Variation Of Step Width Research Articles

Performance of an attention-demanding task during treadmill walking shifts the noise qualities of step-to-step variation in step width

BackgroundThe fractal scaling evident in the step-to-step fluctuations of stepping-related time series reflects, to some degree, neuromotor noise. Research questionThe primary purpose of this study was to determine the extent to which the fractal scaling of step width, step width and step width variability are affected by performance of an attention-demanding task. We hypothesized that the attention-demanding task would shift the structure of the step width time series toward white, uncorrelated noise. MethodsSubjects performed two 10-min treadmill walking trials, a control trial of undisturbed walking and a trial during which they performed a mental arithmetic/texting task. Motion capture data was converted to step width time series, the fractal scaling of which were determined from their power spectra. ResultsFractal scaling decreased by 22% during the texting condition (p < 0.001) supporting the hypothesized shift toward white uncorrelated noise. Step width and step width variability increased 19% and five percent, respectively (p < 0.001). However, a stepwise discriminant analysis to which all three variables were input revealed that the control and dual task conditions were discriminated only by step width fractal scaling. SignificanceThe change of the fractal scaling of step width is consistent with increased cognitive demand and suggests a transition in the characteristics of the signal noise. This may reflect an important advance toward the understanding of the manner in which neuromotor noise contributes to some types of falls. However, further investigation of the repeatability of the results, the sensitivity of the results to progressive increases in cognitive load imposed by attention-demanding tasks, and the extent to which the results can be generalized to the gait of older adults seems warranted.

Cognitive Processing for Step Precision Increases Beta and Gamma Band Modulation During Overground Walking.

The aim of this study was to investigate whether cognitive processing for defining step precision during walking could induce changes in electrocortical activity. Ten healthy adults (21-36years) were asked to walk overground in three different conditions: (1) normal walking in a straight path (NW); (2) walking in a pre-defined pathway forcing variation in step width and length by stepping on green marks on the floor (only one color: W1C), and (3) walking in the same pre-defined W1C pathway while evaluating different combinations among the colors green, yellow and red, in which only one color was the footfall target (evaluating two colors: W2C). Walking speed, stride duration and scalp electroencephalography (EEG) were recorded from all conditions. Event-related spectral perturbation was calculated for channels Fz, Cz, C3, C4, Pz and Oz in each condition, which were all time-normalized in relation to the gait cycle. The results showed that walking speed was reduced and stride duration was increased for W2C when compared to both NW and W1C (p < 0.01). Moreover, Event-related spectral perturbation analysis revealed significant changes (p < 0.05) during mid-stance in the frontal lobe and motor/sensorimotor regions, a phase in the gait cycle in which participants define the correct foot placement for the next step. These results suggest that greater cognitive demands during precision stepping influences electrocortical dynamics especially towards step transitions. Therefore, increased electrocortical activity in cognitive, motor and sensorimotor areas may be relevant to produce patterned and safe locomotion through challenging paths.

A Theory Treatment of Pedestrian-Induced Lateral Vibration of Structure

The lateral excessive sway motion caused by pedestrian traffic has attracted great public attention in the past decades years. However, the theories about exploring the effect of pedestrian on the lateral dynamic properties of structure are scarce. The new contribution of this paper is that a new pedestrian-structure system is proposed for exploring the effect of human on structural dynamic properties based on a sway assumption. Study shows that pedestrian deteriorates the natural frequency of structure and improves structural damping. The influence tendencies of pedestrian on structure can be supported by measurements. The further parametric study shows that the changes of human dynamic parameters have some evident impacts on structural dynamic performances. For example, the increase of leg damping can trigger an improvement of structural damping capacity. In addition, the walking step frequency closing structural harmonic natural frequency can incur the worst response. The increase of step width deteriorates lateral vibration and structural frequency but can slightly improve structural damping. One of essential reasons influencing structural lateral dynamic properties is the dynamic human system including body mass, damping, stiffness, and its motion behavior such as step frequency. This theory is proposed to analyze how pedestrian alters the lateral dynamic performances on those sensitive structures such as the footbridges or stadium bleachers. For example, how the variation of step width influences the change of natural frequency of structure?

Stokes Flow Inside Topographically Patterned Microchannel Using Boundary Element Method

Abstarct This study focuses on the investigation of two-dimensional steady Stokes flow inside topographically patterned microchannel. Boundary element method (BEM) is used to solve the Stokes equation and obtain the streamline profiles. The velocity field and pressure gradients are obtained by taking the appropriate spatial derivatives of the stream function and vorticity variables. We restrict ourselves to rectangular stepped geometries and study the effect of variation of step width, step height and step frequency. Interestingly, ‘crown-shaped’ patterns in the horizontal velocity profiles are formed when a sudden contraction is met in the flow region. Pressure gradients, together with the velocity and streamline profiles are analyzed to gain a wholesome understanding of the flow physics.

