Postural Sway Variability Research Articles

Potential Prodromal Digital Postural Sway Markers for Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) Detected via Dual-Tasking and Sensory Manipulation.

FXTAS is a neurodegenerative disorder occurring in some Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene premutation carriers (PMCs) and is characterized by cerebellar ataxia, tremor, and cognitive deficits that negatively impact balance and gait and increase fall risk. Dual-tasking (DT) cognitive-motor paradigms and challenging balance conditions may have the capacity to reveal markers of FXTAS onset. Our objectives were to determine the impact of dual-tasking and sensory and stance manipulation on balance in FXTAS and potentially detect subtle postural sway deficits in FMR1 PMCs who are asymptomatic for signs of FXTAS on clinical exam. Participants with FXTAS, PMCs without FXTAS, and controls underwent balance testing using an inertial sensor system. Stance, vision, surface stability, and cognitive demand were manipulated in 30 s trials. FXTAS participants had significantly greater total sway area, jerk, and RMS sway than controls under almost all balance conditions but were most impaired in those requiring vestibular control. PMCs without FXTAS had significantly greater RMS sway compared with controls in the feet apart, firm, single task conditions both with eyes open and closed (EC) and the feet together, firm, EC, DT condition. Postural sway deficits in the RMS postural sway variability domain in asymptomatic PMCs might represent prodromal signs of FXTAS. This information may be useful in providing sensitive biomarkers of FXTAS onset and as quantitative balance measures in future interventional trials and longitudinal natural history studies.

The Effects of Concussions on Static Postural Stability

Concussions among the athletic population are extremely common, which could lead to postural instabilities. The purpose of this study was to assess the effect of concussions on postural stability in young healthy adults. The static postural stability of thirty volunteers (age 21.63 ± 2.50 years; height 1.70 ± 0.14 m; weight 75.00 ± 15.58 kg; 17 with a history of concussions) was assessed using a force platform during three tests: baseline stability test, clinical test of sensory interaction and balance test, and unilateral stability test. Postural sway variables during each test were statistically analyzed using an independent t-test between the concussion group (CONC) and no concussion (NO CONC) groups. Two secondary analyses were performed with the CONC group: individuals who had one concussion (ONCE) vs. who had multiple concussions (MULTIPLE) and individuals who had their last concussion in 2023–2018 (RECENT) and in 2017–2011 (OLD). The CONC, MULTIPLE, and RECENT groups demonstrated greater postural sway than the NO CONC, SINGLE, and OLD groups. Concussions cause postural decrements in young healthy adults compared to their counterparts with no history of concussions. The results of the study exhibit that concussions could lead to imbalances, which is decisive in athletes’ performance and injury risk during play.

Spatial variability and directional shifts in postural control in Parkinson’s disease

Individuals with Parkinson’s disease exhibit tremors, rigidity, and bradykinesia, disrupting normal movement variability and resulting in postural instability. This comprehensive study aimed to investigate the link between the temporal structure of postural sway variability and Parkinsonism by analyzing multiple datasets from young and older adults, including individuals with Parkinson’s disease, across various task conditions. We used the Oriented Fractal Scaling Component Analysis (OFSCA), which identifies minimal and maximal long-range correlations within the center of pressure time series, allowing for detecting directional changes in postural sway variability. The objective was to uncover the primary directions along which individuals exerted control during the posture. The results, as anticipated, revealed that healthy adults predominantly exerted control along two orthogonal directions, closely aligned with the anteroposterior (AP) and mediolateral (ML) axes. In stark contrast, older adults and individuals with Parkinson’s disease exhibited control along suborthogonal directions that notably diverged from the AP and ML axes. While older adults and those with Parkinson’s disease demonstrated a similar reduction in the angle between these two control directions compared to healthy older adults, their reliance on this suborthogonal angle concerning endogenous fractal correlations exhibited significant differences from the healthy aging cohort. Importantly, individuals with Parkinson’s disease did not manifest the sensitivity to destabilizing task settings observed in their healthy counterparts, affirming the distinction between Parkinson’s disease and healthy aging.

