Gait & Posture

2012-01-01

Editorial Board

2012-01-01

The interdependency of peak pressure and pressure–time integral in pressure studies on diabetic footwear: No need to report both parameters

R. Waaijman, S.A. Bus — 2011-09-26

Highlights: ► Peak pressure (MPP) and peak pressure–time integral (PTI) may be interchangeable. ► We examined the interdependency of MPP and PTI in diabetic footwear. ► MPP and PTI are interdependent in diabetic patients wearing prescribed footwear. ► Interdependency is strongest in foot regions most prone to ulceration. ► The value of reporting PTI next to MPP in the same footwear study is small.Abstract: Background: In plantar pressure studies on diabetic footwear, both the maximum peak pressure (MPP) and peak pressure–time integral (PTI) are often reported. However, specific conclusions for each parameter are not commonly reported, suggesting these parameters may be interchangeable. The aim was to explore the interdependency of MPP and PTI in diabetic patients wearing different types of footwear.Methods: In-shoe plantar pressure was measured in 69 neuropathic diabetic patients who walked in custom made footwear, forefoot offloading shoes, cast shoes, and/or standard footwear. For each of six anatomical foot regions, correlation coefficients were calculated between MPP and PTI. To assess parameter congruency, the percentage of patients showing correlation coefficients >0.7 or coefficients of variation for both MPP and PTI <10%, was calculated.Results: Across all footwear conditions, MPP and PTI were highly correlated in the forefoot and midfoot (r>0.78 in all but one foot region in one footwear condition). Lower correlations coefficients were found in the rearfoot (r=0.43–0.45). Across regions, between 46% and 87% of patients (mean 72%) showed parameter congruency in the forefoot and midfoot.Conclusions: The results showed that the MPP and PTI are highly interdependent in those foot regions most at risk for plantar ulceration in patients wearing commonly prescribed footwear. Since MPP has been shown to date to be the clinically more relevant parameter of the two, these results suggest that the value of reporting PTI in addition to MPP in the same diabetic footwear study is small.

Strategies used during a challenging weighted walking task in healthy adults and individuals with knee osteoarthritis

Andrew J. Kubinski, Jill S. Higginson — 2011-10-03

Highlights: ► Healthy adults and those with knee OA walked at 1.0 m/s unweighted and with a weight vest. ► Healthy adults respond differently to weighted walking than individuals with knee OA. ► Weighted healthy group increases hip flexion at heel strike but knee OA does not. ► The knee OA group only made minor compensations during weighted walking.Abstract: Knee osteoarthritis (OA) is a disease that affects millions of people. While numerous gait differences have been identified between healthy adults and adults with knee OA under normal and challenging conditions, adults with knee OA have not been studied during a challenging weighted walking task. Investigation of the effect of weighted walking on the initial contact and loading response phases of gait was undertaken in 20 healthy and 20 knee OA subjects ages 40–85 years old walking at 1.0m/s while unweighted and weighted with 1/6th of their body weight in a weight vest. Subjects were grouped according to their Kellgren and Lawrence radiographic score and healthy subjects were age-matched to those with knee OA. ANOVA revealed significant effects for hip flexion angle at initial contact, step length, initial double support percent, and load rate. Post hoc t-tests revealed that subjects with knee OA had a larger initial double support percent and hip flexion angle at initial contact and a decreased load rate compared to unweighted, healthy adults. Also, both groups increased their initial double support percent in response to the challenging weighted walking task, but only the healthy adults increased their hip flexion angle at initial contact and decreased their load rate. During the weighted condition, the knee OA group had a shorter step length compared to the healthy group. Because the knee OA group only made minor compensations to their gait strategy, it appears that they may be unable or prefer not to adjust their gait mechanics due to underlying issues.

Postural sway during quiet standing is related to physiological tremor and muscle volume in young and elderly adults

Motoki Kouzaki, Kei Masani — 2011-08-22

Abstract: To examine the age-related deterioration in postural control, we investigated the association between postural sway during quiet standing and either amplitude of physiological tremor or muscle volume of the plantar flexors in 20 young and 20 elderly adults. They maintained a quiet standing position on a force platform for 60s with their eyes open or closed. During quiet standing, physiological tremors detected using a piezoresistive accelerometer were recorded from the soleus muscle, and the center of pressure (COP) displacement and body acceleration in the antero-posterior direction were calculated using the ground reaction forces as an assessment of postural sway. Muscle volume was predicted from muscle thickness by an ultrasonographic image. The physiological tremor of the soleus muscle during quiet standing was significantly greater in elderly than in young adults, and a positive association between physiological tremor and the amplitude of postural sway was found for young and elderly adults combined. Furthermore, physiological tremor was positively correlated with the high-frequency component of COP sway during quiet standing. A significantly negative relation between the muscle volume of the plantar flexors and postural sway was found in both age groups. These results suggest that physiological tremor reflects high-frequency fluctuations in postural sway during quiet standing in young and elderly adults, and age-related increases in the postural sway amplitude in the antero-posterior direction may be related to a decrease in muscle volume of the plantar flexors for maintaining an upright posture.

Concurrent validation of a magnetometer-based step counter in various walking surfaces

Estelle Raffin, Stéphane Bonnet, Pascal Giraux — 2011-09-26

Highlights: ► We develop a new quantitative gait assessment based on one shank magnetometer (MAG system). ► MAG system step counting is compared to two other step counting approaches. ► The three step counting are well correlated, especially in level-surface conditions. ► Our results demonstrate that the use of a single magnetometer is an accurate tool for step counting over varied surfaces.Abstract: Background and aim: Clinicians need a simple method for quantifying gait activity. The aim of this study was to develop and validate the reliability of a quantitative gait assessment based exclusively on one magnetometer located on the shank.Methods: Twenty-five healthy volunteers were simultaneously equipped with a magnetometer (MAG system) on the right shank, and two validated step-counter systems: the StepWatch Activity Monitor (SAM) and three Force-Sensing Resistors (FSRs). Volunteers performed a standard circuit including level walking, up and down stairs and up and down a slope. The three step counting approaches were compared using the Pearson correlation coefficient and the Bland–Altman method for each of the surface-types.Results: The step counts measured by the MAG and FSR were highly correlated for all the surfaces (r>.83). Congruently, the Bland–Altman analysis revealed an overall ±5% limit of agreement. The step counts measured by the MAG and SAM were also well correlated for the level-surface condition (r=.85), with a Bland–Altman ±5% limit of agreement but comparisons were less satisfying for the other surfaces.Conclusions: These results demonstrate that the use of a single magnetometer is an accurate tool for step counting over varied surfaces. These small sensors are easy to set up and to use and the signal processing is robust, making the MAG method highly applicable for clinical purposes, especially for the analysis of long walking periods in daily life conditions.

