scholarly journals Positive Relations Between Vision and Posture in the Fixation Task Performed Upright

Motor Control ◽  
2020 ◽  
Vol 24 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Cédrick T. Bonnet
Keyword(s):  
Postural Control ◽  
Center Of Pressure ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Upright Stance ◽  
Lower Back ◽  
Free Viewing ◽  
Fixation Task ◽  
Cognitive Involvement ◽  
Head Neck

In an upright stance, individuals sway in unpredictable ways. Their eyes also move in unpredictable ways in fixation tasks. The objective of this study was to analyze visual functions, postural control, and cognitive involvement in stationary gaze. A total of 14 healthy young adults performed a fixation task and a free-viewing task (three trials per task, 45 s per trial). As expected, the results showed many (n = 32) significant positive Pearson correlation coefficients between the eye and center of pressure/body (head, neck, and lower back) movements in the fixation task. In the free-viewing task, the correlations were nonsignificant. Only 3 of the 32 significant correlations (9.4%) were significantly related to cognitive involvement (measured with a subjective questionnaire). These results indirectly strengthened the validity of the synergistic model of postural control.

scholarly journals Relationship between postural control in upright stance and virtual reality in post-stroke individuals

2020 ◽  
Vol 33 ◽  
Author(s):  
João Paulo Paes ◽  
Alaércio Perotti Junior ◽  
Ana Maria Forti Barela ◽  
José Angelo Barela
Keyword(s):  
Virtual Reality ◽  
Postural Control ◽  
Center Of Pressure ◽  
Mean Amplitude ◽  
Berg Balance Scale ◽  
Upright Stance ◽  
Nintendo Wii ◽  
Mean Velocity ◽  
Post Stroke ◽  
Time Required

Abstract Introduction: Considered the second leading cause of death worldwide, stroke leads to several consequences resulting from the injury in regions responsible for the processing of sensorimotor information, leading to deficits in the maintenance and performance of postural control. Objective: To relate the performance of postural control during upright stance and a virtual reality task in post-stroke individuals. Method: Nine post-stroke individuals, aged 30 to 76 years, characterized by the Berg balance scale, Fugl - Meyer scale and Mini Mental State Examination participated in this study. Postural performance was measured by the center of pressure under bipedal conditions, in anteroposterior and mediolateral directions and unipedal with the affected and unaffected sides, using a force platform. Virtual reality performance was measured by distance and time required to perform a task in the Nintendo Wii®. Results: Revealed significant correlations between distance and displacement time of the affected side (distance x disc_affected = 0.667 | p = 0.025; time x disc_affected = 0.683 | p = 0.021) and between variables time and mean amplitude of mediolateral oscillation (time x amo_ml = -0.733 | p = 0.012), time and mediolateral and anteroposterior mean velocity (time x vm_ml = -0.617 | p = 0.038; time x vm_ap = -0.833 | p = 0.003) and between time and area (time x area = -0.633 | p = 0.034). Conclusion: the performance of standing postural control in post-stroke individuals, represented by measures of weight discharge and variables of postural control, presented a significant relation with the variables of virtual reality.

scholarly journals Reliability and Validity of a Mobile Device Application for Use in Sports-Related Concussion Balance Assessment

2017 ◽  
Vol 04 (01) ◽  
pp. e1-e6 ◽  
Author(s):  
Mark Burghart ◽  
Jordan Craig ◽  
Jeff Radel ◽  
Jessie Huisinga
Keyword(s):  
Mobile Device ◽  
Center Of Pressure ◽  
Pearson Correlation ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Force Platform ◽  
Balance Assessment ◽  
Retest Reliability ◽  
Device Application ◽  
Test Retest Reliability

Background Balance assessment is necessary when evaluating athletes after a concussion. We investigated a mobile device application (app) for providing valid, reliable, and objective measures of static balance. Objectives The mobile device app would demonstrate similar test–retest reliability to force platform center of pressure (COP) sway variables and that SWAY scores and force platform COP sway variables would demonstrate good correlation coefficients. Methods Twenty-six healthy adults performed balance stances on a force platform while holding a mobile device equipped with SWAY (Sway Medical LLC) to measure postural sway based on acceleration changes detected by the mobile device's accelerometer. Participants completed four series of three 10-second stances (feet together, tandem, and single leg), twice with eyes open and twice with eyes closed. Test–retest reliability was assessed using intraclass correlation coefficients (ICC). Concurrent validity of SWAY scores and COP sway variables were determined with Pearson correlation coefficients. Results Reliability of SWAY scores was comparable to force platform results for the same test condition (ICC = 0.21–0.57). Validity showed moderate associations between SWAY scores and COP sway variables during tandem stance (r = –0.430 to –0.493). Lower SWAY scores, indicating instability, were associated with greater COP sway. Discussion The SWAY app is a valid and reliable tool when measuring balance of healthy individuals in tandem stance. Further study of clinical populations is needed prior to assessment use. Conclusion The SWAY app has potential for objective clinical and sideline evaluations of concussed athletes, although continued evaluation is needed.

