Measures Of Walking Performance Research Articles

Walking speeds are lower for short distance and turning locomotion: Experiments and modeling in low-cost prosthesis users.

Preferred walking speed is a widely-used performance measure for people with mobility issues, but is usually measured in straight line walking for fixed distances or durations, and without explicitly accounting for turning. However, daily walking involves walking for bouts of different distances and walking with turning, with prior studies showing that short bouts with at most 10 steps could be 40% of all bouts and turning steps could be 8-50% of all steps. Here, we studied walking in a straight line for short distances (4 m to 23 m) and walking in circles (1 m to 3 m turning radii) in people with transtibial amputation or transfemoral amputation using a passive ankle-foot prosthesis (Jaipur Foot). We found that the study participants' preferred walking speeds are lower for shorter straight-line walking distances and lower for circles of smaller radii, which is analogous to earlier results in subjects without amputation. Using inverse optimization, we estimated the cost of changing speeds and turning such that the observed preferred walking speeds in our experiments minimizes the total cost of walking. The inferred costs of changing speeds and turning were larger for subjects with amputation compared to subjects without amputation in a previous study, specifically, being 4x to 8x larger for the turning cost and being highest for subjects with transfemoral amputation. Such high costs inferred by inverse optimization could potentially include non-energetic costs such as due to joint or interfacial stress or stability concerns, as inverse optimization cannot distinguish such terms from true metabolic cost. These experimental findings and models capturing the experimental trends could inform prosthesis design and rehabilitation therapy to better assist changing speeds and turning tasks. Further, measuring the preferred speed for a range of distances and radii could be a more comprehensive subject-specific measure of walking performance than commonly used straight line walking metrics.

Walking asymmetry and its relation to patient-reported and performance-based outcome measures in individuals with unilateral lower limb loss

ABSTRACT Gait asymmetry persists for most people after lower limb amputation and is associated with slower walking speeds. However, the relationship between gait asymmetry and patient-reported function remains unclear because they are not commonly assessed together. The purpose of this study was to determine relationships between gait asymmetries in people with lower limb loss and (1) patient-reported outcomes and (2) performance-based prosthetic functional measures. This cross-sectional analysis included nine people with unilateral limb loss aged 48.2 ± 13.1 years of mixed amputation etiology. Patient-reported outcomes included the Prosthetic Evaluation Questionnaire mobility subscale and Activities-specific Balance Confidence scale. Performance outcomes included the Berg Balance Scale and the 30-second sit-to-stand test. Walking performance measures included the 2-Minute Walk Test, during which APDM Opal sensors recorded spatiotemporal gait parameters, and daily step-counts from StepWatch4 activity monitors. The study found that the most asymmetric gait symmetry ratios (prosthetic-limb divided by intact-limb) could be attributed to prosthetic foot dorsiflexion-plantarflexion and rotation motion limitations: prosthetic-limb trailing double support (0.789 ± 0.052), toe-off (0.760 ± 0.068) and toe-out angle (0.653 ± 0.256). Single limb stance, and stance and swing phase durations were most strongly associated with balance and walking performance measures. Notably, no symmetry ratio was significantly associated with patient-reported prosthetic function (unadjusted Pearson correlation coefficients r < 0.50, P > 0.05). More gait symmetry was associated with better balance and walking performance but had no significant relationship with patient-reported function. Although achieving gait symmetry after lower limb loss is a common walking goal, symmetry was unrelated to the perception of functional mobility for people with lower limb loss.

A New Robotic Knee Impedance Control Parameter Optimization Method Facilitated by Inverse Reinforcement Learning

Recent efforts in the design of intelligent controllers for configuring robotic prostheses have demonstrated new possibilities in improving mobility and restoring locomotion for individuals with lower-limb disabilities. In these efforts, personalizing the controller of the robotic device is a crucial step in order to meet individual user's needs and physical conditions. Reinforcement learning (RL) based control designs are among some of the most promising approaches to achieving real-time, optimal adaptive tuning capability. However, such designs to date rely on subjectively determining human-robot walking performance measures, commonly in a quadratic form. To further automate the RL design for robotic knee control parameter tuning and potentially improve human-robot locomotion performance, this study introduces a new bilevel optimization method to objectively specify such control design performance measures via inverse reinforcement learning (IRL), which in turn, will be used in low level (forward) RL design of the impedance control parameters. We demonstrate the effectiveness of the bilevel optimization approach with improved human-robot walking performance using systematic OpenSim simulation studies.