Is age or speed the predominant factor in the development of trunk movement in normally developing children?

Yvonne Thummerer, Rüdiger von Kries, Michael-Andor Marton, Andreas Beyerlein — 2011-08-26

Highlights: ► No systematic evaluation of the normal trunk movement development has yet been made. ► We analyzed data of n=85 healthy normal-walking children. ► Sagittal thorax and spine movement was found to be gradually associated with age. ► In contrast, frontal and transverse spine and pelvic movement depended mainly on speed. ► Age dependency has to be considered with respect to thorax and spine movements.Abstract: Background: Gait analysis is an increasingly used tool in the evaluation of neurological or orthopaedic problems in children. A good insight into age-related changes in normal paediatric gait is necessary to evaluate gait inefficiency caused by pathological walking patterns in children. However, no systematic evaluation of the normal development of trunk movement has yet been made.Methods: Data of n=85 healthy children were available. They were asked to walk at self selected speed. The gait data were measured with the Vicon Plug-In-Gait model, including the trunk. We assessed gait cycles of thorax, spine and pelvis in the sagittal, frontal and transverse plane, respectively, stratified by age (categories: <4, 4–6, 7–9, 10–12 and 13–16 years) as well as by normalized speed (≤0.40, 0.41–0.49, ≥0.50).Results: The sagittal thorax and spine movement was found to be gradually and significantly associated with age, but less so with speed, indicating that, with increasing age, children tend to lean their trunk forward relative to both the global co-ordinate system and the pelvis. In contrast, the frontal and transverse parameters of spine and pelvic movement seemed to depend mainly on speed, not age.Conclusion: Our study shows that age dependency has to be considered with respect to sagittal thorax and spine movements. This finding might be of great importance with respect to the identification of pathological patterns in trunk movement.

Adjustments after an ankle dorsiflexion perturbation during human running

M. Scohier, D. De Jaeger, B. Schepens — 2011-08-29

Abstract: In this study we investigated the effect of a mechanical perturbation of unexpected timing during human running. With the use of a powered exoskeleton, we evoked a dorsiflexion of the right ankle during its swing phase while subjects ran on a treadmill. The perturbation resulted in an increase of the right ankle dorsiflexion of at least 5°. The first two as well as the next five steps after the perturbation were analyzed to observe the possible immediate and late biomechanical adjustments. In all cases subjects continued to run after the perturbation. The immediate adjustments were the greatest and the most frequent when the delay between the right ankle perturbation and the subsequent right foot touch-down was the shortest. For example, the vertical impact peak force was strongly modified on the first step after the perturbations and this adjustment was correlated to a right ankle angle still clearly modified at touch-down. Some late adjustments were observed in the subsequent steps predominantly occurring during left steps. Subjects maintained the step length and the step period as constant as possible by adjusting other step parameters in order to avoid stumbling and continue running at the speed imposed by the treadmill. To our knowledge, our experiments are the first to investigate perturbations of unexpected timing during human running. The results show that humans have a time-dependent, adapted strategy to maintain their running pattern.

Kinematic strategies for walking across a destabilizing rock surface

2011-09-05

Abstract: It is important to understand how people adapt their gait when walking in real-world conditions with variable surface characteristics. This study quantified lower-extremity joint kinematics, estimated whole body center of mass height (COMVT), and minimum toe clearance (MTC) while 15 healthy, young subjects walked on level ground (LG) and a destabilizing loose rock surface (RS) at four controlled speeds. There were no significant differences in average step parameters (length, time, or width) between the walking surfaces. However, the variability of these parameters increased twofold on the RS compared to LG. When walking on the RS, subjects contacted the surface with a flatter foot and increased knee and hip flexion, which enabled them to lower COMVT. Subjects exhibited increased hip and knee flexion and ankle dorsiflexion during swing on the RS. These changes contributed to a 3.8 times greater MTC on the RS compared to LG. Peak hip and knee flexion during early stance and swing increased with walking speed, contributing to decreased COMVT and increased MTC. Overall, subjects systematically adapted their movement kinematics to overcome the challenge imposed by the destabilizing loose rock surface.

Functional correlates of gait and balance difficulty in essential tremor: Balance confidence, near misses and falls

Elan D. Louis, Ashwini K. Rao, Marina Gerbin — 2011-09-20

Highlights: ► We assessed balance confidence, falls and near misses in essential tremor cases. ► Balance confidence was lower in essential tremor cases than controls. ► Near misses in the past year were the highest in cases with head tremor. ► Essential tremor cases experience more functional gait difficulty than controls.Abstract: Background: Although a mild objective abnormality of gait and balance has been observed in essential tremor (ET) cases in research settings, the clinical significance of this finding for patients is far from clear. In this study, we assessed whether ET patients subjectively experience more gait difficulty, more falls or near misses than controls.Methods: Activities-specific Balance Confidence (ABC) scores were obtained in 59 ET cases (15 with head tremor and 44 without head tremor) and 82 controls enrolled in a clinical-epidemiological study.Results: ABC scores were lower in ET cases than controls (61.8±27.7 vs. 70.3±28.1, p=0.035) of similar age (71.2±14.6 years vs. 71. 6±0.8 years), indicating significantly lower balance confidence in cases. The lowest scores (51.4±26.9) were observed in cases with head tremor (p=0.02). Near misses in the past year were the highest in cases with head tremor (67.3±112.1) and lowest in controls (6.1±33.3, p=0.008). The proportion who had had ≥5 near misses or falls in the past year was 11 (13.4%) for controls, 8 (18.2%) for cases without head tremor and 6 (40.0%) for cases with head tremor (p=0.048). For the ABC score, we created a receiver operating curve (ROC) curve and optimal cut-off score to differentiate between our two most different groups, namely, ET with head tremor and controls. Using this cut-off (≤67), sensitivity and specificity were moderate.Conclusions: ET patients experience a loss of confidence in balance. The subgroup of patients with head tremor experienced the most gait and balance difficulty, with nearly one-in-two having had multiple near misses or falls during the previous year.

