Body composition of English Premier League soccer players: Influence of playing position,international status,and ethnicity

Abstract

Body composition is a key consideration in the physical make-up of professional soccer players. The aims of the present study were to determine whether the body composition of professional soccer players varied according to playing position, international status or ethnicity, and to establish which variables best distinguished the soccer players from a reference group. Body composition was assessed using dual-energy X-ray absorptiometry in 64 male professional soccer players. Measured variables included bone mineral density and the relative amounts of lean and fat mass. Data were analysed using analysis of variance and stepwise discriminant function. The soccer players recorded better values than a reference group (n = 24) for all body composition compartments. Percent lean mass and bone mineral density were the variables best able to identify the soccer players (95.5% correctly classified). Differences in body composition were evident between goalkeepers and outfield players, but not between outfield playing positions. No differences were found on the basis of international status. The non-Caucasian players demonstrated significantly lower percent body fat (9.2 ± 2.0%) than the Caucasian players (10.7 ± 1.8%). It was concluded that body composition is important for elite soccer players, but that homogeneity between players at top professional clubs results in little variation between individuals.     

The Hit & Turn Tennis Test: An acoustically controlled endurance test for tennis players

Abstract

This study was conducted to validate and evaluate the “Hit & Turn Tennis Test”, an acoustically progressive on-court endurance test for tennis players. Ninety-eight competitive tennis players (53 males, 45 females) of different age groups participated in the study. For validation, the adult male players completed three Hit & Turn tests, one on a clay court and two on a carpet surface, a tennis-specific ball machine test and an incremental treadmill run in a randomized order. A stronger correlation between maximal performance (r = 0.81, P < 0.01) and maximal oxygen uptake (r = 0.96, P < 0.01) was observed between the Hit & Turn test and the ball machine test, than between the Hit & Turn test and the treadmill test. For test–retest, we found a significant correlation between maximal performance on the same (r = 0.83, P < 0.01) and on different surfaces (r = 0.74, P < 0.01). During test evaluation, maximal performance was higher in males than in females (P < 0.01) and increased by consecutive age group in boys (P < 0.01) but not in girls (P = 0.97). In conclusion, Hit & Turn maximum test performance can be recommended as a valid and reliable indicator for tennis-specific endurance.     

Mothers’ Implicit and Explicit Attitudes and Attributions in Relation to Self-Reported Parenting Behavior

Objective. Parenting behavior is presumed to be related to the thoughts about child behavior that parents report in a controlled and explicit manner and to more implicit parent cognitions that occur outside of conscious awareness and are less accessible to verbal report. Design. We examined mothers’ attitudes toward their children as correlates of self-reported parenting behavior. We used a combination of a self-report questionnaire and a reaction-time method (the Implicit Association Test) to assess explicit and implicit attitudes, respectively. We also assessed mothers’ implicit and explicit attributions for child misbehavior in relation to parenting, using a questionnaire measure of attributions completed under high-cognitive load (implicit attributions) or under low-cognitive load (explicit attributions). Mothers of 124, 6- to 10-year-olds (52% male) participated. Results. Attitudes assessed by self-report questionnaire and the Implicit Association Test were uniquely associated with negative parenting. The cognitive load manipulation moderated associations between attributions and parenting, such that child-blaming attributions were inversely associated with positive parenting only under conditions of high-cognitive load. Conclusions. Compared to traditional self-report questionnaires, methods such as the Implicit Association Test or cognitive load manipulations may more effectively assess implicit parent cognitions.     

Predictors and outcomes of low-income fathers’ reading with their toddlers

Most studies of parent–child bookreading have focused on mothers reading to their children. Though the role of fathers in children's lives is widely emphasized, we know almost nothing about father–child bookreading, particularly among low-income families. The present study was designed to examine how often low-income fathers report reading to their children and what the predictors and effects of paternal bookreading are. The fathers in this study were participants in the national evaluation of Early Head Start (EHS) and were recruited via mothers enrolled in the EHS study. Participating fathers were interviewed at home and their children's cognitive and language development were assessed using standardized measures from ages 2 to 5. Results demonstrated a wide variety in frequency of bookreading among fathers. Fathers were more likely to read to their children frequently if they spoke English at home, if they had a high school education, and if their children had better language skills. Fathers’ bookreading predicted children's cognitive outcome. Paternal bookreading did predict children's language outcomes but only for children whose fathers had at least a high school education.     

