Table 2 also shows the data relative to the velocity and space tr

Table 2 also shows the data relative to the velocity and space travelled in the vertical components of the CM��s movement at the moment of the ball��s release (VZ-REL and eZ-REL, respectively) as well as 100 ms before the release (VZ-100 and eZ-100, respectively). The measures of central tendency on the goalkeepers�� vertical movements show statistically significant differences between expert and inexperienced subjects (F(1, 68) = 4.96, p = 0.03). During the anticipation period, the experts demonstrated a clear tendency to lower their CM with a slower velocity than did their counterparts (VZ-REL) (?0.16 �� 0.21 and ?0.32 �� 0.33, respectively) and therefore moved a shorter distance at the moment of the ball��s release (ez-REL) (?0.03 �� 0.045m and ?0.055 �� 0.085m, respectively).

This lesser vertical movement of the CM in expert goalkeepers is substantiated by the values recorded for maximum vertical velocity during the anticipation phase (VZ-MAX), which was less for expert players than for inexperienced ones (?0.16 �� 0.22 m/s and ?0.24 �� 0.42 m/s, respectively). Moreover, the spatial data as well as the data on velocity components show less dispersion in expert goalkeepers. Discussion and conclusions As might be expected, the differences in the performance of both test groups confirm that the elite goalkeepers were efficient at gathering and interpreting information during the anticipation period, which was subsequently used to determine a precise intercepting movement with a higher percentage of success.

However, the inexperienced goalkeepers intercepted fewer throws, found it difficult to anticipate and identify the path of the throws, and more frequently moved in incorrect directions. When they moved in correct directions, they lacked sufficient precision. These results coincide with those of Ca?al-Bruland et al. (2010) and Vignais et al. (2009), who state that the ability to intercept a ball comes from precise technical execution, specifically of arm movements, and the ability to perceive cues up to the moment the ball leaves the player��s hand. The data gathered from the start of the goalkeepers�� movements, (TSTART-X) corroborate the studies of Savelsbergh et al. (2002, 2005) in which elite goalkeepers tended to begin movement before the thrower released the ball. The minor temporal difference in elite and inexperienced goalkeepers supports the study by Vignais et al.

(2009) reporting a similar response time between groups with varying experience levels. Nonetheless, the statistical values for the start of lateral movement, (TSTART-X), are lower than those of Savelsbergh et al. (2002), who measured 230 ms for soccer goalkeeper using a joystick. These differences could be attributed to the Entinostat different movement structures analyzed: in our study, a complex body movement to intercept a ball, and a simple joystick movement in Savelsbergh et al. (2002).

99 years) They were all right-handed and able to perform first s

99 years). They were all right-handed and able to perform first serves. None of the participants played tennis outside the timetable for data collection during the research. All the participants provided informed consent according to the Declaration of Helsinki. The Extremadura University Ethical Committee selleck chemicals approved the procedure. Measures Product variables analyzed were stroke accuracy, measured by radial error (Robins et al., 2006), variable error, which represents serve errors made in respect of deviation from the serve target area, and the ball speed. Process variables (Table 1) were measured over the trajectory of the hand holding the racket along the antero-posterior (X), the transverse (Y), and the longitudinal (Z) axes.

With respect to non-linear variables, these give information about the structure and characteristics of the variability present in the time series. These time series were derived from the position of the hand holding the racket during its trajectory, from the beginning of the movement until the moment the racket hit the ball. Table 1 Dependent variables analyzed in the research. In each instant kinematic variable the standard deviation (SD) and the variation coefficient (CV) was analyzed Tasks, material and measurements Each tennis player performed 20 first serves. They were instructed to hit the ball with as much power and accuracy as they could, and to avoid sending the balls into the area known in tennis slang as the ��T�� (the line intersection which divides both service boxes from their respective service lines).