Recurrence quantification analysis of gait in normal and hypovestibular subjects

Francesca Sylos Labini, Annalisa Meli, Yuri P. Ivanenko, Davide Tufarelli — 2011-09-07

Abstract: The study of postural control processes during locomotion may provide useful outcome measures of stability for people with unilateral vestibular hypofunction (UVH). Since nonlinear analysis techniques can characterize complex behaviour of a system, this may highlight mechanisms underlying dynamic stability in locomotion, although only few efforts have been made. In particular, there have been no studies that use recurrence quantification analysis (RQA), which can be applied even to short and non-stationary data. The purpose of this study was to develop a new method for walking balance assessment measuring the complexity of head, trunk and pelvis three-dimensional accelerations and angular velocities during normal overground locomotion by means of RQA in normal subjects and UVH patients. The results showed differential effect of upper body parts on pattern regularity, with better head than pelvis stabilization in both groups of subjects. The RQA outputs such as percent determinism and recurrence were nevertheless significantly lower in the UVH group for all measures, suggesting that body accelerations and angular velocities, although not significantly different in amplitude, were more chaotic in patients. The observed lower regularity of upper body movements in UVH is consistent with an important role of the vestibular system in controlling dynamic stability during walking. The findings suggest that RQA can be used as a quantitative tool to assess walking performance and rehabilitation outcome in patients with different balance disorders.

Impact of stroke on anterior–posterior force generation prior to seat-off during sit-to-walk

2011-09-07

Highlights: ► Post-stroke, there is a risk of falling during transfers, such as sit-to-walk (STW). ► Force generation during STW was examined in a stroke and a control group. ► Intra- and interlimb dys-coordination was demonstrated in the stroke group. ► Further, substantial use of braking impulses post-stroke was found. ► These results are suggested to be important to consider in stroke rehabilitation.Abstract: Force generation during sit-to-walk (STW) post-stroke is a poorly studied area, although STW is a common daily transfer giving rise to a risk of falling in persons with disability. The purpose of this study was to describe and compare strategies for anterior–posterior (AP) force generation prior to seat-off during the STW transfer in both subjects with stroke and in matched controls.During STW at self-selected speed, AP force data were collected by 4 force plates, beneath the buttocks and feet from eight subjects with stroke (>6 months after onset) and 8 matched controls.Subjects with post-stroke hemiparesis and matched controls generated a similar magnitude of total AP force impulses (F1,71=0.67; p=0.42) beneath buttocks and feet prior to seat-off during STW. However, there were significant group differences in AP force impulse generation beneath the stance buttock (i.e. the non-paretic buttock in the stroke group), with longer duration (F1,71=8.78; p<0.005), larger net AP impulse (F1,71=6.76; p<0.05) and larger braking impulse (F1,71=7.24; p<0.05) in the stroke group. The total braking impulse beneath buttocks and feet was about 4.5 times larger in the stroke group than in the control group (F1,71=8.84; p<0.005).An intra- and inter-limb dys-coordination with substantial use of braking impulses was demonstrated in the stroke group. This motor strategy differed markedly from the smooth force interaction in the control group. These results might be important in the development of treatment models related to locomotion post-stroke.

Contralateral hip and knee gait biomechanics are unchanged by total hip replacement for unilateral hip osteoarthritis

Kharma C. Foucher, Markus A. Wimmer — 2011-09-07

Abstract: Both the hip and knee contralateral to a total hip replacement (THR) have an increased risk of osteoarthritis (OA) progression, and ultimate joint replacement. It is also known that abnormal gait contributes to OA progression. For these reasons, we conducted a longitudinal analysis of contralateral hip and knee gait during the first year after unilateral THR to determine whether abnormal contralateral gait biomechanics emerge after THR. We analyzed the sagittal plane dynamic range of motion and 3D peak external moments from the asymptomatic hip and knee contralateral to a THR in a group of 26 subjects, evaluated preoperatively, and 3, 12, 24, and 52 weeks after THR, and a group of control subjects. We used t-tests and repeated measures ANOVA to test the hypotheses that contralateral hip and knee gait parameters are normal preoperatively, but change after THR. Preoperatively, the contralateral hip abduction moment and the contralateral knee adduction, flexion, and external rotation moments were significantly higher than normal in the THR group (p≤0.048). Apart from the peak hip extension moment, which decreased three weeks after surgery but returned to its preoperative value thereafter, there were no longitudinal changes during the study period (p≥0.141). Preoperative gait abnormalities persisted postoperatively. Notably, the contralateral knee adduction moment was 32% higher than normal in the THR group. These results indicate a biomechanical basis for the increased contralateral OA risk after unilateral THR, and suggest that some patients may benefit from strategies to reduce loading on the contralateral limb.

Walking speed, unilateral leg loading, and step symmetry in young adults

Einat Kodesh, Michal Kafri, Gali Dar, Ruth Dickstein — 2011-09-07

Abstract: The purpose of this study was to examine the effects of gait speed and unilateral lower limb loading on step time and step length symmetry in healthy adults. Spatiotemporal gait data were collected from 22 healthy subjects (11 men, 11 women), using the GaitRite walkway, under four randomly sequenced test conditions: self-selected speed (SS), fast speed (F), self-selected speed with the right leg loaded (LSS), and the fastest attainable speed with the right leg loaded (LF). The symmetry index, calculated with the formula [((R−L)/0.5×(R+L))×100], was used to quantify step time and step length symmetry. It was found that over-ground gait speed had no significant effects on the symmetry of step time or step length. Unilateral lower limb loading significantly increased step time asymmetry, with longer step time for the loaded leg. Step symmetry was further compromised and became more asymmetrical when, in addition to unilateral leg loading, subjects maximized their gait speed. This effect of fast speed with unilateral leg loading was particularly prominent in relation to step length, with its shortening in the unloaded leg and lengthening in the loaded leg. These observations in healthy subjects may serve as a reference for the assessment of gait symmetry in patients with unilateral lower limb pathologies.

The effect of an exercise ball on trunk muscle responses to rapid limb movement

H. Weaver, D. Vichas, P.H. Strutton, I. Sorinola — 2011-11-03

Highlights: ► We determined the effect of an exercise ball on trunk muscles responses. ► Timing and magnitude of responses to rapid arm and leg movements was examined. ► Earlier and larger trunk muscles activation occurred with leg movements only. ► The results may have implication for stroke rehabilitation.Abstract: The use of exercise balls as an aid to facilitate improvements in posture in patients with trunk weakness is widely advocated. However, mechanisms underlying any effect on postural mechanisms have received little attention. This study compared the increases in trunk EMG activity in response to limb movement when seated on an exercise ball or on a chair in 16 healthy, moderately active subjects. At the sound of an auditory cue, the subjects carried out either hip flexion or arm flexion (unilateral or bilateral), as fast as possible, whilst sitting on an exercise ball or a standard chair. The amplitude of EMG activity was recorded from selected trunk muscles (erector spinae, external obliques, internal obliques and rectus abdominis) and either an upper limb muscle (deltoid) or a lower limb muscle (rectus femoris).There were minimal differences in amplitudes of EMG activity in any of the trunk muscles between the conditions (ball or chair) following the upper limb movements. These results suggest that there is no benefit in simple arm flexion movements whilst seated on the exercise ball in comparison to a chair. The onset and amplitude of the rectus abdominis (RA) and external obliques (EO) were significantly different between conditions in the hip flexion protocol. However, they do suggest significant benefit in decreasing RA and EO muscle activity onsets and increasing amplitude in the hip flexion condition. These results may have implications for rehabilitation of those with trunk muscle deficits such as stroke.