Comparison of Self-Reported vs Objective Measures of Long-Term Community Ambulation in Lower Limb Prosthesis Users

ObjectiveTo determine normal variation in walking metrics in a population of lower limb amputees who use lower limb prostheses over a 6-month period and to provide a means to interpret clinically meaningful change in those community walking metrics. DesignProspective cohort study monitoring walking behavior and subjective and objective measures of activity. SettingVeterans Administration and university amputee clinics. Participants86 individuals with lower limb amputation who use protheses. InterventionsStepWatch activity monitor tracked subjects’ walking for 24 weeks; Global Mobility Change Rating collected weekly. Main Outcome MeasuresAssociation between change in Global Mobility Change Rating and change in any of the walking metrics. ResultsWalking metrics including step count, cadence, cadence variability, and walking distance in a population of lower limb prosthesis users were obtained. There was a high correlation in the walking metrics indicating higher function with higher functional classification level (K-levels) but also substantial overlap in all metrics and a very weak correlation between subject-reported activity level and objective measures of walking performance. ConclusionThe overlap in walking metrics with all K-levels demonstrates that no single metric measured by StepWatch can determine K-level with 100% accuracy. As previously demonstrated in other populations, subjects’ interpretations of their general activity level was inaccurate, regardless of their age or activity level. Objective measures of walking appear to provide a more accurate representation of patients’ activity levels in the community than self-report. Therefore, objective measures of walking are useful in supporting K-level determinations. However, clinicians cannot rely on a single metric to determine K-level.

Effects of a Low-Intensity Walking Intervention on Walking Performance Measures in Patients with Peripheral Artery Disease

The purpose of this study was to examine the effects of a low-intensity (pain-free) walking intervention on walking performance and self-report measures in patients with peripheral arterial disease (PAD). Thirty-three participants who experienced intermittent claudication were assigned to either a walking group (n = 18) or a comparison group (n = 15). The walking group performed a structured walking program (pain-free walking, 5 days per week for 12 weeks). The comparison group maintained their usual daily activities. Tests of walking performance included a treadmill test (pain-free, functional and maximal walking distances were measured) and the 6-minute walk test. Self-perception of walking ability was determined using the walking impairment questionnaire. Circulatory measures were obtained from the ankle-brachial index, (ABI). Participants were assessed at the beginning (Week 1) and end of the study (Week 12). Members of the walking group significantly increased their walking performance and self-perception of walking ability, whereas the ABI remained the same. These results show that participation in a 12-week, low-intensity (pain-free) exercise program can enhance physical performance, perception of walking ability and maintain the ABI suggesting that a home-based exercise program is a viable alternative to traditional exercise programs prescribed for patients with symptomatic PAD. Keywords: peripheral artery disease, exercise, walking performance, ankle-brachial index, walking impairment questionnaire

Do physical activity, cardiorespiratory fitness, and subcortical brain structures explain reduced walking performance in older adults with multiple sclerosis?

BackgroundAs adults with multiple sclerosis (MS) age, walking speed and endurance progressively decline, yet there is limited understanding of factors that explain such age-related declines. The current study examined subcortical brain structures, cardiorespiratory fitness, and moderate-to-vigorous physical activity (MVPA) as explanations for reduced walking performance in older adults with MS. MethodsOlder adults with MS (n = 29, 62.8 ± 5.8 years) and age-and-sex matched controls (n = 28, 63.8 ± 5.5 years) completed measures of walking speed (Timed-25 ft Walk) and walking endurance (Six-minute Walk), cardiorespiratory fitness, device-measured MVPA, and underwent an MRI to provide composite volumes of the thalamus, caudate, putamen, and pallidum. We used a mediator variable framework to describe group differences, determine correlations in the overall sample, and identify variables that explain reduced walking performance. ResultsCompared to controls, older adults with MS had worse walking speed (p<0.001) and endurance (p<0.001), lower fitness (p = 0.04), lower levels of MVPA (p = 0.001), and smaller composite volumes of the thalamus (p=<0.001), putamen (p = 0.04), and pallidum (p = 0.007). In the overall sample, both measures of walking performance were significantly correlated with fitness, MVPA, and volumes of the thalamus and putamen (r range 0.34–0.65). Regression analyses indicated that MVPA (β=0.007094) partially explained the group differences in walking speed, and fitness (β=7.7640) and MVPA (β=17.5797) partially explained the group differences in walking endurance. ConclusionsCollectively, these results suggest that cardiorespiratory fitness and MVPA, but not subcortical brain structures, may be modifiable targets of future interventions for improving walking in older adults with MS.

