Fitness Level of Young Female Competitive Basketball Players

Defending beach volleyball attacks requires good anticipation skills due to the highly time-constrained situations (Vansteenkiste et al., 2014). For examining the underlying mechanisms of these skills, using virtual reality is a promising approach because speci fi c variations of players ’ movements can be manipulated (e.g., the run- up of the attacker) to evaluate important cues for anticipating attacks. As a 1st step, animated virtual-reality scenes were created from natural beach volleyball attacking sequences by manually animating players ’ movements in Autodesk 3dsMax. Four conditions of attacking scenes were created: animated occluded, animated not-occluded, natural occluded, and natural not-occluded. In occluded trials, videos were occluded 5 video frames (167 ms) before ball – hand contact of the attacker. Participants were instructed to decide as accurately as possible (accuracy in %) in occluded trials and to respond as fast as possible (response time in milliseconds) in nonoccluded trials. Eighty-two sport science students were tested in 120 trials with the same 30 mother trials in each condition (counterbalanced order). Videos were back-projected on a large screen, and participants responded using a 3-button response system (WiiMote). After the study, participants evaluated the animated scenes with a questionnaire. Response accuracy was analyzed with paired t tests. Performance was lower for animated scenes compared with natural scenes (55.3 % vs. 64.4 %), t (81) ¼ 7.06, p , .01, d ¼ 0.71), and participants responded later in animated compared with natural scenes ( – 170 ms vs. 2 237 ms before ball – hand contact), t (81) ¼ 7.46, p , .01, d ¼ 0.32. Lower accuracies in animated scenes imply that visual cues were less helpful for anticipation. Questionnaire data revealed that the dynamics of a shot negatively affected anticipation in animated scenes and that rather late cues were used for decisions, which could explain the later responses. Future virtual-reality applications should especially focus on the animation of relevant visual cues and the dynamics of the attack. q 2016 SHAPE America Downloaded by [Deutsche Sporthochschule Koeln] at 02:21 20 July 2016 Development and Position Data-Related Application of a Stochastic Model for Trajectory Simulation of a Nonspinning Volleyball B. Meyer University of Brunswick, Canada ( [email protected] ) Background/Purpose: Modeling the knuckling effect in volleyball aerodynamics is essential for representing and analyzing erratic motion in a competition-related task. Based on net crossings of constant height (cf. Lithio & Webb, 2006), this study investigated the in fl uence of position data on uncertainty quanti fi cation in numerical ball fl ight trajectories evaluation. Method: The addition of Langevin forces for drag and lift to measured mean values taken from Asai et al. (2010) covers parameter uncertainty modeling in Newton ’ s 2nd law, while taking into consideration only 1 low-frequency component with magnitude as proposed by Wei, Lin, and Liu (1988) and phase angle as a random variable. To simplify output uncertainty modeling, an analysis of s _{LP}^{2}, the variance of landing points, based on Wiener-Askey polynomial chaos expansion using Legendre polynomials, is carried out. Calculated ratios of Sobol ’ s indexes (17.8 ^ 3.8, Q_{0.05} ¼ 11.5) for a wide range of initial values of velocity (11.1 – 23.6 ms^{ – 1}) and elevation angle (10 8 – 21 8 ) indicate a dominant effect driven by drag-force fl uctuations and enable a reduction in the number of random variables. Furthermore, using lift coef fi cient-induced dimension reduction results in neglect of the lateral direction of fl ight (cf. Goff & Carré, 2009) corresponding to a moderate relative error in s _{LP}^{2} (3.4 ^ 1.7%). Methods chosen for a subsequent charac- terization of fl uttering fl ights include time-averaging 99% con fi dence interval lengths for magnitude of position vector as well as Gauss-Legendre integration for calculation of s _{LP}^{2}. Additionally, a calibration of results based on recalculation assuming a speed- independent drag coef fi cient is used. Analysis/Results: Overall, numerical simulations reveal a predominant occurrence of effective volleyball knuckle- balls for the low-value range of initial conditions and a smooth decrease to higher values. Conclusions: Optimizing tactics in fl oat-serving play and volleyballs engineering outline potential fi elds of application. Moreover, model application without uncer- tainty quanti fi cation may include sensitivity analysis- based investigation of perceptual trajectory illusion (McBeath, 1990). Fitness Level of Young Female Competitive Basketball Players P. F. Aschendorf, C. Zinner, and J. Mester German Sport University Cologne, Germany ( [email protected] ) Introduction: Physiological testing of team-sport athletes is a fundamental element for designing training and for tracking each athlete ’ s and team ’ s development. To evaluate the athletic status of young elite female basketball players, several anthropometric and physio- logical tests were conducted. Methods: Seventy young female basketball players ( M age ¼ 14.7 ^ 1.2 years) were tested for height, body weight, body fat, vertical jump, standing long jump (SLJ), chest pass (CP), and the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR 1). Results: The female basketball players were 171 ^ 7.3 cm tall, weighed 61.8 ^ 8.8 kg with a body fat of 16.9 ^ 5.15%. For the different vertical jumps, the highest heightwasmeasuredinthecountermovementjump(CMJ) with arm swing (31.1 ^ 4.86 cm). The mean jump heights were 27.14 ^ 3.97 cm for the CMJ, 25.62 ^ 3.89 cm for the squat jumps, and 158 ^ 60 cm for the SLJ. The distance for the CP was 9.82 ^ 1.01 cm. The mean distance covered during the Yo-Yo IR 1 was 1,465.8 ^ 464.7 m (estimated peak oxygen consumption ¼ 48.60 ^ 4.02 mL/kg/min). Discussion: Compared with results of previously published studies, the adolescent players were smaller and less heavy but showed a similar CMJ jump height. Furthermore, the endurance level was lower than in previously published studies (58.8 ^ 6.85 mL/kg/min). Therefore, basketball-speci fi c training interventions are needed to improve the fi tness level of young female basketball players speci fi cally