Gait & Posture

2010-02-01

Editorial Board

2010-02-01

Evaluation of force plate-less estimation of the trajectory of the centre of pressure during gait. Comparison of two anthropometric models

Hélène Pillet, Xavier Bonnet, François Lavaste, Wafa Skalli — 2009-10-28

Abstract: The estimation of the trajectory of the centre of pressure during gait is possible without using force plate by modelling the whole body as a multi-segment chain. The kinematics and inertial parameters of each segment are necessary to determine the ground reaction forces and moments. The position of the centre of pressure can then be calculated at each frame of time. The objective of the study was to evaluate the accuracy of the estimation of the position of the centre of pressure during gait obtained without force plate data. Segment inertial parameters were determined using a proportional model and a geometric model. The modelling and calculations were computed for six volunteers and the estimated centres of pressure were compared to the centre of pressure measured using force plates considered as the gold standard. The estimation was better using the geometric model with an accuracy of 33mm (4.1% of the peak-to-peak amplitude) on the longitudinal axis and 14.2mm (12.9% of the peak-to-peak amplitude) on the lateral axis.

A comparison of subtalar joint motion during anticipated medial cutting turns and level walking using a multi-segment foot model

T.R. Jenkyn, R. Shultz, J.R. Giffin, T.B. Birmingham — 2009-11-09

Abstract: The weight-bearing in-vivo kinematics and kinetics of the talocrural joint, subtalar joint and joints of the foot were quantified using optical motion analysis. Twelve healthy subjects were studied during level walking and anticipated medial turns at self-selected pace. A multi-segment model of the foot using skin-mounted marker triads tracked four foot segments: the hindfoot, midfoot, lateral and medial forefoot. The lower leg and thigh were also tracked. Motion between each of the segments could occur in three degrees of rotational freedom, but only six inter-segmental motions were reported in this study: (1) talocrural dorsi-plantar-flexion, (2) subtalar inversion–eversion, (3) frontal plane hindfoot motion, (4) transverse plane hindfoot motion, (5) forefoot supination–pronation twisting and (6) the height-to-length ratio of the medial longitudinal arch.The motion at the subtalar joint during stance phase of walking (eversion then inversion) was reversed during a turning task (inversion then eversion). The external subtalar joint moment was also changed from a moderate eversion moment during walking to a larger inversion moment during the turn. The kinematics of the talocrural joint and the joints of the foot were similar between these two tasks.During a medial turn, the subtalar joint may act to maintain the motions in the foot and talocrural joint that occur during level walking. This is occurring despite the conspicuously different trajectory of the centre of mass of the body. This may allow the foot complex to maintain its function of energy absorption followed by energy return during stance phase that is best suited to level walking.

Reproducibility of energy cost of locomotion in ambulatory children with spina bifida

2009-10-30

Abstract: Objectives: Many ambulatory children with Spina Bifida (SB) experience functional decline in ambulation despite stable or even improving motor exams. Improving or maintaining low energy cost of locomotion during childhood and throughout the teenage years, could be an important goal for children and adolescents with SB. Purpose of this study was to determine reproducibility of energy expenditure measures during gait in ambulatory children with SB.Design: Reproducibility study.Setting: Child Development and Exercise Center of the University Children's Hospital in Utrecht, the Netherlands.Participants: Fourteen ambulatory children (6 boys/8 girls) with SB. Mean age was 10.8 years (±3.4).Interventions: Net and gross energy expenditure measures during locomotion were determined during a six-minute walking test. These measures consisted of energy consumption (ECS), expressed in J/kg/min, and energy cost (EC), expressed in J/kg/m. For reliability, the intra-class coefficient (ICC) was determined. For agreement, the smallest detectable difference (SDD) was calculated.Results: ICCs vary from 0.86 to 0.96 for both EC and ECS. The SDD ranges from 18–24% for gross measures, up to over 30% for net values.Conclusion: Reproducibility of energy expenditure during ambulation in children with SB should be considered carefully when using these measures in the evaluation of gait. High reliability of energy expenditure measurements makes these measurements appropriate to use as discriminative tools in children with SB, while agreement of only gross EC seems acceptable to use as a evaluative tool in children with SB. Overall, measures of reliability and agreement seem higher in young children when compared to adolescents. Further research is recommended to determine clinically relevant changes in energy expenditure in children with SB.

