Elsevier

Gait & Posture

Volume 39, Issue 1, January 2014, Pages 410-414
Gait & Posture

Effectiveness of different visual biofeedback signals for human balance improvement

https://doi.org/10.1016/j.gaitpost.2013.08.005Get rights and content

Highlights

  • Effectiveness of different VBF signals is compared.

  • VBF is the most effective in the body segment from which the signal is sensed.

  • The CoP position and L5 position provide the best signals for VBF.

  • Upper body segments have small impact on controlling lower segments, and vice versa.

  • Accelerometers offer new opportunities to optimize VBF systems.

Abstract

The aim of this study was to examine the effectiveness of visual biofeedback (VBF) signals from a force platform and accelerometer sensors placed on different body segments. The study was performed on 20 young subjects during standing on a firm and foam support surface with a VBF signal sensed from CoP, lower trunk (L5) and upper trunk (Th4). The VBF signal was controlled by 2D-movement of chosen body segment, which was presented as a red point on a monitor screen. Location of VBF signal had a significant effect on each postural parameter of CoP and trunk segments. RMS and amplitudes of postural sway in medial–lateral and anterior–posterior directions decreased during standing on both types of support surface due to VBF. L5-VBF and CoP-VBF significantly reduced CoP displacements and lower trunk tilts. Th4-VBF reduced upper trunk tilts. Frequency analysis of postural sway revealed a decrease of power spectral density (PSD) values in low frequency range (0.02–0.3 Hz) and an increase of PSD values in higher frequency range (0.5–1.4 Hz) in the VBF conditions during the stance on the firm surface in anterior–posterior direction. Reduction of body sway was the most significant in the body segment from which the VBF signal was sensed. The CoP position and L5 position provided the best signals for VBF. Changes in frequency ranges of body sway suggest voluntary activation of balance control. The results open new opportunities to optimize VBF system for balance improvement using accelerometers.

Introduction

Undisturbed upright stance control is a complex task based on an integration process involving visual, vestibular and proprioceptive information [1]. Postural stability is often evaluated by outputs from the force platform, which measures the centre of foot pressure (CoP) variability. However, posturography has its limitations because human body is multi-segmental and does not always act as an inverted pendulum. Upper body segments are often more independent from lower body segments, especially in challenged situations [2].

Visual biofeedback (VBF) consists of supplying individuals with additional artificial visual information about body motion to supplement the natural visual information and improve human balance [3]. The use of real-time visual biofeedback (VBF) from CoP during a standing task is a common tool incorporated in evaluation and training of the postural control [4]. The CoP position is presented in real time on a monitor screen and the subject is required to confine it to the narrowest possible zone [5].

The sensor of body motion is, besides the processor and interface, one of the main components of each biofeedback device [6]. The question of optimal sensor location for VBF has not been examined yet, despite the fact that accelerometers allow to measure inclination of body segment with respect to the vertical position. They can be attached to any part of the body. Body tilts measured by the accelerometer could be displayed on a monitor screen as well as outputs from a force platform. That offers new possibilities for VBF experiments.

In the present study, the effectiveness of VBF sensed from accelerometers attached to upper and lower trunk and VBF sensed from CoP were investigated. It was hypothesized that VBF from accelerometer attached to lower trunk would have similar influence on the body sway as VBF from CoP, because both reflect similar postural activities.

Section snippets

Methods

Twenty young subjects (9 men and 11 women) within the range of 20–33 years (mean age 22.6 years, mean BMI 21 kg m−2) participated in the study. Subjects did not report any neurological, orthopaedic, or balance impairments. They gave their informed consent in agreement with the Declaration of Helsinki. The study was approved by the local Ethics Committee.

Balance control was measured in eight conditions: standing on a firm (EO)/foam (thickness 10 cm) surface (FEO) with eyes open (control

Results

The results showed a decrease of body sway amplitudes and RMS characterized by CoP displacements and trunk tilts during the condition with VBF. Repeated measures ANOVA revealed a significant effect of VBF location for each evaluated parameter and body segment. There was also a significant interaction between the VBF location and support surface for each parameter of CoP displacements and for some parameters of trunk tilts (Table 1).

Post-hoc comparisons were performed for each VBF condition

Discussion

We confirmed the previous results about stabilizing effect of VBF on balance control. Furthermore, we found that the postural improvement was in relation to the location from which the body sway was sensed due to the visual biofeedback. The results showed that VBF is the most effective in reducing the postural sway of that body segment from which the signal was sensed. The CoP position and L5 position were found to be the best locations for VBF signal.

Visual biofeedback sensed from CoP

Acknowledgement

This work was supported by VEGA grant no. 2/0186/10.

Conflict of interest statement: We certify that none of the authors have a financial or personal relationship with other people or organizations that could inappropriately influence (bias) this work.

Cited by (47)

  • Influence of visual biofeedback and inherent stability on trunk postural control

    2020, Gait and Posture
    Citation Excerpt :

    Similarly, a recent review of therapies for children with moderate to severe cerebral palsy summarized the field as lacking appropriate treatments for this population [24]. Direct visual feedback reduced RMS sway to a greater extent than velocity (similar to a previous standing study by Jehu et al. [10]) and sway reductions were most evident at low frequencies (consistent with Halicka et al. [11] in standing). In contrast, altering natural sensory feedback (eyes closed) resulted in increases across a wide bandwidth of frequencies and increased both RMS sway and velocity.

  • Weighting and reweighting of visual input via head mounted display given unilateral peripheral vestibular dysfunction

    2019, Human Movement Science
    Citation Excerpt :

    This suggests that increased PSD in mid to high frequencies may reflect somatosensory reliance (Gilfriche et al., 2018). Therefore, our second purpose was to compare PSD of postural sway between groups in four frequency categories (0 to 0.25 Hz, 0.25 to 0.5 Hz, 0.5 to 1 Hz and 1 to 3 Hz) (Aoki, Tokita, Kuze, Mizuta, & Ito, 2014; Halická et al., 2014) in response to the varying visual and somatosensory manipulations. To be included in this study an individual needed to be 18 or older, of any gender (female participants could not be pregnant), with normal or corrected to normal vision, and be able to comprehend and sign an informed consent in English and no diagnosis of peripheral neuropathy.

  • Trunk motion visual feedback during walking improves dynamic balance in older adults: Assessor blinded randomized controlled trial

    2018, Gait and Posture
    Citation Excerpt :

    Most visual feedback (VFB) balance interventions have focused on standing or weight-shifting tasks [9–16], however, falls primarily occur during locomotion [3,17,18]. While virtual/augmented reality (VR) training has recently been shifting to more dynamic activities like walking, the majority of the walking VFB training is based on foot or leg kinematics with an emphasis on normalizing the gait cycle [19–23]. Control of foot placement is important for controlling displacement of the whole body center of mass, but upright trunk orientation is degraded for individuals with balance problems [24,25].

View all citing articles on Scopus
View full text