Screening tools to expedite assessment of frailty in people receiving haemodialysis: a diagnostic accuracy study

BackgroundFrailty is associated with multiple adverse outcomes in stage-5 chronic kidney disease (CKD-5) and upwards of one third of people receiving haemodialysis (HD) are frail. While many frailty screening methods are available in both uremic and non-uremic populations, their implementation in clinical settings is often challenged by time and resource constraints. In this study, we explored the diagnostic accuracy of time-efficient screening tools in people receiving HD.MethodsA convenience sample of 76 people receiving HD [mean age = 61.1 years (SD = 14), 53.9% male] from three Renal Units were recruited for this cross-sectional study. Frailty was diagnosed by means of the Fried phenotype. Physical performance-based screening tools encompassed handgrip strength, 15-ft gait speed, timed up and go (TUG), and five-repetition sit to stand (STS-5) tests. In addition, participants completed the SF-36 Health Survey, the short-form international physical activity questionnaire and the Tinetti falls efficacy scale (FES) as further frailty-related measures. Outcome measures included the area under the curve (AUC), sensitivity, specificity, positive (PPV) and negative predictive values (NPV). The diagnostic performance of screening tools in assessing fall-risk was also investigated.ResultsOverall, 36.8% of participants were classified as frail. All the examined instruments could significantly discriminate frailty status in the study population. Gait speed [AUC = 0.89 (95%CI: 0.81–0.98), sensitivity = 75%, specificity = 93%] and TUG [AUC = 0.90 (95%CI: 0.80–0.99), sensitivity = 89%, specificity = 85%] exhibited the highest diagnostic accuracy. There was a significant difference in gait speed AUC (20%, p = 0.013) between participants aged 65 years or older (n = 36) and those under 65 years of age (n = 40), with better discriminating performance in the younger sub-group. The Tinetti FES was the only instrument showing good diagnostic accuracy (AUCs≥0.80) for both frailty (sensitivity = 82%, specificity = 79%) and fall-risk (sensitivity = 82%, specificity = 71%) screening.ConclusionsThis cross-sectional study revealed that time- and cost-efficient walking performance measures can accurately be used for frailty-screening purposes in people receiving HD. While self-selected gait speed had an excellent performance in people under 65 years of age, TUG may be a more suitable screening method for elderly patients (≥65 years). The Tinetti FES may be a clinically useful test when physical testing is not achievable.

U-turn speed is a valid and reliable smartphone-based measure of multiple sclerosis-related gait and balance impairment

BackgroundPeople living with multiple sclerosis (MS) experience impairments in gait and mobility, that are not fully captured with manually timed walking tests or rating scales administered during periodic clinical visits. We have developed a smartphone-based assessment of ambulation performance, the 5 U-Turn Test (5UTT), a quantitative self-administered test of U-turn ability while walking, for people with MS (PwMS). Research questionWhat is the test-retest reliability and concurrent validity of U-turn speed, an unsupervised self-assessment of gait and balance impairment, measured using a body-worn smartphone during the 5UTT? Methods76 PwMS and 25 healthy controls (HCs) participated in a cross-sectional non-randomised interventional feasibility study. The 5UTT was self-administered daily and the median U-turn speed, measured during a 14-day session, was compared against existing validated in-clinic measures of MS-related disability. ResultsU-turn speed, measured during a 14-day session from the 5UTT, demonstrated good-to-excellent test-retest reliability in PwMS alone and combined with HCs (intraclass correlation coefficient [ICC] = 0.87 [95 % CI: 0.80–0.92]) and moderate-to-excellent reliability in HCs alone (ICC = 0.88 [95 % CI: 0.69–0.96]). U-turn speed was significantly correlated with in-clinic measures of walking speed, physical fatigue, ambulation impairment, overall MS-related disability and patients’ self-perception of quality of life, at baseline, Week 12 and Week 24. The minimal detectable change of the U-turn speed from the 5UTT was low (19.42 %) in PwMS and indicates a good precision of this measurement tool when compared with conventional in-clinic measures of walking performance. SignificanceThe frequent self-assessment of turn speed, as an outcome measure from a smartphone-based U-turn test, may represent an ecologically valid digital solution to remotely and reliably monitor gait and balance impairment in a home environment during MS clinical trials and practice.