Postural Control Behavior in a Virtual Moving Room Paradigm

Background: Taking inspiration from the classical 1974, “moving room experiment” by Lee and Aronson, a “virtual moving room paradigm (Vroom)” was designed using virtual reality (VR) to assess postural control behavior. Methods: Thirty healthy adults (age: 21 ± 1 years; height: 166.5 ± 7.3 cm; mass: 71.7 ± 16.2 kg) were tested for postural stability in a virtual moving room paradigm (Vroom). The Vroom consisted of randomized virtual and visual perturbations of the virtual room moving toward and away from the individual, during both unexpected and expected trials. Objective postural sway variables and subjective experiences to VR using the simulator sickness questionnaire as well as balance confidence scale were also assessed and analyzed using a two way (2 × 2 [2 moving room direction (Toward vs. Away) and 2 knowledge of moving room (unexpected vs. expected)] repeated measures analysis of variance (ANOVA), and a one-way repeated measures ANOVA and paired sample t-test, respectively at an alpha level of 0.05. Results: Significantly greater postural sway was observed when the virtual room moved toward the participant than when moving away, and when it moved unexpectedly, compared with the expected moving room. Significantly improved balance confidence with realistic immersion and without simulator sickness was also observed. Conclusions: Our findings provide evidence indicating that the virtual moving room induces postural perturbations that challenge the postural control system, especially when the moving room is unexpected and moves toward the individual. Additionally, increased balance confidence and realistic immersion in the virtual environment with no adverse effects of simulator sickness were observed, providing evidence for the beneficial effects of the Vroom. Thus, the Vroom can be an easy and cost-effective method to expose individuals to realistic, virtual, and visual perturbations that challenge the postural control system and increase balance confidence, with realistic immersion and without adverse effects.

Does vibration frequency and location influence the effect of neck muscle vibration on postural sway? A cross-sectional study in asymptomatic participants.

Postural control is of utmost importance for human functioning. Cervical proprioception is crucial for balance control. Therefore, any change to it can lead to balance problems. Previous studies used neck vibration to change cervical proprioception and showed changes in postural control, but it remains unknown which vibration frequency or location causes the most significant effect. Therefore, this study aimed to investigate the effect of different vibration frequencies and locations on postural sway and to serve as future research protocol guidance. Seventeen healthy young participants were included in the study. We compared postural sway without vibration to postural sway with six different combinations of vibration frequency (80, 100, and 150Hz) and location (dorsal neck muscles and sternocleidomastoid). Postural sway was evaluated using a force platform. The mean center of pressure (CoP) displacement, the root mean square (RMS), and the mean velocity in the anteroposterior and mediolateral direction were calculated, as well as the sway area. The aligned rank transform tool and a three-way repeated measures ANOVA were used to identify significant differences in postural sway variables. Neck vibration caused a significant increase in all postural sway variables (p < 0.001). Neither the vibration frequency (p > 0.34) nor location (p > 0.29) nor the interaction of both (p > 0.30) influenced the magnitude of the change in postural sway measured during vibration. Neck muscle vibration significantly changes CoP displacement, mean velocity, RMS, and area. However, we investigated and found that there were no significant differences between the different combinations of vibration frequency and location.

Quantitative Analysis of Postural Balance in Faller and Nonfaller Patients with Parkinson's Disease.

Postural instability has been identified as a fall risk factor with a significant impact on the quality of life of patients with Parkinson's disease (PD). The aim of this study was to compare the center of pressure (COP) between faller and nonfaller patients with PD during static standing. Thirty-two faller patients and 32 nonfaller patients with PD participated in this study. All patients performed the static balance test on a force plate. COP data were recorded during quiet standing. Mean distance, sway area, mean velocity, mean frequency, and peak power were derived from the COP data. Statistical analysis was performed using independent t-tests to compare faller and nonfaller patients. Fallers presented a greater average distance, wider sway area, faster average speed, and greater peak power than nonfallers (p < 0.05). In contrast, no significant group differences were observed in peak frequency and mean frequency (p > 0.05). Although falls occur during dynamic activities, our study demonstrated that even a safe and simple static postural balance test could significantly differentiate between faller and nonfaller patients. Thus, these results suggest that quantitatively assessed static postural sway variables would be useful for distinguishing prospective fallers among PD patients.