Naming speed deficits in adults with reading disabilities: a test of the double-deficit hypothesis

The present study investigated the persistent nature of naming speed deficits within the context of the double-deficit hypothesis in a university sample of adults with reading disabilities (RD). Twenty-five university students with RD were compared to 28 typically achieving readers on measures of reading skill, phonological processing, and naming speed. The results indicated that both naming speed and phonological processing deficits characterized the RD group. In a regression analysis, neither naming speed nor phonological processing were important variables in explaining comprehension when reading rate was in the model. The results of the present study are mixed at best and are consistent with earlier conclusions that support for the double-deficit hypothesis of dyslexia remains limited.     

Why Don't More Students Major in IS?

The large increases in the number of information systems (IS) majors about 10 years ago have been matched by equally large decreases in IS enrollments over the last few years. This article addresses the question of why students choose any major in general, and why students no longer choose to become an IS major in particular. We used a validated survey instrument and the responses from 163 students to examine this question in detail. Not surprisingly, we found that "genuine interest" in the subject was the most salient factor affecting the decision to major in IS. More surprising were what factors did not appear to influence this decision—for example, the promise of good job salaries, job security, the advice of others, or even the image of those who become IS professionals. Students seem aware that information technology employment opportunities exist; if job and salary issues contribute to choosing majors  other than IS , it is due to the perception of an unfavorable work/salary ratio for our field rather than one of job security or availability. That is, the amount of work to get an IS degree (the perception of harder-than-average courses) combined with (for many students) the perception of an undesirable amount of continuous training to keep an IS career just do not seem to balance with salary levels. These findings have important implications for the recruiting efforts of IS faculty seeking to attract more IS majors.     

Creatine kinase activity weakly correlates to volume completed following upper body resistance exercise

In the current study, we examined the relationship between serum creatine kinase (CK) activity following upper body resistance exercise with a 1- or 3-min rest between sets. Twenty men performed two sessions, each consisting of four sets with a 10-repetition maximum load. The results demonstrated significantly greater volume for the 3-min condition (M = 4156 kg, SD = 867, for 3 min; vs. M = 3503 kg SD = 759, for 1 min; p < .001), with no significant differences in delta CK activity between conditions (p = .574). Nevertheless, there was a weak correlation between the delta CK activity and total volume of exercise completed (r = .55 with a 1-min rest, and r = .45 with a 3-min rest). Therefore, the volume following upper body resistance exercise correlates weakly with serum CK levels, irrespective of rest interval length between sets.     

Value Profiles During Middle Childhood: Developmental Processes and Social Behavior

Little is known about how children's value priorities develop over time. This study identifies children's value priority profiles and follows their development during middle childhood. Australian children (N = 609; ages 5–12 at Time 1) reported their values over 2 years. Latent Transition Analysis indicated four profiles: Social-Focus, Self-Focus, Growth-Focus and Undifferentiated. Within person development was characterized by profile stability or transfer to the Social-Focus profile. Younger children were more likely to have an Undifferentiated profile (or Self-Focus among boys) than older ones. Girls were more likely to have a Social-Focus profile or transfer to it, and less likely to have a Self- or Growth-Focus profile than boys. Social-Focus profile membership over time predicted more prosocial and less aggressive behavior.     

Can we further improve tablet-based drawing to enhance learning? An empirical test of two types of support

Instructional Science - Digital drawing can foster learning, but only if the drawing is of sufficient quality. Hence, the focus of the present study was to investigate whether and how two types of...     

Robust block second order sliding mode control for a quadrotor

This paper presents the design of a controller based on the block control technique combined with the super twisting control algorithm for trajectory tracking of a quadrotor helicopter. A first order exact differentiator is used in order to estimate the virtual control inputs, which simplifies the control law design. In addition, the wind parameter resulting from the aerodynamic forces is also estimated in order to ensure robustness against these unmatched perturbations. The stability and finite time convergence of the exact differentiator have been recently proved by means of Lyapunov functions, and therefore the stability analysis of the proposed controller has been carried out along the same lines. The performance and effectiveness of the proposed controller are tested in a simulation study taking into account external disturbances.