Swing Time Variability Research Articles

Adaptive gait responses to varying weight-bearing conditions: Inferences from gait dynamics and H-reflex magnitude.

This study investigates the effects of varying loading conditions on excitability in neural pathways and gait dynamics. We focussed on evaluating the magnitude of the Hoffman reflex (H-reflex), a neurophysiological measure representing the capability to activate motor neurons and the timing and placement of the foot during walking. We hypothesized that weight manipulation would alter H-reflex magnitude, footfall and lower body kinematics. Twenty healthy participants were recruited and subjected to various weight-loading conditions. The H-reflex, evoked by stimulating the tibial nerve, was assessed from the dominant leg during walking. Gait was evaluated under five conditions: body weight, 20% and 40% additional body weight, and 20% and 40% reduced body weight (via a harness). Participants walked barefoot on a treadmill under each condition, and the timing of electrical stimulation was set during the stance phase shortly after the heel strike. Results show that different weight-loading conditions significantly impact the timing and placement of the foot and gait stability. Weight reduction led to a 25% decrease in double limb support time and an 11% narrowing of step width, while weight addition resulted in an increase of 9% in step width compared to body weight condition. Furthermore, swing time variability was higher for both the extreme weight conditions, while the H-reflex reduced to about 45% between the extreme conditions. Finally, the H-reflex showed significant main effects on variability of both stance and swing phases, indicating that muscle-motor excitability might serve as feedback for enhanced regulation of gait dynamics under challenging conditions.

Alprazolam Reduces Freezing of Gait (FOG) and Improves FOG-Related Gait Deficiencies.

Freezing of gait (FOG) is an intractable motor symptom in Parkinson's disease (PD) that increases fall risk and impairs the quality of life. FOG has been associated with anxiety, with experimental support for the notion that anxiety itself provokes FOG. We investigated the effect of acute anxiety reduction via alprazolam on FOG in PD. In ten patients with PD, FOG, and normal cognition, we administered 0.25 mg alprazolam in one session and placebo in another, in counterbalanced order. At each session, on separate days, patients walked on a pressure-sensitive walkway. Using Oculus Rift virtual-reality goggles, patients walked along a plank that appeared to be (a) level with the floor, in the low-anxiety condition or (b) raised high above the ground, in the high-anxiety conditions. In this way, we assessed the impacts of anxiety and alprazolam (i.e., anxiety reduction) on FOG frequency and other gait parameters. FOG events appeared only in the high-anxiety conditions. Alprazolam significantly reduced subjective and objective measures of anxiety, as well as the prevalence of FOG (p = 0.05). Furthermore, alprazolam improved swing time (p < 0.05) and gait variability in all conditions, particularly during the elevated plank trials. Interpretation. Our results suggest that (1) anxiety induces FOG, and (2) alprazolam concomitantly reduces anxiety and FOG. Alprazolam further improved gait stability (i.e., swing time and gait variability). These findings reveal that anxiety triggers FOG in PD. Treating anxiety can reduce FOG and improve gait stability, potentially offering new therapeutic avenues for this intractable and disabling symptom in PD.

INCREASED TEMPORAL GAIT VARIABILITY OVER TIME IS RELATED TO FUTURE DEMENTIA

Abstract Age-related brain changes affect the timing and coordination of gait. High gait variability may stem from impaired brain motor control and has been associated with compromised cognition and cognitive impairment. Whether increased gait variability over time is associated with future MCI or dementia is unknown. In the Baltimore Longitudinal Study of Aging, we used age-, sex-, and race-adjusted linear mixed-effects models to examine whether changes in gait variability were associated with future MCI or dementia in participants aged 65+. Gait characteristics were quantified by 3D motion analysis. Independent of baseline gait speed and compared to cognitively normal participants (n=387), those who developed dementia (n=24) had greater rates of increase in gait cycle time variability, stance time variability, and swing time variability (but not mean performance) before the symptom onset (all p&amp;lt;0.05). Further adjustment for concurrent assessment of visuospatial ability or manual dexterity attenuated these associations. Adjustments for verbal memory, psychomotor speed, attention, or executive function did not attenuate these associations. Rates of changes in these gait variability measures were not statistically different between cognitively normal participants (n=387) and those who developed MCI (n=41). Baseline gait variability measures were not different across groups. These findings suggest that longitudinal trajectories of gait variability, not one-time assessment, provide the additional predictive value of future dementia over and beyond gait speed. Mechanisms may include compromised visuospatial ability or manual dexterity. Future neuroimaging studies are warranted to understand neural substrates connecting increased gait variability and dementia risk.

