Decreased Walking Speed Research Articles

Validity of visual perceptive computing for static posturography in patients with multiple sclerosis

Background: Multiple sclerosis (MS) patients frequently have postural control impairment but quantitative posturography is difficult to perform in clinical care. Recent technology facilitates new posturography approaches. Objective: To evaluate construct validity of visual perceptive computing (VPC) for static posturography to study postural control in MS patients. Methods: A total of 90 MS patients and 59 healthy controls (HCs) performed three stance tests: open, closed and tandem stance. Static posturography was performed using a VPC system with Microsoft Kinect. Clinical assessments included Expanded Disability Status Scale (EDSS), Timed-25-Foot-Walk, Short-Maximum-Speed-Walk and 12-item MS Walking Scale (MSWS-12) questionnaire. Reliability was assessed with intra-class correlation coefficients at retest. Results: As a group, MS patients performed worse than HCs in all tests. The closed stance test showed best applicability and reliability. With closed eyes, in 36.7% of patients, the three-dimensional mean angular sway velocity (MSV-3D) was above HCs’ 95th percentile. Higher MSV-3D was associated with decreased walking speed (p < 0.001); worse clinical scores, mainly attributable to the cerebellar functional system score (p < 0.001); and reflected in self-reported walking disability (MSWS-12, p < 0.001). Conclusion: Postural control can be reliably assessed by VPC-based static posturography in patients with MS. Abnormal postural control seems to predominantly reflect involvement of cerebellar circuits with impact on gait and walking disability.

Superficial warming and cooling of the leg affects walking speed and neuromuscular impairments in people with spastic paraparesis

BackgroundPeople with hereditary and spontaneous spastic paraparesis (HSSP) report that their legs are stiffer and walking is slower when their legs are cold. ObjectivesThis study explored the effects of prolonged superficial cooling and warming of the lower leg on walking speed and local measures of neuromuscular impairments. MethodsThis was a randomised pre- and post-intervention study of 22 HSSP participants and 19 matched healthy controls. On 2 separate occasions, one lower leg was cooled or warmed. Measurements included walking speed and measures of lower limb impairment: ankle movement, passive muscle stiffness, spasticity (stretch reflex size), amplitude and rate of force generation in dorsi- and plantarflexors and central and peripheral nerve conduction time/velocity. ResultsFor both participants and controls, cooling decreased walking speed, especially for HSSP participants. For both groups, cooling decreased the dorsiflexor rate and amplitude of force generation and peripheral nerve conduction velocity and increased spasticity. Warming increased dorsiflexor rate of force generation and nerve conduction velocity and decreased spasticity. ConclusionsSuperficial cooling significantly reduced walking speed for people with HSSP. Temperature changes were associated with changes in neuromuscular impairments for both people with spastic paraparesis and controls. This study does not support the use of localised cooling in rehabilitation for people with spastic paraparesis as reported in other neurological conditions. Rehabilitation interventions that help prevent heat loss (insulation) or improve limb temperature via passive or active means, particularly when the legs and/or environment are cool, may benefit people with spastic paraparesis.

The influence of monocular vision on the plantar pressure distribution

BackgroundAlthough the influence of monocular vision to upper limb biomechanics has been well documented, data about lower extremity biomechanics are limited. The objective of the present study was to demonstrate pedobarographic differences between both feet of the individuals with monocular vision in static and dynamic conditions. MethodsPedobarographic analysis of twenty-four participants with monocular vision was performed. Relative static pressure load (%) and dynamic peak plantar pressure (N/cm2), force (N) distributions and contact area percentages (%) were recorded under both low vision and normal vision side foot. FindingsThe results showed that relative static pressure loads did not differ between low vision and normal vision foot. Under midfoot of low vision side, a significant increment was found in peak plantar pressures (2.42 (SD 1.09) N/cm2) and forces (136.77 (SD 64.96) N) compared to normal vision side foot (1.87 (SD 0.96) N/cm2; 106.94 (SD 65.03) N). No difference in contact area percentages was detected. InterpretationThese results indicate that there are differences in plantar pressure measurements between feet of individuals with monocular vision. These pedobarographic differences reported here appear to support the assumption that individuals with monocular vision have adaptive gait strategies such as, decreased walking speed, limited ankle motion and postural compensations.

