Does binocular instability influence static body balance in adults with developmental dyslexia?

Attentional Demands of Postural Control in Chronic Ankle Instability, Copers and Healthy Controls: A Controlled Cross-sectional Study

Center of pressure (CoP) metrics, including CoP path length and sway area, have been used as gold standard measurements of postural and balance control in biomechanical studies. A recent study of computer-vision-based CoP metrics estimation from 3D body landmark sequences offers a more portable and comprehensive solution than conventional force plate methods to obtain these important metrics for real-time evaluation of balance control. However, obtaining accurate 3D body landmarks requires a calibrated motion capture system or on-body markers, which involves lengthy data collection and processing time and limits their implementation in home and clinical environments. Existing methods that instead use 2D body landmarks fail to adapt to different camera positions. To overcome these challenges, we propose a view-invariant deep learning framework for video-level CoP metrics estimation, including CoP path length and sway area, using pose dimension lifting and graph convolutional network (GCN). This work is the first step toward obtaining gold-standard CoP metrics with an accessible, monocular RGB camera. We propose to use a dimension lifting convolutional neural network (CNN) to obtain view-invariant 3D body landmark features from 2D body landmarks. We also propose a two-stream regression model using GCN and discrete cosine transform (DCT) for a robust CoP metrics estimation. To facilitate the line of research, we release a novel multi-view body landmark dataset containing 2D body landmarks of a wide variety of action patterns from four different camera views with synchronized CoP labels and corresponding 3D body landmarks, which enables cross-view evaluation with different camera angles. We subsequently validate the proposed method through a cross-dataset training by training the dimension lifting model on an existing balance dataset and evaluating the CoP metrics estimation on the multi-view body landmark dataset. The experiments validate that our framework achieves state-of-the-art accuracy for both CoP path length and CoP sway area using a monocular RGB camera input for unseen views.

Intrasession reliability of center of pressure measures of postural steadiness in healthy elderly people

ObjectiveTo examine how acute sport-related concussion influences centre of pressure (COP) sway during quiet stanceDesignProspective cohortSettingLaboratoryParticipantsEighty-seven male contact-sport (football and hockey) athletes entered the study. Seven subjects (age range 17–22)...

Influence of visual inputs on quasi-static standing postural steadiness in individuals with spinal cord injury

Intuitively, a broad stance (i.e., standing with the feet farther apart than usual) should significantly improve postural stability. However, this intuition was not confirmed in quiet stance. Hence, a motion analysis system (markers attached to the trunk and head) and a force platform were used to investigate 13 healthy, young adults who performed 8 trials in standard and broad stances. In broad stance, the medialateral center of pressure (COP) sway mean power frequency was expected to be greater, whereas the variability (standard deviation) of COP, head, and trunk sway and the mean velocity of head and trunk sway was expected to be significantly lower. Accordingly, adoption of a broad stance significantly increased the medialateral mean power frequency of COP sway; decreased the standard deviation of medialateral COP, trunk, and head sway; and decreased the medialateral mean velocity of head sway. A broad stance was also associated with lower variability for head and COP sways in the anteroposterior axis. Unexpectedly, an effect of trial repetition was found for the variability of medialateral trunk sway. This was probably due to the break halfway through the study. In practical terms, broad stance conditions can improve postural control in the medialateral and anteroposterior axes.

In this study, an altered switch for rehabilitation was invented to make home training accessible for the stroke patients, by modifying a computer mouse into a foot switch. This study examined the effects of training with an adaptive foot switch and video games (VG) on walking performance and balance abilities (Centre of Pressure (CoP) sway) in people after stroke.The intervention was evaluated through a randomised controlled trial. The intervention group received 10 weeks of VG rehabilitation, for approximately 3.5 hours/week, using a pressure-activated electronic foot switch, in addition to standard rehabilitation. The control group received regular rehabilitation only. The experiment included a force platform (measuring CoP sway kinematics) and a 10-Metre Test of Walking (10MWT) to measure the standing balance and walking performance of 56 stroke patients.There were no differences between the two groups (intervention and control) at baseline in terms of the demographic or dependent variables. Multivariate tests indicated a significant interaction between the Patient Group and the Time-type variables. Subsequent analysis of the main effects revealed significant between-group differences over time in all dependent variables (10MWT, sway area, CoP sway in anterior–posterior direction (AP sway) and CoP sway in medial–lateral direction (ML sway)). Patients in the intervention group demonstrated better performance than those in the control group after the VG rehabilitation according to the post-test.This study suggests that ankle muscle training using an adaptive foot switch and VG may improve exercise compliance and enhance recovery of balance and mobility following stroke.

ObjectiveThe objective of this study was to assess, for individuals with hemiparesis after a stroke in subacute phase, the validity and reliability of center of pressure (CoP) parameters measured during sitting balance on an unstable support. Materials and methodsThirty-two individuals after stroke were included in this observational study for validity and reliability (mean age: 64.34 ± 9.30y, 23 men, mean post-stroke duration: 55.64 ± 27days). Intra-Class Correlation (ICC) and Bland Altman plot assessed intra-rater reliability and inter-rater reliability of CoP parameters during unstable sitting balance test (anteroposterior or mediolateral imbalance). Validity was established by correlating CoP parameters with the Modified Functional Reach Test, trunk strength, Balance Assessment in Sitting and Standing and Timed Up and Go tests. ResultsThe findings highlighted significant correlations between CoP parameters and trunk strength for anteroposterior seated destabilization. Good to excellent intra and inter-rater reliability (0.87 ≤ ICC ≤ 0.95) was observed for all CoP length parameters and CoP mean velocity in both mediolateral and anteroposterior imbalance conditions. CoP parameters for mediolateral unstable sitting condition were more reliable than for anteroposterior instability. ConclusionTrunk control assessment during unstable sitting position on a seesaw is a reliable test for assessing trunk control ability in individuals after a stroke. CoP length and mean velocity are found to be the best parameters.