Abstract 15269: Baseline Relationships of Walking, Physical Activity Habits and Self-perceived Recovery After Stroke in People Engaged in a Healthy Lifestyle Program

Introduction: Recovery of walking is an important goal for people after stroke and is linked with acquiring secondary conditions deleterious to health. Our purpose was to assess the baseline relationships between walking performance, physical activity habits and self-perceived recovery after stroke in people engaged in a healthy lifestyle program. Hypothesis: We hypothesized that walking performance would be strongly related to self-reported stroke recovery and physical activity habits. Methods: Community dwelling adults at least 12 months post-stroke with a body mass index (BMI) of 25 or greater were recruited to participate in a healthy lifestyle program adapted for people with stroke. Baseline measures of walking performance [10-meter walk test (10MWT); 6-minute walk test (6MWT)] and self-reported outcomes [Self-Report Habits Index (SRHI); Stroke Impact Scale (SIS)] were correlated. Results: Adults (34 male, 31 female; 64.6% scored as having some disability on the Modified Rankin Scale) aged 57.9±12.8 years with a BMI of 33.0±5.9 and median of 3 years post-stroke participated. 10MWT walking speed was 1.0±0.4m/s and 6MWT distance walked was 343.3±132.3m. SRHI physical activity scores of 4.6±1.7 (above average habit formation; scale = 1 - 7) and SIS subscales ADL/IADL and mobility normed scores of -0.1±0.7 and -1.3±0.8 respectively, and perceived recovery of 70.9±16.9% were reported. The 10MWT was significantly and moderately correlated with SIS ADL/IADL (r=0.48; p&lt;0.001) and mobility (r=0.41; p&lt;0.001), but weakly with SIS perceived recovery (r=0.34; p&lt;0.01) and SRHI physical activity (r=-0.32; p&lt;0.01). The 6MWT was significantly and moderately correlated with SIS ADL/IADL (r=0.48; p&lt;0.001) and mobility (r=0.47; p&lt;0.001), but weakly with SIS perceived recovery (r=0.33; p&lt;0.01) and SRHI physical activity (r=-0.33; p&lt;0.01). Conclusions: Walking performance among our participants post-stroke was consistent with community dwelling adults, but only somewhat related to their perception of recovery of function and mobility. Additional factors beyond perceived recovery likely contribute to walking abilities post-stroke.

Mitochondrial DNA damage in calf skeletal muscle and walking performance in people with peripheral artery disease

