Fast force changes with hand-held objects are an important prerequisite for object manipulation in everyday life. This study examines the development of fastest isometric force changes in a precision grip. One hundred sixty-five children (76 girls, 89 boys), 3–14 years, without neurological abnormalities increased and decreased repetitively isometric grip forces as rapidly as possible by their dominant hand using a small cylindrical pinch grip object (20 g). The frequency of repetitive force changes increased in a linear way from the age of 4 years until about 12 years by 0.23 Hz per year (r 2 = .54) without noticeable gender difference. The ratio of the duration of force increase and decrease slightly declined from 1.05 (4-year-olds) to 0.95 (11- to 14-year-olds). The development of force amplitudes and the mean force were more variable. Temporal parameters become less variable with age, whereas force parameters become more variable. In particular, the temporal parameters of fastest isometric force changes are best predictors for developmental changes. Fastest isometric force changes may be an important basic capacity for fast object manipulation, particularly in young children and in children with movement disorders.
Rainer Blank and Joachim Hermsdörfer
Sandrine Isoard-Gautheu, Emma Guillet-Descas, Patrick Gaudreau and Julien Chanal
This study examined (a) the developmental trajectories of athlete burnout perceptions, (b) the gender differences on these trajectories, and (c) the interactions in the developmental trajectories of the three burnout dimensions. A five-wave longitudinal study was conducted with 895 athletes (47.6% female; M age = 15.67). Results of multilevel growth models revealed that during adolescence, “reduced sense of accomplishment” linearly decreased and was higher for girls than boys. Moreover, “emotional/physical exhaustion” increased then decreased, and seemed to have been attenuated at time points in which athletes also had higher levels of “sport devaluation.” Finally, “sport devaluation” increased over time with higher increases for girls than boys. Results of our study depicted the general and the gendered shape of the trajectory of burnout perceptions during adolescence, and underlined the advantages of considering the multifaceted nature of burnout to enable a deeper examination of the within-person synergies in the development of the three dimensions.
Andrew Mills, Joanne Butt, Ian Maynard and Chris Harwood
This study examined the factors perceived by successful coaches to underpin optimal development environments within elite English soccer academies. A semistructured interview guide was developed to interview 10 expert coaches about the environments they create for players at a key stage in their development. The interviews were transcribed verbatim and inductively content analyzed. The results identified a wide range of factors resulting in a conceptual framework that explained how these factors interact to underpin an optimal environment. Subcomponents of this framework included organizational core (e.g., advocate a player-driven ideology), adaptability (e.g., embrace novel ideas & approaches), player welfare (e.g., understand players’ world-view), key stakeholder relationships (e.g., build trust with parents), involvement (e.g., encourage players’ ideas/feedback), and achievement oriented (e.g., establish an explicit pathway to senior level). Collectively, the findings highlight the importance of establishing strong, dynamic, organizational cultures at elite youth soccer academies. Ways that academies might be helped to establish such environments are discussed.
Stewart Cotterill, Richard Cheetham and Katrien Fransen
made, a clustering of themes emerged. Checks were made with the original transcripts to make sure connections still worked with the primary source materials. This step led to the development of a coherent table of themes. Once the transcripts had been analyzed by this interpretative process, a final
Juanita Weissensteiner, Bruce Abernethy, Damian Farrow and Sean Müller
The link between the anticipation skills of cricket batsmen and their practice histories was examined. Skilled and lesser skilled batsmen of U15, U20, and adult age completed a temporal occlusion task, in which they were required to use prerelease kinematic information to predict the type and length of delivery being bowled, and a structured interview, in which their accumulated hours of experience in organized and unorganized sporting activities were estimated. Skilled adult and U20 players showed an ability to use prerelease kinematic information to anticipate ball type that was not evident among any other group, and skilled players of all ages were distinguishable in terms of their accumulated hours of cricket-specific experience. Hours of cricket-spe-cific practice, however, explained only a modest percentage of the variance in anticipatory skill. Discussion focuses upon future refinements to the measurement of anticipation and practice history plus the role that variables other than the quantum of cricket experience may play in developing anticipation.
phenomenologist—pragmatic in the sense of C.S. Peirce ( Peirce, 1878 ) and W. James ( Gunn, 2000 ). For Feldenkrais a concept was meaningful if it made a difference for individual human development. He was a phenomenologist because his method is drawn from his own experience while subjecting it to rigorous
Dirk Aerenhouts, Jelle Van Cauwenberg, Jacques Remi Poortmans, Ronald Hauspie and Peter Clarys
This study aimed to estimate nitrogen balance and protein requirements in adolescent sprint athletes as a function of growth rate and physical development. Sixty adolescent sprint athletes were followed up biannually over a 2-yr period. Individual growth curves and age at peak height velocity were determined. Skeletal muscle mass (SMM) was estimated based on anthropometric measurements and fat mass was estimated by underwater densitometry. Seven-day diet and physical activity diaries were completed to estimate energy balance and protein intake. Nitrogen analysis of 24-hr urine samples collected on 1 weekday and 1 weekend day allowed calculation of nitrogen balance. Body height, weight, and SMM increased throughout the study period in both genders. Mean protein intakes were between 1.4 and 1.6 g kg−1 day−1 in both genders. A protein intake of 1.46 g kg−1 day−1 in girls and 1.35 g kg−1 day−1 in boys was needed to yield a positive nitrogen balance. This did not differ between participants during and after their growth spurt. None of the growth parameters was significantly related to nitrogen balance. It can be concluded that a mean protein intake around 1.5 g kg−1 day−1 was sufficient to stay in a positive nitrogen balance, even during periods of peak growth. Therefore, protein intake should not be enhanced in peak periods of linear or muscular growth.
David Whiteside, Bruce Elliott, Brendan Lay and Machar Reid
The importance of the flat serve in tennis is well documented, with an abundance of research evaluating the service technique of adult male players. Comparatively, the female and junior serves have received far less attention. Therefore, the aims of this study were to quantify the flat serve kinematics in elite prepubescent, pubescent, and postpubescent female tennis players. Full body, racket, and ball kinematics were derived using a 22-camera Vicon motion capture system. Racket velocity was significantly lower in the prepubescent group than in the two older groups. In generating racket velocity, the role of the serving arm appears to become more pronounced after the onset of puberty, whereas leg drive and “shoulder-over-shoulder” rotation mature even later in development. These factors are proposed to relate to strength deficits and junior players’ intentions to reduce the complexity of the skill. Temporally, coupling perception (cues from the ball) and action (body movements) are less refined in the prepubescent serve, presumably reducing the “rhythm” (and dynamism) of the service action. Practically, there appears scope for equipment scaling to preserve kinematic relevance between the junior and senior serve and promote skill acquisition.
Terry L. Rizzo, Penny McCullagh and Donna Pastore
, serve on a budget-type committee. If you are versed in curriculum development, serve on a committee that needs those skills. It is important that faculty maximize their skills and their time wisely. As previously mentioned, some universities are supporting an active overlay between teaching, scholarly
Jenny Meggs, Mark Chen and Danielle Mounfield
There have been research developments around individual differences in biological markers of hormonal development. There are several sources of evidence to suggest that the prenatal markers of testosterone (2D4D) ratio is an indicator of fetal sex hormones such as testosterone and estrogen. The 2D4