Effects of Sport Participation on Gait Coordination, Symmetry, and Variability in Older Adults.

The aim of this study was to compare the interlimb coordination, asymmetry, and variability between older adults who participated in sports (n = 25; age = 72.6 ± 6.46years) and sedentary older adults (n = 20; age = 70.85 ± 3.82years). The sport participants were selected from tennis and badminton clubs, whereas the sedentary participants were recruited from local community centers. The participants walked at their preferred speed in a 10-m walkway for 2min. The interlimb coordination was measured by the phase coordination index. Other walking metrics were speed, cadence, swing time, stance time, double-support time, stride time, and swing time asymmetry. The results showed that the sport participants relative to the sedentary group had better interlimb coordination, higher walking speed and cadence, and less swing time variability. Young older adults also had a better interlimb coordination. In conclusion, the findings of this study showed that long-term participation in sports has some antiaging benefits on gait coordination and symmetry in older adults.

Gait Variability at Different Walking Speeds.

Gait variability (GV) is a crucial measure of inconsistency of muscular activities or body segmental movements during repeated tasks. Hence, GV might serve as a relevant and sensitive measure to quantify adjustments of walking control. However, it has not been clarified whether GV is associated with walking speed, a clarification needed to exploit effective better bilateral coordination level. For this aim, fourteen male students (age 22.4 ± 2.7 years, body mass 74.9 ± 6.8 kg, and body height 1.78 ± 0.05 m) took part in this study. After three days of walking 1 km each day at a self-selected speed (SS) on asphalt with an Apple Watch S. 7 (AppleTM, Cupertino, CA, USA), the participants were randomly evaluated on a treadmill at three different walking speed intensities for 10 min at each one, SS - 20%/SS + 20%/ SS, with 5 min of passive recovery in-between. Heart rate (HR) was monitored and normalized as %HRmax, while the rate of perceived exertion (RPE) (CR-10 scale) was asked after each trial. Kinematic analysis was performed, assessing the Contact Time (CT), Swing Time (ST), Stride Length (SL), Stride Cycle (SC), and Gait Variability as Phase Coordination Index (PCI). RPE and HR increased as the walking speed increased (p = 0.005 and p = 0.035, respectively). CT and SC decreased as the speed increased (p = 0.0001 and p = 0.013, respectively), while ST remained unchanged (p = 0.277). SL increased with higher walking speed (p = 0.0001). Conversely, PCI was 3.81 ± 0.88% (high variability) at 3.96 ± 0.47 km·h-1, 2.64 ± 0.75% (low variability) at SS (4.94 ± 0.58 km·h-1), and 3.36 ± 1.09% (high variability) at 5.94 ± 0.70 km·h-1 (p = 0.001). These results indicate that while the metabolic demand and kinematics variables change linearly with increasing speed, the most effective GV was observed at SS. Therefore, SS could be a new methodological approach to choose the individual walking speed, normalize the speed intensity, and avoid a gait pattern alteration.

CCR5-Δ32 polymorphism-a possible protective factor from gait impairment amongst post-stroke patients.

Stroke and small vessel disease cause gait disturbances and falls. The naturally occurring loss-of-function mutation in the C-C chemokine receptor 5 gene (CCR5-Δ32) has recently been reported as a protective factor in post-stroke motor and cognitive recovery. We sought to examine whether it also influences gait and balance measures up to 2 years after stroke. Participants were 575 survivors of first-ever, mild-moderate ischaemic stroke or transient ischaemic attack from the TABASCO prospective study, who underwent a 3T magnetic resonance imaging at baseline and were examined by a multi-professional team 6, 12 and 24 months after the event, using neurological, neuropsychological and mobility examinations. Gait rhythm and the timing of the gait cycle were measured by force-sensitive insoles. CCR5-Δ32 status and gait measures were available for 335 patients. CCR5-Δ32 carriers (16.4%) had higher gait speed and decreased (better) stride and swing time variability 6 and 12 months after the index event compared to non-carriers (p < 0.01 for all). The association remained significant after adjustment for age, gender, education, ethnicity and stroke severity. Significant associations were found between gait measurements and CCR5-Δ32 loss-of-function mutation amongst stroke survivors. This is the first study showing that genetic predisposition may predict long-term gait function after ischaemic stroke.

