Regulating stepping during fixed-speed and self-paced treadmill walking

textBackground: Treadmill walking should closely simulate overground walking for research validation and optimal skill transfer. Traditional fixed-speed treadmill (FS) walking may not simulate natural walking because of the fixed belt speed and lack of visual cues. Self-paced (SP) treadmill walking, especially feedback controlled SP treadmill walking, enables close-to-real-time belt speed changes with users' speed changes. Different sensitivity levels of SP treadmill feedback determine how fast the treadmill respond to user's speed change. Few studies have examined the differences between FS and SP treadmill walking, or the difference between sensitivity levels of SP treadmills, and their methods were questionable because of averaging kinematics and kinetics parameters, and failing to examine directly treadmill and subjects' speed data. This study compared FS with two SP modes with variation of treadmill speed and user's speed as dependent variables. Method: Thirteen young healthy subjects participated. Subjects walked on a motorized split-belt treadmill under FS, high sensitivity SP (SP-H) and low sensitivity SP (SP-L) conditions at normal walking speed. Root mean square error (RMSE) for subject's pelvis global speed (Vpg), pelvis speed with respect to treadmill speed (Vpt), and treadmill speed (Vtg) data were collected for all trials. Results: Significant condition effects were found between FS and the two SP modes in all RMSE values (p < 0.001). The two sensitivity levels of SP had similar speed patterns. Large subject × condition interaction effects were found for all variables (p < 0.001). Only small subject effects were found. Conclusions: The results of the study reveal different walking patterns between FS and SP. However, the two sensitivity levels failed to differ much. More habituation time may be needed for subjects to learn to optimally respond to the SP algorithm. Future work should include training subjects for more natural responses, applying a feed-forward algorithm, and testing the effect of optic flow on FS and SP speed variation.Kinesiology and Health Educatio

The Effects of Gesture-based Learning with Virtual Reality on Counting Ability for Children with Cerebral Palsy

This study investigated the effects of gesture-based learning with virtual reality (GBLVR) on the counting ability of three children with Cerebral Palsy (CP). Those elected were the children who had difficulty with counting skills in the classroom. By attending GBLVR math courses, children with CP learned counting numbers from 1 to 10 intuitively by moving their body and interacting with the design made for them. The single-subject experimental design within the multiple probe design across subjects was used to evaluate the effects. Virtual Reality Gesture-based Learning was the independent variable; the score from the Counting Ability was the dependent variable. The results of this study show an instant effect, a maintenance effect, and a generalization effect of the score of Counting Ability were found

Strategies of Healthy Adults Walking on a Laterally Oscillating Treadmill

We mounted a treadmill on top of a six degree-of-freedom motion base platform to investigate locomotor responses produced by healthy adults introduced to a dynamic walking surface. The experiment examined self-selected strategies employed by participants when exposed to continuous, sinusoidal lateral motion of the support surface while walking. Torso translation and step width were used to classify responses used to stabilize gait in a novel, dynamic environment. Two response categories emerged. Participants tended to either fix themselves in space (FIS), allowing the treadbelt to move laterally beneath them, or they fixed themselves to the base (FTB), moving laterally as the motion base oscillated. The degree of fixation in both extremes varied across participants. This finding suggests that normal adults have innate and varied preferences for reacquiring gait stability, some depending more heavily on vision (FIS group) and others on proprioception (FTB group). Keywords: Human locomotion, Unstable surface, Treadmill, Adaptation, Stabilit

Walking speed and spatiotemporal step mean measures are reliable during feedback-controlled treadmill walking; however, spatiotemporal step variability is not reliable

The purpose of the study was to compare the effects of a feedback-controlled treadmill (FeedbackTM) to a traditional fixed-speed treadmill (FixedTM) on spatiotemporal gait means, variability, and dynamics. The study also examined inter-session reliability when using the FeedbackTM. Ten young adults walked on the FeedbackTM for a 5-minute familiarization followed by a 16-minute experimental trial. They returned within one week and completed a 5-minute familiarization followed by a 16-minute experimental trial each for FeedbackTM and FixedTM conditions. Mean walking speed and step time, length, width, and speed means and coefficient of variation were calculated from all experimental conditions. Step time, length, width, and speed gait dynamics were analyzed using detrended fluctuation analysis. Mean differences between experimental trials were determined using ANOVAs and reliability between FeedbackTM sessions was determined by intraclass correlation coefficient. No difference was found in mean walking speed nor spatiotemporal variables, with the exception of step width, between the experimental trials. All mean spatiotemporal variables demonstrated good to excellent reliability between sessions, while coefficient of variation was not reliable. Gait dynamics of step time, length, width, and speed were significantly more persistent during the FeedbackTM condition compared to FixedTM, especially step speed. However, gait dynamics demonstrated fair to poor reliability between FeedbackTM sessions. When walking on the FeedbackTM, users maintain a consistent set point, yet the gait dynamics around the mean are different when compared to walking on a FixedTM. In addition, spatiotemporal gait dynamics and variability may not be consistent across separate days when using the FeedbackTM

