Sagittal plane momentum control during walking in elderly fallers

ObjectiveThe purpose of this study was to examine sagittal plane momentum control during walking with the use of center of mass (COM) velocity and acceleration.MethodsCOM control in the antero-posterior direction during walking of healthy young and elderly adults, and elderly fallers (n = 15/group) was examined. Using a single-link-plus-foot inverted pendulum model, boundaries for the region of stability were determined based on the COM position at toe-off and its instantaneous velocity or the peak acceleration prior to toe-off (ROSv or ROSa, respectively).ResultsAlthough no significant difference in forward COM velocity was detected between healthy young and elderly subjects, the peak forward COM acceleration differed significantly, suggesting age-related differences in momentum control during walking. Elderly fallers demonstrated significantly slower forward COM velocities and accelerations and placed their COM significantly more anterior than healthy young and elderly subjects at toe-off, which resulted in their COM position-velocity combination located within the ROSv. Similar results were obtained in the ROSa, where elderly fallers demonstrated a larger stability margin than healthy young and elderly subjects.InterpretationsSignificantly slower peak COM accelerations could be indicative of a poor momentum control ability, which was more pronounced in elderly fallers. Examining COM acceleration, in addition to its velocity, would provide a greater understanding of person's momentum control, which would allow us to better reveal underlying mechanisms of gait imbalance or falls.     

Effectiveness of backward walking training on balance performance: A systematic review and meta-analysis

BackgroundBackward walking (BW) training is thought to impact balance performance through improving motor system proprioception and gait characteristic, but relevant evidence remains sparse and inconclusive.ObjectiveThis study systematically reviewed and quantified the scientific evidence regarding the effectiveness of BW training on balance performance.MethodsKeyword and reference search on BW training interventions was conducted in six electronic databases (PubMed, Web of science, SPORTDiscus, CINAHL, Cochrane Library, and CNKI) for peer-reviewed articles published till November 2017. A standardized form was used to extract data from each selected article that met the pre-specified eligibility criteria. Meta-analysis was conducted to estimate the pooled effects of BW training on balance performance measures.ResultsEleven studies (nine randomized controlled trials and two pre-post studies) met the eligibility criteria and were included in the review. All studies reported some beneficial effects of BW training on balance performance. Compared to control, BW training was associated with a reduction in overall stability index score by 0.99 (95% CI = 0.37, 1.61; I² = 0.0%; fixed-effect model), medial-lateral stability index score by 0.95 (95% CI = 0.34, 1.57; I² = 0.0%; fixed-effect model), and anterior-posterior stability index score by 0.99 (95% CI = 0.37, 1.61; I² = 0.0%; fixed-effect model). Meanwhile, BW training was associated with an increase in open-eyes single leg standing duration by 0.91 s (95% CI = 0.29, 1.53; I² = 75.9%; random-effect model) in comparison to control.ConclusionsBW training could serve as a potentially useful tool to improve balance performance among those with a high risk of fall. However, current evidence remains preliminary due to the small cohort of studies and possible learning effect in pre-post studies. Future work with larger scale and randomized experimental design is warranted to evaluate the effectiveness of BW training on balance performance across diverse population and disease subgroups, and elucidate the underlying biomechanical and neurological pathways.     

Reactive balance adjustments to unexpected perturbations during human walking

The purpose of this investigation was to determine the effect of unexpected forward perturbations (FP) during gait on lower extremity joint mechanics and muscle Electromyographic (EMG) patterns in healthy adults. The muscles surrounding the hip were found to be most important in maintaining control of the trunk and preventing collapse in response to the FP. Distinct lower extremity joint moment and power patterns were observed in response to the FP but an overall positive moment of support (M_s) was maintained. Therefore, reactive balance control was a synchronized effort of the lower extremity joints to prevent collapse during the FP.     