A novel method for determining ground-referenced contacts during stair ascent: Comparing relative hip position to quiet standing hip height

J.H.M. Bergmann, R.E. Mayagoitia, I.C.H. Smith — 2009-10-26

Abstract: Stair climbing can be measured using body-fixed sensors, whereby the origin and axes of the coordinate system are fixed with respect to the geometry of a body segment. These sensors can be part of a portable system, which provides the possibility to collect data in complex real-life environments. However due to the fact that the sensors are body-fixed, difficulties in determining the ground-based parameters of stair ascent can occur. The purpose of this study is to present a new approach for determining initial contacts based on a multi-chain biomechanical model combined with a new analysis method, in which relative hip height is compared to hip height during normal standing. Initial contacts obtained from the proposed method were compared to those obtained using an optical tracking device. An average absolute timing difference ranging from 0.04 (SD±0.03) to 0.06 (±0.03)s and a root mean square error ranging from 0.05 to 0.07s were found between the two techniques. This shows that the new approach presented in this study can be used to accurately determine initial contacts during stair ascent using portable equipment.

Executive dysfunction and attention contribute to gait interference in ‘off’ state Parkinson's Disease

Sue Lord, Lynn Rochester, Vicki Hetherington, Liesl M. Allcock, David Burn — 2009-11-06

Abstract: Motor and cognitive processes are required for successful ‘real world’ walking. We explored the specific contribution of motor function, executive function, and attention to functional gait performance in people with Parkinson's Disease (PD) when ‘off’ medication. Twenty-nine people with PD wearing an accelerometer were tested in their home whilst walking under four task conditions. Explanatory characteristics included age, motor function, executive function, sustained attention and divided attention. Repeated measures ANOVA compared gait speed under different task conditions. Multiple regression analysis explored the effect of characteristics on gait speed and gait interference (difference between dual and single task). Gait performance deteriorated under complex conditions (F=51.0, P<.001). Motor function and attention explained up to 65% variance in gait speed. Motor function, attention and executive function explained up to 66% variance in gait interference. Sustained attention explained up to 10% variance in gait speed; executive function explained up to 21% variance in gait interference and divided attention explained up to 22% variance in gait interference. Motor function, executive function and attention contribute to gait speed and gait interference in PD during a functional walking task whilst ‘off’ medication. When both executive function and attention are included as explanatory variables, attention discriminates gait performance more effectively. Whilst both contribute to functional gait, they are used selectively to optimise performance for different conditions and to meet complex task requirements.

Meaningful change in measures of gait variability in older adults

2009-11-04

Abstract: Objectives: Gait variability is an important indicator of impaired mobility in older adults; however, little is known about the meaning of change in gait variability over time. This study estimated clinically meaningful change in measures of gait variability using both distribution- and anchor-based approaches.Design: Community-based observational cohort study.Setting: Bronx County and the research center at Albert Einstein College of Medicine.Participants: Of 1148 participants in the Einstein Aging Study, 241 had quantitative gait assessments in two consecutive years between 2001 and 2005.Measurements: Gait variables were collected using a 12-foot instrumented walkway as participants walked at their normal walking speed. Gait variability was defined as the within-person standard deviation (SD) across steps in two 12-foot walks. Distribution-based meaningful change estimates used Cohen's effect size (0.2 for small and 0.5 for moderate effects). Anchor-based estimates were obtained using dichotomous and ordinal self-reported walking ability ratings as anchors.Results: Distribution-based estimates for small and substantial changes of variability measures were: stance time 0.005 and 0.014s; swing time 0.003 and 0.009s; step length 0.24 and 0.61cm; and step width 0.03 and 0.08cm. Among those reporting no change in walking ability, measures of gait variability were stable over 1 year. Among those reporting a decline in walking, stance time and swing time variability increased. Among those reporting an improvement in walking, only step length variability improved.Conclusion: Preliminary criteria for meaningful change are 0.01s for stance time and swing time variability and 0.25cm for step length variability. These estimates may identify important changes over time in both clinical settings and research studies.