Barefoot walking is more stable in the gait of balance recovery in older adults

BackgroundPerturbation-based balance training on a treadmill is an emerging method of gait stability training with a characteristic task nature that has had positive and sustained effects on balance recovery strategies and fall reduction. Little is known about the effects produced by shod and barefoot walking. We aimed to investigate which is more appropriate, shod or barefoot walking, for perturbation-based balance training in older adults.MethodsFourteen healthy older adults (age: 68.29 ± 3.41 years; body height: 1.76 ± 0.10 m; body mass: 81.14 ± 14.52 kg) performed normal and trip-like perturbed walking trials, shod and barefoot, on a treadmill of the Gait Real-time Analysis Interactive Lab. The marker trajectories data were processed by Human Body Model software embedded in the Gait Offline Analysis Tool. The outcomes of stride length variability, stride time variability, step width variability, and swing time variability were computed and statistically analyzed by a two-way repeated-measures analysis of variance (ANOVA) based on gait pattern (normal gait versus perturbed recovery gait) and footwear condition (shod versus barefoot).ResultsFootwear condition effect (p = 0.0310) and gait pattern by footwear condition interaction effect (p = 0.0055) were only observed in swing time variability. Gait pattern effects were detected in all four outcomes of gait variability.ConclusionsSwing time variability, independent of gait speed, could be a valid indicator to differentiate between footwear conditions. The lower swing time variability in perturbed recovery gait suggests that barefoot walking may be superior to shod walking for perturbation-based balance training in older adults.

Parkinson's Disease Wearable Gait Analysis: Kinematic and Dynamic Markers for Diagnosis.

Introduction: Gait features differ between Parkinson's disease (PD) and healthy subjects (HS). Kinematic alterations of gait include reduced gait speed, swing time, and stride length between PD patients and HS. Stride time and swing time variability are increased in PD patients with respect to HS. Additionally, dynamic parameters of asymmetry of gait are significantly different among the two groups. The aim of the present study is to evaluate which kind of gait analysis (dynamic or kinematic) is more informative to discriminate PD and HS gait features. Methods: In the present study, we analyzed gait dynamic and kinematic features of 108 PD patients and 88 HS from four cohorts of two datasets. Results: Kinematic features showed statistically significant differences among PD patients and HS for gait speed and time Up and Go test and for selected kinematic dispersion indices (standard deviation and interquartile range of swing, stance, and double support time). Dynamic features did not show any statistically significant difference between PD patients and HS. Discussion: Despite kinematics features like acceleration being directly proportional to dynamic features like ground reaction force, the results of this study showed the so-called force/rhythm dichotomy since kinematic features were more informative than dynamic ones.

The effect of limb selection methods on gait analysis in Parkinson's disease

IntroductionAsymmetry of motor symptoms is a common characteristic of Parkinson's disease (PD), yet gait outcomes are often reported as limb averages or authors fail to report which limb is being analyzed. This study aimed to investigate how varying limb selection methods may impact statistical comparisons of common gait measures amongst fallers and non-fallers with PD. Methods: Overground walking data was collected on 53 fallers and 117 non-fallers during routine clinical visits. The relationship between limb selection method (left, right, most-affected, least-affected, and limbs averaged) and faller status (faller vs non-faller) on spatiotemporal gait parameters was analyzed using a mixed linear model. Results: Significant interactions between limb selection method and faller status were found for step time variability and swing time variability. Regardless of selection method, it was possible to discern significant differences between fallers and non-fallers. Yet, if researchers only analyze the least-affected limb during gait analysis, the differences between fallers and non-fallers are less apparent. Conclusion: In individuals experiencing uneven laterality of symptoms that affect gait, limb averaging may alter interpretation of statistical findings and mask compensation patterns. This study promotes a refined gait analysis process, particularly in individuals that present with possible asymmetric walking. Including limb selection methods in future studies encourages holistic and transparent analyses within the literature.