Sagittal standing posture and relationships with anthropometrics and body composition during childhood

BackgroundAnthropometry and body composition are plausible influences on pediatric sagittal standing posture. Despite that, the relationship of anthropometrics since birth and body composition with individual postural parameters in children has never been assessed.Research questionTo assess the associations between anthropometrics since birth and body composition parameters, and angles of sagittal standing posture in children.MethodsThe sample included 1021 girls and 1096 boys, evaluated in the population-based birth cohort Generation XXI, Portugal. Weight and height were obtained at birth, 4 and 7 years of age. At age 7, total body less head fat/fat-free mass and bone properties were estimated from whole body dual energy X-ray absorptiometry scans and posture was assessed through right-side photographs during habitual standing with retro-reflective markers placed on body landmarks.ResultsGirls showed increased values of lumbar angle, head and neck flexion, and craniocervical angle with the largest mean (standard deviation) difference in lumbar angle [281.7° (7.4) vs. 276.8° (7.1) in boys, p < 0.001]. In both genders, weight and body mass index were weakly associated with lumbar angle: 0.24 ≥ r ≤ 0.31 in girls and 0.16 ≥ r ≤ 0.26 in boys, all p < 0.001. Fat and fat-free mass and bone mineral density were weakly associated with lumbar angle in both genders.SignificanceOur study showed clear postural heterogeneity between girls and boys in early ages. Lumbar angle is likely to be the single most relevant proxy of overall posture based on the associations with the exposures reported in this study.     

One-leg standing balance and sports activity

The objective of the present cross-sectional study was to estimate one-leg standing balance in athletes and to investigate the relationship with type and amount of sports activity. The study comprised 339 active, competitive, non-pregnant athletes, aged 14–24 years from two sports clubs in the county of Aarhus, Denmark. The athletes answered a questionnaire about occupation and sports activity. One-leg standing balance was measured as the maximum time of one-legged balancing. The mean of the maximum time of one-legged balancing was 29 s (interquartile range 11.25–33.5 s). One-leg standing balance was positively associated with years of participation in basketball and was not associated with sex and age. We conclude that participation in basketball may induce significantly adaptive effects on standing balance.     

Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study

For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M₁ ‘moving the centre of pressure’ and M₂ ‘segment acceleration’ and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K–Km), or Km data only concerning M₂. For this purpose nine physically fit persons aged 70–78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% CI, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M₁ and M₂ can be measured with acceptable inter- and intrasession reliability, and that both Km and K–Km based calculations may be useful for M₂, although Km data may give slightly lower values. The proportional M₁:M₂ usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.     

Age-related changes in human postural control of prolonged standing

The aim of this study was to characterize prolonged standing and its effect on postural control in elderly individuals in comparison to adults. It is unknown how elderly individuals behave during prolonged standing and how demanding such a task is for them. We recorded the center of pressure (COP) position of 14 elderly subjects and 14 adults while they performed prolonged standing (30 min) and quiet stance tasks (60 s) on a force plate. The number and amplitude of the COP patterns, the root mean square (RMS), speed, and frequency of the COP sway were analyzed. The elderly subjects were able to stand for prolonged periods but they produced postural changes of lesser amplitude and a decreased sway during the prolonged standing task. Both the adults and the elderly subjects were influenced by the prolonged standing task, as demonstrated by their increased COP RMS and COP speed in the quiet standing trial after the prolonged standing task, in comparison to the trial before. We suggest that the lack of mobility in elderly subjects may be responsible for the observed sub-optimal postural changes in this group. The inability of elderly individuals to generate similar responses to adults during prolonged standing may contribute to the increased risk of falls in the older population.     

The cross-sectional relationships between age,standing static balance,and standing dynamic balance reactions in typically developing children

BackgroundStatic balance performance is a common metric for evaluating the development of postural control in children. Less is known about the potentially independent development of dynamic balance performance.Research questionHow does age relate to static (i.e. postural sway) and dynamic (i.e. stepping thresholds) standing balance performance, and what is the relationship between postural sway and stepping thresholds?MethodsTwenty-six typically developing children (12 males, 14 females; 5–12 years of age) were recruited for this cross-sectional study. Static balance performance was quantified as the total path length during a postural sway assessment using a force platform with conditions of eyes open and eyes closed. Dynamic balance performance was quantified using a single-stepping threshold assessment, whereby participants attempted to prevent a step in response to treadmill-induced perturbations in the anterior and posterior directions. Relationships between age and body-size scaled measures of static and dynamic balance performance were assessed using Spearman rank correlations.ResultsThere was a weak correlation between age and postural sway (|r_s| < 0.10, p > 0.68), but a moderate-to-strong correlation between age and single-stepping thresholds (r_s > 0.68, p < 0.001). A weak correlation was found between postural sway and single-stepping thresholds (|r_s| < 0.20, p > 0.39).SignificanceDynamic, but not static standing balance performance, may improve with typical development between the ages of 5 and 12 years. Static and dynamic balance should be considered as unique constructs when assessed in children.     

