center of pressure

Synchronization of EEG Activity with Body Balance During Cognitive Visual Exercises

When evaluation cognition, there is a certain complexity surrounding electroencephalographic (EEG) recordings, which would greatly benefit from being supplemented by secondary recordings, such as those from a force platform. Currently, there is also a lack of evidence supporting the need to implement creative exercise on analytical coursework, specifically in STEM degrees where there is gaining momentum to incorporate the arts [3]. This pilot study aims to correlate electroencephalography (EEG, Brain Vision) and postural sway (AMTI AccuSway) data to verify cognitive changes. This study hypothesizes that participants will have 1) increased EEG alpha activity and 2) increased postural sway when participating in iterations of a problem-solving tasks administered after the participant engages in creative activities. The study will use human-subject data gathered from electroencephalography (Brain Vision) and postural sway (AMTI AccuSway) to quantify the cognitive engagement of participants during the learning of new concepts in a unique manner that allows the participants to think about them visually. The hypothesis is that the teaching methods introduced will encourage participants to have increased cognitive attention. Two participants were evaluated on their postural sway and EEG activity during the answering of Raven’s Progressive Matrices tests before and after artistic viewing and drawing activities. The data generated by this study by these means will show that increased cognition is apparent when concepts are presented in a visual manner, fortifying a philosophy that engineering curricula would benefit from artistic additions.
Listed In: Neuroscience, Posturography

Standing steadiness and variability of older adults on a step ladder

MOTIVATION: Ladder fall injury rates are highest among older adults. While standing stability has been quantified using center of pressure (COP) to classify general fall risk of older adults, it has not been applied to older adults’ balance and performance on ladders. This study investigates the standing stability of older adults while performing a task on a ladder. METHODS: One-hundred four older adults completed the Physiological Profile Assessment (PPA) to classify fall risk and climbed to the second step of a household step ladder to change a light bulb. Force plates under the step ladder were used to calculate the COP. COP parameters were extracted to assess stability on the step ladder including path length (time-normalized), RMS and elliptical area. Task time and COP parameters were compared between 10 participants with the highest fall risk and 10 participants with the lowest fall risk based on the PPA. RESULTS: Task time was 8.4 seconds (63.9%) longer for the high fall risk group. Time-normalized path lengths were similar between the two groups. The high fall risk group showed an increase in RMS by 18.1% and elliptical area by 44.6%. CONCLUSIONS: Differences in tasks time, RMS and elliptical area were observed between low and high fall risk groups. Larger RMS values and elliptical area indicate more movement away from the average COP location. This suggests high fall risk older adults to be more variable than low fall risk older adults in their standing stability when completing a task on a step ladder.
Listed In: Biomechanical Engineering, Biomechanics, Posturography

Immediate Effects of Vibrotactile Feedback on Postural Sway in Healthy Older Adults

Previous research has shown the utility of vibrotactile feedback to improve postural sway characteristics in persons with vestibular deficits. Tactile feedback given through vibration has been used more as a modality of training but immediate effects on postural control among older adults have not been investigated. PURPOSE: To compare the immediate effects of tactile vibration on postural sway in healthy older adults in challenging stance and sensory conditions. METHODS: 10 healthy older adults (76.4 ± 6.8years), performed five standing balance conditions on a AMTI forceplate for 30s each: feet together on firm surface eyes open (C1), eyes closed (C2); feet together on foam surface eyes open (C3), eyes closed (C4), and tandem stance on firm surface eyes open (C5). Participants did 2 trials of each condition both with and without vibrotactile feedback. The feedback was given using a waist belt with sensors that were activated when participants swayed in a particular direction as detected by an Xbox Kinect camera (Sensory Kinetics system; Engineering Acoustics, Casselberry, FL). Center of pressure sway area was compared within each condition using a paired samples t-test to estimate the effect of vibration. RESULTS: See Table 1. Since only 5 subjects could complete C4 data was not included in statistical analysis. CONCLUSION: Tactile vibration did not acutely effect postural sway in challenging stance conditions in healthy older adults. Long term effects of tactile vibration on postural sway in challenging stance conditions need to be investigated.
Listed In: Physical Therapy

The Effect of Work Boots on Center of Pressure Location at the Knee in Static Kneeling

INTRODUCTION: Workers in industry wear steel toe boots; however, these boots are inflexible and may restrict foot movement. Occupational kneeling is also associated with an increased risk of knee osteoarthritis. Examination of the effects of work boots in kneeling is needed to better understand potential injury risk. Therefore, the purpose of this study was to analyze the center of pressure (COP) at the knee during kneeling when shod and barefoot. METHODS: Fifteen, young, healthy males completed five 10-second static kneeling trials in each condition. Lower body kinematics were obtained using the Optotrak system (Certus and 3020, NDI, Waterloo, ON, CA). Force data were measured from a force plate under the knee of the dominant leg (OR6-7, AMTI, Watertown, MA, USA). The mean COP location was determined with respect to the medial tibial plateau (normalized to tibial width) and the tibial tuberosity (normalized to tibial length) for the medial/lateral and longitudinal directions, respectively. RESULTS: COP was located more medially in the shod condition (34% (±10.6%) tibial width) compared to the barefoot condition (40% (±11.9%) tibial width) (p=0.0485). COP was located above the tibial tuberosity, with no difference between conditions (shod 11% (±3.2%) tibial length, barefoot: (7%) (±8.8%) tibial length) (p=0.97). DISCUSSION: There is a difference in COP location in shod compared to barefoot kneeling. A COP location farther from the joint center of rotation, as occurred in the frontal plane of the shod condition, would increase the moment arm of the ground reaction force and thus the moment at the knee.
Listed In: Biomechanics