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John L. Woodard and Annalise A.M. Rahman

Recent progress in technology has allowed for the development and validation of computer-based adaptations of existing pencil-and-paper neuropsychological measures and comprehensive cognitive test batteries. These computer-based assessments are frequently implemented in the field of clinical sports psychology to evaluate athletes’ functioning postconcussion. These tests provide practical and psychometric advantages over their pencil-and-paper counterparts in this setting; however, these tests also provide clinicians with unique challenges absent in paper-and-pencil testing. The purpose of this article is to present advantages and disadvantages of computer-based testing, generally, as well as considerations for the use of computer-based assessments for the evaluation of concussion among athletes. Furthermore, the paper provides suggestions for further development of computerized assessment of sports concussion given the limitations of the current technology.

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Mallory S. Kobak, Andrew Lepp, Michael J. Rebold, Hannah Faulkner, Shannon Martin and Jacob E. Barkley

equipment and technology ( 5 , 7 , 12 – 14 , 18 , 23 , 34 , 35 , 37 , 43 ). In recent years, young children have become a growing part of the population who utilize mobile Internet-connected electronic devices (eg, cellular telephones, tablet computers) for purposes such as talking/texting, accessing

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Akinori Nagano, Senshi Fukashiro and Taku Komura

Contribution of series elasticity of the human mm. triceps surae in cyclic heel-raise exercise (similar to hopping but the feet do not leave the floor) was examined via computer modeling and simulation. A two-dimensional skeletal model of the human body was constructed. Upright posture was maintained throughout the simulation to prevent the model from falling. A mathematical representation of the mm. triceps surae was implemented in the skeletal model. The muscle was activated by the neural activation input signal with a time resolution of 0.050 sec. Cyclic heel-raise exercises of cycle duration ranging from 0.300 sec to 0.900 sec, corresponding to the motion frequency of 200 to 66.7 cycles/min, were generated using an optimization approach. The goal of the numerical optimization was to generate cyclic motions with as much range of motion as possible. As a result, realistic heel-raise motions were generated with the range of motion between 0.0023 m (cycle duration = 0.300 sec) and 0.0414 m (cycle duration = 0.900 sec). It was found that contribution of the series elasticity in positive mechanical work output of the muscle-tendon complex during the pushoff phase (from the lowest position to the termination of a cycle) increased as motion frequency increased (3% at 66.7 cycles/min to 47% at 200 cycles/min). Relatively higher muscle activation was found during the downward moving phase when the motion frequency was higher. These tendencies are consistent with the findings reported in preceding studies involving experimental animals as well as human participants. It is suggested that series elasticity plays an integral role in the generation of cyclic human motions.

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Gunnar Treff, Kay Winkert, Katja Machus and Jürgen M. Steinacker

of the computer screen, which was placed in front of the RowErg. The display of the Concept2 ergometer was tilted down and not visible for the rowers during the test. Figure 1 —Schematic view of the screen during the ramp test. The solid diagonal line represents target power output; the broken lines

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Janet E. Fulton, Xuewen Wang, Michelle M. Yore, Susan A. Carlson, Deborah A. Galuska and Carl J. Caspersen

Background:

To examine the prevalence of television (TV) viewing, computer use, and their combination and associations with demographic characteristics and body mass index (BMI) among U.S. youth.

Methods:

The 1999 to 2006 National Health and Nutrition Examination Survey (NHANES) was used. Time spent yesterday sitting and watching television or videos (TV viewing) and using the computer or playing computer games (computer use) were assessed by questionnaire.

Results:

Prevalence (%) of meeting the U.S. objective for TV viewing (≤2 hours/day) ranged from 65% to 71%. Prevalence of no computer use (0 hours/day) ranged from 23% to 45%. Non-Hispanic Black youth aged 2 to 15 years were less likely than their non-Hispanic White counterparts to meet the objective for TV viewing. Overweight or obese school-age youth were less likely than their normal weight counterparts to meet the objective for TV viewing

Conclusions:

Computer use is prevalent among U.S. youth; more than half of youth used a computer on the previous day. The proportion of youth meeting the U.S. objective for TV viewing is less than the target of 75%. Time spent in sedentary behaviors such as viewing TV may contribute to overweight and obesity among U.S. youth.

