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Hiroshi R. Yamasaki, Hiroyuki Kambara, and Yasuharu Koike

The purpose of this study was to clarify criteria that can predict trajectories during the sit-to-stand movement. In particular, the minimum jerk and minimum torque-change models were examined. Three patterns of sit-to-stand movement from a chair, i.e., upright, natural, and leaning forward, were measured in five young participants using a 3-D motion analysis device (200 Hz). The trajectory of the center of mass and its smoothness were examined, and the optimal trajectories predicted by both models were evaluated. Trajectories of the center of mass predicted by the minimum torque-change model, rather than the minimum jerk model, resembled the measured movements in all rising movement patterns. The upright pattern required greater extension torque of the knee and ankle joints at the instant of seat-off. The leaning-forward pattern required greater extension hip torque and higher movement cost than the natural and upright patterns. These results indicate that the natural sit-to-stand movement might be a result of dynamic optimization.

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Katherine A.J. Daniels, Eleanor Drake, Enda King, and Siobhán Strike

Cutting maneuvers can be executed at a range of angles and speeds, and these whole-body task descriptors are closely associated with lower-limb mechanical loading. Asymmetries in angle and speed when changing direction off the operated and nonoperated limbs after anterior cruciate ligament reconstruction may therefore influence the interpretation of interlimb differences in joint-level biomechanical parameters. The authors hypothesized that athletes would reduce center-of-mass heading angle deflection and body rotation during the change-of-direction stance phase when cutting from the operated limb, and would compensate for this by orienting their center-of-mass trajectory more toward the new intended direction of travel prior to touchdown. A total of 144 male athletes 8 to 10 months after anterior cruciate ligament reconstruction performed a maximum-effort sidestep cutting maneuver while kinematic, kinetic, and ground reaction force data were recorded. Peak ground reaction force and knee joint moments were lower when cutting from the operated limb. Center-of-mass heading angle deflection during stance phase was reduced for cuts performed from the operated limb and was negatively correlated with heading angle at touchdown. Between-limb differences in body orientation and horizontal velocity at touchdown were also observed. These systematic asymmetries in cut execution may require consideration when interpreting joint-level interlimb asymmetries after anterior cruciate ligament reconstruction and are suggestive of the use of anticipatory control to co-optimize task achievement and mechanical loading.

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Dimitrios-Sokratis Komaris, Cheral Govind, Andrew Murphy, Alistair Ewen, and Philip Riches

side dominance (ie, left or right leg first to walk). Whole-body center of mass trajectory and vertical velocity along with the mediolateral ground reaction force may be used to identify the phases of the continuous sit-to-walk movement 43 and select the desirable frame(s) f 1 and f 2. In this study

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Jill L. McNitt-Gray

of the body (effect) and affects multijoint control of the limb. The data visualization using free body diagrams over time enable coaches and athletes to picture how the magnitude, direction, and point of application of each force generated by the athlete acts relative to the body center of mass

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Travis J. Peterson and Jill L. McNitt-Gray

: 27345107 doi:10.1016/j.jbiomech.2016.06.014 10.1016/j.jbiomech.2016.06.014 27345107 12. Mathiyakom W , McNitt-Gray JL , Requejo PS , Costa K . Modifying center of mass trajectory during sit-to-stand tasks redistributes the mechanical demand across the lower extremity joints . Clin Biomech

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Daniel G. Miner, Brent A. Harper, and Stephen M. Glass

of mass trajectories were compared with the BioSway™ sway angles during volitional postural sway tasks. The authors found BioSway™ to be a valid tool for postural sway assessment compared with 3-dimensional motion capture. Outside of the aforementioned methodological distinctions (ie, static vs

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Jill L. McNitt-Gray

(yellow) legs during lateral quick first steps initiated with minimal momentum (Ready-Go-Lateral (top) and with vertical momentum resulting from a basketball rebound (Land-Go-Lateral (bottom). Initiating the task with momentum affects reaction forces, center of mass trajectory, and segment configuration

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Thiago R.T. Santos, Sergio T. Fonseca, Vanessa L. Araújo, Sangjun Lee, Fabricio Saucedo, Stephen Allen, Christopher Siviy, Thales R. Souza, Conor Walsh, and Kenneth G. Holt

): 614 – 629 . PubMed ID: 27705050 doi:10.1123/jab.2015-0339 27705050 10.1123/jab.2015-0339 9. Caron RR , Wagenaar RC , Lewis CL , Saltzman E , Holt KG . Center of mass trajectory and orientation to ankle and knee in sagittal plane is maintained with forward lean when backpack load changes

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Yuwei Song, Momotaz Begum, Sajay Arthanat, and Dain P. LaRoche

vertical displacement of the body’s center of mass during STS, using 12 infrared video cameras at a frame rate of 300 Hz. A single reflective marker was placed at the participant’s sacrum and tracked, as this location has been shown to be a very good approximation of the center of mass trajectory during

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Bernard Liew, Kevin Netto, and Susan Morris

.1080/14763141.2012.759614 24245052 10.1080/14763141.2012.759614 32. Caron RR , Wagenaar RC , Lewis CL , Saltzman E , Holt KG . Center of mass trajectory and orientation to ankle and knee in sagittal plane is maintained with forward lean when backpack load changes