Determinants of Slow Walking Speed in Ambulatory Patients Undergoing Maintenance Hemodialysis.

Walking ability is significantly lower in hemodialysis patients compared to healthy people. Decreased walking ability characterized by slow walking speed is associated with adverse clinical events, but determinants of decreased walking speed in hemodialysis patients are unknown. The purpose of this study was to identify factors associated with slow walking speed in ambulatory hemodialysis patients. Subjects were 122 outpatients (64 men, 58 women; mean age, 68 years) undergoing hemodialysis. Clinical characteristics including comorbidities, motor function (strength, flexibility, and balance), and maximum walking speed (MWS) were measured and compared across sex-specific tertiles of MWS. Univariate and multivariate logistic regression analyses were performed to examine whether clinical characteristics and motor function could discriminate between the lowest, middle, and highest tertiles of MWS. Significant and common factors that discriminated the lowest and highest tertiles of MWS from other categories were presence of cardiac disease (lowest: odds ratio [OR] = 3.33, 95% confidence interval [CI] = 1.26–8.83, P<0.05; highest: OR = 2.84, 95% CI = 1.18–6.84, P<0.05), leg strength (OR = 0.62, 95% CI = 0.40–0.95, P<0.05; OR = 0.57, 95% CI = 0.39–0.82, P<0.01), and standing balance (OR = 0.76, 95% CI = 0.63–0.92, P<0.01; OR = 0.81, 95% CI = 0.68–0.97, P<0.05). History of fracture (OR = 3.35, 95% CI = 1.08–10.38; P<0.05) was a significant factor only in the lowest tertile. Cardiac disease, history of fracture, decreased leg strength, and poor standing balance were independently associated with slow walking speed in ambulatory hemodialysis patients. These findings provide useful data for planning effective therapeutic regimens to prevent decreases in walking ability in ambulatory hemodialysis patients.

Two- and 6-minute walk tests assess walking capability equally in neuromuscular diseases.

This methodologic study investigates if the 2-minute walk test (2MWT) can be a valid alternative to the 6-minute walk test (6MWT) to describe walking capability in patients with neuromuscular diseases. Patients (n = 115) with different neuromuscular diseases were invited to participate on 2 test days, each consisting of 1 2MWT and 1 6MWT separated by a minimum 30-minute period of rest. The order of the walk tests was randomly assigned via sealed envelopes. A group of 38 healthy controls completed 1 6MWT. The mean walking distance for the 2MWT was 142.8 meters and for the 6MWT 405.3 meters. The distance walked in the 2MWT was highly correlated to the distance walked in the 6MWT (r = 0.99, p < 0.001). There was a significant decrease in walking speed from the first to last minute in the 6MWT, both among patients and healthy controls, which was not evident in the 2MWT. Results were consistent across diagnoses and levels of disease severity. The 2MWT is a potential alternative to the 6MWT to describe walking capability among patients with neuromuscular diseases during clinical trials.

Adaptive changes in spatiotemporal gait characteristics in women during pregnancy

Spatiotemporal gait cycle characteristics were assessed at early (P1), and late (P2) pregnancy, as well as at 2 months (PP1) and 6 months (PP2) postpartum. A substantial decrease in walking speed was observed throughout the pregnancy, with the slowest speed (1±0.2m/s) being during the third trimester. Walking at slower velocity resulted in complex adaptive adjustments to their spatiotemporal gait pattern, including a shorter step length and an increased duration of both their stance and double-support phases. Duration of the swing phase remained the least susceptible to changes. Habitual walking velocity (1.13±0.2m/s) and the optimal gait pattern were fully recovered 6 months after childbirth. Documented here adaptive changes in the preferred gait pattern seem to result mainly from the altered body anthropometry leading to temporary balance impairments. All the observed changes within stride cycle aimed to improve gait safety by focusing on its dynamic stability. The pregnant women preferred to walk at a slower velocity which allowed them to spend more time in double-support compared with their habitual pattern. Such changes provided pregnant women with a safer and more tentative ambulation that reduced the single-support period and, hence, the possibility of instability. As pregnancy progressed a significant increase in stance width and a decrease in step length was observed. Both factors allow also for gait stability improvement.