BackgroundPeripheral artery disease (PAD) is associated with mitochondrial dysfunction in calf skeletal muscle and a greater abundance of mitochondrial DNA (mtDNA) heteroplasmy. However, it is unknown whether calf skeletal muscle mtDNA of PAD participants harbors a greater abundance of mitochondrial DNA 4977-bp common deletion (mtDNA4977), strand breaks and oxidative damage (i.e., oxidized purines) compared to non-PAD participants and whether these mtDNA abnormalities are associated with poor walking performance in participants with PAD. MethodsCalf muscle biopsies were obtained from 50 PAD participants (ankle-brachial index (ABI) < 0.95) and 25 non-PAD participants (ABI = 0.99–1.40) matched by age, sex, and race. The abundance of mtDNA copy number, mtDNA4977 deletion, strand breaks, and oxidized purines in selected mtDNA regions coding for electron transport chain (ETC) constituents and the non-coding D-Loop region was determined in calf muscle. All participants completed measurement of 6-min walk and usual and fast-paced 4-m walking velocity test. ResultsParticipants with PAD (mean age = 65.4 years, SD = 6.9; 14 (28%) women, 38 (76%) black) and without PAD (mean age = 65.2 years, SD = 6.7; 7 (28%) women, 16 (64%) black) did not differ in the abundance of calf muscle mtDNA4977 deletion, mtDNA strand breaks, and oxidized purines. Though, a greater abundance of mtDNA strand breaks within ND4/5 genes was significantly associated with poorer 6-min walk distance, lower usual-paced 4-m walking velocity, and lower fast-paced 4-m walking velocity in non-PAD participants. Significant associations were also found in the density of strand break damage (i.e., damage per mtDNA copy) within ND1/2, ND4/5 and COII/ATPase 6/8 region with 6-min walk distance, usual-paced 4-m walking velocity and fast-paced 4-m walking velocity in non-PAD participants. Significant interactions were found between PAD presence vs. absence and density of strand break damage within ND1/2, ND4/5, COII/ATPase 6/8 regions for the associations with 6-min walk distance, usual-paced 4-m walking velocity, fast-paced 4-m walking velocity. Conversely, of the three walking performance measures only the usual-paced 4-m walking velocity showed a significant, although modest, negative association with the abundance of oxidized purines in the D-Loop (P = 0.031) and ND4/5 (P = 0.033) regions in the calf skeletal muscle of people with PAD. ConclusionOverall, these data suggest that the abundance of calf muscle mtDNA strand breaks and mtDNA4977 common deletion are not associated with walking performance in people with PAD and may not be directly involved in the pathophysiology of PAD. Conversely, strand breaks in specific mtDNA regions may contribute to poor walking performance in people without PAD. Further study is needed to confirm whether usual-paced 4-m walking velocity is associated significantly with a greater abundance of oxidized purines in the D-loop, a “mutational hotspot” for oxidative damage, and why this association may differ from the association with 6-min walk distance and fast-paced 4-m walking velocity.

Day-to-Day Variability of Walking Performance Measures in Individuals Poststroke and Individuals With Parkinson Disease

Improvement of walking performance is a primary goal for individuals poststroke or with Parkinson disease (PD) who receive physical therapy. More data about day-to-day variability of walking performance are critical for determining if changes in performance have occurred. Baseline assessments were utilized from an ongoing, observational, prospective cohort study including 84 individuals poststroke (n = 37) or with PD (n = 47) receiving outpatient physical therapy services to improve mobility. Participants wore step activity monitors for up to 7 days to measure walking performance (steps per day, walking duration, maximum 30-minute output, and peak activity index) in daily life. Correlation analyses evaluated relationships between both capacity and performance measures as well as the relationships between mean performance variables and day-to-day variability. Regression analyses explored factors that contribute to variability in day-to-day performance variables. Mean steps per day for participants poststroke (5376 ± 2804) and with PD (8149 ± 4490) were consistent with previously reported cohorts. Greater amounts of walking were related to more day-to-day variability, with moderate correlations found between the mean and day-to-day variability of each performance measure, regardless of medical diagnosis or walking speed. Day-to-day variability is large (upwards of 50% of the mean), with the amount of walking performance serving as the primary predictor of day-to-day variability in walking performance. The results of this study elucidate the factors that are related to and predict day-to-day variability of performance. Walking performance metrics should be evaluated over multiple days and greater variability should be anticipated with greater amounts of performance.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A319).

Differential deficits in spatial and temporal interlimb coordination during walking in persons with incomplete spinal cord injury

BackgroundReturning to community walking remains a major challenge for persons with incomplete spinal cord injury (iSCI) due, in part, to impaired interlimb coordination. Here, we examined spatial and temporal features of interlimb coordination during walking and their associations to gait deficits in persons with chronic iSCI. Research QuestionDo deficits in spatial and temporal interlimb coordination correspond differentially to clinical indicators of walking performance in persons with iSCI? MethodsSixteen persons with chronic iSCI and eleven able-bodied individuals participated in this study. Participants walked at self-selected gait speeds along an instrumented walkway that recorded left and right step lengths and times. We quantified interlimb coordination in terms of normalized differences between left and right step lengths (spatial asymmetry index) and step times (temporal asymmetry index), as well as, gap and phase coordination indices. We then assessed the extent to which these indices independently associated with clinical measures of walking performance. ResultsParticipants with iSCI demonstrated greater spatial and temporal asymmetry, as well as, reduced gap and phase interlimb coordination as compared to age-matched controls (p < 0.001). We found no linear relationships between spatial and temporal asymmetry indices (p > 0.05) or between gap and phase coordination indices (p > 0.05). Spatial and temporal asymmetry indices weakly correlated with SCI-FAI composite scores (r2 = 0.26; p = 0.04). However, only spatial asymmetry indices strongly correlated with slower walking speed (r2 = 0.51; p < 0.002). We also found participants who used a hand-held assistive device (walker) demonstrated great spatial asymmetry as compared to those who did not (p < 0.03). SignificanceDifferential impairments in spatial and temporal interlimb coordination correspond to overground walking deficits in persons with chronic iSCI. Spatial asymmetry associated with decreased walking speed and increased reliance on hand-held assistive devices. Gait training methods that target well-defined space and time domains of interlimb coordination may enhance overground gait training in persons with iSCI.

