Physiological complexity and system adaptability: evidence from postural control dynamics of older adults

The degree of multiscale complexity in human behavioral regulation, such as that required for postural control, appears to decrease with advanced aging or disease. To help delineate causes and functional consequences of complexity loss, we examined the effects of visual and somatosensory impairment on the complexity of postural sway during quiet standing and its relationship to postural adaptation to cognitive dual tasking. Participants of the MOBILIZE Boston Study were classified into mutually exclusive groups: controls [intact vision and foot somatosensation, n = 299, 76 ± 5 (SD) yr old], visual impairment only (<20/40 vision, n = 81, 77 ± 4 yr old), somatosensory impairment only (inability to perceive 5.07 monofilament on plantar halluxes, n = 48, 80 ± 5 yr old), and combined impairments ( n = 25, 80 ± 4 yr old). Postural sway (i.e., center-of-pressure) dynamics were assessed during quiet standing and cognitive dual tasking, and a complexity index was quantified using multiscale entropy analysis. Postural sway speed and area, which did not correlate with complexity, were also computed. During quiet standing, the complexity index (mean ± SD) was highest in controls (9.5 ± 1.2) and successively lower in the visual (9.1 ± 1.1), somatosensory (8.6 ± 1.6), and combined (7.8 ± 1.3) impairment groups ( P = 0.001). Dual tasking resulted in increased sway speed and area but reduced complexity ( P < 0.01). Lower complexity during quiet standing correlated with greater absolute ( R = −0.34, P = 0.002) and percent ( R = −0.45, P < 0.001) increases in postural sway speed from quiet standing to dual-tasking conditions. Sensory impairments contributed to decreased postural sway complexity, which reflected reduced adaptive capacity of the postural control system. Relatively low baseline complexity may, therefore, indicate control systems that are more vulnerable to cognitive and other stressors.

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Stiffness Control of Balance During Quiet Standing and Dual Task in Older Adults: The MOBILIZE Boston Study

Journal of Neurophysiology ◽

10.1152/jn.00820.2009 ◽

2010 ◽

Vol 104 (6) ◽

pp. 3510-3517 ◽

Cited By ~ 25

Author(s):

Hyun Gu Kang ◽

Lewis A. Lipsitz

Keyword(s):

Older Adults ◽

Postural Control ◽

Dual Task ◽

Postural Sway ◽

Center Of Pressure ◽

Muscle Tone ◽

Community Dwelling ◽

Quiet Standing ◽

Study Cohort ◽

Boston Study

Distractions affect postural control, but this mechanism is not well understood. Diversion of resources during cognitive stress may lead to decreased motor drive and postural muscle tone. This may appear as decreased postural stiffness and increased postural sway amplitude. We hypothesized that dual tasking leads to decreased stiffness and increased sway amplitude. Postural sway (center of pressure; COP) data were used from 724 participants aged 77.9 ± 5.3 yr, a representative sample of community-dwelling older adults, the MOBILIZE Boston Study cohort. Subjects stood barefoot with eyes open for 30 s per trial on a force plate. Five trials were performed each with and without a serial subtractions-by-3 task. Sway data were fit to a damped oscillator inverted pendulum model. Amplitudes (COP and center of mass), mechanical stiffness, and damping of the sway behavior were determined. Sway amplitudes and damping increased with the dual task ( P < 0.001); stiffness decreased only mediolaterally ( P < 0.001). Those with difficulty doing the dual task exhibited larger sway and less damping mediolaterally ( P ≤ 0.001) and an increased stiffness with dual task anteroposteriorly (interaction P = 0.004). Dual task could still independently explain increases in sway ( P < 0.001) after accounting for stiffness changes. Thus the hypothesis was supported only in mediolateral sway. The simple model helped to explain the dual task related increase of sway only mediolaterally. It also elucidated the differential influence of cognitive function on the mechanics of anteroposterior and mediolateral sway behaviors. Dual task may divert the resources necessary for mediolateral postural control, thus leading to falls.