Auditory cues behind congenitally blind subjects improve their balance control in bipedal upright posture

BackgroundCongenitally blind subjects developed postural adaptations improving somatosensory and vestibular systems to maintain upright stability and auditory skills to orient them in environment. However, the influence of auditory cues on upright stability in congenitally blind subjects stays unknown.Research questionThe aim of this study is to define the influence of an auditory cue in congenitally blind subjects back space on their balance posture.MethodsEleven sighted subjects and eleven congenitally blind subjects performed upright bipedal and unipedal quiet stances on a force plate with two conditions of auditory cue played by a loudspeaker placed 2 m behind them. Mean CoP velocity were recorded. Student test was used to compare significant difference between blind and sighted subjects bipedal and unipedal postures stability in both conditions of auditory cue.Results and significanceResults showed that congenitally blind subjects had no significant difference in mean sway velocity compared to sighted subjects in bipedal upright posture in auditory signal condition. However, blind subjects had significant lower mean sway velocity than sighted subjects in bipedal upright posture without sound. Blind subjects had significant increased mean sway velocity during unipedal quiet standing in both auditory cue conditions (with and without sound). The results showed that congenitally blind subjects used auditory cues placed behind them in order to improve their balance control in bipedal upright posture. In this case, blind subjects could better use compensatory mechanisms to perform quiet standing as sighted subjects. Without sound or in unipedal upright posture, congenitally blind subjects probably have sensory perturbations or limitations that impose them adaptations in order to avoid falling risk. Auditory cues should be study in the aim to better understand the compensatory mechanisms used by congenitally blind subjects to perform postural balance in usual environment.     

The energy cost for balance control during upright standing

The aim of this study was to investigate whether balance control during a static upright standing task with and without balance perturbations elicits a significant and meaningful metabolic energy demand and to test whether this energy demand correlates with conventional posturography measures for balance control. Ten healthy subjects were assessed in four 4-min upright standing conditions on a force platform while energy consumption was measured using open circuit respirometry. In the reference condition subjects stood upright in parallel stance without balance perturbation (PS). In the other conditions balance was perturbed by placing the subjects in tandem stance (TS), in tandem stance blind folded (TSBF) and in tandem stance on a balance board (TSBB). Gross and net energy consumption was assessed and various conventional posturography measures were derived from the excursion of the center of pressure (CoP) of the ground reaction force. Energy consumption was substantially affected by all balance perturbations, compared to the reference condition. The highest increase in energy consumption was found for the TSBF condition (increase of 0.86 J kg^?1 s^?1 or 60% of PS). Significant correlations were found between energy consumption and posturography measures. The strongest correlation was found between gross energy consumption and the CoP path and normalized CoP path along the anterior–posterior axis (resp. r = 0.57 and r = 0.66, p < 0.001). It was concluded that the effort for balance control can elicit a meaningful metabolic energy demand. Conventional posturography provided significant, though moderate, predictors of this metabolic effort for balance control.     