Gait characteristics associated with the foot and ankle in inflammatory arthritis: a systematic review and meta-analysis.

BackgroundGait analysis is increasingly being used to characterise dysfunction of the lower limb and foot in people with inflammatory arthritis (IA). The aim of the systematic review was to evaluate the spatiotemporal, foot and ankle kinematic, kinetic, peak plantar pressure and muscle activity parameters between patients with inflammatory arthritis and healthy controls.MethodsAn electronic literature search was performed on Medline, CINAHL, SportsDiscus and The Cochrane Library. Methodological quality was assessed using a modified Quality Index. Effect sizes with 95 % confidence intervals (CI) were calculated as the standardised mean difference (SMD). Meta-analysis was conducted if studies were homogenous.ResultsThirty six studies with quality ranging from high to low met the inclusion criteria. The majority of studies reported gait parameters in Rheumatoid arthritis (RA). The gait pattern in RA was characterised by decreased walking speed (SMD 95 % CI −1.57, −2.25 to −0.89), decreased cadence (SMD −0.97, −1.49 to −0.45), decreased stride length (SMD −1.66, −1.84 to −1.49), decreased ankle power (SMD −1.36, −1.70 to −1.02), increased double limb support time (SMD 1.03, 0.84 to 1.22), and peak plantar pressures at the forefoot (SMD 1.11, 0.76 to 1.45). Walking velocity was reduced in psoriatic arthritis and gout with no differences in ankylosing spondylitis. No studies have been conducted in polymyalgia rheumatica, systemic sclerosis or systemic lupus erythematosus.ConclusionsThe review identified the majority of studies reporting gait adaptations in RA, but limited evidence relating to other IA conditions. Poor data reporting, small sample sizes and heterogeneity across IA conditions limit the interpretation of the findings. Future studies may consider a standardised analytical approach to gait analysis that will provide clinicians and researchers with objective evidence of foot function in people with IA.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0596-0) contains supplementary material, which is available to authorized users.

Gait Asymmetries as a Predictors of Walking Speed Five Years Following Total Ankle Arthroplasty

More than 50,000 new cases of ankle arthritis are being reported annually. Total ankle arthroplasty (TAA) is increasing in popularity as the treatment for end-stage disease with the goal of decreasing pain and improving function. Decreased walking speed is often associated with decreased function. Following TAA gait asymmetry is prevalent and often associated with impaired function. PURPOSE: Determine if kinematic and kinetic asymmetries are predictors of walking speed following TAA. METHODS: Three-dimensional motion capture was used to collect bilateral kinematic and kinetic data during 7 walking trials at a self-selected speed on 34 patients 5 years following TAA. Patients were excluded from this analysis if they had any complications requiring additional surgical intervention or were unable to walk without the use of an assistive device. Discrete ankle kinematic and kinetic variables as well as ground reaction forces (GRF) were extracted from ensemble curves for analysis. A linear regression model was used to identify significant predictors of walking speed based on gait asymmetries. Variables were removed from the model if they did not provide a statistically significant improvement to the model (p<0.05). Finally, individual limbs as well as symmetry measures were included in one regression model to determine the interaction between the asymmetry and individual limb measures. RESULTS: Asymmetries in the anterior GRF, peak dorsiflexion angle and the weight acceptance vertical GRF were able to explain 32.5% of the variance (P=0.008) in walking speed. The addition of the independent limb measures explained an additional 54% of the variance in walking speed. A model that combined peak plantarflexion moment and propulsion vertical GRF asymmetries in combination with the surgical side peak plantarflexion moment and the non-surgical weight acceptance vertical GRF explained 86.5% of the variance in walking speed (p<0.001). CONCLUSIONS: Asymmetries in movement patterns predicts post-TAA walking speed, however, the addition of individual limb mechanics more than doubles the explained variance. These results suggest that rehabilitation programs in the post-TAA patient aimed at improving function should target the restoration of symmetrical gait mechanics in addition to targeting surgical side propulsion.

