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Erik Bijleveld and Harm Veling

To better understand the characteristics of athletes who tend to underperform under pressure, we investigated how (a) working memory (WM) capacity and (b) responsiveness of the dopamine system shape real-life performance under pressure. We expected that athletes with smaller WM capacity or a more responsive dopamine system (as operationalized with a risk-taking measure) are especially prone to fail during decisive moments. In a sample of competitive tennis players, WM capacity was measured with the Automated Operation Span task (AOSPAN); responsiveness of the dopamine system was measured with a risk-taking measure, the Balloon Analogue Risk Task (BART). As expected, higher AOSPAN scores predicted better performance during decisive sets; higher BART scores predicted worse performance during decisive sets. These findings indicate that real-life tennis performance can be predicted from behavioral tasks that tap into WM functioning and risk taking, and suggest that the ability to effectively use WM despite pressure separates chokers from nonchokers.

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Raymonde E. Jean, Manideep Duttuluri, Charlisa D. Gibson, Sadaf Mir, Katherine Fuhrmann, Edward Eden and Azhar Supariwala

Background:

Exercise improves sleep quality, yet people with untreated obstructive sleep apnea (OSA) may engage in less physical activity (PA) due to fatigue and daytime sleepiness. We examined changes in PA and sleep quality before and after treatment with continuous positive airway pressure (CPAP) in OSA patients.

Methods:

In this prospective longitudinal study, persons with a primary diagnosis of OSA were enrolled at a community-based hospital in New York City. At 3 time intervals pre- and post-CPAP (3–8 months), we measured sleep quality using validated questionnaires, perceived PA using the International Physical Activity Questionnaire (IPAQ), and actual PA using pedometer steps per day. We sought to investigate how CPAP use and changes in sleep quality impacted the number of steps taken, as recorded in pedometer steps.

Results:

In total, 62 patients were enrolled in the study from March 2012 to July 2014. In all, patients averaged 53 years of age, and 26 patients (42%) were female. Among all participants, 86% of persons had moderate to severe sleep apnea (AHI ≥15). Approximately 73% of participants were compliant with CPAP use. Poor sleep quality correlated with lower actual PA (P = .004) at baseline. At 3 and 7 months, there was significant improvement in sleep quality (Δ –2.63 ± 3.4 and Δ –3.5 ± 3.8; P < .001) and actual PA (Δ 840 ± 1313 and Δ 1431 ± 1419 steps/day, P < .001) compared with baseline. On multivariate analyses, participants with a higher waist circumference had a significantly greater increase in actual PA (P = .018).

Conclusion:

Treatment of OSA with CPAP had a progressive incremental improvement in sleep quality and actual PA.

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Ksenia I. Ustinova, Valery M. Goussev, Ramesh Balasubramaniam and Mindy F. Levin

To determine how arm movements influence postural sway in the upright position after stroke, interactions between arm, trunk, and center of pressure (CoP) displacements in the sagittal direction were investigated in participants with hemiparesis and healthy subjects. Participants swung both arms sagittally in either of 2 directions (in-phase, anti-phase) and at 2 speeds (preferred, fast) while standing on separate force plates. Variables measured included amplitude and frequency of arm swinging, shoulder and trunk range of motion, CoP displacements under each foot and of the whole body, and the relationships between the arm, trunk, and CoP displacements. CoP displacements under the non-paretic leg were greater than those under the paretic leg, which may in part be related to the larger amplitude of swinging of the non-paretic arm. CoP displacements under each foot were not related to arm swinging during in-phase swinging at the preferred speed in healthy subjects. When speed of arm swinging was increased, however, the CoP moved in a direction opposite to the arm movement. In contrast, in individuals with hemiparesis, CoPs and arms moved in the same direction for both speeds. During anti-phase swinging in healthy subjects, the trunk counterbalanced the arm movements, while in participants with hemiparesis, the trunk moved with the affected arm. Results show that stroke resulted in abnormal patterns of arm-trunk-CoP interactions that may be related to a greater involvement of the trunk in arm transport, an altered pattern of coordination between arm and CoP displacements, and an impaired ability of the damaged nervous system to adapt postural synergies to changes in movement velocity.