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Complexity-Based Measures of Postural Sway during Walking at Different Speeds and Durations Using Multiscale Entropy

Entropy ◽

10.3390/e21111128 ◽

2019 ◽

Vol 21 (11) ◽

pp. 1128 ◽

Cited By ~ 3

Author(s):

Liau ◽

Wu ◽

Lung ◽

Zhang ◽

Wang ◽

...

Keyword(s):

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Physical Activities ◽

Multiscale Entropy ◽

Complexity Index ◽

Significant Difference ◽

Daily Physical Activities ◽

Walking Speeds ◽

Pressure Measurement System

: Participation in various physical activities requires successful postural control in response to the changes in position of our body. It is important to assess postural control for early detection of falls and foot injuries. Walking at various speeds and for various durations is essential in daily physical activities. The purpose of this study was to evaluate the changes in complexity of the center of pressure (COP) during walking at different speeds and for different durations. In this study, a total of 12 participants were recruited for walking at two speeds (slow at 3 km/h and moderate at 6 km/h) for two durations (10 and 20 minutes). An insole-type plantar pressure measurement system was used to measure and calculate COP as participants walked on a treadmill. Multiscale entropy (MSE) was used to quantify the complexity of COP. Our results showed that the complexity of COP significantly decreased (p < 0.05) after 20 min of walking (complexity index, CI = −3.51) compared to 10 min of walking (CI = −3.20) while walking at 3 km/h, but not at 6 km/h. Our results also showed that the complexity index of COP indicated a significant difference (p < 0.05) between walking at speeds of 3 km/h (CI = −3.2) and 6 km/h (CI = −3.6) at the walking duration of 10 minutes, but not at 20 minutes. This study demonstrated an interaction between walking speeds and walking durations on the complexity of COP.

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Characteristics of Functional Stability in Young Adolescent Female Artistic Gymnasts

Journal of Human Kinetics ◽

10.2478/hukin-2021-0051 ◽

2021 ◽

Vol 77 (1) ◽

pp. 51-59

Author(s):

Agnieszka Opala-Berdzik ◽

Magdalena Głowacka ◽

Kajetan J. Słomka

Keyword(s):

Postural Control ◽

Center Of Pressure ◽

National Level ◽

Stability Limit ◽

Young Adolescent ◽

Quiet Standing ◽

Adolescent Female ◽

Functional Stability ◽

Postural Control System ◽

Stability Limits

Abstract The aim of this study was to determine whether young adolescent female artistic gymnasts demonstrate better functional stability than age- and sex-matched non-athletes. Different characteristics of the gymnasts’ postural control were expected to be observed. Twenty-two 10- to 13-year-old healthy females (ten national-level artistic gymnasts and twelve non-athletes) participated in the study. To assess their forward functional stability, the 30-s limit of stability test was performed on a force plate. The test consisted of three phases: quiet standing, transition to maximal forward leaning, and standing in the maximal forward leaning position. Between-group comparisons of the directional subcomponents of the root mean squares and mean velocities of the center of pressure and rambling-trembling displacements in two phases (quiet standing and standing in maximal leaning) were conducted. Moreover, anterior stability limits were compared. During standing in maximal forward leaning, there were no differences in the center of pressure and rambling measures between gymnasts and non-athletes (p > 0.05). The values of trembling measures in both anterior-posterior and medial-lateral directions were significantly lower in gymnasts (p < 0.05). Both groups presented similar values for anterior stability limits (p > 0.05). The comparisons of rambling components may suggest a similar supraspinal control of standing in the maximal leaning position between gymnasts and healthy non-athletes. However, decreased trembling in gymnasts may indicate reduced noise in their postural control system possibly due to superior control processes at the spinal level. The anterior stability limit was not influenced by gymnastics training in female adolescents.

