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Mohan Ganesan, Yun-Ju Lee, and Alexander S. Aruin

The use of a footrest while performing activity in standing is frequently associated with improvement of a user’s well-being however no information exists on the role of a footrest in improving postural stability. The aim of the study was to evaluate the effects of using a footrest in postural control. Twenty healthy young volunteers were tested using three experimental conditions: standing with two feet on the force platform and standing on the force platform when one foot was placed on a 15 cm footrest positioned in front or laterally. The mean and root mean square distance, range and velocity of the center of pressure (COP) were calculated in the anterior-posterior (AP) and medio-lateral (ML) directions using the force platform data. The COP displacements in AP and ML directions increased in conditions of standing with one foot placed on the footrest regardless of its location. Standing with eyes closed increased COP displacements further. The outcome of the study suggests the importance of using COP measures for evaluation of postural stability and provides additional information needed for optimization of working conditions involving standing with a footrest.

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Satoshi Matsuno, Takuya Yoshiike, Atsushi Yoshimura, Sachiyo Morita, Yusuke Fujii, Motoyasu Honma, Yuji Ozeki, and Kenichi Kuriyama

Standing postural stability in humans requires adequate coordination of axial and lower-limb muscles to stabilize the trunk and head positions to compensate for various movements of distal body parts. Postural stability is crucial for performing activities of daily living. However, standing

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Olivier Caron, Thierry Gélat, Patrice Rougier, and Jean-Pierre Blanchi

The center of foot pressure (CP) motions, representing the net neuromuscular control, was compared to the center of gravity (CG) motions, representing the net performance. The comparison focused on the trajectory path length parameter along the mediolateral and antero-posterior axes because these two variables depend on amplitude versus frequency relationship. This relationship was used to evaluate the CG motions based on the CP motions. Seven subjects stood still on a force plate with eyes open and eyes closed. The results showed that the ratio of (CP – CG)/CP trajectory path length was personal for each subject. These results suggest different levels of passive (ligaments, elastic properties) and active (reflex activity) stiffness. For some subjects, this ratio was significantly lower for the eyes open condition than for the eyes closed condition, indicating a decrease of the active stiffness for the eyes open condition. Therefore, a CG – CP comparative analysis appeared helpful in understanding the control of balance and necessary to quantify the subjects’ net performance.

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Alex J.Y. Lee and Wei-Hsiu Lin

The purpose of this study was to investigate the influence of gender and somatotypes on single-leg upright standing postural stability in children. A total of 709 healthy children from different schools were recruited to measure the anthropometric somatotypes and the mean radius of center of pressure (COP) on a force platform with their eyes open and eyes closed. The results were that (a) girls revealed significantly smaller mean radius of COP distribution than boys, both in the eyes open and eyes closed conditions, and (b) the mesomorphic, muscular children had significantly smaller mean radius of COP distribution than the endomorphic, fatty children and the ectomorphic, linear children during the eyes closed condition. The explanation for gender differences might be due to the larger body weight in boys. The explanation for somatotype differences might be due to the significantly lower body height and higher portion of muscular profile in the mesomorphic children.

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Fatemeh Ehsani, Rozita Hedayati, Rasool Bagheri, and Shapour Jaberzadeh

increase the deep trunk muscles activity that stabilizes the spine during standing postural tasks. However, general exercise (GE) has been demonstrated to strengthen the trunk muscle. Yet, unlike SE, these GEs could not result in motor control improvement and synergy of local and global muscles and focus

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Ghazala T. Saleem, Jeanne Langan, Jacob I. McPherson, Beth S. Slomine, E. Mark Mahone, Martha Bridge Denckla, and Stacy J. Suskauer

perturbations in postural stability ( Horak, 2006 ). Achieving and maintaining standing postural control is a critical and complex skill that is learned at an early age ( Assaiante, Mallau, Viel, Jover, & Schmitz, 2005 ; Flatters et al., 2014 ). Postural stability enables youth to engage in daily routines and

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Joshua J. Liddy, Amanda J. Arnold, HyeYoung Cho, Nathaniel L. Romine, and Jeffrey M. Haddad

Humans regularly interact with and manipulate handheld objects during daily life. Holding graspable, lightweight objects has been found to reduce standing postural sway relative to conditions where no object was grasped. 1 – 5 For example, holding a 1-kg load resulted in slower sway in young

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James R. Chagdes, Joshua J. Liddy, Amanda J. Arnold, Laura J. Claxton, and Jeffrey M. Haddad

mass of the BoS and vertical distance from the support surface to the pivot point will vary with body anthropometrics (e.g., infants vs. adults) and posture (e.g., sitting vs. standing). For sitting and standing postures, there are reaction forces and moments acting at the pivot point (i.e., the ankle

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Pedro Paulo Deprá, Avelino Amado, and Richard E.A. van Emmerik

, the participant was instructed to accurately track the moving target with the head-mounted laser pointer. Each target condition was performed under a unipedal (preferred leg) and bipedal standing posture in a randomized order. For each postural condition, there were four blocked trials taking 60 s

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Gregory S. Walsh, Daniel C. Low, and Marco Arkesteijn

sway parameters. 22 To assess quiet standing postural control, participants performed 5 trials of 60 seconds in each load condition. To test the LOS participants performed a total of nine 30-second trials in each condition. Each LOS trial consisted of 3 phases (Figure  2A ). In phase 1, participants