The effects of symmetric and asymmetric foot placements on sit-to-stand joint moments

Jason C. Gillette, Catherine A. Stevermer — 2011-09-05

Abstract: The purpose of this study was to determine the effects of symmetric and asymmetric foot placements on joint moments during sit-to-stand movements. Three symmetric (foot-neutral, foot-back, and foot-intermediate) and three asymmetric foot placements (preferred stagger, nonpreferred stagger, and intermediate stagger) were tested. Standard (46cm) and low (41cm) seat heights were chosen to represent an average public seat height and a 10% lower seat height. Using inverse dynamics, maximum ankle plantarflexion, knee extension, hip extension, and hip abduction moments were calculated. Hip extension moments were significantly increased when using foot-neutral as compared to foot-back. Ankle plantarflexion and knee extension moments were significantly increased when a foot was placed in the posterior position as compared to the anterior position for preferred and nonpreferred stagger. Knee extension moments were significantly increased at the low seat height as compared to the standard seat height. When shifting the feet anterior or posterior for symmetric placements during sit-to-stand, the most dramatic effect was an increase in hip extension moments when the feet are shifted anteriorly. Utilizing asymmetric foot placements during sit-to-stand produced increases in ankle plantarflexion and knee extension moments for the posteriorly placed limb, with reductions in the anteriorly placed limb.

Joint coordination in young and older adults during quiet stance: Effect of visual feedback of the center of pressure

Sandra Maria Sbeghen Ferreira Freitas, Marcos Duarte — 2011-10-03

Highlights: ► We investigated the body sway and joint coordination of young and older adults during quiet stance. ► The effect of the use of visual feedback of the center of pressure position was also investigated. ► The joint coordination variability was assessed by the uncontrolled manifold analysis. ► Young and older adults modified their joint coordination under the visual feedback condition. ► Body sway of older adults was more affected by the use of the visual feedback.Abstract: How aging affects body sway and joint coordination during quiet standing was investigated under two visual feedback conditions provided on a monitor screen: fixed and moving cursor representing the center of pressure (COP) position measured by a platform. The across-time joint motion variance of ankle, knee, hip, mid-trunk, and cervical spine leading to COP displacement was analyzed using the uncontrolled manifold approach. The body sway was assessed by the COP displacement. Young and older adults showed greater ankle joint contribution to COP displacement than the other joints. However, older adults showed larger variability of knee and mid-trunk joint motions than young adults. During the moving condition, the ankle joint contribution decreased and hip joint contribution increased for both groups, but the COP displacement increased only for the older adults. We conclude that joint coordination and body sway during quiet standing can be modified by providing COP visual feedback and that joint coordination is affected by aging.

The effects of muscle strength on center of pressure-based measures of postural sway in obese and heavy athletic individuals

2011-09-26

Highlights: ► A heavier and stronger athletic group swayed similarly to an obese sedentary group. ► Increased sway in heavy individuals is not related to lower muscular strength. ► Strength training for balance control is put into question for heavy individuals.Abstract: Introduction: Obesity affects postural sway during normal quiet standing; however, the reasons for the increased postural sway are unknown. Improving muscular strength is regarded as a potential way to improve postural control, particularly for obese and overweight subjects. The purpose of this investigation is to evaluate the role of muscular strength on postural sway in obese and overweight individuals.Methods: Fifteen healthy weight (control group), seventeen obese (obese group) subjects and nine football players (heavy athletic group) participated in this investigation. Isometric knee extension force and postural sway were measured. Muscular strength was calculated in absolute measures as well as relative to body mass (muscular strength to body mass).Results: The heavy athletic group demonstrated significantly stronger (absolute) lower limb strength (1593.9N (95% CI 1425.5, 1762.3)) than both the obese (796.2N (95% CI 673.8, 824.5)) and control (694.1N (95% CI 563.7, 824.5)) groups. As well, when muscular strength was expressed as a ratio to body mass the heavy athletic group had significantly higher values (1.27 (95% CI 1.11, 1.43)) than obese (0.78 (95% CI 0.66, 0.89) and control (1.00 (95% CI (0.88, 1.12)) individuals. Despite this, they swayed similarly to the obese (mean center of pressure speed of 0.83cms−1 (95% CI 0.72, 0.93) vs. 0.87cms−1 (95% CI 0.80, 0.95)), that is, significantly more than the controls (0.60cms−1 (95% CI 0.52, 0.68)).Conclusion: Isometric knee extensor strength has a minimal effect on postural sway in heavier athletic individuals during normal quiet stance.

Transitioning to a narrow path: The impact of fear of falling in older adults

2011-09-26

Abstract: Background: Everyday ambulation requires navigation of variable terrain, transitions from wide to narrow pathways, and avoiding obstacles. While the effect of age on the transition to a narrow path has been examined briefly, little is known about the impact of fear of falling on gait during the transition to a narrow path. The purpose was to examine the effect of age and fear of falling on gait during transition to a narrow path.Methods: In 31 young, mean age=25.3 years, and 30 older adults, mean age=79.6 years, step length, step time, step width and gait speed were examined during usual and transition to narrow pathway using an instrumented walkway.Findings: During the transition to narrow walk condition, fearful older adults compared to young had a wider step width (0.06m vs 0.04m) prior to the narrow path and took shorter steps (0.53m vs 0.72m; p<0.001). Compared to non-fearful older adults, fearful older adults walked slower and took shorter steps during narrow path walking (gait speed: 1.1m/s vs 0.82m/s; p=0.01; step length: 0.60m vs 0.47m; p=0.03). In young and non-fearful older adults narrow path gait was similar to usual gait. Whereas older adults who were fearful, walked slower (0.82m/s vs 0.91m/s; p=0.001) and took shorter steps (0.44m vs 0.53m; p=0.004) during narrow path walking compared to usual walking.Interpretation: Changes in gait characteristics with transitioning to a narrow pathway were greater for fear of falling than for age.