Strength of Plantar- and Dorsiflexors Mediates Step Regularity During a High Cognitive Load Situation in a Cross-sectional Cohort of Older and Younger Adults

Background and Purpose: Completing simultaneous tasks while standing or walking (ie, a high cognitive load situation [HCLS]) is inevitable in daily activities and can lead to interference in task performances. Age-related physical and cognitive changes may confound performance variability during HCLS in older and younger adults. Identification of these confounding effects may reveal therapy targets to maintain optimal physical function later in life. The aim of this study was to investigate the effect of increasing the difficulty levels of an additional motor task and restricting visual information, on gait parameters in younger and older adults while considering the effect of cognitive and physical covariates. Methods: Fifteen healthy younger and 14 healthy older adults were asked to complete assessments of cognitive function, balance, and strength. They were then asked to walk on a self-paced treadmill with or without carrying a plastic tray. Opaqueness of the tray (vision) and the presence of water in glasses placed on the tray (increasing task difficulty) were varied. Mean, standard deviation, and regularity (sample entropy) of step width and length were compared across conditions and groups using repeated-measures analyses of variance with and without covariate analysis. Only significantly correlated covariates of cognition, balance, and strength were entered into each model. Results and Discussion: Older adults had greater step width irregularity compared with younger adults across all conditions when controlling for concentric plantar- and dorsiflexion strength. A decline in strength may likely alter neuromuscular control of gait, specifically control of step width, which has been associated with fall risk in older adults. Adjusting for the same covariates revealed increased regularity of step length, as visual feedback from the feet was restricted. Specifically, step length was more regular while carrying an opaque tray compared with not carrying a tray. Visual restriction was a contributing factor, which led to more predictable gait kinematics, indicating the role of sensory information to enhance the adaptability during walking under HCLS. Conclusion: The knowledge of the regularity behavior of human movement can expand physical therapists\u27 treatment approaches to promote further interactivity and coordination across body systems that model behavior of healthy young individuals. Targeting strength during therapy may provide additional benefits for gait performance under HCLS

Viewing medium affects arm motor performance in 3D virtual environments

<p>Abstract</p> <p>Background</p> <p>2D and 3D virtual reality platforms are used for designing individualized training environments for post-stroke rehabilitation. Virtual environments (VEs) are viewed using media like head mounted displays (HMDs) and large screen projection systems (SPS) which can influence the quality of perception of the environment. We estimated if there were differences in arm pointing kinematics when subjects with and without stroke viewed a 3D VE through two different media: HMD and SPS.</p> <p>Methods</p> <p>Two groups of subjects participated (healthy control, n = 10, aged 53.6 ± 17.2 yrs; stroke, n = 20, 66.2 ± 11.3 yrs). Arm motor impairment and spasticity were assessed in the stroke group which was divided into mild (n = 10) and moderate-to-severe (n = 10) sub-groups based on Fugl-Meyer Scores. Subjects pointed (8 times each) to 6 randomly presented targets located at two heights in the ipsilateral, middle and contralateral arm workspaces. Movements were repeated in the same VE viewed using HMD (Kaiser XL50) and SPS. Movement kinematics were recorded using an Optotrak system (Certus, 6 markers, 100 Hz). Upper limb motor performance (precision, velocity, trajectory straightness) and movement pattern (elbow, shoulder ranges and trunk displacement) outcomes were analyzed using repeated measures ANOVAs.</p> <p>Results</p> <p>For all groups, there were no differences in endpoint trajectory straightness, shoulder flexion and shoulder horizontal adduction ranges and sagittal trunk displacement between the two media. All subjects, however, made larger errors in the vertical direction using HMD compared to SPS. Healthy subjects also made larger errors in the sagittal direction, slower movements overall and used less range of elbow extension for the lower central target using HMD compared to SPS. The mild and moderate-to-severe sub-groups made larger RMS errors with HMD. The only advantage of using the HMD was that movements were 22% faster in the moderate-to-severe stroke sub-group compared to the SPS.</p> <p>Conclusions</p> <p>Despite the similarity in majority of the movement kinematics, differences in movement speed and larger errors were observed for movements using the HMD. Use of the SPS may be a more comfortable and effective option to view VEs for upper limb rehabilitation post-stroke. This has implications for the use of VR applications to enhance upper limb recovery.</p