scholarly journals Analysis of Postural Stability After Concussion Using Empirical Mode Decomposition: A Pilot Study

2017 ◽  
Author(s):  
Charles M. Schneider ◽  
Ajay K. Verma ◽  
Tamanna T. K. Munia ◽  
Mark Romanick ◽  
Kouhyar Tavakolian ◽  
...  
Keyword(s):  
Postural Control ◽  
Empirical Mode Decomposition ◽  
Postural Stability ◽  
Center Of Pressure ◽  
Return To Play ◽  
Electrode Placement ◽  
Upright Stance ◽  
Post Injury ◽  
Mode Decomposition ◽  
Postural Equilibrium

Maintaining upright stance is a complex process, it requires appropriate functioning of a postural control system which consists of inputs from somatosensory, vestibular, musculoskeletal, and proprioceptive systems as well as from several brain regions [1–4]. A concussion is defined as a brain injury caused due to unexpected acceleration/deceleration of the head causing temporary alteration of brain function and it is a prevalent source of injury to football athletes [1]. With the altered function of the brain, the ability to maintain postural equilibrium becomes challenging due to the inability of individuals to respond promptly to stressors, thus, making maintenance of postural equilibrium rather difficult for individuals with a concussion. Effects of concussion on postural ability are shown to last up to three days post injury [5]. Postural stability test, therefore, can be performed to make a valid return to play (RTP) decision, pre-mature RTP is shown to have been catastrophic due to its potential to permanently impair previously affected region/functioning [1,5]. Postural sway data (center of pressure, COP) is traditionally analyzed to study the postural control. Therefore, COP can provide critical information regarding individual’s ability to maintain upright stance post injury. A more sensitive concussion assessment tool based on electroencephalogram (EEG) is used to accurately track effects of concussion [6]. However, sophisticated electrode placement requirement inhibits its immediate applicability. In current preliminary research, we attempt to differentiate athletes with a history of concussion (experimental) from healthy (control) using postural data. In order to do so, a concept of empirical mode decomposition (EMD) was adopted. EMD has shown evidence in the literature to infer vital information pertaining to the complex underlying physiological phenomenon [4, 7–8]. In the current research, the resultant COP (COPr) was decomposed into its finite set of band-limited signals termed as intrinsic mode functions (IMFs) [8], a set of linear and nonlinear features were extracted from COPr and its IMfs. Lastly, a test of significance was conducted to infer the potential of postural data for differentiating concussed from healthy athletes.

scholarly journals Comparison of HTC Vive™ Virtual Reality Headset Position Measures to Center of Pressure Measures

2019 ◽  
Vol 63 (1) ◽  
pp. 2333-2336
Author(s):  
Brian Sylcott ◽  
Keith Williams ◽  
Mark Hinderaker ◽  
Chia-Cheng Lin
Keyword(s):  
Virtual Reality ◽  
Optical Flow ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Pearson Correlation ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Cost Effective ◽  
Study Participants ◽  
Further Development

This study was completed to validate a virtual reality (VR) headset (HTC ViveTM, Taiwan) as a tool to measure postural sway using the position and orientation tracking capabilities built into the VR system. If validated, the headset could be a cost-effective tool for balance assessments. Unity was used to develop an optical flow environment for VR. Study participants were able to experience three different speeds of optical flow displayed through the HTC Vive headset. However, for this study, participants were shown a scene in the virtual environment that did not move, causing no optical flow for the participant. A force plate and VR headset recorded position measurements during each trial. The Pearson correlation coefficients between the headset and the force plate data measurements were calculated in MATLAB, along with the root-mean-squared and peak-to-peak values for each trial. Results show that correlations in the AP plane tended to be greater than 0.4 and correlation in the ML plane tended to be greater than 0.6. The VR headset may be used for postural control measurements in clinic. However, further development of software and testing protocols for balance assessments is needed.

scholarly journals Genetic evaluation of Hanoverian warmblood horses for conformation traits considering the proportion of genes of foreign breeds

2010 ◽  
Vol 53 (4) ◽  
pp. 377-387 ◽  
Author(s):  
W. Schröder ◽  
K. F. Stock ◽  
O. Distl
Keyword(s):  
Fixed Effects ◽  
Pearson Correlation ◽  
Random Effect ◽  
Correlation Coefficients ◽  
Genetic Evaluation ◽  
Linear Unbiased Prediction ◽  
Residual Maximum Likelihood ◽  
Best Linear Unbiased ◽  
Inspection Data ◽  
Head Neck