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Jorge Mota, José Ribeiro, Maria Paula Santos and Helena Gomes

This study aimed to examine the relationship between obesity status (body mass index: BMI) and physical and sedentary activities in adolescents. The sample comprised 230 girls and 220 boys (14.6 years old, SD = 1.6). Physical Activity (PA) was assessed by a questionnaire. Sedentary behaviors, such as TV viewing, computer use, and commuting to and from school were analyzed. Participants were categorized as nonobese or overweight/obese according to age-adapted BMI. No significant differences were found in relation to PA characteristics or in TV watching on weekdays vs. weekends. Nonobese participants spent significantly less time using computers on weekends (p = .04) and weekdays (p = .025) than their overweight/obese counterparts. Logistic regression analysis showed that those who used computers on weekdays more than 4 hrs per day were likely (odds ratio: 5.79; p < .003) to be overweight or obese. This study identified a relationship between computer use, but not physical activity or TV viewing, and weight status among Portuguese adolescents.

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Sally A. McLure, John J. Reilly, Sean Crooks and Carolyn D. Summerbell

A novel computer tool (peas@tees), designed to assess habitual physical activity levels in children aged 9 and 10 years, was evaluated. Study 1 investigated agreement between peas@tees and accelerometry in 157 children. Bland-Altman limits of agreement (LOA) revealed peas@tees underestimated physical activity levels compared with accelerometry (bias −21 min; 95% LOA -146–105). Study 2 investigated stability of peas@tees in a separate sample of 42 children. Intraclass correlation coefficient was 0.75 (95% CI 0.62–0.84). Computer tools are promising as a cheap, feasible, and useful method to monitor children’s habitual levels of physical activity at the group level.

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Pascal Madeleine

This laboratory study investigated seated computer work before and after prolonged constrained sitting. Discomfort ratings and kinetic and kinematics data were recorded in nine healthy males performing computer work for 5 min before and after 96 min of sitting. The displacement of the center of pressure (CoP) in anterior-posterior and medial-lateral directions and lumbar curvature (LC) were calculated. The root mean square, standard deviation, and sample entropy values were computed from the CoPs and LC signals to assess the magnitude, amount of variability, and regularity of sitting dynamics, respectively. The discomfort increased for the buttocks (p = .02).The standard deviation and sample entropy values of the CoPs and LC signals, respectively, increased (p < .04) and decreased (p < .004) whereas the root mean square remained unchanged (p > .15) after prolonged constrained sitting compared with before. This present study showed that during seated computer work, prolonged constrained sitting affected the amount of variability and the regularity of sitting postural control, whereas the magnitude was not affected. The importance of the dynamics of sitting control may challenge the idea of a static and ideal seated posture at work.

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Jennifer L. Bruno, Zhizhong Li, Matthieu Trudeau, Sachin M. Raina and Jack T. Dennerlein

The goal of this study was to evaluate the performance of a single video camera system for measuring shoulder rotation during computer work, and to quantify the work and postural space within which the system performs optimally. Shoulder rotation angles calculated using the video system were compared with angles calculated using an active infrared LED three-dimensional motion analysis system while 10 adult volunteers simulated postures for two different trials: typical of normal computer work (freestyle) and with forced shoulder abduction (constrained). Average and absolute errors were calculated to determine the accuracy and precision of the system, respectively, for each trial, for each position, and for both the right and left hands. For the right hand, mean values for the average and absolute errors were –1 and 0 degrees, respectively. Only the absolute error increased significantly to 12 degrees for the constrained posture compared with freestyle. During normal computer work, the video system provided shoulder rotation angle values similar to those of a three-dimensional system, thus making it a viable and simple instrument to use in field studies.

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David J. Sanderson

The purpose of this experiment was to assess the efficacy of using real-time generated computer feedback of a selected biomechanical variable, force, for modifying the pattern-of-force application of inexperienced cyclists while they cycled at a steady rate (60 rpm) and power output (approximately 112 watts). Positive results would imply that the technique of using biomechanical variables as augmented feedback could be applied in a learning study in such a way to train for the enhancement of performance of cyclists. This approach differs from the traditional one of using novices performing novel tasks. Even though the cyclists were inexperienced, they nonetheless knew how to cycle and thus modifications of the pattern of force application were made to an already existing complex skill.