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The Effects of Active Self-Correction on Postural Control in Girls with Adolescent Idiopathic Scoliosis: The Role of an Additional Mental Task

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17051640 ◽

2020 ◽

Vol 17 (5) ◽

pp. 1640 ◽

Cited By ~ 1

Author(s):

Elżbieta Piątek ◽

Michał Kuczyński ◽

Bożena Ostrowska

Keyword(s):

Adolescent Idiopathic Scoliosis ◽

Idiopathic Scoliosis ◽

Postural Control ◽

Repeated Measures ◽

Postural Sway ◽

Center Of Pressure ◽

Force Plate ◽

Stroop Test ◽

Quiet Standing ◽

Mental Task

Due to balance deficits that accompany adolescent idiopathic scoliosis (AIS), the potential interaction between activities of daily living and active self-correction movements (ASC) on postural control deserves particular attention. Our purpose was to assess the effects of ASC movements with or without a secondary mental task on postural control in twenty-five girls with AIS. It is a quasi-experimental within-subject design with repeated measures ANOVA. They were measured in four 20-s quiet standing trials on a force plate: no task, ASC, Stroop test, and both. Based on the center-of-pressure (COP) recordings, the COP parameters were computed. The ASC alone had no effect on any of the postural sway measures. Stroop test alone decreased COP speed and increased COP entropy. Performing the ASC movements and Stroop test together increased the COP speed and decreased COP entropy as compared to the baseline data. In conclusion, our results indicate that AIS did not interfere with postural control. The effects of the Stroop test accounted for good capacity of subjects with AIS to take advantage of distracting attentional resources from the posture. However, performing both tasks together exhibited some deficits in postural control, which may suggest the need for therapeutic consultation while engaging in more demanding activities.

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Center-of-Pressure Parameters Used in the Assessment of Postural Control

Journal of Sport Rehabilitation ◽

10.1123/jsr.11.1.51 ◽

2002 ◽

Vol 11 (1) ◽

pp. 51-66 ◽

Cited By ~ 176

Author(s):

Riann M. Palmieri ◽

Christopher D. Ingersoll ◽

Marcus B. Stone ◽

B. Andrew Krause

Keyword(s):

Control System ◽

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Data Sources ◽

Postural Control System ◽

Type Data

Objective:To define the numerous center-of-pressure derivatives used in the assessment of postural control and discuss what value each might provide in the assessment of balance.Data Sources:MEDLINE and SPORTDiscus were searched with the termsbalance, postural control, postural sway,andcenter of pressure. The remaining citations were collected from references of similar papers. A total of 67 references were studied.Conclusions:Understanding what is represented by each parameter used to assess postural control is crucial. At the present time the literature has failed to demonstrate how the variables reflect changes made by the postural-control system. Until it can be shown that the center of pressure and its derivatives actually reveal changes in the postural-control system, the value of using these measures to assess deficits in postural control is minimized.

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Attentional demands associated with augmented visual feedback during quiet standing

PeerJ ◽

10.7717/peerj.5101 ◽

2018 ◽

Vol 6 ◽

pp. e5101 ◽

Cited By ~ 4

Author(s):

Krzysztof Kręcisz ◽

Michał Kuczyński

Keyword(s):

Postural Control ◽

Visual Feedback ◽

Center Of Pressure ◽

Quiet Standing ◽

Mean Power ◽

Mean Power Frequency ◽

Postural Control System ◽

Power Frequency ◽

Auditory Reaction Time ◽

Anterior Posterior

To investigate how additional visual feedback (VFB) affects postural stability we compared 20-sec center-of-pressure (COP) recordings in two conditions: without and with the VFB. Seven healthy adult subjects performed 10 trials lasting 20 seconds in each condition. Simultaneously, during all trials the simple auditory reaction time (RT) was measured. Based on the COP data, the following sway parameters were computed: standard deviation (SD), mean speed (MV), sample entropy (SE), and mean power frequency (MPF). The RT was higher in the VFB condition (p < 0.001) indicating that this condition was attention demanding. The VFB resulted in decreased SD and increased SE in both the medial-lateral (ML) and anterior-posterior (AP) planes (p < .001). These results account for the efficacy of the VFB in stabilizing posture and in producing more irregular COP signals which may be interpreted as higher automaticity and/or larger level of noise in postural control. The MPF was higher during VFB in both planes as was the MV in the AP plane only (p < 0.001). The latter data demonstrate higher activity of postural control system that was caused by the availability of the set-point on the screen and the resulting control error which facilitated and sped up postural control.