Trunk balance control during beam walking improves with the haptic anchors without the interference of an auditory-cognitive task in older adults

BackgroundPrior studies have shown that older adults reduced trunk acceleration when walking on a balance beam with haptic inputs provided by anchors; however, it is unknown whether these benefits would remain in the presence of a concurrent cognitive task.Research questionThis study aimed to evaluate the effect of a cognitive task on balance control when using the anchors while walking on a balance beam in older adults.MethodsThirty older adults participated in this study. They walked on a balance beam under four conditions combining haptic inputs (with and without anchors) and a cognitive task (present and absent). The anchors consisted of a flexible cable with a small load (125 g) attached at the end contacting the ground. Participants held one anchor in each hand and dragged the loads over the ground while walking. In the cognitive task, participants silently counted the number of times they heard a target number within a series of random numbers and provided their response at the end of each trial. Trunk acceleration and normalized step speed were assessed.ResultsThe anchors reduced the normalized step speed and the trunk acceleration amplitude in the frontal plane when walking on the beam. The cognitive task also diminished the normalized step speed in the beam walking. The use of the anchors did not influence the cognitive task performance.SignificanceEven on a balance beam in the presence of a cognitive task, haptic anchors were able to reduce trunk acceleration in older adults to improve balance control. The cognitive task did not affect the use of haptic anchors.     

Recurrence dynamics reveals differential control strategies to maintain balance on sloped surfaces

BackgroundStudies on postural control have primarily focused on the maintenance of balance in quiet upright standing on flat horizontal support surfaces that can reveal only a subset of the potential postural stability/instability configurations in everyday contexts.ObjectivesHere we investigated the nature of dynamical properties of postural coordination in an upright standing task as a function of the systematic scaling of seven support surface angles, +20°, +10° dorsiflexion (+), 0 °Flat, −10°, −20°, −30°, −35° plantarflexion (−), mounted on a force plate.MethodsThe center of pressure (CoP) and virtual time-to-contact (VTC) were analyzed to examine the spatial and spatio-temporal aspects of postural coordination dynamics, respectively. Recurrence quantification analysis (RQA) was used to characterize the dynamic postural control strategies as a function of slope surface angle.ResultsThe recurrence findings showed that on a flat surface the postural CoP dynamic are recurrent with a largely deterministic process and higher Shannon entropy compared to elevated slope angles in dorsiflexion and plantarflexion. There were asymmetrical patterns between similar slope angles for dorsiflexion and plantarflexion postures. The recurrence measures revealed that VTC operates on a higher embedding dimension than that of CoP.SignificanceVTC showed an enhanced sensitivity to detection of postural instability in relation to the stability boundary that was magnified on the flat surface but progressively reduced over larger surface angles for both the dorsiflexion and plantarflexion postures.     

The effect of visual field manipulations on standing balance control in people with multiple sclerosis

BackgroundMultiple sclerosis (MS) is associated with an increased risk of falls, degeneration of sensory organization, and possible increased reliance on vision for balance control.Research questionThe aim of this study was to assess differences in standing postural control between people with MS and age and sex matched controls during medial-lateral (ML) oscillations of the visual field, with and without blinders to the lower periphery.MethodsTen persons with MS (mean age 54.0 ± 5.3 years) and ten age and sex matched controls (mean age: 56.3 ± 6.0 years) participated in this study. Balance control was assessed while participants stood in a Christie Cave system while wearing stereoscopic glasses that projected an immersive forest scene. Visual conditions consisted of 2 m ML visual oscillations of the scene at five frequencies (0.0, 0.3, 0.6, 0.7 and 0.8 Hz) with and without blinders to block the lower periphery.Results and significanceThe results demonstrated that, in comparison to controls, participants with MS had a significantly larger center of pressure sway in both the ML and AP direction to ML visual oscillations. Additionally, participants with MS and controls both increased center of pressure frequency content to the visual oscillation frequency, while participants with MS also increased relative power at the visual oscillation frequency in the AP direction. Blinders of lower periphery reduced the percent power at the visual oscillation frequency in both groups and reduced overall sway in participants with MS during visual oscillations. Overall, results indicate that postural balance is sensitive to visual feedback in people with MS. The elicited AP sway to ML visual oscillation could reflect errors in visual processing for the control of balance, and decreased sway in response to blocking vision of the lower peripheral field could indicate an increased reliance on visual cues to maintain balance.     