Abstract. Conformation data of in total 29 053 Hanoverian warmblood mares were used to determine whether genetic evaluation for conformation in the Hanoverian could benefit from the inclusion of the proportion of genes of foreign breeds in the model. For our analyses, we considered all Hanoverian mares born from 1992 to 2005 with available studbook inspection data. Genetic parameters were estimated univariately for eight routinely scored conformation traits (head, neck, saddle position, frontlegs, hindlegs, type, frame, and general impression and development), and height at withers from studbook inspections, in a linear animal model using Residual Maximum Likelihood (REML). Genetic evaluation was subsequently performed using Best Linear Unbiased Prediction. To investigate the effect of correcting for the proportion of genes of foreign breeds, two different models were used for the analyses. In Model 1, the fixed effect age at studbook inspection, and the random effect date-place interaction were considered. In Model 2, proportions of genes of Thoroughbred, Trakehner and Holsteiner were additionally included as fixed effects. Heritabilities of analyzed conformation traits and withers height ranged in both models between 0.10 and 0.57, with standard errors of ≤0.01. Pearson correlation coefficients determined between breeding values of corresponding traits using Model 1 and 2 were highly positive (>0.99), indicating little effect of the model on the results of genetic evaluation. According to the results using a model which includes the proportion of genes of Thoroughbred, Trakehner and Holsteiner as fixed effects will not relevantly improve genetic evaluation for conformation in the Hanoverian.

Effects of Ankle Angular Position and Standing Surface on Postural Control of Upright Stance

Motor Control ◽  
2020 ◽  
Vol 24 (2) ◽  
pp. 291-303
Author(s):  
Fawaz A. Alwadani ◽  
Huaqing Liang ◽  
Alexander S. Aruin
Keyword(s):  
Young Adults ◽  
Postural Control ◽  
Center Of Pressure ◽  
Angular Position ◽  
Force Platform ◽  
Upright Stance ◽  
Surface Type ◽  
Natural Position ◽  
Ankle Joints

The purpose of the study was to investigate the effects of ankle angular position and standing surface type on static upright balance. Ten young adults stood on a force platform or on a firm wedge that induced 15° of either dorsiflexion or plantarflexion. In addition, a piece of foam was placed on top of the force platform and on the wedge. The center of pressure distance and velocity in the anteroposterior and mediolateral directions were calculated. Significantly larger magnitudes in most of the investigated variables were seen while standing with ankles in the dorsiflexion when compared with standing with the ankle joints in a natural position (p < .05). Plantarflexion increased the center of pressure anteroposterior velocity by 87% when compared with a natural stance (p < .05). Standing on the foam surfaces resulted in increases in all of the center of pressure measures by an average of 38% in all of the ankle conditions.

Reliability and Validity of Center-of-Pressure Quantification

2003 ◽  
Vol 93 (2) ◽  
pp. 142-149 ◽  
Author(s):  
Mark W. Cornwall ◽  
Thomas G. McPoil
Keyword(s):  
Center Of Pressure ◽  
Pearson Correlation ◽  
Phase 1 ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Correlation Coefficients ◽  
Frontal Plane ◽  
Area Index ◽  
Rearfoot Eversion ◽  
Medial Area

The purpose of this study was to determine the reliability and validity of two center-of-pressure quantification methods. One hundred five individuals (33 men and 72 women) with a mean age of 26.7 years participated in phase 1 of the study. Two measures of the center-of-pressure pattern, the lateral-medial area index and the lateral-medial force index, were calculated from plantar pressure data collected on all subjects. Between-trial reliability of the two measurements was assessed using intraclass correlation coefficients. In phase 2, frontal plane motion of the rearfoot was recorded in 30 individuals. Pearson correlation coefficients were then calculated between the two center-of-pressure indices and the magnitude of rearfoot eversion obtained from each subject during walking. Intraclass correlation coefficient values ranged from 0.374 to 0.889 for the lateral-medial area index and from 0.215 to 0.905 for the lateral-medial force index. Pearson correlation coefficients between the two center-of-pressure indices and the rearfoot kinematic variables ranged from 0.050 to 0.165. The lateral-medial area index and the lateral-medial force index may have adequate between-trial reliability but are not related to the magnitude of frontal plane rearfoot eversion during the stance phase of walking. (J Am Podiatr Med Assoc 93(2): 142-149, 2003)

scholarly journals A Critical Review of Position- and Velocity-Based Concepts of Postural Control During Upright Stance

2014 ◽  
Vol 15 (4) ◽  
Author(s):  
Fellipe Machado Portela ◽  
Erika Carvalho Rodrigues ◽  
Arthur de Sá Ferreira
Keyword(s):  
Postural Control ◽  
Quantitative Methods ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Quiet Standing ◽  
Supporting Evidence ◽  
Upright Stance ◽  
Motor Tasks ◽  
Control Loops ◽  
Control Concept