Gait assessment in mild cognitive impairment and Alzheimer's disease: The effect of dual-task challenges across the cognitive spectrum

2011-09-23

Highlights: ► We tested gait under single and dual-task conditions in adults with normal cognition, MCI, and AD. ► Single-task testing, walking at usual speed, did not distinguish between the three groups. ► Gait disturbances were present only in dual-task test conditions for MCI and AD. ► Gait disturbances in MCI were similar in magnitude to those seen in older adults with AD. ► We recommend dual-task gait testing to detect fall risk in all cognitively impaired older adults.Abstract: Gait impairment is a prominent falls risk factor and a prevalent feature among older adults with cognitive impairment. However, there is a lack of comparative studies on gait performance and fall risk covering the continuum from normal cognition through mild cognitive impairment (MCI) to Alzheimer's disease (AD). We evaluated gait performance and the response to dual-task challenges in older adults with AD, MCI and normal cognition without a history of falls. We hypothesized that, in older people without history of falls, gait performance will deteriorate across the cognitive spectrum with changes being more evident under dual-tasking. Gait was assessed using an electronic walkway under single and three dual-tasks conditions. Gait velocity and stride time variability were not significantly different between the three groups under the single-task condition. By contrast, significant differences of decreasing velocity (p<0.0001), increasing stride time (p=0.0057) and increasing stride time variability (p=0.0037) were found under dual-task testing for people with MCI and AD. Less automatic and more complex dual-task tests, such as naming animals and serial subtraction by sevens from 100, created the greatest deterioration of gait performance. Gait changes under dual-tasking for the MCI and AD groups were statistically different from the cognitively normal controls. Dual-task assessment exposed gait impairments not obvious under a single-task test condition and may facilitate falls risk identification in cognitively impaired persons without a history of falls.

Abnormal muscle activation during gait in diabetes patients with and without neuropathy

2011-11-18

Highlights: ► Abnormal muscle activation in diabetic and neuropathic subjects, comparison with controls. ► Lower limb muscle activation was acquired during gait through surface emg. ► Peak of envelope and its position within gait cycle, time and space parameters, were calculated. ► One-way Anova on both emg and gait time and space parameters. ► Statistically significant muscle alterations on non neuropathic subjects.Abstract: The World Health Organization warns that, in 2000, as many as 33 million Europeans suffered from diabetes, approximately 15% will likely develop foot ulcers, and approximately 15–20% of these patients will face lower-extremity amputation. Changes in some gait parameters that appear to be specific in diabetes have been identified in the literature: shorter stride length, reduced walking speed, and altered lower limb and trunk mobility. The present study aimed at evaluating the role of altered muscle activity in gait alterations of diabetic subjects with and without neuropathy. This study involved 50 subjects: 10 controls (BMI 24.4±2.8, age 61.2±5.07), 20 diabetics (BMI 26.4±2.5, age 56.53±13.29) and 20 neuropathics (BMI 26.8±3.4, age 61.2±7.7). The electrical activity of six muscles was collected bilaterally on the lower limb during gait: gluteus medius, rectus femoris, tibialis anterior, peroneous longus, gastrocnemius lateralis, and extensor digitorum communis. Electromyographic activity was represented through linear envelopes. Time and space parameters were also evaluated by means of two Bertec force plates and a six cameras motion capture system (BTS, 60–120Hz). At initial contact and loading response, an early peak of rectus femoris activity occurred in diabetic subjects with and without neuropathy. During midstance a delay of gastrocnemius activity was observed in diabetic non-neuropathic subjects. During terminal swing a delay of rectus femoris and gluteus medius activity was seen in diabetic non-neuropathic subjects’.The results suggest that important muscle activity deviations are present in diabetic subjects although these are not directly related to neuropathy.

Dynamic stability control during volitional stepping: A focus on the restabilisation phase at movement termination

Jonathan C. Singer, Stephen D. Prentice, William E. McIlroy — 2011-10-24

Highlights: ► We sought to advance understanding of stability control during voluntary stepping. ► Incongruity between peak and final centre of mass position was quantified. ► Incongruity occurred in all conditions, with a strong bias toward overshoot. ► Frontal plane overshoot magnitude was greater in trials with increased step width. ► Overshoot may be a strategy to simplify reactive control during restabilization.Abstract: This work sought to advance the understanding of dynamic stability control during stepping. The specific intention was to better understand the control of the centre of mass during voluntary stepping, by characterizing its trajectory and intertrial variability. Young participants (n=10) performed five different stepping tasks to vary the challenge to COM control: (1) preferred step, (2) long step, (3) wide step, (4) long and wide step and (5) rapid step. The trajectory of the total body COM during the restabilisation phase was assessed by quantifying the magnitude of incongruity between the peak and final COM position. The intertrial variability of incongruity and the extent to which incongruity was reduced with trial repetition were also evaluated. Interestingly, incongruity was typical during preferred stepping, with a strong bias toward overshoot. In the frontal plane, the magnitude of incongruity and the incidence of overshoot were greater in trials with increased step width. The variability of incongruity did not vary by condition nor was there evidence of adaptive changes. Together, these results suggest that overshoots may represent a strategy linked to gait initiation or to the simplification of reactive control during the restabilisation phase. Further insight into these mechanisms will be gained by examining the kinetic determinants of dynamic stability control.

Synergy of EMG patterns in gait as an objective measure of muscle selectivity in children with spastic cerebral palsy

Esther Zwaan, Jules G. Becher, Jaap Harlaar — 2011-09-19

Abstract: Selective motor control (SMC) is an important determinant of functioning in cerebral palsy (CP). Currently its assessment is based on subjective clinical tests with a low sensitivity. Electromyography (EMG) profiles during gait represent muscle coordination and might be used to assess SMC.EMG measurements during gait were processed into a measure of extensor synergy and thigh synergy. This was obtained in two groups of children with CP, and 30 typically developing children.Extensor synergy in CP was higher (0.95) than in healthy children (0.77), thigh synergy was almost equal in both groups. GMFM scores in the first group of 39 children with CP did not correlate to EMG based synergy measures. In a second group of 38 children with CP, a clear relation of clinical SMC score with extensor synergy was found, but only a weak relation with thigh synergy.Although an extensor synergy was validated at group level, our results present no convincing evidence for the use of EMG during gait to assess SMC in individual subjects with CP. Since gait involves both synergistic and selective contractions, the inherent motor control properties of this task will not allow for an assessment of selectivity comparable to the ability to perform isolated movements. Nevertheless, our results support the sensitive nature of EMG to represent an aberrant motor control in CP.