Longitudinal trajectories of physical activity and walking performance by gross motor function classification system level for children with cerebral palsy

Purpose: This study aims to present developmental trajectories for physical activity (PA) and walking performance for children with cerebral palsy (CP).Materials and methods: Seventy-nine children with CP, 39 (49%) female, Gross Motor Functional Classification System levels I–V, and mean age 91.3 months (+/−27.7 SD) participated. Participants in levels I–V wore the Actigraph to capture PA and children in levels I-II also wore a StepWatch (SW) (n = 43) to measure walking performance. Trajectories for average PA counts/minute and number of minutes of moderate to vigorous PA were generated for levels I, II, and III/IV/V (aggregate). Single leg strides/day and average strides faster than 30 strides/min trajectories were generated for levels I–II.Results: Participants did not display plateaus in PA or walking performance based on functional level. Children in all levels showed a decrease in amount and intensity of PA from 3.0 to 12 years old, with participants in level I demonstrating the steepest decline. Children in level I decreased slightly, and level II increased slightly in both walking performance measures from 3.0 to 12 years old.Conclusions: Longitudinal curves demonstrate variations in PA and walking performance by functional level and provide prognostic information as to what changes may be anticipated for children with CP.Implications for rehabilitationLongitudinal developmental trajectories for physical activity and walking performance for children with cerebral palsy across functional levels are documented.Trajectories have potential to support collaborative intervention planning between therapists and families relative to physical activity and walking performance.

Knee extension rate of velocity development affects walking performance differently in men and women.

Acceleration capacity affects physical function, but whether it differentially affects men versus women or weak versus strong individuals is less known. We investigated whether knee extension rate of velocity development (RVD, a measure of acceleration) is associated with walking performance independent of peak torque and whether the relationships differ in men versus women and in weak versus strong individuals. Relationships of RVD with walking performance were assessed in 326 women and 365 men aged 26-96 years enrolled in the Baltimore Longitudinal Study of Aging. Tests included knee extension peak torque and RVD assessed during a 180°·s-1 isokinetic strength test and four walking performance measures (usual-paced and fast-paced 6 m walks and 2.5 min usual-paced and 400 m fast-paced walks). Sex-stratified linear regression models were adjusted for age, race, height, appendicular lean mass, fat mass, peak torque, knee pain, and RVD*peak torque interaction. In men, RVD was not independently associated with any walking performance measure (p > 0.05), and, for the 6 m-usual walk only, there was a significant RVD*peak torque interaction (p < 0.0001). In women, RVD was independently associated with usual-paced walks (p < 0.05) and there were significant RVD ∗ peak torque interactions for all measures. Strength-specific analyses indicated that RVD was most associated with performance among weaker individuals. RVD is associated with walking performance in women, but less in men, and is most related to performance when strength is low. Strategies to accomplish motor tasks may be sex-specific. Future studies are needed to understand the mechanisms underlying such sex differences.

Associations of functional connectivity and walking performance in multiple sclerosis

BackgroundPersons with multiple sclerosis (MS) often demonstrate impaired walking performance, and neuroimaging methods such as resting state functional connectivity (RSFC) may support a link between central nervous system damage and disruptions in walking. ObjectivesThis study examined associations between RSFC in cortical networks and walking performance in persons with MS. Methods29 persons with MS underwent 3-T brain magnetic resonance imaging (MRI) and we computed RSFC among 68 Gy matter regions of interest in the brain. Participants completed the Timed 25-foot Walk as a measure of walking performance. We examined associations using partial Pearson product-moment correlation analyses (r), controlling for age. ResultsThere were eight cortical brain regions that were significantly associated with the T25FW, including the left parahippocampal gyrus and transverse temporal gyrus, and the right fusiform gyrus, inferior temporal gyrus, lingual gyrus, pericalcarine cortex, superior temporal gyrus, and transverse temporal gyrus. ConclusionsWe provide novel evidence that RSFC can be a valuable tool to monitor the motor and non-motor networks impacted in MS that relate to declines in motor impairment. RSFC may identify critical nodes involved in a range of motor tasks such as walking that can be more sensitive to disruption by MS.