Balance is integral in ankle injury prevention and therapy, especially in high-risk sports like volleyball. For balance assessment, the recommended wobble board (WB) performance (i.e., time at equilibrium) has never been compared with the gold standard. The objective was to investigate the relationships of force-plate-derived center of pressure (CoP) with WB performance and the accuracy of WB-derived CoP estimates. Twelve high-level volleyball players completed six unipedal standing trials on a computerized WB. WB tilt angles and CoP were obtained simultaneously via tri-axis accelerometers on the WB (200 Hz) and a force plate (1000 Hz), respectively. WB performance, polynomial-transformed CoP estimates, and CoP fractal sway, sway area, and mean sway velocity were assessed via Pearson and concordance correlation, root mean square errors, and dependent t-tests. WB performance was related with CoP sway and sway area (|rlinear| = 0.714–0.842, |rnonlinear| = 0.833–0.910, p < 0.01). The strongest concordance (0.878–0.893, p < 0.001) and smallest errors (6.5–10.7%) were reported for anterior–posterior sway and sway area. Moderate to excellent relationships between the WB performance and force plate CoP variables supported the usefulness of WB performance and estimates (especially sway area) in balance assessment. Furthermore, this study presents recommendations for future analyses and modeling approaches to reflect the complexity of postural control.

Objective To quantitatively assess measures of static balance and limits of stability (LOS) in an aquatic environment compared to on land. Methods Fifteen healthy, young adults (23 + or - 2 years) performed 90 s static balance trials on land and aquatic immersion at two different depths (greater trochanter, xiphoid process). Measures of 95% ellipse area and center of pressure (CoP) mean velocity were computed from the force data. Additionally, participants completed a visual analog scale (VAS) of perceived stability for each environmental condition. Following the static balance trials, participants performed anterior-posterior and medial-lateral LOS assessments. Results Significant differences in 95% ellipse area and CoP mean velocity were observed for the aquatic environments compared to on land (p < 0.05). VAS data revealed significant differences in perceived balance in an aquatic environment compared to on land (p < 0.05). LOS assessments revealed a significant difference in maximum CoP excursions in an aquatic environment compared to land (p < 0.05). Conclusion When participants performed a quiet double-leg stance task, measures of balance and perceived stability were inferior when the task was performed in water than on land. Additionally, participants achieved greater CoP maximum excursions in the water compared to on land. Although future research is needed to assess factors influencing balance in the water, the added instability in the water is clinically relevant. Results of this study further highlight the importance of considering the inclusion of aquatic training as part of a comprehensive training / rehabilitation program.

Influence of Anaerobic and Aerobic Exercises on the Center of Pressure During an Upright Posture

BackgroundKnee osteoarthritis (OA) is the most common disease affecting human locomotion, and one of the most important causes of disability among the elderly population. In order to assess health status...

Noisy galvanic vestibular stimulation effect on center of pressure sway during one-legged standing

Dynamic balance has frequently been evaluated by using center of pressure (COP) during stepping movement. COP sway may be greater during stepping on foam rubber, which is a kind of external load. This study aimed to examine the effect of leg-joint angles and COP sway during stepping on a spot in 13 young male adults (mean age 25.6 ± 4.8 years, mean height 170.6 ± 5.2 cm, mean mass 69.1 ± 8.2 kg), with or without foam rubber and with eyes open or closed. When subjects stepped on foam rubber placed on two force plates (right and left), while matching a tempo of 100 bpm for 20 s under the above four conditions, characteristics such as mean angles of hip, knee, and ankle joints and COP sway were measured. In the results of two-way ANOVA (rubber condition × eye condition) and post-hoc tests, the hip-joint angle was significantly greater with eyes open, regardless of with or without foam rubber. The knee-joint angle was significantly greater in eyes closed with off-foam-rubber than on-foam-rubber. The ankle-joint angle was significantly greater in off- foam-rubber, regardless of eyes open or closed, and with eyes open than with eyes closed, regardless of with or without foam rubber. The total trace length and velocity were significantly greater in off-foam-rubber with eyes open, and on-foam-rubber with eyes closed than on-foam-rubber with eyes open. The other sway parameters were significantly greater with eyes open than with eyes closed regardless of with or without foam rubber. The hip-joint angle was significantly greater with eyes open regardless of with or without foam rubber. In conclusion, the COP sway during stepping with a stipulated tempo is less with eyes open than eyes closed, but the motion of knee and ankle joints is greater with eyes open. The sway distance and velocity during stepping with eyes open and motion of knee and ankle joints during stepping with eyes closed are both affected by the foam-rubber load. When stepping on the foam rubber, movement of the knee joints relates to distance and velocity of COP regardless of open or closed eyes. The findings in this study will be used to evaluate balance functions that are closely related to basic movements.

Benefits of postural sway to succeed in goal-directed visual tasks