Effects of interventions on normalizing step width during self-paced dual-belt treadmill walking with virtual reality, a randomised controlled trial

BackgroundStep width is increased during dual-belt treadmill walking, in self-paced mode with virtual reality. Generally a familiarization period is thought to be necessary to normalize step width. AimThe aim of this randomised study was to analyze the effects of two interventions on step width, to reduce the familiarization period. MethodsWe used the GRAIL (Gait Real-time Analysis Interactive Lab), a dual-belt treadmill with virtual reality in the self-paced mode. Thirty healthy young adults were randomly allocated to three groups and asked to walk at their preferred speed for 5min. In the first session, the control-group received no intervention, the ‘walk-on-the-line’-group was instructed to walk on a line, projected on the between-belt gap of the treadmill and the feedback-group received feedback about their current step width and were asked to reduce it. Interventions started after 1min and lasted 1min. During the second session, 7–10days later, no interventions were given. FindingsLinear mixed modeling showed that interventions did not have an effect on step width after the intervention period in session 1. Initial step width (second 30s) of session 1 was larger than initial step width of session 2. Step width normalized after 2min and variation in step width stabilized after 1min. InterpretationInterventions do not reduce step width after intervention period. A 2-min familiarization period is sufficient to normalize and stabilize step width, in healthy young adults, regardless of interventions. A standardized intervention to normalize step width is not necessary.

균형능력 향상 운동프로그램이 보행안정성에 미치는 영향

The purpose of this study was to evaluate the effect of balance training on gait stability. The study population included 17 male high school students who were divided into 3 groups, each of which underwent one of the following types of balance-training programs for 8 weeks: 1 foot standing on cushion foam, trunk muscle training, and inverted body position training. 0, 4, and 8 weeks, the following experiment was performed: The participants were asked to close their eyes and take 17 steps; the stability of forward and sideward movement was determined, and the direction linearity was measured. The results revealed that all the training programs caused a decrease in stride deviation and an increase in the and the stride length, thereby improving the stability of forward movement. All the programs decreased the variation in step width and were thus also effective in improving the stability of sideward movement. The inverted body position training program was considered very effective because the cross point appeared on post hoc graphic analysis after 4 weeks, and the deviation length for 10 m was low, i.e., below 4 cm. All the programs were effective with respect to direction linearity because they decreased the deviation in direction widths. The results indicate that whole-body neurocontrol training is more effective than simple muscle training and local focused balance training, although this neurocontrol training-in the form of inverted body position training-required a longer training period than did the other programs.

Variation in trunk kinematics influences variation in step width during treadmill walking by older and younger adults

Step-by-step variations in step width have been hypothesized to reflect adjustments to swing foot placement in response to preceding frontal plane trunk kinematics. The present study tested this hypothesis while 12 younger and 11 older subjects walked on treadmill for 10 min at a self-selected velocity. The relationship between step-by-step variations in step width and frontal plane trunk COM kinematics was determined using multiple regression analysis. Trunk kinematics at midstance were significantly ( p < 0.001) and strongly ( R 2 = 0.54) related to the subsequent foot placement supporting the primary hypothesis. Additionally, this relationship was significantly affected by age ( p < 0.001) and stepping limb ( p < 0.001). These results implicate feedback driven control of foot trajectory during the swing phase. Further, they provide a biomechanical framework by which loss of frontal plane dynamic stability may result from a step width that is insufficient to decelerate and redirect trunk kinematics in preparation for the next step.

The Influence Of Thigh Circumference And Waist-to-hip Ratio On Step Width In A Large Sample Of Women

Kinematic analyses of obese individuals have found significantly altered gait mechanics. Of the dynamic changes routinely identified, increased step width (SW) appears to be one of the most common and crucial adjustments that occur. The prevailing hypothesis asserts that this increase, resulting from either disproportionate thigh girth or excessive thigh adiposity, provides for greater control of lateral balance while walking. However, little research has been published in this area and, as is typical with gait analyses, the sample sizes are very small. To date, no studies have looked at thigh circumference (TC) and SW across a large spectrum of obese and non-obese women. PURPOSE To examine the influence of TC, waist-to-hip ratio (WH), BMI and percent body fat on SW in a population of middle aged women. METHODS Gait data were collected from a sample of 125 healthy women (mean age 36.9 ± 8.6 years, mean BMI 26.2 ± 5.3) participating in research testing at the Lifespan Health Research Center. Participants walked barefoot at a self-selected velocity across a 13.5 meter walkway in the center's Motion Analysis Laboratory. These trials were recorded by a six camera, three force plate motion capture system (Motion Analysis Corporation). Three walking trials in which each foot contacted separate force plates were subsequently analyzed. Additionally, anthropometrics including stature, weight, and abdomen, hip and thigh circumferences were obtained. Standard descriptive statistics and Pearson's product moment correlations were computed. A multiple regression analysis was used to determine the influence of TC and waist-to-hip ratio on SW. RESULTS Significant correlations were found when comparing TC, WH, BMI and percent body fat to SW (0.40, 0.44, 0.41, and 0.33 respectively, p<0.01). TC alone accounted for just over sixteen percent of the variance (R2 = 0.16, p<0.01), whereas TC and WH combined to account for one quarter of the variance in SW (R2 = 0.25, p<0.01). Models run with TC, WH and BMI or TC, WH and percent body fat did not account for any increase in variance, and in fact, both BMI and percent body fat caused the each model to become statistically insignificant due to multicolinearity. CONCLUSIONS Although thigh girth does affect variation in SW, differences in SW appear to be more strongly tied to body proportionality rather than obesity in adult women. The influence of the distribution of body mass throughout the trunk and lower body suggests that certain body types may be more prone to the typical gait changes, such as increased SW, associated with obesity. Supported by NIH grants HD12252 and HL06995