotation