analysis, it was observed that, in many cases, urinary LH concentrations close to or below the threshold of 1.0 IU/L were related to low SG values (diluted samples, SG < 1.005). Based on anecdotal evidence, hyperhydration is being used by a number of athletes as a masking method, since urine dilution is
Ioanna Athanasiadou, Sven Christian Voss, Wesal El Saftawy, Hind Al-Jaber, Najib Dbes, Sameera Al-Yazedi, Waseem Samsam, Vidya Mohamed-Ali, Mohammed Alsayrafi, Georgia Valsami and Costas Georgakopoulos
Mark B. Andersen
John Strickland and Grant Bevill
review of biomechanics literature demonstrates that only the protective equipment available to batters and catchers have been evaluated, 5 – 9 whereas, to the authors’ knowledge, no tests have been performed for the facemasks available for fielders. Data from studies examining catcher’s masks are
Jennifer L. Huberty, Jeni L. Matthews, Meynard Toledo, Lindsay Smith, Catherine L. Jarrett, Benjamin Duncan and Matthew P. Buman
measured twice using an electronic stadiometer and weighing scale (Seca 274, Medical Measuring Systems, Chino, CA). Lab personnel discussed what could be expected from the general protocol, and how to navigate certain parts of the yoga sequence while wearing the measurement tools (mask, backpack, and
Blake D. McLean, Cloe Cummins, Greta Conlan, Grant Duthie and Aaron J. Coutts
% during straight line running), which could mask any small load increases in the anteroposterior and mediolateral axes that may occur during tackling drills. It has previously been shown that 3D accelerometer loads are strongly influenced by total distance traveled during locomotor activities (due to the
Adam D. G. Baxter-Jones, Joey C. Eisenmann and Lauren B. Sherar
The process of maturation is continuous throughout childhood and adolescence. In a biological context, the effects of a child’s maturation might mask or be greater than the effects associated with exposure to exercise. Pediatric exercise scientists must therefore include an assessment of biological age in study designs so that the confounding effects of maturation can be controlled for. In order to understand how maturation can be assessed, it is important to appreciate that 1 year of chronological time is not equivalent to 1 year of biological time. Sex- and age-associated variations in the timing and tempo of biological maturation have long been recognized. This paper reviews some of the possible biological maturity indicators that the pediatric exercise scientist can use. As a result, we recommend that any of the methods discussed could be used for gender-specific comparisons. Gender-comparison studies should either use skeletal age or some form of somatic index.
Matthieu M. de Wit, Rich S.W. Masters and John van der Kamp
Based upon evidence that vision for action has quicker access to visual information than vision for perception, we hypothesized that the two systems may have differentiated visual thresholds. There is also evidence that, unlike vision for perception, vision for action is insensitive to cognitive dual-task interference. Using visual masking, we determined the visual thresholds of 15 participants in a perception task, an action task and an action plus concurrent cognitive secondary task. There was no difference in threshold between the perception task and the action task, but the action plus concurrent secondary task was accompanied by a greater visual threshold than both the perception task and the action task alone, indicating dual-task interference. The action task was thus most likely informed by vision for perception. The implications of these results are reviewed in the context of recent discussions of the two visual systems model.
Bruce Abernethy and David G. Russell
Two experiments are described comparing the temporal and spatial characteristics of the anticipatory cues used by expert (n=20) and novice (n=35) racquet sport players. In both experiments the perceptual display available in badminton was simulated using film, and display characteristics were selectively manipulated either by varying the duration of the stroke sequence that was visible (Experiment 1) or by selectively masking specific display features (Experiment 2). The subjects* task in all cases was to predict the landing position of the stroke they were viewing. It was found in Experiment 1 that experts were able to pick up more relevant information from earlier display cues than could novices, and this appeared in Experiment 2 to be due to their ability to extract advance information from the playing side arm, in addition to the racquet itself. These differences, it was concluded, were congruent with predictions that could be derived from traditional information-processing notions related to recognition of display redundancy. The roles of different anticipatory cue sources in the independent predictions of stroke speed and direction were also examined, and it was concluded that directional judgments were more dependent on cue specificity than were depth judgments.
Per-Ludvik Kjendlie and Robert Keig Stallman
The aims of this study were to compare drag in swimming children and adults, quantify technique using the technique drag index (TDI), and use the Froude number (Fr) to study whether children or adults reach hull speed at maximal velocity (v max). Active and passive drag was measured by the perturbation method and a velocity decay method, respectively, including 9 children aged 11.7 ± 0.8 and 13 adults aged 21.4 ± 3.7. The children had significantly lower active (k AD) and passive drag factor (k PD) compared with the adults. TDI (k AD/k PD) could not detect any differences in swimming technique between the two groups, owing to the adults swimming maximally at a higher Fr, increasing the wave drag component, and masking the effect of better technique. The children were found not to reach hull speed at v max, and their Fr were 0.37 ± 0.01 vs. the adults 0.42 ± 0.01, indicating adults’ larger wave-making component of resistance at v max compared with children. Fr is proposed as an evaluation tool for competitive swimmers.
Matheus M. Gomes and José A. Barela
The purpose of this study was to examine the effects of visual and somatosensory information on body sway in individuals with Down syndrome (DS). Nine adults with DS (19–29 years old) and nine control subjects (CS) (19–29 years old) stood in the upright stance in four experimental conditions: no vision and no touch; vision and no touch; no vision and touch; and vision and touch. In the vision condition, participants looked at a target placed in front of them; in the no vision condition, participants wore a black cotton mask. In the touch condition, participants touched a stationary surface with their right index finger; in the no touch condition, participants kept their arms hanging alongside their bodies. A force plate was used to estimate center of pressure excursion for both anterior-posterior and medial-lateral directions. MANOVA revealed that both the individuals with DS and the control subjects used vision and touch to reduce overall body sway, although individuals with DS still oscillated more than did the CS. These results indicate that adults with DS are able to use sensory information to reduce body sway, and they demonstrate that there is no difference in sensory integration between the individuals with DS and the CS.