Posturography measures in specific ballet stance position discriminate ballet dancers with different occurrences of musculoskeletal injuries

BackgroundThis study aimed to identify the postural sway variables that can distinguish between ballet dancers with high and low occurrences of musculoskeletal injuries. MethodsFourteen professional ballet dancers were assigned to a high-occurrence group (N = 5, reports >2 injuries in the previous 6-months) or a low-occurrence group (N = 9, reports ≤1 injury). Center-of-pressure (COP) data were acquired using a force platform during the following tasks: single-leg stance with eyes open, single-leg stance with eyes closed, and demi-pointe stance with eyes open. The COP standard deviation (SD) and range (RA) in both the medial-lateral (ML) and anterior-posterior (AP) directions were estimated. Between-group comparisons were made through Welch's t-tests for unequal sample size along the effect size measure (Cohen's d). Spearman's rho was used to estimate the association between the number of injuries and the COP variables. The statistical threshold was set at 1%. ResultsA between-group effect was found only for the demi-pointe stance, with large effects for SDML (P = 0.006, d = 1.7), RAAP (P = 0.006, d = 1.7), and RAML (P = 0.005, d = 1.7). An inverse relationship was found between the number of injuries and the demi-pointe's COP range in both directions (Spearman's rho from −0.681 to −0.726, P = 0.007). ConclusionsCOP measures taken in ballet-specific positions can distinguish between dancers with a high and low occurrence of musculoskeletal injuries. Suggestions are made to include ballet-specific tasks in the functional assessments of professional dancers.

Auditory, tactile, and multimodal noise reduce balance variability

Auditory and somatosensory white noise can stabilize standing balance. However, the differential effects of auditory and tactile noise stimulation on balance are unknown. Prior work on unimodal noise stimulation showed gains in balance with white noise through the auditory and tactile modalities separately. The current study aims to examine whether multimodal noise elicits similar responses to unimodal noise. We recorded the postural sway of healthy young adults who were presented with continuous white noise through the auditory or tactile modalities and through a combination of both (multimodal condition) using a wearable device. Our results replicate previous work that showed that auditory or tactile noise reduces sway variability with and without vision. Additionally, we show that multimodal noise also reduces the variability of sway. Analysis of different frequency bands of sway is typically used to separate open-loop exploratory (< 0.3 Hz) and feedback-driven (> 0.3 Hz) sway. We performed this analysis and showed that unimodal and multimodal white noise affected postural sway variability similarly in both timescales. These results support that the sensory noise effects on balance are robust across unimodal and multimodal conditions and can affect both mechanisms of sway represented in the frequency spectrum. In future work, the parameters of acoustic/tactile manipulation should be optimized for the most effective balance stabilization, and multimodal therapies should be explored for older adults with typical age-related balance instabilities.

Subthreshold electrical stimulation with pink noise enhances feedback control as evaluated by scaling exponent of postural sway

Subthreshold somatosensory stimulation with pink noise has been shown to attenuate postural sway better than stimulation with white noise. This might be due to the different frequency structures of the noise signals. However, their effects on the underlying somatosensory feedback pathway are still unknown. Thus, we aimed to determine whether pink noise enhances the somatosensory feedback pathway more effectively than other noises with different frequency structures, such as white and red noises. Sixteen young adults stood quietly for 65 s under four stimulation conditions: no stimulation and stimulations with white-, pink-, and red-noise-like signals. Based on a stabilogram-diffusion analysis, we calculated the long-term diffusion coefficient and scaling exponent in the radial direction to evaluate the effects of these noise signals on their somatosensory feedback control. The root mean square (CoPRMS) and mean velocity of the foot center of pressure were also computed to assess the amount of postural sway. The results showed that the stimulation condition had a significant effect on the scaling exponent, with the value under the pink-noise-like signal significantly lower than that under the no-stimulation condition. We also found that among the participants, the percentage of reduction in CoPRMS by the pink-noise-like signal was positively correlated with the CoPRMS value under the no-stimulation condition. Altogether, the somatosensory feedback control for balancing for quiet standing posture was improved by pink noise, and its effect on the variability of postural sway correlated with inherent postural sway variability.

Sport-specific training induced adaptations in postural control and their relationship with athletic performance.