The ball bounce on the tennis court surface was video recorded in every serve (Sony HDR- HC3E). The video camera was set at a height of 3 meters and was positioned at the back of the court. In order to measure accuracy, a Visual Basic 5.0 application was developed (Menayo, 2010). This facilitated the calculation of real-space Cartesian coordinates for the ball bounces through a digitization process from the video recording of the serves. Non-linear kinematic variables were analyzed by using a software application created with Visual Basic 5.0, from an algorithm for calculating Approximate Entropy (Pincus, 1991). To measure ball speed, a radar gun (Sports Radar SR3600) was used. This radar device, which records the speed of moving objects with an accuracy of +/? 1 km/h, was positioned behind the tennis player, facing the direction of the stroke (Figure 1).

An electromagnetic motion tracking system Polhemus Fastrak? was used to record and analyze kinematic variables and this was connected to a computer (Toshiba Satellite 1900). This tracking system has 6 Degree-of-Freedom motion tracking sensors, with an accuracy of 0.08 cm for position (X, Y and Z Cartesian space coordinates) and 0.15 degrees for angular orientation (azimuth, elevation, and roll), and records at a frequency Drug_discovery of 120 Hz. Figure 1 Automated measurement system.

Written informed consent was received from all participants and p

Written informed consent was received from all participants and parents after detailed explanation about Volasertib cancer the aims, benefits, and risks involved with this investigation. Participants with self-reported history of neurological or musculoskeletal conditions affecting the balance control system were excluded from the study. Prior to testing, all participants completed a physical activity questionnaire (PAQ-C) to assess their basic activity level. Body height was measured and recorded in cm to the nearest mm. Body mass was measured to the nearest 0.1 kg with an electronic weight scale with the participant in shorts and T-shirt. BMI was calculated for each participant. The experimental session comprised of nine balance trials, three trials each of three sensory conditions, with each trial lasting 30 seconds in order to have reliable postural sway measures (Le Clair and Riach, 1996).

According to the findings of Geldhof et al. (2006) who used similar methods to the present study, the composite inter-test reliability of three trials has an ICC of 0.77. The sequence of the conditions was randomised with a one-minute rest period between conditions to avoid learning or fatigue effects. Participants were asked to stand barefoot quietly, with each foot on a separate force platform (1Hz, Models 4060-08 and 6090, Bertec Corporation, Columbus, OH, USA) embedded in the ground. Participants used a safety harness to prevent them from injury in case of an irrecoverable balance loss. The harness has proven to be safe without impeding natural quiet standing (Freitas et al., 2005).

The children stood with feet shoulder-width apart and arms hanging loosely at their sides for each trial. During the CONTROL and EOCS conditions, children were standing and gazed straight ahead at a 3 m far target. However, they were not required to fix their gaze on any particular spot. For the latter condition, a 10 cm thick layer of foam was placed on top of each force platform to interfere with somatosensory information from the feet and ankles. The COP and torque on the force platform were calculated from the force and moment components of the force platform data. The displacement of COP is the reaction to body dynamics (Winter, 1995) and follows the neuromuscular control signal to maintain the position the COM within the BOS and achieve equilibrium (Riley et al., 1990).

To obtain a quantitative description of standing ability, the following COP parameters were computed. COP path velocity (COP-PV): the average distance travelled by the COP per second. COP-PV is assumed to decrease with better balance performance. Brefeldin_A COP radial displacement (COP-RD): the mean radial distance of the COP from the centroid of the COP path over the entire trial. COP-RD data were normalized by expressing the results relative to the height of the participant. COP-RD is presumed to decrease with better balance performance.

Cohesion is understood as a ��dynamic process that is reflected i

Cohesion is understood as a ��dynamic process that is reflected in part by the tendency of a group to stick together and remain united in the pursuit of Brefeldin A protein transport its instrumental objectives and/or for the satisfaction of member affective needs�� (Carron et al., 1998). The conceptual model of Carron et al. (1998) consists of four dimensions: Group integration-Task (GI-T), Group integration-Social (GI-S), Individual attraction to the group-Task (ATG-T), and Individual attraction to the group-Social (ATG-S). To create profiles according to this construct, this study divides cohesion into task and social dimensions because these dimensions have been shown to have more differences with respect to performance (Leo et al., 2010a). Carron et al.