The effects of narrow and elevated path walking on aperture crossing

The study investigated the impact that action capabilities have on identifying possibilities for action, particularly how postural threat influences the passability of apertures. To do this, the ability to maintain balance was challenged by manipulating the level of postural threat while walking. First, participants walked along a 7m path and passed through two vertical obstacles spaced 1.1–1.5×the shoulder width apart during normal walking. Next, postural threat was manipulated by having participants complete the task either walking on a narrow, ground level path or on an elevated/narrow path. Despite a decrease in walking speed as well as an increase in trunk sway in both the narrow and elevated/narrow walking conditions, the passability of apertures was only affected when the consequence of instability was greatest. In the elevated/narrow walking condition, individuals maintained a larger critical point (rotated their shoulders for larger aperture widths) compared to normal walking. However, this effect was not observed for the narrow path walking suggesting that the level of postural threat was not enough to impose similar changes to the critical point. Therefore, it appears that manipulating action capabilities by increasing postural threat does indeed influence aperture crossing behavior, however the consequence associated with instability must be high before both gait characteristics and the critical point are affected.

Description of spatio-temporal gait parameters in elderly people and their association with history of falls: results of the population-based cross-sectional KORA-Age study.

BackgroundIn this epidemiological study we described the characteristics of spatio-temporal gait parameters among a representative, population-based sample of 890 community-dwelling people aged 65 to 90 years. In addition, we investigated the associations between certain gait parameters and a history of falls in study participants.MethodsIn descriptive analyses spatio-temporal gait parameters were assessed according to history of falls, frailty, multimorbidity, gender, multiple medication use, disability status, and age group. Logistic regression models were calculated to examine the association between gait velocity and stride length with a history of falls (at least one fall in the last 12 month). Data on gait were collected on an electronic walkway on which participants walked at their usual pace.ResultsWe found significant differences within gait parameters when stratifying by frailty, multimorbidity, disability and multiple medication use as well as age (cut point 75 years) and sex, with p < 0.05 for all gait parameters (velocity, cadence, time, stride duration, stride length, step width). After stratification by history of falls, only stride length showed a significant difference (p < 0.05) between the groups of fallers and non-fallers. Logistic regression models showed that a decreased stride length was independently associated with falls in men aged older than 74 years (OR 1.34 (CI: 1.05-1.70 per 10 cm decrease)), while this was neither the case for women of similar age nor for men or women aged 65 to 74 years. A decreased walking speed was not associated with falls.ConclusionAge, frailty, multimorbidity, disability, history of falls, sex, and multiple medication use show an association with different gait parameters measured during gait assessment on an electronic walkway in elderly people. Furthermore, stride length is a good indicator to differentiate fallers from non-fallers in older men from the general population.

Gait patterns of chronic ambulatory hemiplegic elderly compared with normal Age-Matched elderly

This study compares the gait of chronic ambulatory hemiplegic elderly (HE) with those of non-hemiplegic elderly (NHE) using Vicon® 512 motion analysis system to track movement trajectories. Subjects walked with self-selected gait speeds while temporal, spatial, and kinematic variables were analyzed. HE showed significantly decreased walking speed, cadence, stride length, and step length, and increased stride time, step time, and double limb support periods in comparison with NHE. Double limb support of stance phase was significantly increased in HE. In HE, affected pelvis showed marked upward elevation from terminal stance to mid swing phase, and greater external rotation than the NHE (p<0.05). Affected hip showed increased external rotation than the NHE. Affected knee showed loss of first and second flexion waves in sagittal plane. Affected ankle also showed reduced first rocker, and outward foot progression angle compared to NHE. Our results suggest that the major coping mechanism of HE to maintain balance and to continue walking is to increase the stance time of affected limb inevitably sacrificing walking speed. This study points to the importance and necessity of building a rehabilitation program that decrease the double limb support of affected limb while maintaining gait speed in the HE.

Screening for frailty in older adults using a self-reported instrument.