Effects of various exercise programs on postural balance control in athletes and their underlying physiological mechanisms have been extensively investigated. However, little is known regarding how challenging sport-specific conditions contribute to the improvement of body balance and to what extent these changes may be explained by sensorimotor and/or neuromuscular function adaptations. Analysis of the literature could provide useful information on the interpretation of changes in postural sway variables in response to long-term sport-specific training and their association with performance measures. Therefore, the aim of this scoping review was (1) to analyze the literature investigating postural control adaptations induced by sport-specific training and their relationship with measures of athletic performance, and (2) to identify gaps in the existing research and to propose suggestions for future studies. A literature search conducted with Scopus, Web of Science, MEDLINE and Cochrane Library was completed by Elsevier, SpringerLink and Google Scholar with no date restrictions. Overall, 126 articles were eligible for inclusion. However, the association between variables of postural balance control and measures of sport-specific performance was investigated in only 14 of the articles. A relationship between static and/or dynamic balance and criterion measures of athletic performance was revealed in shooting, archery, golf, baseball, ice-hockey, tennis, and snowboarding. This may be ascribed to improved ability of athletes to perform postural adjustments in highly balanced task demands. However, the extent to which sport-specific exercises contribute to their superior postural stability is unknown. Although there is a good deal of evidence supporting neurophysiological adaptations in postural balance control induced by body conditioning exercises, little effort has been made to explain balance adaptations induced by sport-specific exercises and their effects on athletic performance. While an enhancement in athletic performance is often attributed to an improvement of neuromuscular functions induced by sport-specific balance exercises, it can be equally well ascribed to their improvement by general body conditioning exercises. Therefore, the relevant experiments have yet to be conducted to investigate the relative contributions of each of these exercises to improving athletic performance.

Community-based postural control assessment in autistic individuals indicates a similar but delayed trajectory compared to neurotypical individuals.

Autistic individuals exhibit significant sensorimotor differences. Postural stability and control are foundational motor skills for successfully performing many activities of daily living. In neurotypical development, postural stability and control develop throughout childhood and adolescence. In autistic development, previous studies have focused primarily on individual age groups (e.g., childhood, adolescence, adulthood) or only controlled for age using age-matching. Here, we examined the age trajectories of postural stability and control in autism from childhood through adolescents using standardized clinical assessments. In study 1, we tested the postural stability of autistic (n=27) and neurotypical (n=41) children, adolescents, and young adults aged 7-20 years during quiet standing on a force plate in three visual conditions: eyes open (EO), eyes closed (EC), and eyes open with the head in a translucent dome (Dome). Postural sway variability decreased as age increased for both groups, but autistic participants showed greater variability than neurotypical participants across age. In study 2, we tested autistic (n=21) and neurotypical (n=32) children and adolescents aged 7-16 years during a dynamic postural control task with nine targets. Postural control efficiency increased as age increased for both groups, but autistic participants were less efficient compared to neurotypical participants across age. Together, these results indicate that autistic individuals have a similar age trajectory for postural stability and control compared to neurotypical individuals, but have lower postural stability and control overall.

Impact of Joint Fixation on Postural Dynamics during Single-Leg Stance

We investigated the relationship between the mechanical degrees of freedom (DoF) and its postural dynamics. The joint DoF was fixed to constrain the mechanical DoF. Nine participants were required to perform a single-leg stance task. The center of pressure trajectory data was analyzed. Ankle fixation induced a larger amount of variability in the anteroposterior direction, and less dimensionality and complexity in the mediolateral direction. These results suggest that the ankle joint fixation caused limited postural sway in the mediolateral direction; therefore, functional DoF and complexity decreased. In contrast, it increased the amount of postural sway variability in the anteroposterior direction. Our findings imply a direct relationship between the mechanical DoF of the human movement system and its postural dynamics.

PREFACE

PREFACE

Biopsychosocial Factors Related to Postural Sway During Sit-to-Stand Movement in Children and Adolescents With Down Syndrome: A Cross-Sectional Study.

We investigated factors related to postural sway during sit-to-stand movement in children and adolescents with Down syndrome (DS). Our assessment of participants followed the biopsychosocial model. Body function and structure were represented by muscle strength and postural sway during sit-to-stand movement, which were assessed by manual muscle testing and kinetics analysis, respectively. The Gross Motor Function Measure and Pediatric Balance Scale depicted the activity component. In addition, we included these relevant contextual factors: age, Home Observation for Measurement of the Environment, family income, and maternal schooling. A correlation analysis verified a suspected association between biopsychosocial and postural sway variables. There were significant separated correlations between postural sway in the three phases of the sit-to-stand movement, and age, GMFM-88 dimension D, and muscle strength. Thus, postural control in sit-to-stand movement was related to biopsychosocial factors involving different life aspects of children and adolescents with DS, and these factors should be addressed in rehabilitation therapy intended to improve postural control among these individuals.

