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Marcus A. Badgeley, Natalie M. McIlvain, Ellen E. Yard, Sarah K. Fields and R. Dawn Comstock

Background:

With more than 1.1 million high school athletes playing annually during the 2005−06 to 2009−10 academic years, football is the most popular boys’ sport in the United States.

Methods:

Using an internet-based data collection tool, RIO, certified athletic trainers (ATs) from 100 nationally representative US high schools reported athletic exposure and football injury data during the 2005−06 to 2009−10 academic years.

Results:

Participating ATs reported 10,100 football injuries corresponding to an estimated 2,739,187 football-related injuries nationally. The injury rate was 4.08 per 1000 athlete-exposures (AEs) overall. Offensive lineman collectively (center, offensive guard, offensive tackle) sustained 18.3% of all injuries. Running backs (16.3%) sustained more injuries than any other position followed by linebackers (14.9%) and wide receivers (11.9%). The leading mechanism of injury was player-player contact (64.0%) followed by player-surface contact (13.4%). More specifically, injury occurred most commonly when players were being tackled (24.4%) and tackling (21.8%).

Conclusions:

Patterns of football injuries vary by position. Identifying such differences is important to drive development of evidence-based, targeted injury prevention efforts.

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Jeffrey J. Milroy, Stephen Hebard, Emily Kroshus and David L. Wyrick

seeking is delayed ( Asken, McCrea, Clugston, Snyder, & Houck, 2016 ). At present time, it is estimated that between 12% and 60% of athletes delay seeking care after sustaining a concussion. Differences in sport-related concussion (SRC) care seeking have been attributed to a number of different immutable

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Daniela Corbetta, Rebecca F. Wiener, Sabrina L. Thurman and Emalie McMahon

-proprioceptive unitary system, infants performed visually-triggered reaches where the sight of the target and the feel of their arm were undifferentiated. From that point on, researchers increasingly reported that infants sustained their visual fixations on the target and did not look at their hand during learning to

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Shane R. Wurdeman, Jessie M. Huisinga, Mary Filipi and Nicholas Stergiou

Patients with multiple sclerosis (MS) have less-coordinated movements of the center of mass resulting in greater mechanical work. The purpose of this study was to quantify the work performed on the body’s center of mass by patients with MS. It was hypothesized that patients with MS would perform greater negative work during initial double support and less positive work in terminal double support. Results revealed that patients with MS perform less negative work in single support and early terminal double support and less positive work in the terminal double support period. However, summed over the entire stance phase, patients with MS and healthy controls performed similar amounts of positive and negative work on the body’s center of mass. The altered work throughout different periods in the stance phase may be indicative of a failure to capitalize on passive elastic energy mechanisms and increased reliance upon more active work generation to sustain gait.

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Zheng Wang, Peter C. M. Molenaar and Karl M. Newell

The experiment was set up to investigate the inter- and intrafoot coordination dynamics of postural control on balance boards. A frequency domain principal component analysis (PCA) was applied on 4 center of pressure (COP) time series collected from two force platforms to reveal their contributions to postural stability. The orientation of support played a more significant role than its width in channeling the foot coordination dynamics. When the support was oriented along the AP-challenging direction, the 4 COPs revealed a parallel contribution to the 1st principal component (PC1) indicating an interdependence of the foot coordination in both directions. When the support was positioned along the ML-challenging direction, the COPs in the AP direction showed larger weightings to PC1 implying an interfoot coordination. These findings provide evidence that COP coordination operates in adaptive ways to sustain postural stability in light of changing support constraints to standing.

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David M. Buchner and Paul H. Gobster

The purpose of this paper is to discuss the shared interest of the public health and parks and recreation sectors in promoting active visits to parks. At the institutional level, both sectors have missions to promote physical activity and view parks as key components in attaining physical activity goals. While some balancing among park goals may be necessary to avoid overuse and resource degradation, active visits more often complement park sustainability goals by reducing automobile and other motorized use impacts. The public health and parks and recreation sectors have each developed ecologic models to understand the determinants and outcomes of park-related physical activity. Transdisciplinary integration of these modeling efforts can lead to a better understanding of how active visits fit within the context of the overall recreational experience and the full range of benefits that parks provide. We conclude by identifying strategies for improving collaboration between the public health and parks and recreation sectors.

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Liria Akie Okai and André Fabio Kohn

Surprisingly little attention has been devoted to the role played by the intrinsic muscles of the human foot. The aim of this study was to quantify the capabilities of the flexor digitorum brevis (FDB) muscle to contribute to upright postural control. The approaches consisted of analysis of the effects of FDB contraction elicited by external electrical stimulation and quantification of the magnitude of FDB torque generation. The results showed the FDB can produce significant changes in static posture by itself as shown by changes in the center of pressure. Moreover, the FDB contribution to counterbalance the gravity’s toppling force was estimated at around 14.5% of the total required active torque at the ankle to keep the subject from falling. A posteriori functional analysis during horizontal perturbations showed high and self-sustained activity of FDB. These results demonstrated that the FDB has a significant capability of contributing to postural control.

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Dobromir G. Dotov and Till D. Frank

A novel method for the analysis of repetitive limb behavior oscillation is presented. It is based on a model used to account for self-sustained limit cycles that involve energy pumping compensating for dissipative processes. The experiment involved a uni-manual pendulum swinging task paced at five frequencies. The median frequency corresponded to the resonant one for the chosen pendulum and hand parameters. We applied the model-based analysis to explore the relationship between behavioral observables and model parameters not available from previous methods. Oscillation amplitude and energy, and motor variability were the behavioral observables we focused on while energy pumping, attractor strength, and noise amplitude were the model parameters. As expected, energy pumping was found to increase with pacing frequency. Noise amplitude did not change and stability decreased.

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William A. Sparrow, Rezaul K. Begg and Suzanne Parker

Visual reaction time (RT) was measured in 10 older men (mean age, 71.1 years) and gender-matched controls (mean age, 26.3 years) when standing (single task) and when walking on a motor-driven treadmill (dual task). There were 90 quasirandomly presented trials over 15 min in each condition. Longer mean and median RTs were observed in the dual task compared to the single task. Older males had significantly slower mean and median RTs (315 and 304 ms, respectively) than the younger group (273 and 266 ms, respectively) in both task conditions. There were no age or condition effects on within-subject variability. Both groups showed a trend of increasing RT over the 90 single task trials but when walking only the younger group slowed. These novel findings demonstrate high but sustained attention by older adults when walking. It is proposed that the motor task’s attentional demands might contribute to their slower preferred walking speed.

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Neil M. Johannsen and Rick L. Sharp

The purpose of this study was to investigate differences in substrate oxidation between dextrose (DEX) and unmodified (UAMS) and acid/alcohol-modified (MAMS) cornstarches. Seven endurance-trained men (VO2peak = 59.1 ± 5.4 mL·kg−1·min−1) participated in 2 h of exercise (66.4% ± 3.3% VO2peak) 30 min after ingesting 1 g/kg body weight of the experimental carbohydrate or placebo (PLA). Plasma glucose and insulin were elevated after DEX (P < 0.05) compared with UAMS, MAMS, and PLA. Although MAMS and DEX raised carbohydrate oxidation rate through 90 min of exercise, only MAMS persisted throughout 120 min (P < 0.05 compared with all trials). Exogenous-carbohydrate oxidation rate was higher in DEX than in MAMS and UAMS until 90 min of exercise. Acid/alcohol modification resulted in augmented carbohydrate oxidation with a small, sustained increase in exogenous-carbohydrate oxidation rate. MAMS appears to be metabolizable and available for oxidation during exercise.