Relationship between foot sensation and standing balance in patients with multiple sclerosis

The aims of the present study were to investigate the relationship between the foot sensations and standing balance in patients with Multiple Sclerosis (MS) and find out the sensation, which best predicts balance. Twenty-seven patients with MS (Expanded Disability Status Scale 1-3.5) and 10 healthy volunteers were included. Threshold of light touch-pressure, duration of vibration, and distance of two-point discrimination of the foot sole were assessed. Duration of static one-leg standing balance was measured. Light touch-pressure, vibration, two-point discrimination sensations of the foot sole, and duration of one-leg standing balance were decreased in patients with MS compared with controls (p < 0.05). Sensation of the foot sole was related with duration of one-leg standing balance in patients with MS. In the multiple regression analysis conducted in the 27 MS patients, 47.6% of the variance in the duration of one-leg standing balance was explained by two-point discrimination sensation of the heel (R² = 0.359, p = 0.001) and vibration sensation of the first metatarsal head (R² = 0.118, p = 0.029). As the cutaneous receptors sensitivity decreases in the foot sole the standing balance impairs in patients with MS. Two-point discrimination sensation of the heel and vibration sensation of the first metatarsal head region are the best predictors of the static standing balance in patients with MS. Other factors which could be possible to predict balance and effects of sensorial training of foot on balance should be investigated.     

Comparison of standing balance between female collegiate dancers and soccer players

STUDY DESIGN: This study was designed as a comparison study of two cohorts. OBJECTIVES: The hypothesis of this study was that soccer players and dancers have different balance abilities and that these differences could be objectively measured using center of pressure measurements. BACKGROUND: Center of pressure (COP) measurements are reproducible and have been validated in the literature for assessing standing balance. The literature does not provide sensitive enough techniques for discriminating between two groups of athletes with excellent standing balance. METHODS AND MEASURES: A Matscan pressure mat (Tekscan, Boston, MA) was used to compare COP change variability between 32 female collegiate soccer players and 32 dancers. COP was used to calculate sway index, center acquisition time, sway path length and sway velocity as measures of standing balance. RESULTS: The dancers had significantly better balance scores (p<0.05) in 5 of 20 balance tests. Results for the remaining 15 balance tests were not significantly different. CONCLUSION: These data show that standing balance characteristics of dancers and soccer players can be objectively measured using COP data. Dancers have certain standing balance abilities that are better than those of soccer players. The COP measurements in this study can be used as a tool in future studies investigating standing balance in different groups of athletes.     

Compliant support surfaces affect sensory reweighting during balance control

To maintain upright posture and prevent falling, balance control involves the complex interaction between nervous, muscular and sensory systems, such as sensory reweighting. When balance is impaired, compliant foam mats are used in training methods to improve balance control. However, the effect of the compliance of these foam mats on sensory reweighting remains unclear.In this study, eleven healthy subjects maintained standing balance with their eyes open while continuous support surface (SS) rotations disturbed the proprioception of the ankles. Multisine disturbance torques were applied in 9 trials; three levels of SS compliance, combined with three levels of desired SS rotation amplitude. Two trials were repeated with eyes closed. The corrective ankle torques, in response to the SS rotations, were assessed in frequency response functions (FRF). Lower frequency magnitudes (LFM) were calculated by averaging the FRF magnitudes in a lower frequency window, representative for sensory reweighting.Results showed that increasing the SS rotation amplitude leads to a decrease in LFM. In addition there was an interaction effect; the decrease in LFM by increasing the SS rotation amplitude was less when the SS was more compliant. Trials with eyes closed had a larger LFM compared to trials with eyes open.We can conclude that when balance control is trained using foam mats, two different effects should be kept in mind. An increase in SS compliance has a known effect causing larger SS rotations and therefore greater down weighting of proprioceptive information. However, SS compliance itself influences the sensitivity of sensory reweighting to changes in SS rotation amplitude with relatively less reweighting occurring on more compliant surfaces as SS amplitude changes.     