��s (2002) meta-analysis demonstrated the importance of determining whether social or task aspects were related to performance. Their work identified studies that used only two dimensions and hence demonstrated problems with the presentation of the four factors of cohesion (Heuz�� et al., 2006; Leo et al., 2012). Thus, in this study, we differentiate between task cohesion, which reflects the degree to which group members work together to achieve common goals, and social cohesion, which reflects the degree to which team members empathise with each other and enjoy the group fellowship (Carron et al., 1998; Carron and Eys, 2012). These two dimensions are generated by environmental, personal, leadership and team factors that affect the perception of cohesion and produce individual and collective results, such as an influence on performance (Carron and Eys, 2012; Heuz�� et al.

, 2006; Leo et al., 2010; Paskevich et al., 1999). Many studies have assessed players�� and coaches�� opinions of team members�� efficacy (Bandura, 1997; Chase et al., 1997; Lent and L��pez, 2002). Three main types of sports-related team efficacy (Beauchamp, 2007) are noteworthy: perceived coach efficacy reflects a trainer��s confidence in a player��s abilities to perform given tasks (Beauchamp, 2007; Chase et al., 1997); perceived peer efficacy in sports represents players�� beliefs in their teammates�� abilities to accomplish a task successfully (Lent and L��pez, 2002); and collective efficacy is a group��s shared belief in its joint ability to organise and execute the courses of action required to produce certain achievement levels (Bandura, 1997).

Players form a perception of efficacy through these aspects, which lead to knowledge, affective and behavioural consequences, such as Dacomitinib increasing or decreasing sport performance (Beauchamp, 2007; Watson et al., 2001). Numerous investigations have found a positive relationship between both psychological constructs��cohesion and perceived efficacy��and sport performance (Heuz�� et al., 2006; Kozub and McDonnell, 2000; Leo et al., 2010a; Paskevich et al., 1999; Ramzaninezhad et al., 2009; Spink, 1990; Myers et al., 2007).

In fact, the SEM micrographs (Fig 2) showed a good integration o

In fact, the SEM micrographs (Fig. 2) showed a good integration of the microparticles in the ceramic matrix, which was likely the more info reason for the increased mechanical strength for one of the cements. It was also clear from the SEM micrographs that the polymer microparticles were much larger than the brushite and monetite crystallites, which could also have an effect on the resulting strength of the cement. Since the polymer microparticles were produced by mechanical crushing of a solid piece,19 smaller particles are hard to produce and the yield is quite low; however, smaller particles could possibly increase the strength further, and might be good to investigate in future studies. Figure 5. Conceptual drawing of the composite setting reaction.

(1) An exchange of glycerol to water starts when the cement is immersed in body fluids at 37 ��C. (2) The ceramic grains start to dissolve and since the temperature is around … From the XRD results it could be concluded that the ��-TCP content measured for all groups was slightly higher than the 10 mol% excess that was added to the mixtures. However, this was not surprising since the fast dissolving MCPA might diffuse out from the cement before the proper amount of ��-TCP has been dissolved and can react to form the end product. Since ��-TCP has a limited solubility at physiological pH��it needs a lower pH to dissolve��and MCPA decreases the pH in the vicinity after dissolution, the excess ��-TCP will not be dissolved after all MCPA is consumed.

It has previously been observed that the main product after reaction for premixed acidic calcium phosphate cements is dicalcium phosphate anhydrous, or monetite,16,20 and not brushite, which is seen when MCPM (or MCPA) and ��-TCP is mixed directly with water. Under physiological conditions monetite is the more stable phase; however, the nucleation and growth demands high energies, due to the high energies needed to dehydrate calcium, and nucleation and growth of brushite is thus favorable.23,24 In conditions where an insufficient amount of water is present two things can occur with the result of monetite being formed after setting. Either nucleation of brushite occurs, which is then decomposed to monetite to release water and continue the reaction,25 or if no water is present and the temperature is high enough to bridge the energy needed for monetite formation, it is likely that monetite is formed directly.

However, in this study a large variation of the monetite vs. brushite ratio was seen. This could be explained by the PEG enclosed inside the polymer microparticles. PEG is highly hydroscopic and due to its high molecular weight compared with glycerol it is retained within the material for a longer time. In the vicinity Drug_discovery of PEG more water will be present than anywhere else in the material, thus the brushite will not be decomposed to monetite as easily as without the PEG.