Gait‐Related Metabolic Covariance Networks at Rest in Parkinson's Disease

BackgroundGait impairments are characteristic motor manifestations and significant predictors of poor quality of life in Parkinson's disease (PD). Neuroimaging biomarkers for gait impairments in PD could facilitate effective interventions to improve these symptoms and are highly warranted.ObjectiveThe aim of this study was to identify neural networks of discrete gait impairments in PD.MethodsFifty‐five participants with early‐stage PD and 20 age‐matched healthy volunteers underwent quantitative gait assessment deriving 12 discrete spatiotemporal gait characteristics and [18F]‐2‐fluoro‐2‐deoxyglucose‐positron emission tomography measuring resting cerebral glucose metabolism. A multivariate spatial covariance approach was used to identify metabolic brain networks that were related to discrete gait characteristics in PD.ResultsIn PD, we identified two metabolic gait‐related covariance networks. The first correlated with mean step velocity and mean step length (pace gait network), which involved relatively increased and decreased metabolism in frontal cortices, including the dorsolateral prefrontal and orbital frontal, insula, supplementary motor area, ventrolateral thalamus, cerebellum, and cuneus. The second correlated with swing time variability and step time variability (temporal variability gait network), which included relatively increased and decreased metabolism in sensorimotor, superior parietal cortex, basal ganglia, insula, hippocampus, red nucleus, and mediodorsal thalamus. Expression of both networks was significantly elevated in participants with PD relative to healthy volunteers and were not related to levodopa dosage or motor severity.ConclusionsWe have identified two novel gait‐related brain networks of altered glucose metabolism at rest. These gait networks could serve as a potential neuroimaging biomarker of gait impairments in PD and facilitate development of therapeutic strategies for these disabling symptoms. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Temporal But Not Spatial Gait Parameters Associated With Lower Balance Capacity in Moderate-High Functioning Persons With Stroke.

Falls are a major health concern after stroke. Spatial and temporal gait asymmetry and variability can contribute to instability and increased fall risk in persons with stroke (PwS). We aimed to quantify gait spatiotemporal symmetry and variability parameters in PwS undergoing rehabilitation in the subacute stage of the disease, by comparison to healthy participants, and to examine the associations between these parameters and patients' reactive and proactive balance capacity. Twenty-two PwS and 12 healthy adults walked over a computerized treadmill system at their self-selected walking speed. Symmetry and variability of gait parameters (step length, swing time, and stance time) as well as upper extremity and lower extremity angular range of motion in the sagittal plane were extracted. In addition, the Berg Balance Scale (BBS) and the fall threshold in response to sudden surface translations at increasing intensities were assessed. PwS demonstrated significantly higher asymmetry in all gait parameters in comparison to controls. Also, PwS demonstrated increased stance time variability in comparison to healthy controls and increased swing time variability in the paretic lower extremity. Significant negative associations were found between fall threshold and stance time asymmetry in PwS (r = -0.48, P = 0.022), between the BBS and swing time asymmetry (r = -0.50, P = 0.018), and between the BBS and stance time variability of the paretic lower extremity (r = -0.56, P = 0.006). Findings highlight the importance of gait temporal symmetry and variability measures for dynamic balance control after stroke. These parameters should be considered when assessing gait recovery and safety in PwS.Video Abstract available for more insight from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A355).

Effect of different residential settings on gait kinematic parameters in older adults with cognitive impairment.

To compare the parameters of gait kinematics of older adults with cognitive impairment who live in community dwellings or those living or spending most of the time in non-family environment settings. The sample was composed of 33 older adults of both sexes with cognitive impairment. Participants were separated into three groups: a community-dwelling older adult group comprised of 11 subjects; a semi-institutionalized older adult group comprised of 10 older adults attended in a geriatric daycare institution; and an institutionalized older adult group comprised of 12 older adults living in long-term institutions. Gait kinematics were recorded by pressure sensors (footswitches). Fifty gait cycles at self-selected pace were analyzed to obtain: gait speed, stride length, stance, swing, and stride time. The variability of these parameters was also analyzed. MANCOVA identified the main effect of groups (p<0.001). Gait speed of older adults living in long-term institutions and older adults attended in geriatric daycare institutions was slower than community-living older adults (p<0.001 and p=0.04, respectively). Swing and stride time variability was higher in older adults living in long-term institutions (p=0.003 and p=0.001) and in older adults attended in geriatric daycare institutions (p=0.02 and p=0.001) than in community-dwelling older adults. The most important finding was that older adults with cognitive impairment who need non-family residential setting care had higher gait kinematics abnormalities, which may increase the risk of falls, compared to those who live in the community.