Correlations between joint kinematics and dynamic balance control during gait in pregnancy

BackgroundDynamic balance control degrades during pregnancy, but it is not yet understood why. Mechanical aspects of the body should directly affect walking balance control, but we have recently published papers indicating that weight gains during pregnancy explain very little dynamic balance changes. Our goal was to determine if lower extremity joint kinematic changes are an indicator of walking balance control. This information is vital to understanding the route by which pregnancy increases fall risk.MethodsTwenty-three pregnant women were tested at five different times in the 2nd and 3rd trimesters of pregnancy. Participants performed walking trials at a self-selected pace. Motion capture was used to measure joint kinematics (discrete and coordination variables) and body center of mass motion. Changes over time were statistically analyzed. Correlations between kinematics and walking balance were modelled with hierarchical multiple regression models.ResultsAs pregnancy progresses, it appears that a more flexed hip posture could be driving lower extremity kinematic changes toward increased coordination between joints and increased knee and ankle motions. Walking balance changes were also detected through increased COM motion (lateral range of motion and velocity) in the lateral directions. However, there was little correlation between kinematic and balance changes (r² < 0.4). Strong correlations were only observed when all kinematics (including those that don’t ubiquitously change during pregnancy) were used in the regression model (r² > 0.7).SignificanceOur findings suggest that walking balance control is not altered by a common kinematic change between all pregnant women. While increased lateral center of mass motion should be expected with pregnancy, the kinematics leading to this increase may be person-specific. The cause of dynamic imbalance in each pregnant women (physiological, mechanical, and neurocognitive) may play an important role in determining the kinematic means by which lateral center of mass motion increases.     

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls

BackgroundImprovement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable.Research questionWhat is the test-retest reliability of six stability outcome measures during gait?MethodsPatients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoP_AP) and medial-lateral (XCoM-CoP_ML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoP_AP-angle) and medial-lateral (CoM-CoP_ML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects.ResultsThe ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoP_AP (p = 0.008) and CoM-CoP_AP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls.SignificanceBased on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoP_ML and CoM-CoP_ML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoP_ML and CoM-CoP_ML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.     

Trunk accelerometry as a measure of balance control during quiet standing

The goal was to investigate whether body sway measured by trunk accelerometry during quiet standing could differentiate between young and elderly healthy subjects, and between conditions with eyes open and closed on firm and compliant surfaces. Raw data demonstrated poor discrimination, but horizontal transformation to eliminate a constant gravity component disclosed consistent mean differences across groups (P < or = 0.0025), and also between conditions (P < or = 0.0005), except for the most marginal difference. When drift associated with very low frequency body sway was adjusted for, a significant difference appeared also here (P = 0.001). This study indicates that trunk accelerometry can discriminate between populations and conditions during quiet standing.     

Dynamic stability during increased walking speeds is related to balance confidence of older adults: a pilot study

BackgroundSome older individuals walk slower, which may be due to decreases in mechanical stability at faster speeds or due to psychological factors like balance confidence.Research QuestionWhat is the relationship between progressively increasing walking speeds on dynamic stability in older and younger adults and how does this relationship interact with balance confidence in older adults?Methods10 young adults and 14 older adults were recruited for this pilot study. Individuals completed the Activities Specific Balance Confidence Scale. Individuals walked on a treadmill in a robotic device that interfaced with individuals at the pelvis allowing all degrees of freedom of movement and provided safety for a loss of balance. Participants walked at speeds from 0.4 - 2.0m/s in 0.2m/s increments or until the participant chose not to attempt a faster speed. Margin of stability was assessed.ResultsThe ABC of older adults was lower than younger adults (89±13 vs 99±1 scores, p=0.006) and some older adults chose to stop walking before 2.0m/s (n=6). The margin of stability variability of the older adults was significantly greater than young adults in the sagittal (p=0.013) and frontal plane (p=0.007). Older adults became unstable (margin of stability<0) at a slower speed (p<0.001). For older adults, balance confidence was correlated to the fastest speed attempted on the treadmill (rho=0.85, p<0.001). However, the balance confidence and walking speed individuals became unstable were not significantly correlated. Finally, a significant relationship was found between the zero crossing and the fastest speed attempted (rho=0.60, p=0.022).SignificanceSome older adults with lower balance confidence were less willing to experience instability at faster walking speeds on the treadmill, even though the external threat to balance was low. Lower balance confidence and a sense of loss of stability may be factors in decreased willingness to experience activities for some older adults.