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Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Behavioral Sciences ◽

10.3390/bs9110113 ◽

2019 ◽

Vol 9 (11) ◽

pp. 113 ◽

Cited By ~ 4

Author(s):

Harish Chander ◽

Sachini N. K. Kodithuwakku Arachchige ◽

Christopher M. Hill ◽

Alana J. Turner ◽

Shuchisnigdha Deb ◽

...

Keyword(s):

Virtual Reality ◽

Control System ◽

Postural Control ◽

Repeated Measures ◽

Postural Stability ◽

Postural Sway ◽

Center Of Pressure ◽

Postural Control System ◽

Postural Responses ◽

The Impact

Background: Virtual reality (VR) is becoming a widespread tool in rehabilitation, especially for postural stability. However, the impact of using VR in a “moving wall paradigm” (visual perturbation), specifically without and with anticipation of the perturbation, is unknown. Methods: Nineteen healthy subjects performed three trials of static balance testing on a force plate under three different conditions: baseline (no perturbation), unexpected VR perturbation, and expected VR perturbation. The statistical analysis consisted of a 1 × 3 repeated-measures ANOVA to test for differences in the center of pressure (COP) displacement, 95% ellipsoid area, and COP sway velocity. Results: The expected perturbation rendered significantly lower (p < 0.05) COP displacements and 95% ellipsoid area compared to the unexpected condition. A significantly higher (p < 0.05) sway velocity was also observed in the expected condition compared to the unexpected condition. Conclusions: Postural stability was lowered during unexpected visual perturbations compared to both during baseline and during expected visual perturbations, suggesting that conflicting visual feedback induced postural instability due to compensatory postural responses. However, during expected visual perturbations, significantly lowered postural sway displacement and area were achieved by increasing the sway velocity, suggesting the occurrence of postural behavior due to anticipatory postural responses. Finally, the study also concluded that VR could be used to induce different postural responses by providing visual perturbations to the postural control system, which can subsequently be used as an effective and low-cost tool for postural stability training and rehabilitation.

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Complexity and Frailty: Multiscale Entropy of Balance Dynamics During Quiet Standing and Dual-Task: The Mobilize Boston Study

Volume 2: Biomedical and Biotechnology Engineering ◽

10.1115/imece2008-68973 ◽

2008 ◽

Author(s):

Hyun Gu Kang ◽

Madalena Costa ◽

Attila A. Priplata ◽

Olga V. Starobinets ◽

Ary L. Goldberger ◽

...

Keyword(s):

Postural Control ◽

Dual Task ◽

Center Of Pressure ◽

Balance Control ◽

Community Dwelling ◽

Multiscale Entropy ◽

Multiple Time Scales ◽

Multiple Time ◽

Boston Study ◽

Balance Dynamics

Balance control during standing is attributable to the complex, nonlinear interactions of multiple postural control systems, manifested as the highly irregular displacements in center of pressure (COP) during standing. Aging and associated frailty may result in the degradation of these complex interactions and manifest as a loss of complexity in COP dynamics. Furthermore, frail individuals may not be able to adapt to a superimposed stress that challenges balance, leading to falls. To test these hypotheses, data were analyzed from the MOBILIZE Boston Study, an ongoing population-based study of community-dwelling older adults. Each participant’s frailty phenotype (not frail, pre-frail, frail) was determined using the Fried et al. 2001 definition. 551 participants (age 77.9±5.5) stood on a balance platform, with or without concurrently performing serial subtractions. Complexity of balance dynamics over multiple time scales was quantified using multiscale entropy (MSE), a more sensitive measure of physiologic health than variance. Of the participants, 39% were pre-frail and 6% were frail. Baseline MSE was lower with each successive frailty condition (p<0.002). When performing the cognitive task, MSE was lowered similarly in all groups (p<0.001). Frailty was associated with a loss of complexity in the dynamics of postural sway, which may be due to the degradation of integrated postural control networks that enable upright stance. Performance of a dual-task further reduced this complexity. Cognitive distractions during standing may further compromise balance control in frail individuals, which may explain their increased fall risk.