Arm swing asymmetry in Parkinson's disease measured with ultrasound based motion analysis during treadmill gait

J. Roggendorf, S. Chen, S. Baudrexel, S. van de Loo, C. Seifried, R. Hilker — 2011-09-30

Highlights: ► Limb motion during treadmill gait was analysed in early Parkinson's disease (PD). ► Patients had a highly significant increase of arm swing asymmetry versus controls. ► Reduced arm retroversion was also closely associated with disease status. ► Limb kinematics during gait reflect complex motor dysfunction in movement disorders.Abstract: The reduction of arm swing during gait is a frequent phenomenon in patients with early Parkinson's disease (PD). However, the objective quantification of this clinical sign using treadmill-based gait analysis has not been systematically evaluated so far.We simultaneously measured ultrasound based limb kinematics and spatiotemporal gait parameters during treadmill walking at different speeds in 21 early PD patients in Hoehn and Yahr (HY) stage I, 19 patients with bilateral PD in HY stage II and 25 age-matched controls.Both PD groups showed a highly significant reduction of the arm swing amplitude on the more affected body side (MAS). Decomposing total arm swing resulted in a bilateral decrease of arm retroversion in both PD groups, whereas anteversion was normal on the less affected side of the HY I cohort. Early stage patients exhibited a highly significant, almost threefold increase of the arm swing asymmetry index (IA) compared with controls. Reduced retroversion on the MAS and increased arm swing IA were the independent variables with the closest association to disease status in a multivariate logistic regression analysis.We conclude that ultrasound based motion analysis during treadmill walking allows reliable investigation of asymmetric arm movements in early PD patients which attenuate with ongoing disease. Impaired active arm retroversion seems to be the earliest sign of upper extremity dysfunction in parkinsonian gait. The measurement of limb kinematics during treadmill gait can broaden our methodological line-up for the analysis of complex motor programs in movement disorders.

Outdoor dynamic subject-specific evaluation of internal stresses in the residual limb: Hydraulic energy-stored prosthetic foot compared to conventional energy-stored prosthetic feet

Sigal Portnoy, Anat Kristal, Amit Gefen, Itzhak Siev-Ner — 2011-09-28

Highlights: ► We calculated internal stresses in the residuum of transtibial amputation patients. ► Subjects walked on various terrains with hydraulic or conventional prosthetic feet. ► We found a decrease in peak internal stress and loading rate, while walking with the hydraulic foot. ► The hydraulic foot may protect the distal tibial end of the residuum from pressure-related injury.Abstract: The prosthetic foot plays an important role in propelling, breaking, balancing and supporting body loads while the amputee ambulates on different grounds. It is therefore important to quantify the effect of the prosthetic foot mechanism on biomechanical parameters, in order to prevent pressure ulcers and deep tissue injury.Our aim was to monitor the internal stresses in the residuum of transtibial amputation (TTA) prosthetic-users ambulating on different terrains, which the amputees encounter during their daily activities, i.e. paved floor, grass, ascending and descending stairs and slope. We specifically aimed to compare between the internal stresses in the TTA residuum of amputees ambulating with a novel hydraulic prosthetic foot compared to conventional energy storage and return (ESR) prosthetic feet. Monitoring of internal stresses was accomplished using a portable subject-specific real-time internal stress monitor.We found significant decrease (p<0.01) in peak internal stresses and in the loading rate of the amputated limb, while walking with the hydraulic foot, compared to walking with ESR feet. The loading rate calculated while ambulating with the hydraulic foot was at least three times lower than the loading rate calculated while ambulating with the ESR foot. Although the average decrease in internal stresses was ∼2-fold larger when replacing single-toe ESR feet with the hydraulic foot than when replacing split-toed ESR feet with the hydraulic foot, the differences were statistically insignificant. Our findings suggest that using a hydraulic prosthetic foot may protect the distal tibial end of the TTA residuum from high stresses, therefore preventing pressure-related injury and pain.

Gait and cognition: The relationship between gait stability and variability with executive function in persons with and without dementia

Trienke IJmker, Claudine J.C. Lamoth — 2011-10-03

Highlights: ► The relation between executive function (EF) and gait variability in dual task gait. ► Differences between Alzheimer patients and old and younger controls. ► Dementia patients showed a less variable but more irregular gait pattern. ► Parameters of gait variability correlated with measures of executive function. ► Decreased EF might play a role in increased gait variability in dementia.Abstract: Besides cognitive decline, dementia is characterized by gait changes and increased fall risk, also in early stages of the disease. The aim of this study was to investigate differences in the relationship between executive function and gait variability and stability during single task and dual task walking in persons with and without dementia. The study sample consisted of three groups: fifteen dementia patients (aged 75–87), fourteen healthy elderly (aged 75–85), and twelve relatively younger elderly (aged 55–70). Participants underwent neuropsychological testing and tests of single and dual task walking while wearing an accelerometer. Outcome measures include stride related measures such as mean and coefficient of variation of stride time, and dynamic measures regarding the magnitude, smoothness, predictability and local stability of trunk accelerations. Patients with dementia exhibited a significantly (p .51) were found between executive tasks and gait parameters. In conclusion, these findings indicate that decreased executive function plays an important role in increased gait variability in dementia patients; a fact that should be considered when designing fall risk interventions for this population. Furthermore, results indicate that measures of gait variability and stability should be deemed worthwhile in the diagnosis of dementia.

Gait pattern classification in children with Charcot–Marie–Tooth disease type 1A

2011-09-23

Abstract: Gait pattern classification may assist in clinical decision making and cluster analysis (CA) has been often adopted to this aim. The goal of this study was to identify, through CA, typical walking patterns in a group of 21 young subjects with CMT1A, a hereditary progressive neuropathy, and to study possible correlation with the disease's clinical status. The protocol included kinematic/kinetic analysis of natural walking and more demanding locomotor tasks, i.e. toe- and heel-walking. Hierarchical cluster analysis was carried out on parameters related to primary signs (foot-drop and push-off deficit) and, separately, to compensatory mechanisms at proximal (pelvis, hip and knee) or distal (ankle) level.CA on primary signs during natural walking identified three clusters: (1) pseudo-normal patients (PN), not significantly different from controls; (2) patients showing only foot-drop (FD); (3) patients with foot-drop and push-off deficit (FD&POD). Patients belonging to the PN subgroup showed distal abnormalities during heel-walking. The FD&POD subgroup was associated to a significantly worse clinical score (CMTES, p<0.05). The main compensatory strategies, which occurred independently from primary clusterization, included augmented hip/knee flexion in swing (steppage) and early ankle plantarflexion at mid stance (vaulting). We concluded that, although a number of young CMT1A patients do not show typical primary deviations during natural walking, they do show significant abnormalities in more demanding locomotor tasks that should be therefore considered. It is also hypothesized that progression of this degenerative condition may be associated to the migration of patients to more severe clusters, with possible appearance of compensatory strategies.