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Carolyn A. Duncan, Scott N. MacKinnon and Wayne J. Albert

The purpose of this study was to examine how wave-induced platform motion effects postural stability when handling loads. Twelve participants (9 male, 3 female) performed a sagittal lifting/lowering task with a 10 kg load in different sea conditions off the coast of Halifax, Nova Scotia, Canada. Trunk kinematics and foot center of force were measured using the Lumbar Motion Monitor and F-Scan foot pressure system respectively. During motion conditions, significant decreases in trunk velocities were accompanied by significant increases in individual foot center of pressure velocities. These results suggest that during lifting and lowering loads in moving environments, the reaction to the wave-induced postural disturbance is accompanied by a decrease in performance speed so that the task can be performed more cautiously to optimize stability.

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Nadav Goldschmied, Max Nankin and Guy Cafri

Icing is a common strategy used in American football during the last moments of a close game when a coach may ask for a time-out to allow an opposing kicker, who is about to attempt a decisive field-kick, an extended period of time possibly to contemplate the negative outcomes if he fails to score (i.e., rumination). Using archival data of pressure kicks from six consecutive National Football League seasons (2002—2008), a mixed-effects hierarchical linear model was applied. It was found that icing was successful in reducing scoring while other environmental factors such as experience, game location or game score were not associated with conversion success. In a secondary analysis it was demonstrated that if a time-out before the pressure kick is requested by the coaches of the kicking team, kickers are not subjected to the debilitating effects of icing. Theoretical and applied implications are also discussed.

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Brian L. Davis, Julie E. Perry, Donald C. Neth and Kevin C. Waters

A device has been designed to simultaneously measure the vertical pressure and the anterior-posterior and medial-lateral distributed shearing forces under the plantar surface of the foot. The device uses strain gauge technology and consists of 16 individual transducers (each with a surface area measuring 2.5 × 2.5 cm) arranged in a 4 × 4 array. The sampling frequency is 37 Hz and data may be collected for 2 s. The device was calibrated under both static and dynamic conditions and revealed excellent linearity (±5%), minimal hysteresis (±7.5%), and very good agreement between applied and measured loads (±5%). Vector addition of the distributed loads gave resultant forces that were qualitatively very similar to those obtained from a standard force plate. Data are presented for measurements from the forefoot of 4 diabetic subjects during the initiation of gait, demonstrating that distributed shear and pressure on the sole of the foot can be measured simultaneously.

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Franklin Camargo-Junior, Marko Ackermann, Jefferson F. Loss and Isabel C.N. Sacco

The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 N m/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected.

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Ann M. Swartz, Scott J. Strath, Sarah J. Parker and Nora E. Miller

The purpose of this study was to investigate the combined impact of obesity and physical activity (PA) on the health of older adults. Pedometer-determined steps/d, body-mass index (BMI), resting blood pressure, and fasting glucose (FG) were assessed in 137 older adults (69.0 ± 8.9 yr). The active group (>4,227 steps/d) had lower systolic blood pressure (SBP; p = .001), diastolic blood pressure (DBP; p = .028), and FG (p < .001) than the inactive group (≤4,227 steps/d). The normal-BMI group (18.5-24.9 kg/m2) had lower SBP (p < .001) and DBP (p = .01) than the obese group (≤30 kg/m2). There were no differences in SBP (p = .963) or DBP (p = 1.0) between active obese and inactive normal-BMI groups. The active obese group, however, had a more favorable FG than the inactive normal-BMI group (χ2 = 18.9, df = 3, p = .001). Efforts to increase PA of older adults should receive the same priority as reducing obesity to improve BP and FG levels.

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Yun Wang and Kazuhiko Watanabe

The notion of limb dominance has been commonly used in the upper extremity, yet the two lower extremities are often treated as equal for analytical purposes. Attempts to determine the effects of limb laterality on gait have produced conflicting results. The purpose of this study was to determine if limb dominance affects the vertical ground reaction force and center of pressure (COP) during able-bodied gait. The Parotec system (Paromed GmbH, Germany) was used to collect plantar foot pressure data. Fifteen subjects volunteered to participate in this study. The coefficient of variation of the COP displacement in the mediolateral direction and the variability of peak force beneath the lateral forefoot in the nondominant foot were significant greater than in the dominant foot. Moreover, COP velocity in the anterior-posterior direction during the terminal stance phase showed greater value in the dominant foot. Our study provides support for limb laterality by showing limb dominance affected the vertical ground reaction force and center of pressure during walking gait. This finding suggests it is an important issue in movement science for clinicians and would assist in improving sports performance and rehabilitation program.

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Nick Wadsworth

, 2012 ). The role of the gymnastics coach should be to create an appropriate motivational climate and reduce any anxiety gymnasts might be experiencing ( White & Bennie, 2015 ). However, based on the phone call with C.S.’s father, it seemed that both he and the coach were putting pressure on C.S. to