Resistance Exercise Does Not Improve Habitual Physical Activity Despite Pain Relief

Osteoarthritis (OA) of the knee leads to physical disability and avoidance of activity. Resistance exercise can reduce pain and increase leg strength, but it is not yet clear how resistance exercise (RX) impacts habitual physical activity levels. PURPOSE: To determine whether resistance-exercise induced changes in physical function and pain relief are related to increased walking related function and habitual physical activity in older adults with knee OA. METHODS: Older adults (N=60; 69.0 ± 6.9 yr; 64% women) were randomized to a 4-month total body RX program or not. Knee pain was estimated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscore. One repetition maximum of leg strength (knee extension and leg press) and walking performance measures (walking speed, walking endurance during progressive treadmill test, 6-minute walk test distance) were collected pre and post-training. Daily step count and intensity of ambulatory activity was determined by a 7-day tracking of ambulation using a StepWatch©. RESULTS: Knee pain severity decreased by 27% in the RX group and increased by 13% by month 4. Leg extension and leg press strength increased from 17% to 22% and decreased by 4% in the control group (p<.05). Walking speed did not differ between the two groups from pre to post-training. Walking endurance treadmill time increased from 12.5 to 13.3 min in control and from 10.1 to 11.2 min in the RX group but these changes were not different between groups. Six-minute walk distance increased by 1.0-4.2% in the RX and control groups (p=.08). Pre-training average daily step counts were 5002 ± 2125 and 3601 ± 1181 in the CON and RX groups, respectively, and decreased by 614 and 356 steps a day by month 4. CONCLUSIONS: Despite pain reduction and strength gains with RX, walking-related functional indices and habitual activity levels were not impacted. Patients should be counseled that RX does not replace daily physical activity, but should be added to ambulatory activity. The importance of combining ambulatory activity and strengthening exercise to maximize possible functional improvements should be discussed.

Motor unit discharge characteristics and walking performance of individuals with multiple sclerosis.

Walking performance of persons with multiple sclerosis (MS) is strongly influenced by the activation signals received by lower leg muscles. We examined the associations between force steadiness and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions with tests of walking performance and disability status in individuals who self-reported walking difficulties due to MS. We expected that worse walking performance would be associated with weaker plantar flexor muscles, worse force steadiness, and slower motor unit discharge times. Twenty-three individuals with relapsing-remitting MS (56 ± 7 yr) participated in the study. Participants completed one to three evaluation sessions that involved two walking tests (25-ft walk and 6-min walk), a manual dexterity test (grooved pegboard), health-related questionnaires, and measurement of strength, force steadiness, and motor unit discharge characteristics of lower leg muscles. Multiple regression analyses were used to construct models to explain the variance in measures of walking performance. There were statistically significant differences (effect sizes: 0.21-0.60) between the three muscles in mean interspike interval (ISI) and ISI distributions during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. The regression models explained 40% of the variance in 6-min walk distance and 47% of the variance in 25-ft walk time with two or three variables that included mean ISI for one of the plantar flexor muscles, dorsiflexor strength, and force steadiness. Walking speed and endurance in persons with relapsing-remitting MS were reduced in individuals with longer ISIs, weaker dorsiflexors, and worse plantar flexor force steadiness. NEW & NOTEWORTHY The walking endurance and gait speed of persons with relapsing-remitting multiple sclerosis (MS) were worse in individuals who had weaker dorsiflexor muscles and greater force fluctuations and longer times between action potentials discharged by motor units in plantar flexor muscles during steady isometric contractions. These findings indicate that the control of motor unit activity in lower leg muscles of individuals with MS is associated with their walking ability.

Validation of the 2-Minute Walk Test with the 6-Minute Walk Test and Other Functional Measures in Persons with Multiple Sclerosis.