An optimized Kalman filter for the estimate of trunk orientation from inertial sensors data during treadmill walking

Claudia Mazzà, Marco Donati, John McCamley, Pietro Picerno, Aurelio Cappozzo — 2011-11-03

Highlights: ► A Kalman filter for the estimate of trunk bending during walking using inertial sensor is proposed. ► Data were collected from 15 healthy subjects walking on a treadmill at slow, natural and fast speed. ► An optoelectronic system was used to assess the accuracy of the angles estimated by the filter. ► The proposed filter proved to be very robust and the angle estimation errors were lower than 1.0°.Abstract: The aim of this study was the fine tuning of a Kalman filter with the intent to provide optimal estimates of lower trunk orientation in the frontal and sagittal planes during treadmill walking at different speeds using measured linear acceleration and angular velocity components represented in a local system of reference.Data were simultaneously collected using both an inertial measurement unit (IMU) and a stereophotogrammetric system from three healthy subjects walking on a treadmill at natural, slow and fast speeds. These data were used to estimate the parameters of the Kalman filter that minimized the difference between the trunk orientations provided by the filter and those obtained through stereophotogrammetry. The optimized parameters were then used to process the data collected from a further 15 healthy subjects of both genders and different anthropometry performing the same walking tasks with the aim of determining the robustness of the filter set up.The filter proved to be very robust. The root mean square values of the differences between the angles estimated through the IMU and through stereophotogrammetry were lower than 1.0° and the correlation coefficients between the corresponding curves were greater than 0.91.The proposed filter design can be used to reliably estimate trunk lateral and frontal bending during walking from inertial sensor data. Further studies are needed to determine the filter parameters that are most suitable for other motor tasks.

The effects of grade and speed on leg muscle activations during walking

Jason R. Franz, Rodger Kram — 2011-10-03

Highlights: ► Leg muscle activities during level, uphill, and downhill walking at various speeds. ► Hip, knee, and ankle extensor muscle activities increase with steeper uphill grade. ► Only knee extensor muscle activities increase with steeper downhill grade. ► Changes in muscle activity with grade are more pronounced at faster walking speedsAbstract: Compared to level walking, additional muscle actions are required to raise and lower the center of mass during uphill and downhill walking, respectively. However, it remains unclear which muscle recruitment strategies are employed at typical grades when walking over a range of speeds. Based on previous reports, we hypothesized that, across a range of walking speeds, hip, knee, and ankle extensor muscle activations would increase with steeper uphill grade, but only knee extensor muscle activations would increase with steeper downhill grade. We also hypothesized that these changes in muscle activations with grade would become more pronounced at faster walking speeds. To test these hypotheses, 10 young adults (5M/5F) walked on a standard treadmill at seven grades (0°, ±3°, ±6°, and ±9°) and three speeds (0.75, 1.25, and 1.75ms−1). We quantified the stance phase electromyographic activities of the gluteus maximus (GMAX), biceps femoris (BF), rectus femoris (RF), vastus medialis (VM), medial gastrocnemius (MG), and soleus (SOL) muscles. On average, compared to level walking, hip (BF: 635%, GMAX: 345%), knee (RF: 165%, VM: 366%), and ankle (MG: 175%, SOL: 136%) extensor muscle activities increased to walk up 9°, but only knee (RF: 310%, VM: 246%) extensor muscle activities increased to walk down 9°. Further, these changes in muscle activations with grade became greater with faster walking speed. We conclude that people employ distinct uphill (hip, knee, and ankle extensors) and downhill (knee extensors) muscle recruitment strategies generally across walking speeds and progressively with steeper grade.

Spring-like Ankle Foot Orthoses reduce the energy cost of walking by taking over ankle work

D.J.J. Bregman, J. Harlaar, C.G.M. Meskers, V. de Groot — 2011-11-03

Highlights: ► The mechanical behavior of a spring-like AFO was studied in 10 patients. ► The spring-like AFO did not augment ankle push-off. ► The spring-like AFO took over part of the ankle work. ► The energy cost of walking was reduced with the spring-like AFO.Abstract: In patients with central neurological disorders, gait is often limited by a reduced ability to push off with the ankle. To overcome this reduced ankle push-off, energy-storing, spring-like carbon-composite Ankle Foot Orthoses (AFO) can be prescribed. It is expected that the energy returned by the AFO in late stance will support ankle push-off, and reduce the energy cost of walking.In 10 patients with multiple sclerosis and stroke the energy cost of walking, 3D kinematics, joint power, and joint work were measured during gait, with and without the AFO. The mechanical characteristics of the AFO were measured separately, and used to calculate the contribution of the AFO to the ankle kinetics.We found a significant decrease of 9.8% in energy cost of walking when walking with the AFO. With the AFO, the range of motion of the ankle was reduced by 12.3°, and the net work around the ankle was reduced by 29%. The total net work in the affected leg remained unchanged. The AFO accounted for 60% of the positive ankle work, which reduced the total amount of work performed by the leg by 11.1% when walking with the AFO.The decrease in energy cost when walking with a spring-like energy-storing AFO in central neurological patients is not induced by an augmented net ankle push-off, but by the AFO partially taking over ankle work.

Rapid force generation is impaired in cerebral palsy and is related to decreased muscle size and functional mobility

Noelle G. Moreau, Michael J. Falvo, Diane L. Damiano — 2011-09-19

Abstract: Limb movements involving contraction times of 50–200ms occur in many everyday activities, such as gait, which is faster than the time required to generate maximal force. Therefore, the ability to rapidly produce force may be even more important for the performance of functional activities. In this study rate of force development (RFD) and impulse of the knee extensors were examined in 12 ambulatory children with cerebral palsy (CP) (age: 11.9±2.9 years) and 11 with typical development (TD) (Age: 11.3±3.0 years). The relationship with muscle architecture and functional mobility was also determined. RFD and impulse were calculated during a maximal isometric knee extension contraction. Rectus femoris (RF) cross-sectional area and RF and vastus lateralis (VL) muscle thickness (MT), fascicle length (FL), and fascicle angle (FA) were measured using ultrasound imaging. Gait temporal–spatial parameters, Pediatric Outcomes Data Collection Instrument (PODCI), and Activities Scale for Kids performance version (ASKp) were collected. Although VL MT was the primary determinant of RFD and impulse in CP, FA and FL were also significant predictors in the TD group. RFD and impulse were significantly lower in CP compared to TD (70% decrease) in addition to maximal strength (50% decrease). RFD and impulse were predictive of measures of functional mobility, including gait, transfers, and sports and higher level activities but not temporal–spatial gait measures. Results suggest that the ability to rapidly generate torque may be of greater importance than maximal strength during certain tasks, such as transfers and sports and higher level activities.