OBJECTIVE To validate a screening instrument using self-reported assessment of frailty syndrome in older adults.METHODS This cross-sectional study used data from the Saúde, Bem-estar e Envelhecimento study conducted in Sao Paulo, SP, Southeastern Brazil. The sample consisted of 433 older adult individuals (≥ 75 years) assessed in 2009. The self-reported instrument can be applied to older adults or their proxy respondents and consists of dichotomous questions directly related to each component of the frailty phenotype, which is considered the gold standard model: unintentional weight loss, fatigue, low physical activity, decreased physical strength, and decreased walking speed. The same classification proposed in the phenotype was utilized: not frail (no component identified); pre-frail (presence of one or two components), and frail (presence of three or more components). Because this is a screening instrument, “process of frailty” was included as a category (pre-frail and frail). Cronbach’s α was used in psychometric analysis to evaluate the reliability and validity of the criterion, the sensitivity, the specificity, as well as positive and negative predictive values. Factor analysis was used to assess the suitability of the proposed number of components.RESULTS Decreased walking speed and decreased physical strength showed good internal consistency (α = 0.77 and 0.72, respectively); however, low physical activity was less satisfactory (α = 0.63). The sensitivity and specificity for identifying pre-frail individuals were 89.7% and 24.3%, respectively, while those for identifying frail individuals were 63.2% and 71.6%, respectively. In addition, 89.7% of the individuals from both the evaluations were identified in the “process of frailty” category.CONCLUSIONS The self-reported assessment of frailty can identify the syndrome among older adults and can be used as a screening tool. Its advantages include simplicity, rapidity, low cost, and ability to be used by different professionals.

Gait characteristics associated with the foot and ankle in inflammatory arthritis: a systematic review and meta‐analysis

Gait analysis is increasingly being used to characterise dysfunction of the lower limb and foot in people with inflammatory arthritis (IA). The aim of the systematic review was to evaluate the spatiotemporal, foot and ankle kinematic, kinetic, peak plantar pressure and muscle activity parameters between patients with inflammatory arthritis and healthy controls. An electronic literature search was performed on Medline, CINAHL, SportsDiscus and The Cochrane Library. Methodological quality was assessed using a modified Quality Index. Effect sizes with 95 % confidence intervals (CI) were calculated as the standardised mean difference (SMD). Meta-analysis was conducted if studies were homogenous. Thirty six studies with quality ranging from high to low met the inclusion criteria. The majority of studies reported gait parameters in Rheumatoid arthritis (RA). The gait pattern in RA was characterised by decreased walking speed (SMD 95 % CI −1.57, −2.25 to −0.89), decreased cadence (SMD −0.97, −1.49 to −0.45), decreased stride length (SMD −1.66, −1.84 to −1.49), decreased ankle power (SMD −1.36, −1.70 to −1.02), increased double limb support time (SMD 1.03, 0.84 to 1.22), and peak plantar pressures at the forefoot (SMD 1.11, 0.76 to 1.45). Walking velocity was reduced in psoriatic arthritis and gout with no differences in ankylosing spondylitis. No studies have been conducted in polymyalgia rheumatica, systemic sclerosis or systemic lupus erythematosus. The review identified the majority of studies reporting gait adaptations in RA, but limited evidence relating to other IA conditions. Poor data reporting, small sample sizes and heterogeneity across IA conditions limit the interpretation of the findings. Future studies may consider a standardised analytical approach to gait analysis that will provide clinicians and researchers with objective evidence of foot function in people with IA.

Gait and Physical Impairments in Patients With Acute Ankle Sprains Who Did Not Receive Physical Therapy

ObjectiveTo assess ankle function 4 weeks after conservative management and to examine the correlation of function with gait. DesignA prospective comparison study. PatientsThirty patients with grade I or II acute ankle sprains were followed up after 4 weeks of conservative management not involving physical therapy. MethodsParticipants underwent a clinical assessment and had to walk at a normal self-selected walking speed. Their results were compared with the data of 15 healthy subjects. Main Outcome MeasuresParticipants' joint swelling, muscle strength, passive mobility, and pain were assessed. In addition, patients' temporal-spatial, kinematic, and kinetic gait data were measured while walking. ResultsMuscle strength and passive mobility were significantly reduced on the injured side compared with the noninjured side (P < .001). During gait analysis, patients with ankle sprains showed slower walking speed, shorter step length, shorter single support time, reduced and delayed maximum plantar flexion, decreased maximum power, and decreased maximum moment (P < .050) compared with healthy persons. Decreased walking speed was mainly correlated with pain (R = −0.566, P = .001) and deficits in muscle strength of dorsiflexors (R = 0.506, P = .004). ConclusionFour weeks after an ankle sprain, patients who did not receive physical therapy showed physical impairments of the ankle that were correlated with gait parameters. These findings might help fine-tune rehabilitation protocols.