The Walls Are Closing In: Postural Responses to a Virtual Reality Claustrophobic Simulation

Background: Changes in the visual environment and thereby, the spatial orientation, can induce postural instability leading to falls. Virtual reality (VR) has been used to expose individuals to virtual environments (VE) that increase postural threats. Claustrophobia is an anxiety disorder categorized under situational phobias and can induce such postural threats in a VE. Purpose: The purpose of the study was to investigate if VR-generated claustrophobic simulation has any impact on postural threats that might lead to postural instability. Methods: Thirty healthy men and women (age: 20.7 ± 1.2 years; height: 166.5 ± 7.3 cm; mass: 71.7 ± 16.2 kg) were tested for postural stability while standing on a force platform, upon exposure to five different testing trials, including a normal stance (NoVR), in stationary VE (VR), and three consecutive, randomly initiated, unexpected claustrophobia trials (VR CP1, VR CP2, VR CP3). The claustrophobia trials involved all four walls closing in towards the center of the room. Center of pressure (COP)-derived postural sway variables were analyzed with a one-way repeated measures analysis of variance at an alpha level of 0.05. Results: Significant main effect differences existed in all but one dependent COP-derived postural sway variables, at p &lt; 0.05. Post-hoc pairwise comparisons with a Bonferroni correction revealed that, predominantly, postural sway excursions were significantly lower in claustrophobia trials compared to NoVR and VR, but only accomplished with significantly increased sway velocity. Conclusion: The VR CP trials induced lower postural sway magnitude, but with increased velocity, suggesting a bracing and co-contraction strategy when exposed to virtual claustrophobic postural threats. Additionally, postural sway decreased with subsequent claustrophobia trials, suggesting potential motor learning effects. Findings from the study offer insights to postural control behavior under virtual claustrophobic simulations and can aid in VR exposure therapy for claustrophobia.

AGE-RELATED DIFFERENCES IN STATIC POSTURAL BALANCE IN KOREAN ELDERLY ADULTS

Poor postural balance has been related to falls in older people. Although fall rates increase with age, age-related declines in postural balance of older people are still unclear. The goal of this study was to investigate age-related changes in the static postural balance ability of Korean elderly adults. Three hundred and eighty-nine normal elderly adults with ages ranging from 57 years to 87 years participated in this study. All elderly adults were instructed to stand in their preferred natural stance on a self-developed force platform. As postural sway variables, peak frequency, mean frequency, mean velocity, and mean distance were calculated from the center of pressure (COP) trajectories in both the medio-lateral (ML) and antero-posterior (AP) directions. The mean velocity in the older-elderly was significantly faster compared to those of the other age groups particularly in the AP direction ([Formula: see text]). In both the ML and AP directions, the older-elderly group showed a greater mean distance compared to the other age groups ([Formula: see text]). Conversely, no significant age group differences were found in mean frequency and peak frequency ([Formula: see text]). Our results mean that the older-elderly group showed postural balance with faster AP sway speed and overall sway size. The results of our study help in the understanding of age-related declines in postural balance for the prevention of falls and the development of a regression model for normative postural balance ability in Korean elderly adults.

Differences between Tempos of Step Error and Postural Sway in the Stipulated Tempo Step Test for Children and Their Relationships

Recently, to evaluate dynamic balance ability, a stipulated tempo step test has been developed, and a step error between tempo and contact time of feet has been used as an evaluation variable. The step error, postural sway, and their relationships may differ between the slow tempo (40 bpm) and fast tempo (120 bpm). This study aimed to examine the aforementioned problem with 62 participant children (30 boys and 32 girls). The step error and postural sway variables (X-axis path length, Y-axis path length, total path length, peripheral area, and rectangular area) during stepping while matching both tempos were measured. Means of one minute and three intervals (0–20 sec, 20–40 sec, and 40–60 sec) for each variable were calculated in both tempos. The results of the paired t-test showed that means of all variables were larger in the 40 bpm tempo than in the 120 bpm tempo. In the multiple comparison tests after the results of the two-way repeated measures ANOVA, the means of three intervals in all variables were larger in the 40 bpm tempo than in the 120 bpm tempo; the means of the sway variables, excluding that of the X-axis path length, in the 40 bpm tempo were larger in the 0–20 sec interval than in the 20–40 sec interval or the 40–60 sec interval. Correlations between step errors and those between the step error and sway variables of both tempos were insignificant or under moderation. The correlations between the step error and sway variables in both tempos were insignificant or significant but low, and those among sway variables were high, except between the X- and Y-axis path lengths. The relationship between both axis path lengths differed according to the tempo. In conclusion, in the case of the stipulated tempo step test targeting children, the slow tempo has a greater step error and postural sway than the fast tempo, and the sway in the early step stage is greater in the slow tempo. The relationships between step errors and between the step error and sway variables of both tempos are low; hence, the ability related to the test may differ in both tempos. The relationships among sway variables in both tempos are high, except between the X- and Y-axis path lengths.