Gait and Balance as Predictors or Mediators of Falls in Glaucoma

Balance and gait are modifiable targets for falls prevention and may play an important role in preventing falls in older visually impaired individuals. Balance and gait were objectively evaluated in the 239 Falls in Glaucoma Study participants (average age=70.5, 22% with moderate-severe visual field (VF) damage). Greater sway, more time in double support and greater swing time variability were associated with higher fall rates, while higher gait velocity and faster cadence were associated with lower rates (p<0.05 for all). Neither gait nor balance mediated the relationship between VF damage and fall rates, with VF damage remaining an independent predictor of fall in models including gait and/or balance features (RR =1.36 to 1.48, p-value= <0.001 to 0.005). While balance and gait measures are associated with fall rates, they do not explain why persons with greater VF damage fall more frequently, suggesting the importance of other factors such as hazard perception.

Prodromal Spinocerebellar Ataxia Type 2 Subjects Have Quantifiable Gait and Postural Sway Deficits.

The search for valid preclinical biomarkers of cerebellar dysfunction is a key research goal for the upcoming era of early interventional approaches in spinocerebellar ataxias. This study aims to describe novel preclinical biomarkers of subtle gait and postural sway abnormalities in prodromal spinocerebellar ataxia type 2 (pre-SCA2). Thirty pre-SCA2 patients and their matched healthy controls underwent quantitative assessments of gait and postural sway using a wearable sensor-based system and semiquantitative evaluation of cerebellar features by SARA (Scale for the Assessment and Rating of Ataxia) score. Quantitative analysis of natural gait showed a significantly larger variability of the swing period, toe-off angle and toe-out angle in pre-SCA2, and larger mean coronal and transverse ranges of motion of the trunk at the lumbar location and of the sagittal range of motion of the trunk at the sternum location compared to controls. During tandem gait, pre-SCA2 subjects showed larger lumbar, trunk, and arm ranges of motion than controls. Postural sway analysis showed excessive body oscillation that was increased in tandem stance. Overall, these abnormalities were detected in pre-SCA2 patients without clinical evidence of abnormalities in SARA. The toe-off angle and swing time variability were significantly correlated with the time to ataxia onset, whereas the toe-off angle and transverse range of motion at trunk position during tandem gait were significantly associated with the SARA score. This study demonstrates early alteration of gait and postural sway control in prodromal SCA2 using a wearable sensor-based system. This offers new pathophysiological hints into this early disease stage and provides novel potential biomarkers for future clinical trials. © 2020 International Parkinson and Movement Disorder Society.

Impact of depression on gait variability in Parkinson’s disease

ObjectiveThe goal of this study was to analyze how depression associated with Parkinson’s disease (PD) affected gait variability in these patients using a dual-task paradigm. Additionally, the dependency of the executive functions and the impact of depression on gait variability were analyzed. Patients and MethodsThree subject groups were included: patients with PD, but no depression (PD-NonDep; 14 patients), patients with both PD and depression (PD-Dep; 16 patients) and healthy controls (HC; 15 subjects). Gait was recorded using the wireless sensors. The participants walked under four conditions: single-task, motor dual- task, cognitive dual-task, and combined dual-task. Variability of stride length, stride duration, and swing time was calculated and analyzed using the statistical methods. ResultsVariability of stride duration and stride length were not significantly different between PD-Dep and PD-NonDep patients. The linear mixed model showed that swing time variability was statistically significantly higher in PD-Dep patients compared to controls (p = 0.001). Hamilton Disease Rating Scale scores were significantly correlated with the swing time variability (p = 0.01). Variability of all three parameters of gait was significantly higher while performing combined or cognitive task and this effect was more pronounced in PD-Dep group of patients. ConclusionsDepression in PD was associated with swing time variability, and this effect was more prominent while performing a dual-task. SignificanceDiagnosing and treating depression might be important for gait improvement and fall reduction in PD patients.

