The aim of the study was to determine whether there is empirical evidence for advantages in performance of soccer teams because of their relative age. The practice of selecting youth players according to their momentary performance leads to relative age effects, which in turn lead to inefficient talent selection. We used the median of the birth dates as a measure of the effect size of the relative age effect and the Kolmogorov-Smirnov test to assess its significance. For the 2008-2009 season, birth dates in the three German U-17 first leagues for soccer were examined (911 players). More than half of the 41 teams differed significantly from the distribution of the corresponding German cohort. There was a significant correlation between the relative age effect and success defined by teams' final rankings (Spearman's ρ = 0.328, P = 0.036). Regression analyses revealed that with a median of birth dates one month earlier the team is expected to finish 1.035 ranks better. Accordingly, selecting early born athletes is an important aspect of success in youth soccer. However, teams with no relative age effect are able to compete in the league, having the benefit to promote players with a better perspective for long and successful careers at an adult age.

There is empirical evidence that children's physical activity is dependent on climatic conditions. In addition, a correlation between physical activity level and physical fitness has been identified. In this longitudinal study, we investigate whether seasons have an influence on physical fitness. A total of 145 German elementary school children were tested every six months over a two-year period. We used the German Motor Test 6-18 to assess physical fitness. Performance in the 6-min endurance run (P < 0.001), bidirectional jumping (P < 0.001), the standing long jump (P = 0.026), the 20 m sprint (P = 0.006) and the stand-and-reach task (P = 0.017) was significantly better in summer than in winter. There were no differences in the ability to balance backwards (P = 0.120); in the winter, the results for push-ups (P < 0.001) and sit-ups (P < 0.001) were better than those in the summer. We have shown that physical fitness is significantly influenced by the season. Consequently, when children's fitness tests are used (e.g. as the basis for intervention programs, for classifying health-risk groups or for recognising talent), the season in which testing occurred should be reported and accounted for in future studies.

Grasping movements are often planned in a way that they end in a position where joints are in an anatomically medial position. This behaviour is termed the "end-state comfort" (ESC) effect (Rosenbaum et al., 1990). We suggest that the anatomically medial position is favoured to control the most difficult part of the movement. In most experiments investigating ESC, objects have to be placed onto a target location, and the highest precision demand occurs at the end of the movement. Thus, ESC is confounded with movement difficulty. In this study, we dissociate movement difficulty and ESC. In our experiments, participants had to execute a task where the critical part of the movement was either at the end or at the beginning of the movement. Participants' grasping behaviour confirmed the hypothesis that movement planning is constrained by a goal for optimal control during the part of the movement that demands the highest precision, rather than by a goal to end in a comfortable state (Rosenbaum, Chapman, Weigelt, Weiss, & van der Wel, 2012). We identified recall and movement plan generating processes of motor planning (Cohen & Rosenbaum, 2004), that ensure the optimal control in the critical part of movement. Our results indicate that recall processes depend on motor experience which is acquired in different time scales. We suggest that motor planning processes are triggered only if the costs for executing movements controlled by recall processes exceed the costs for generating a motor plan.

The secular trend of reduced physical fitness (PF) leads to increased health risks. The aim of the present paper is to analyse various current factors that affect health behaviour with respect to the course of PF over 2 years. A path analysis combined with a latent growth curve analysis was based on a study that was conducted between June 2008 and June 2010 with 145 primary German school children (52.1% male, average age at baseline 7.95 years ± 0.95). PF was tested with the German Motor Test 6-18. For the mean PF and the course of PF, direct and indirect influences were shown over three levels, including migration background on the first level and physical activity (PA) on the second level. Body mass index (BMI) impacted the mean PF but not the course of PF. The influence of sedentary behaviour on the mean PF was diminished (compared to bivariate analysis) due to its common variance mainly with BMI. PA affected not only current PF in children but also the course of PF (a(intercept) = .28, P = .001; a(slope) = .27, P = .21). Consequently, preventive measures should focus on early adoption and maintenance of PA.

The intention of the present study was to examine, if interruptions are used as a tactical means in international competitions and if law changes influence the duration. Therefore, the 32 matches of the knockout stage of the FIFA World Cups 2006 and 2014 were analysed and compared. Free kicks in 2014, when vanishing spray was used, took significantly longer than in 2006 (P < .01). Players were substituted faster by teams behind than at even score (P < .01), but not slower by leading teams (P > .05). The number of injuries with medical intervention was significantly higher for teams ahead than for teams behind (P < .05). When injured players had to be carried off the field by law in 2006, play was continued faster than in 2014 (P < .05). Overall, in 2014 leading teams used game stoppages more intensively to kill time than in 2006. To hinder this undesired development officials could think about introducing the concept of net playing time. At least referees should be sensitised for this behaviour even more than nowadays.