Persons with multiple sclerosis (MS) commonly have difficulty walking. The 6-Minute Walk Test (6MWT) assesses functional capacity but may be considered burdensome for persons with MS, especially those with higher disability levels. The 2-Minute Walk Test (2MWT) may be an alternative measure to the 6MWT. The purpose of this study was to investigate the validity of the 2MWT in persons with MS. Twenty-eight ambulatory persons with MS aged 18 to 64 years participated in this cross-sectional study. Participants completed five measures of walking performance (2MWT, 6MWT, usual and fast gait speed, and Timed Up and Go test) and two functional measures (Berg Balance Scale and five-times sit-to-stand test) during a testing session. Participants were classified into two subgroups based on Disease Steps scale classification. The 2MWT was significantly correlated with the 6MWT (r = 0.947), usual gait speed (r = 0.920), fast gait speed (r = 0.942), the Timed Up and Go test (r = -0.911), and other functional measures. The 2MWT explained 89% of the variance seen during the 6MWT. The distances completed on the 2MWT and 6MWT accurately distinguished the subgroups. This study demonstrated good construct and discriminant validity of the 2MWT in persons with MS, providing an efficient and practical alternative to the 6MWT. Validation of the 2MWT with other functional measures further supports these findings.

Real-World Walking Performance of Individuals with Lower-Limb Amputation Classified as Medicare Functional Classification Level 2 and 3

Introduction Lower-limb prostheses are prescribed based on each patient's individual needs. However, there is no standardized method to identify a patient's needs, which results in difficulty and variability in making prosthetic recommendations. Using measures of real-world walking performance in conjunction with clinical measures and the clinician's expertise may be an ideal way to ensure that patients receive the optimal prosthetic treatment. Currently, there is only limited understanding of the relationship among in-clinic performance-based measures, real-world walking performance, and K-level. Therefore, the purpose of this study was to investigate outcomes of in-clinic performance-based evaluations and real-world walking performance measures for individuals with unilateral lower-limb amputation classified as K2 and K3. Materials and Methods Twenty-seven individuals with unilateral lower-limb amputation classified as K2 or K3 functional levels underwent a clinical assessment visit that included a 10-m walk test and a 6-minute walk test. After the assessment, the individuals were equipped with an activity monitor, which they wore for a 7-day observation period. From these data, participants' self-selected walking speed, total distance walked in 6 minutes, total number of steps taken during the observation period, total number of active minutes during the observation period, and percentage of time spent in low-, moderate-, and high-intensity activity during the observation period were calculated. Results Individuals classified as K2 had, on average, a significantly slower self-selected walking speed, significantly shorter distance walked in 6 minutes, significantly lower total step count, and a significantly fewer number of active minutes when compared with those classified as K3. Although not significant, trends in activity intensity were seen with individuals classified as K2, spending a larger percentage of time in low-intensity activity and less percentage of time in high-intensity activity when compared with those classified as K3. Conclusions This study quantified real-world walking performance, in conjunction with in-clinic performance-based data, for individuals classified as K2 and K3 and showed significant differences between the 2 groups. This study is a step forward toward developing an objective and standardized method to classify an individual's functional ability and make prosthetic recommendations.

Utilization of the Expanded Disability Status Scale as a distinctive instrument forwalking impairment in persons with multiple sclerosis with mild disability.

The Expanded Disability Status Scale (EDSS) is a well-established clinical measure to assess disability in multiple sclerosis (MS). Gait dysfunction is primarily considered for scoring only above EDSS 3.5. However, the changes in functional systems in below EDSS 3.5 may result gait disturbances. To determine the distinctive ability of the EDSS 2.0 in terms of walking impairment as well as fatigue, depression, and quality of life in persons with MS with mild disability. All participants underwent the neurological examination for generating an EDSS score and completed the measures of walking performance, as well as other measures of fatigue, depression, and quality of life. The participants were divided into two groups according to the EDSS scores (i.e. EDSS <2.0 and 2.0-3.5). Participants with EDSS 2.0-3.5 had significantly worse walking performance, as well as fatigue, depression, and quality of life levels than the participants with EDSS <2.0 (p < 0.05). The EDSS significantly correlated with the measures of walking performance, as well as other measures of fatigue, depression, and quality of life. The EDSS 2.0 has a distinctive ability in terms of walking impairment as well as fatigue, depression, and quality of life.