Gait variability is linked to the atrophy of the Nucleus Basalis of Meynert and is resistant to STN DBS in Parkinson's disease

Parkinson's disease (PD) is a systemic brain disorder where the cortical cholinergic network begins to degenerate early in the disease process. Readily accessible, quantitative, and specific behavioral markers of the cortical cholinergic network are lacking. Although degeneration of the dopaminergic network may be responsible for deficits in cardinal motor signs, the control of gait is a complex process and control of higher-order aspects of gait, such as gait variability, may be influenced by cognitive processes attributed to cholinergic networks. We investigated whether swing time variability, a metric of gait variability that is independent from gait speed, was a quantitative behavioral marker of cortical cholinergic network integrity in PD.Twenty-two individuals with PD and subthalamic nucleus (STN) deep brain stimulation (PD-DBS cohort) and twenty-nine age-matched controls performed a validated stepping-in-place (SIP) task to assess swing time variability off all therapy. The PD-DBS cohort underwent structural MRI scans to measure gray matter volume of the Nucleus Basalis of Meynert (NBM), the key node in the cortical cholinergic network. In order to determine the role of the dopaminergic system on swing time variability, it was measured ON and OFF STN DBS in the PD-DBS cohort, and on and off dopaminergic medication in a second PD cohort of thirty-two individuals (PD-med). A subset of eleven individuals in the PD-DBS cohort completed the SIP task again off all therapy after three years of continuous DBS to assess progression of gait impairment.Swing time variability was significantly greater (i.e., worse) in PD compared to controls and greater swing time variability was related to greater atrophy of the NBM, as was gait speed. STN DBS significantly improved cardinal motor signs and gait speed but did not improve swing time variability, which was replicated in the second cohort using dopaminergic medication. Swing time variability continued to worsen in PD, off therapy, after three years of continuous STN DBS, and NBM atrophy showed a trend for predicting the degree of increase. In contrast, cardinal motor signs did not progress. These results demonstrate that swing time variability is a reliable marker of cortical cholinergic health, and support a framework in which higher-order aspects of gait control in PD are reliant on the cortical cholinergic system, in contrast to other motor aspects of PD that rely on the dopaminergic network.

Highly challenging balance and gait training for individuals with Parkinson’s disease improves pace, rhythm and variability domains of gait – A secondary analysis from a randomized controlled trial

Objective: Evaluate immediate and long-term effects of highly challenging balance and gait training on pace-, rhythm-, variability-, asymmetry-, and postural control domains of gait for individuals with Parkinson’s disease (PD). Design: Randomized controlled trial - a secondary analysis. Setting: University hospital setting. Participants: One-hundred older adults with mild to moderate PD (Hoehn & Yahr 2 and 3). Intervention: Training group (n = 51): 10 weeks (3 times/week) of intensive balance and gait training, incorporating dual tasks. Control group (n = 49): care as usual. Main outcome measures: Spatiotemporal gait variables collected during normal and fast walking on a pressure-sensitive mat. A linear mixed model was used to evaluate training effects post intervention and at the 6 and 12 month follow-up. Results: Immediate training effects in the pace domain of gait were increased step velocity (normal speed: 8.2 cm/s, P = 0.04; fast: 10.8 cm/s, P < 0.01), increased step length (normal speed: 3 cm, P = 0.05; fast: 2.3 cm, P = 0.05) and reduced swing time variability (fast speed: –2.5 ms, P = 0.02). In the rhythm domain reduced step time (fast speed: –19.3 ms, P = 0.02), stance time (normal: –24.3 ms, P = 0.01; fast: –29.6 ms, P = 0.02) and swing time (fast speed: –8.7 ms, P = 0.04) was seen. Relative to the variability domain, the training decreased step time variability (fast: –2.8 ms, P = 0.02) and stance time variability (fast: –3.9 ms, P = 0.02). No training effects were retained at 6 months. Conclusions: Highly challenging balance and gait training improved pace, rhythm and variability aspects of PD gait in the short-term, but effects are not retained long-term. Trial registration number: NCT01417598.

Digital Biomarkers of Mobility in Parkinson's Disease During Daily Living.