Why does older adults’ balance become less stable when walking and performing a secondary task? Examination of attentional switching abilities

Teresa D. Hawkes, Ka-Chun Siu, Patima Silsupadol, Marjorie H. Woollacott — 2011-10-03

Highlights: ► Balance-impaired elders shift attention during dual-tasks less efficiently than healthy elders. ► Shifting attention is a component of executive attention function. ► We compared the performance of balance-impaired and healthy elders on a task switch test. ► Compared to healthy elders balance-impaired elders demonstrated deficits in task switch ability. ► The relationship between switch ability and gait should be further investigated in the elderly.Abstract: Previous research using dual-task paradigms indicates balance-impaired older adults (BIOAs) are less able to flexibly shift attentional focus between a cognitive and motor task than healthy older adults (HOA). Shifting attention is a component of executive function. Task switch tests assess executive attention function. This multivariate study asked if BIOAs demonstrate greater task switching deficits than HOAs. A group of 39 HOA (65–80 years) and BIOA (65–87 years) subjects performed a visuo-spatial task switch. A sub-group of subjects performed a dual-task obstacle avoidance paradigm. All participants completed the Berg Balance Scale (BBS) and Timed Up and Go (TUG). We assessed differences by group for: (1) visuo-spatial task switch reaction times (switch/no-switch), and performance on the BBS and TUG. Our balance groups differed significantly on BBS score (p<.001) and switch reaction time (p=.032), but not the TUG. This confirmed our hypothesis that neuromuscular and executive attention function differs between these two groups. For our BIOA sub-group, gait velocity correlated negatively with performance on the switch condition (p=.036). This suggests that BIOA efficiency of attentional allocation in dual task settings should be further explored.

Walking while talking: Investigation of alternate forms

Tamar C. Brandler, Mooyeon Oh-Park, Cuiling Wang, Roee Holtzer, Joe Verghese — 2011-09-26

Highlights: ► We tested alternate forms of the walking while talking (WWT) dual task. ► Four WWT trials with initial letter from beginning (a, b) or mid-alphabet (m, n). ► Differences between beginning and mid-alphabet trials but not shared points. ► Alternating between shared alphabet points on WWT trials reduces practice effects.Abstract: The aim of this study was to develop alternate forms of the walking while talking (WWT) dual task, and to determine whether beginning the WWT in mid-alphabet vs. at the beginning of the alphabet, affects task outcomes. Alternate test forms help reduce practice effects leading to more precise estimates of change over time. We conducted a cross-sectional study in 145 community-residing older adults (mean age, 79.2±6.8y) without dementia or depression. Subjects performed four WWT trials with a different initial letter (a, b, m or n). There were no differences in velocity, correct letters, or errors on WWT trials beginning at shared points in the alphabet (‘a’ compared to ‘b’ and ‘m’ compared to ‘n’). However, trials initiating with letters from the beginning of the alphabet compared to mid-alphabet showed significant differences (with higher number of correct letters and fewer errors for ‘a’ and ‘b’ trials) but not for velocity. Thus, starting WWT in mid-alphabet is different from starting at the beginning of the alphabet. Alternate forms of the WWT with two separate initial letters from a shared point of the alphabet (specifically ‘a’ and ‘b’ or ‘m’ and ‘n’) may be used upon repeated administration to reduce practice effects.

Test–retest reliability and descriptive statistics of geometric measurements based on plantar pressure measurements in a healthy population during gait

2011-09-14

Abstract: Previous studies have demonstrated that pressure, force, area, and time measurements can be reliably collected from pedobaragraphic platforms, but no studies have analyzed geometric measurements. The purpose of this study was to establish the test–retest reliability of geometric measurements obtained during gait at a self-selected speed using a two-step approach. Data were collected on both feet for 10 healthy participants using the emed-x platform. Reliability of 15 geometric measurements was assessed using intraclass correlation coefficients (ICC). All 15 measurements were demonstrated to be reliable (ICC>0.8), with 12 measurements ICC>0.90. Collection of geometric measurements at a self-selected pace with the emed-x platform was found to be reliable and can be used for investigation in research settings.

Relationships between motor function and gait-related dual-task interference after stroke: A pilot study

Prudence Plummer-D’Amato, Lori J.P. Altmann — 2011-09-30

Highlights: ► Slow walking speed is associated with greater dual-task costs on gait after stroke. ► Motor impairment severity is associated with increased dual-task interference. ► Paretic single limb stance is particularly vulnerable to dual-task interference.Abstract: The purpose of this pilot study was to examine the relationships between motor performance measures and dual-task interference in gait among community-dwelling adults with stroke. Dual-task costs on gait were correlated with Fugl-Meyer lower extremity score and usual gait speed in 13 community-dwelling adults with stroke. Individuals with greater lower extremity motor impairment and slower gait speed experienced greater cognitive-motor interference in gait. Paretic single limb stance was particularly susceptible to dual-task interference. Gait speed was only vulnerable to dual-task interference in the most complex dual-task. Thus, global characteristics of gait were vulnerable in the most difficult cognitive tasks, but even easy tasks impaired discrete components of dynamic balance.

Responsiveness of the single-limb stance test

Richard W. Bohannon — 2011-09-05

Responsiveness is a critical measurement property that has received less attention to date than other measurement properties such as reliability and validity. In a recent short communication in Gait and Posture Goldberg et al. provided information on the responsiveness of the single-limb stance test (SLST) . Specifically, they reported a minimum detectable change (MDC95) of 24.1s. While I do not doubt the veracity of their findings, the magnitude of the MDC95 that they report strikes me as large. I find it doubtful that many older adults would demonstrate such a large increase in stance time over the course of an effective rehabilitation intervention.

Reply to the comment “Responsiveness of the single-limb stance test”

Allon Goldberg, Allison Casby, Michelle Wasielewski — 2012-01-01

We thank Dr. Bohannon for his thoughtful comments on our recent Short Communication on single-leg-stance-time (SLST) in older adults. We wholeheartedly agree that responsiveness as a key measurement property has received insufficient study, providing the impetus for our investigation of minimum detectable change at the 95% confidence level (MDC95) of SLST.