The Effects of Optical Flow Perturbations on Standing Balance in People With Multiple Sclerosis.

Multiple sclerosis is a neurodegenerative disease that causes balance deficits, even in early stages. Evidence suggests that people with multiple sclerosis (PwMS) rely more on vision to maintain balance, and challenging balance with optical flow perturbations may be a practical screening for balance deficits. Whether these perturbations affect standing balance in PwMS is unknown.

Effects of aging and target location on reaction time and accuracy of lateral precision stepping during walking.

Older adults have poorer lateral balance and deficits in precision stepping accuracy, but the way these deficits manifest with lateral step distance is unclear. The purpose of this study was to investigate aging effects on lateral precision stepping performance in reaction to near and distant foot placement targets during treadmill walking. We hypothesized that older adults would step to targets later and less accurately than young adults, and that these difference would be more pronounced for distant targets.

Can optical flow perturbations detect walking balance impairment in people with multiple sclerosis?

People with multiple sclerosis (PwMS) who exhibit minimal to no disability are still over twice as likely to fall as the general population and many of these falls occur during walking. There is a need for more effective ways to detect preclinical walking balance deficits in PwMS. Therefore, the purpose of this study was to investigate the effects of optical flow perturbations applied using virtual reality on walking balance in PwMS compared to age-matched controls.

Time-dependent tuning of balance control and aftereffects following optical flow perturbation training in older adults.

Background: Walking balance in older adults is disproportionately susceptible to lateral instability provoked by optical flow perturbations. The prolonged exposure to these perturbations could promote reactive balance control and increased balance confidence in older adults, but this scientific premise has yet to be investigated. This proof of concept study was designed to investigate the propensity for time-dependent tuning of walking balance control and the presence of aftereffects in older adults following a single session of optical flow perturbation training.

Development and Assessment of a Low-Cost Clinical Gait Analysis System.

Clinically, measuring gait kinematics and ground reaction force (GRF) is useful to determine the effectiveness of treatment. However, it is inconvenient and expensive to maintain a laboratory-grade gait analysis system in most clinics. The purpose of this study was to validate a Wii Balance Board, Kinovea motion-tracking software, and a video camera as a portable, low-cost system, and overground gait analysis system.

Changes in mechanical work during neural adaptation to asymmetric locomotion.

Minimizing whole-body metabolic cost has been suggested to drive the neural processes of locomotor adaptation. Mechanical work performed by the legs should dictate the major changes in whole-body metabolic cost of walking while providing greater insight into temporal and spatial mechanisms of adaptation. We hypothesized that changes in mechanical work by the legs during an asymmetric split-belt walking adaptation task could explain previously observed changes in whole-body metabolic cost.

Two biomechanical strategies for locomotor adaptation to split-belt treadmill walking in subjects with and without transtibial amputation.

Locomotor adaptation is commonly studied using split-belt treadmill walking, in which each foot is placed on a belt moving at a different speed. As subjects adapt to split-belt walking, they reduce metabolic power, but the biomechanical mechanism behind this improved efficiency is unknown. Analyzing mechanical work performed by the legs and joints during split-belt adaptation could reveal this mechanism.

Locomotor control of limb force switches from minimal intervention principle in early adaptation to noise reduction in late adaptation.

During movement, errors are typically corrected only if they hinder performance. Preferential correction of task-relevant deviations is described by the minimal intervention principle but has not been demonstrated in the joints during locomotor adaptation. We studied hopping as a tractable model of locomotor adaptation of the joints within the context of a limb-force-specific task space.

Computational fluid dynamics analysis to determine shear stresses and rates in a centrifugal left ventricular assist device.

Axial flow left ventricular assist devices (LVADs) are a significant improvement in mechanical circulatory support. However, patients with these devices experience degradation of large von Willebrand factor (vWF) multimers, which is associated with bleeding and may be caused by high shear stresses within the LVAD. In this study, we used computational fluid mechanics to determine the wall shear stresses, shear rates, and residence times in a centrifugal LVAD and assess the impact on these variables caused by changing impeller speed and changing from a shrouded to a semi-open impeller.

Motor noise removal for determining gait events over treadmill walking using wavelet filter.

The conventional method for filtering force plate data, low-pass filtering, does not always give accurate results when applied to force data from a custom-made, instrumented treadmill. Therefore, this study compares low-pass filtered data to the same data passed through a wavelet filter. We collected data with the treadmill running.