AbstractPurpose. Postural control during quiet standing has been modeled by concepts using kinematic variables estimated from center of pressure (COP) signals. The concept of position-based postural control has had particular ramifications in the literature, although a more recent concept of velocity-based control has been proposed as being more relevant. Methods. This study reviews the literature investigating these concepts and their respective quantitative methods alongside current supporting evidence and criticisms. Results. The position-based control concept suggests the existence of two control loops that alternate whenever certain thresholds are exceeded. Such a theory is supported by studies describing the time delay between the skeletal muscle activation and CoP displacement. However, this concept has been criticized to be the result of statistical artifacts due to it not being adapted to the analysis of bounded time series. Conversely, the velocity-based control concept claims that velocity is the most relevant kinematic variable for postural control. Such a theory suggests that postural adjustments are executed to change the trajectory of the CoP whenever the velocity crosses a threshold. Both theories have their major methodological limitations, while interpretation of data from the position-based concept is difficult, velocity-based thresholds are empirical and still need verification in different motor tasks and populations. Conclusions. Given the observed similarities and mutual exclusivity of both concepts, there is a need for the development of methods that can quantitatively analyze stabilometric signals while simultaneously considering both kinematic variables.

Reliability of the Minimum Masking Level as Outcome Variable in Tinnitus Clinical Research

2020 ◽  
Vol 29 (3) ◽  
pp. 429-435
Author(s):  
Patricia C. Mancini ◽  
Richard S. Tyler ◽  
Hyung Jin Jun ◽  
Tang-Chuan Wang ◽  
Helena Ji ◽  
...  
Keyword(s):  
Standard Deviation ◽  
High Frequency ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Outcome Variable ◽  
Reliable Estimate ◽  
Moderate Correlation ◽  
Trained Subjects ◽  
The Relationship ◽  
Minimum Intensity

Purpose The minimum masking level (MML) is the minimum intensity of a stimulus required to just totally mask the tinnitus. Treatments aimed at reducing the tinnitus itself should attempt to measure the magnitude of the tinnitus. The objective of this study was to evaluate the reliability of the MML. Method Sample consisted of 59 tinnitus patients who reported stable tinnitus. We obtained MML measures on two visits, separated by about 2–3 weeks. We used two noise types: speech-shaped noise and high-frequency emphasis noise. We also investigated the relationship between the MML and tinnitus loudness estimates and the Tinnitus Handicap Questionnaire (THQ). Results There were differences across the different noise types. The within-session standard deviation averaged across subjects varied between 1.3 and 1.8 dB. Across the two sessions, the Pearson correlation coefficients, range was r = .84. There was a weak relationship between the dB SL MML and loudness, and between the MML and the THQ. A moderate correlation ( r = .44) was found between the THQ and loudness estimates. Conclusions We conclude that the dB SL MML can be a reliable estimate of tinnitus magnitude, with expected standard deviations in trained subjects of about 1.5 dB. It appears that the dB SL MML and loudness estimates are not closely related.

Comparative Responses to Squats Completed with Free Weights and an Exoskeleton

2020 ◽  
Vol 4 (1) ◽  
pp. 51-63
Author(s):  
Peter Neuhaus ◽  
Chris Jumonville ◽  
Rachel A. Perry ◽  
Roman Edwards ◽  
Jake L. Martin ◽  
...  
Keyword(s):  
Data Collection ◽  
Female Athletes ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Actual Data ◽  
Limited Data ◽  
Comparative Similarity ◽  
Insufficient Amount ◽  
Force Data ◽  
Familiarization Session

AbstractTo assess the comparative similarity of squat data collected as they wore a robotic exoskeleton, female athletes (n=14) did two exercise bouts spaced 14 days apart. Data from their exoskeleton workout was compared to a session they did with free weights. Each squat workout entailed a four-set, four-repetition paradigm with 60-second rest periods. Sets for each workout involved progressively heavier (22.5, 34, 45.5, 57 kg) loads. The same physiological, perceptual, and exercise performance dependent variables were measured and collected from both workouts. Per dependent variable, Pearson correlation coefficients, t-tests, and Cohen's d effect size compared the degree of similarity between values obtained from the exoskeleton and free weight workouts. Results show peak O2, heart rate, and peak force data produced the least variability. In contrast, far more inter-workout variability was noted for peak velocity, peak power, and electromyography (EMG) values. Overall, an insufficient amount of comparative similarity exists for data collected from both workouts. Due to the limited data similarity, the exoskeleton does not exhibit an acceptable degree of validity. Likely the cause for the limited similarity was due to the brief amount of familiarization subjects had to the exoskeleton prior to actual data collection. A familiarization session that accustomed subjects to squats done with the exoskeleton prior to actual data collection may have considerably improved the validity of data obtained from that device.

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