Identifying digital biomarkers of mobility is important for clinical trials in Parkinson's disease (PD). To determine which digital outcome measures of mobility discriminate mobility in people with PD from healthy control (HC) subjects over a week of continuous monitoring. We recruited 29 people with PD, and 27 age-matched HC subjects. Subjects were asked to wear three inertial sensors (Opal by APDM) attached to both feet and to the lumbar region, and a subset of subjects also wore two wrist sensors, for a week of continuous monitoring. We derived 43 digital outcome measures of mobility grouped into five domains. An Area Under Curve (AUC) was calculated for each digital outcome measures of mobility, and logistic regression employing a 'best subsets selection strategy' was used to find combinations of measures that discriminated mobility in PD from HC. Duration of recordings was 66±14 hours in the PD and 59±16 hours in the HC. Out of a total of 43 digital outcome measures of mobility, we found six digital outcome measures of mobility with AUC > 0.80. Turn angle (AUC = 0.89, 95% CI: 0.79-0.97) and swing time variability (AUC = 0.87, 95% CI: 0.75-0.96) were the most discriminative individual measures. Turning measures were most consistently selected via the best subsets strategy to discriminate people with PD from HC, followed by gait variability measures. Clinical studies and clinical practice with digital biomarkers of daily life mobility in PD should include turning and variability measures.

Gait and Balance as Predictors and/or Mediators of Falls in Glaucoma.

PurposeTo investigate the association between balance and gait measures with fall rates in glaucoma patients.MethodsBalance and gait were measured for 239 participants with glaucoma or suspected glaucoma. Daily falls were evaluated over 24 months. Annual accelerometer trials captured average daily steps. Multivariable negative binomial models evaluated balance and gait associations with average daily steps and rates of falls per time or step, as well as whether balance and gait parameters mediated the association between integrated visual field (IVF) sensitivity and falls.ResultsAverage age was 70.5 years (SD = 7.6), and 22% of the participants had moderate to severe visual field damage. Over the first 12 months of the follow-up, the cumulative probability of falling one or more times was 44.8%, and the cumulative probability of falling two or more times was 17.7%. Gait deficits were associated with fewer daily steps (P < 0.03), but no balance parameters were (P > 0.19). Worse balance was associated with a higher rate of falls per year and step (P < 0.03). No gait measures were associated with the rate of falls per year (P > 0.17). More time in double support and greater swing time variability were associated with higher falls per step, and higher velocity and faster cadence were associated with fewer falls per step (P < 0.05 for all). Neither gait nor balance measures mediated the relationship between visual field damage and fall rates. IVF remained an independent predictor of falls per step (rate ratio = 1.36 to 1.48; P < 0.001 to P < 0.005) in multivariable models including individual balance/gait parameters.ConclusionsAlthough balance and gait measures are associated with fall rates, they do not explain why persons with greater visual field damage fall more frequently, suggesting the importance of other potential factors such as hazard perception.

Comparison of forward and backward gait characteristics between those with and without a history of breast cancer

BackgroundDecreased muscular strength and poorer postural stability impact the physical function of breast cancer survivors (BCS) and increases their risk of falls. Gait assessment, particularly in the backward direction, is often used as an indicator of fall risk in several populations. However this information is unknown in BCS. Research questionWhat are the differences in forward, backward, and accelerated forward walking in BCS in comparison to individuals without a prior cancer diagnosis? Methods17 postmenopausal BCS (mean age: 58.5 (8.5) years) and 17 age-matched women without a prior cancer diagnosis (mean age: 59.11 (5.55) years) completed 5 trials each of forward, backward, and fast forward walking conditions. Absolute (Means) and variability (Coefficient of variation) estimates were obtained for spatio-temporal gait parameters. Lower body, upper body and handgrip strengths were measured. ResultsFor absolute estimates of gait, significant group main effects indicated that BCS had 7% shorter step length (P = 0.019) and 8% slower gait speed (P = 0.048). For variability estimates of gait, there was a significant interaction for stance time (P = 0.035). BCS had greater stance time variability during forward and fast forward conditions, but lesser variability during backward condition. Averaged across all the conditions, BCS had 38% greater step length variability (P = 0.043), 50% greater gait speed variability (P = 0.028), and 28.5% greater single support time variability (P = 0.004). Averaged across both the groups, all the variables except for swing time variability were significantly different among the conditions (all P< = 0.013). BCS also had significantly reduced upper body strength (P = 0.036). SignificanceSlower and shorter steps while walking both forwards and backwards could be indicative of a more cautious gait strategy by BCS. Also, BCS possibly focused on controlling spatial parameters during forward walking but temporal parameters while backward walking. Whether these alterations are related to an increased fall risk within BCS needs to be determined.