Apolipoprotein E genotype and physical function among older people with mild cognitive impairment.

Mild cognitive impairment (MCI) is conceptualized as prodromal of Alzheimer's disease (AD). Declined physical function is one of the risk factors for progression to AD, whereas genetic factors, especially the apolipoprotein E ε4 allele (APOE4), also contribute to the risk of AD and affect the risk factors. However, the association between APOE4 and physical function in MCI is still unclear. To elucidate the association, we carried out the present study to compare physical function between APOE4 carriers and non-carriers in MCI. The study included 386 MCI patients (mean age 71.6 years) who were classified into APOE4 carrier and non-carrier groups. The participants' characteristics were assessed by face-to-face interviews. Grip strength, five chair stand test, walking speed and 6-min walking test were measured as physical functions. In univariate analysis, the APOE4 carrier group had decreased walking speed compared with the non-carrier group (P < 0.05), but other measures of physical function were not significantly different between the groups. The linear regression model showed a significant association between walking speed and APOE4 after adjusting for covariates (P < 0.05). The present study showed that APOE4 carrier participants with MCI had decreased walking speed compared with non-carrier participants. Thus, APOE4 genotypes should be considered as a potential mediator when the measure of walking speed is used as a risk factor of dementia in older adults with MCI. Further studies using prospective data are required to clarify the relationship between physical function and genetic factors in MCI.

Physical fitness evolution in octogenarian population and its relationship with a sedentary lifestyle

The aim of this study was to determine the changes in physical fitness over two years of following up in octogenarian people and to check whether a sedentary lifestyle modify these variations. Physical fitness of 182 subject (48 men, 134 women) with a mean age of 82,3 ± 2,3 years were evaluated using 8 different tests. A repeated measures analysis was carried out to see the differences between the two evaluation periods and to see the physical fitness differences between sedentary people (sit ≥ 4 hours/day) and non sedentary people (sit < 4 hours/day). Between the two evaluation periods, we found a significant decrease in the agility test (p < 0.05), walking speed (p < 0.01) and endurance (p < 0.01). In relation to the subjects who spent sitting 4 hours/day there was a decrease in the walking speed test between the two evaluations (p < 0.05). Moreover, there was a decrease of walking speed and endurance between the two evaluation periods in both sedentary and nonsedentary people (p < 0.05). In two years of following up, there are adverse changes in the level of physical fitness in octogenarians. Long periods of sitting time may translate into a loss of agility. Walking speed and endurance seem to be the components of physical fitness more affected by the ageing process in this population; and this loss is not determined by the hours of sitting per day.

Using Gastrocnemius sEMG and Plasma α-Synuclein for the Prediction of Freezing of Gait in Parkinson's Disease Patients

Freezing of gait (FOG) is a complicated gait disturbance in Parkinson's disease (PD) and a relevant subclinical predictor algorithm is lacking. The main purpose of this study is to explore the potential value of surface electromyograph (sEMG) and plasma α-synuclein levels as predictors of the FOG seen in PD. 21 PD patients and 15 normal controls were recruited. Motor function was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Freezing of gait questionnaire (FOG-Q). Simultaneously, gait analysis was also performed using VICON capture system in PD patients and sEMG data was recorded as well. Total plasma α-synuclein was quantitatively assessed by Luminex assay in all participants. Recruited PD patients were classified into two groups: PD patients with FOG (PD+FOG) and without FOG (PD-FOG), based on clinical manifestation, the results of the FOG-Q and VICON capture system. PD+FOG patients displayed higher FOG-Q scores, decreased walking speed, smaller step length, smaller stride length and prolonged double support time compared to the PD-FOG in the gait trial. sEMG data indicated that gastrocnemius activity in PD+FOG patients was significantly reduced compared to PD-FOG patients. In addition, plasma α-synuclein levels were significantly decreased in the PD+FOG group compared to control group; however, no significant difference was found between the PD+FOG and PD-FOG groups. Our study revealed that gastrocnemius sEMG could be used to evaluate freezing gait in PD patients, while plasma α-synuclein might discriminate freezing of gait in PD patients from normal control, though no difference was found between the PD+FOG and PD-FOG groups.