Normative database of postural sway measures using inertial sensors in typically developing children and young adults.

Reference values utilizing the APDM MobilityLab® inertial sensor system have not been established in children and young adults ages 5-30. These values are necessary for clinicians and researchers to compare to children with balance impairments. A group of 144 typically developing children and young adults from age 5-30 years completed the instrumented SWAY test during 6 test conditions: normal stance, firm surface, eyes open (EO) and closed (EC); normal stance, foam surface, EO and EC; and tandem stance, firm surface, EO and EC. Selected variables for normative outcomes included total sway area, and the mean, sagittal and coronal values for RMS sway, jerk, sway velocity and path length. Sex differences were examined within age groups via t tests. The effect of age on postural sway variables was analyzed using a one-way ANOVA for the mean values of total sway area, RMS sway, velocity and jerk, followed by post-hoc pairwise comparisons. All sway parameters decreased significantly with age (p < 0.0001). Adult-like total sway area and jerk were achieved by ages 9-10 except for jerk during EC on foam. RMS sway and sway velocity reached adult levels by ages 11-13 during all EO and tandem stance conditions, and 14-21 with EC during normal stance on firm and foam surfaces for RMS sway and EC on firm surfaces for velocity. Females ages 5-6 performed more poorly during EO firm and EC foam for certain variables, but better during EO tandem and females ages 7-13 outperformed males when sex differences were found. These reference values can now be used by clinicians and researchers to evaluate abnormal postural sway and response to interventions in children and young adults.

Impact of Prolonged Exposure to a Slippery Surface on Postural Stability.

Falls are extremely common in occupational settings. Intrinsic factors such as overexertion and extrinsic factors such as the supporting surface are causative factors of falls. The impact of prolonged exposure to a slippery surface on postural stability has not been previously studied. The purpose of the study was to analyze the effect of extended exposure to a dry and a slippery surface on postural stability. Eighteen males (age: 21.17 ± 3.38 years; height: 1.77 ± 0.08 m; mass: 89.81 ± 14.23 kg) were recruited and subjected to one-hour walking on a dry surface and a slippery surface on two different days. Participants’ balance was assessed using a force platform in stable and unstable conditions at 0, 30, and 60 min. Postural sway variables were analyzed using a 2 (surface) × 3 (time) repeated-measures ANOVA. Significant time main effects were observed in the stable condition with greater balance decrements at 30 and 60 min. Greater balance decrements were observed on the slippery surface compared to the dry surface in the unstable condition. The balance decrements can be attributed to overexertion due to the physiological workload of prolonged walking and to the potential gait modifications due to walking on the slippery surface.

Age-associated increase in postural variability relate to greater low-frequency center of pressure oscillations

BackgroundPostural control is impaired in older adults, as evidenced from greater variability of the center of pressure (COP) during postural tasks. Although COP variability associates with low-frequency COP oscillations (<1 Hz) in young adults, it remains unknown if the age-associated increase in COP variability relates to greater low-frequency COP oscillations. Research questionDo low-frequency oscillations contribute to greater postural sway (center of pressure (COP) variability) in older adults when attempting to voluntarily maintain posture in a forward leaning position compared to young adults? MethodsSeven young (25.7 ± 4.8) and seven older (71.0 ± 7.0) adults performed a postural lean forward task and attempted to match a COP target in the anterior-posterior direction as steady as possible. We quantified the COP variability as the standard deviation (SD) of COP displacements in the anterior-posterior and medial-lateral directions and quantified the frequency modulation of COP as the power in COP displacement spectra from 0-1 Hz. ResultsWe found that older adults had significantly greater anterior-posterior SD of COP (p = 0.027) and power below 0.5 Hz (p = 0.048) than young adults, but power from 0.5-1 Hz was similar (p = 0.083). In contrast, the medial-lateral SD of COP (p = 0.5) and power from 0-1 Hz (p = 0.228) was similar for the two age groups. For both the anterior-posterior and medial-lateral direction, the SD of COP was related to low frequency oscillations below 0.5 Hz. SignificanceFor the first time, we show that the age-associated increase in postural variability relates to greater COP oscillations below 0.5 Hz.