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Effectiveness and Limitations of Unsupervised Home-Based Balance Rehabilitation with Nintendo Wii in People with Multiple Sclerosis

BioMed Research International ◽

10.1155/2015/916478 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 11

Author(s):

Massimiliano Pau ◽

Giancarlo Coghe ◽

Federica Corona ◽

Bruno Leban ◽

Maria Giovanna Marrosu ◽

...

Keyword(s):

Multiple Sclerosis ◽

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Balance Training ◽

Frontal Plane ◽

Nintendo Wii ◽

Postural Control System ◽

Home Based ◽

Before And After

Balance training represents a critical part of the rehabilitation process of individuals living with multiple sclerosis (MS) since impaired postural control is a distinctive symptom of the disease. In recent years, the use of the Nintendo Wii system has become widespread among rehabilitation specialists for this purpose, but few studies have verified the effectiveness of such an approach using quantitative measures of balance. In this study, we analyzed the postural sway features of a cohort of twenty-seven individuals with MS before and after 5 weeks of unsupervised home-based balance training with the Wii system. Center of pressure (COP) time-series were recorded using a pressure platform and processed to calculate sway area, COP path length, displacements, and velocities in mediolateral (ML) and anteroposterior (AP) directions. Although the results show a significant reduction in sway area, COP displacements, and velocity, such improvements are essentially restricted to the ML direction, as the Wii platform appears to properly stimulate the postural control system in the frontal plane but not in the sagittal one. Available Wii games, although somewhat beneficial, appear not fully suitable for rehabilitation in MS owing to scarce flexibility and adaptability to MS needs and thus specific software should be developed.

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The effect of age, sex and a firm-textured surface on postural control

Experimental Brain Research ◽

10.1007/s00221-021-06063-2 ◽

2021 ◽

Author(s):

Francesco Palazzo ◽

Alessandra Nardi ◽

Niloofar Lamouchideli ◽

Alfio Caronti ◽

Anas Alashram ◽

...

Keyword(s):

Postural Control ◽

Postural Sway ◽

Center Of Pressure ◽

Sensory System ◽

The Body ◽

Quiet Standing ◽

Textured Surface ◽

Textured Surfaces ◽

Experimental Conditions ◽

Eyes Open

AbstractIn previous studies, the influence of plantar sensation has been examined using various textured surfaces with different stiffness materials to assess static balance. This study investigated the effects of a Firm Textured Surface (FTS) along with age and sex-related influences on postural control under different visual conditions. Forty subjects (20 elderly, 10 males, mean age 68.30, 10 females, mean age 68.00, and 20 young people, 10 males, mean age 25.45, 10 females, mean age 27.30) participated in this study maintained a quiet standing on FTS, foam and firm surfaces with eyes open and closed. The center of pressure displacement (CoPDISP), CoP velocity (CoPVEL), and sway velocity of the CoP in anteroposterior (AP) and mediolateral (ML) direction (VA/P and VM/L) were measured. FTS was associated with lower postural sway measures in both the groups with eyes open and closed. However, the foam surface showed the worst results in all postural parameters under all experimental conditions. Separate four-way ANOVAs were applied to each dependent variable. The main effects of surface (p < 0.0001), vision (p < 0.0001) and age (p < 0.0001 for CoPDISP, CoPVEL and VA/P; p = 0.0003 for VM/L) were significant in each of the four fitted models. Sex was never significant, either as a main effect or an interaction with other experimental factors. Eyes open were able to reduce the negative effects of the foam surfaces but without vision the proprioceptive sensory system cues of the body state become more important for maintaining balance. A good stimulation with rigid texture should be considered as relief to reduce the physiological-related decline of afferent information with age.

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