Stepping strategies used by post-stroke individuals to maintain margins of stability during walking

BackgroundPeople recovering from a stroke are less stable during walking compared to able-bodied controls. The purpose of this study was to examine whether and how post-stroke individuals adapt their steady-state gait pattern to maintain or increase their margins of stability during walking, and to examine how these strategies differ from strategies employed by able-bodied people. MethodsTen post-stroke individuals and 9 age-matched able-bodied individuals walked on the Computer Assisted Rehabilitation Environment. Medio-lateral translations of the walking surface were imposed to manipulate gait stability. To provoke gait adaptations, a gait adaptability task was used, in which subjects occasionally had to hit a virtual target with their knees. We measured medio-lateral and backward margins of stability, and the associated gait parameters walking speed, step length, step frequency, and step width. FindingsPost-stroke participants showed similar medio-lateral margins of stability as able-bodied people in all conditions. This was accomplished by a larger step width and a relatively high step frequency. Post-stroke participants walked overall slower and decreased walking speed and step length even further in response to both manipulations compared to able-bodied participants, resulting in a tendency towards an overall smaller backward margins of stability, and a significantly smaller backward margin of stability during the gait adaptability task. InterpretationPost-stroke individuals have more difficulties regulating their walking speed, and the underlying parameters step frequency and step length, compared to able-bodied controls. These quantities are important in regulating the size of the backward margin of stability when walking in complex environments.

Diabetes, peripheral neuropathy, and lower-extremity function

ObjectiveDiabetes among older adults causes many complications, including decreased lower-extremity function and physical disability. Diabetes can cause peripheral nerve dysfunction, which might be one pathway through which diabetes leads to decreased physical function. The study aims were to determine the following: (1) whether diabetes and impaired fasting glucose are associated with objective measures of physical function in older adults, (2) which peripheral nerve function (PNF) tests are associated with diabetes, and (3) whether PNF mediates the diabetes–physical function relationship. Research Design and MethodsThis study included 983 participants, age 65years and older from the InCHIANTI study. Diabetes was diagnosed by clinical guidelines. Physical performance was assessed using the Short Physical Performance Battery (SPPB), scored from 0 to 12 (higher values, better physical function) and usual walking speed (m/s). PNF was assessed via standard surface electroneurographic study of right peroneal nerve conduction velocity, vibration and touch sensitivity. Clinical cutpoints of PNF tests were used to create a neuropathy score from 0 to 5 (higher values, greater neuropathy). Multiple linear regression models were used to test associations. Results and ConclusionOne hundred twenty-six (12.8%) participants had diabetes. Adjusting for age, sex, education, and other confounders, diabetic participants had decreased SPPB (β=−0.99; p<0.01), decreased walking speed (β=−0.1m/s; p<0.01), decreased nerve conduction velocity (β=−1.7m/s; p<0.01), and increased neuropathy (β=0.25; p<0.01) compared to non-diabetic participants. Adjusting for nerve conduction velocity and neuropathy score decreased the effect of diabetes on SPPB by 20%, suggesting partial mediation through decreased PNF.

Cholinergic Dysfunction in Parkinson’s Disease

There is increasing interest in the clinical effects of cholinergic basal forebrain and tegmental pedunculopontine complex (PPN) projection degeneration in Parkinson's disease (PD). Recent evidence supports an expanded role beyond cognitive impairment, including effects on olfaction, mood, REM sleep behavior disorder, and motor functions. Cholinergic denervation is variable in PD without dementia and may contribute to clinical symptom heterogeneity. Early in vivo imaging evidence that impaired cholinergic integrity of the PPN associates with frequent falling in PD is now confirmed by human post-mortem evidence. Brainstem cholinergic lesioning studies in primates confirm the role of the PPN in mobility impairment. Degeneration of basal forebrain cholinergic projections correlates with decreased walking speed. Cumulatively, these findings provide evidence for a new paradigm to explain dopamine-resistant features of mobility impairments in PD. Recognition of the increased clinical role of cholinergic system degeneration may motivate new research to expand indications for cholinergic therapy in PD.