Visuomotor adaptation of voluntary step initiation in older adults

Shih-Chiao Tseng, Steven J. Stanhope, Susanne M. Morton — 2009-11-04

Abstract: It has been suggested that feedforward planning of gait and posture is diminished in older adults. Motor adaptation is one mechanism by which feedforward commands can be updated or fine-tuned. Thus, if feedforward mechanisms are diminished in older adults, motor adaptation is also likely to be limited. The purpose of the study was to compare the ability of healthy older versus young adults in generating a voluntary stepping motor adaptation in response to a novel visual sensory perturbation. We recorded stepping movements from 18 healthy older and 18 young adults during baseline and adaptation stepping blocks. During baseline, the stepping target remained stationary; in adaptation, a visual perturbation was introduced by shifting the target laterally during mid-step. We compared adaptation between groups, measured by improvements in endpoint accuracy and movement duration. Older adults adapted stepping accuracy similarly to young adults (accuracy improvement: 29.7±27.6% vs. 37.3±22.9%, older vs. young group respectively, p=0.375), but showed significant slowness during movement. Thus older adults were able to achieve accuracy levels nearly equivalent to younger adults, but only at the expense of movement speed, at least during the early adaptation period (movement duration: 1143.7±170.6ms vs. 956.0±74.6ms, p<0.001). With practice, however, they were able to reduce movement times and gain speed and accuracy to levels similar to young adults. These findings suggest older adults may retain the ability for stepping adaptations to environmental changes or novel demands, given sufficient practice.

Speeding up gait initiation and gait-pattern with a startling stimulus

Ana Queralt, Josep Valls-Solé, Juan M. Castellote — 2009-11-16

Abstract: Human gait involves a repetitive leg motor pattern that emerges after gait initiation. While the automatic maintenance of the gait-pattern may be under the control of subcortical motor centres, gait initiation requires the voluntary launching of a different motor program. In this study, we sought to examine how the two motor programmes respond to an experimental manipulation of the timing of gait initiation. Subjects were instructed to start walking as soon as possible at the perception of an imperative signal (IS) that, in some interspersed trials was accompanied by a startling auditory stimulus (SAS). This method is known to shorten the latency for execution of the motor task under preparation. We reasoned that, if the two motor programmes were launched together, the gait-pattern sequence would respond to SAS in the same way as gait initiation. We recorded the gait phases and the electromyographic (EMG) activity of four muscles from the leg that initiates gait. In trials with SAS, latency of all gait initiation-related events showed a significant shortening and the bursts of EMG activity had higher amplitude and shorter duration than in trials without SAS. The events related to gait-pattern were also advanced but otherwise unchanged. The fact that all the effects of SAS were limited to gait initiation suggests that startle selectively can affect the neural structures involved in gait initiation. Additionally, the proportional advancement of the gait-pattern sequence to the end of gait initiation supports the view that gait initiation may actually trigger the inputs necessary for generating the gait-pattern sequence.

Perspectives for clinical measures of dynamic foot function—Reference data and methodological considerations

M.S. Rathleff, R.G. Nielsen, O. Simonsen, C.G. Olesen, U.G. Kersting — 2009-11-09

Abstract: Several studies have investigated if static posture assessments qualify to predict dynamic function of the foot showing diverse outcomes. However, it was suggested that dynamic measures may be better suited to predict foot-related overuse problems. The purpose of this study was to establish the reliability for dynamic measures of longitudinal arch angle (LAA) and navicular height (NH) and to examine to what extent static and dynamic measures thereof are related. Intra-rater reliability of LAA and NH measures was tested on a sample of 17 control subjects. Subsequently, 79 subjects were tested while walking on a treadmill. The ranges and minimum values for LAA and NH during ground contact were identified over 20 consecutive steps. A geometric error model was used to simulate effects of marker placement uncertainty and skin movement artifacts. Results demonstrated the highest reliability for the minimum NH (MinNH), followed by the minimum LAA (MinLAA), the dynamic range of navicular height (ΔNH) and the range of LAA (ΔLAA) while all measures were highly reliable. Marker location uncertainty and skin movement artifacts had the smallest effects on measures of NH. The use of an alignment device for marker placement was shown to reduce error ranges for NH measures. Therefore, ΔNH and MinNH were recommended for functional dynamic foot characterization in the sagittal plane. There is potential for such measures to be a suitable predictor for overuse injuries while being obtainable in clinical settings. Future research needs to include such dynamic but simple foot assessments in large-scale clinical studies.

Differentiation of young and older adult stair climbing gait using principal component analysis

Samantha M. Reid, Ryan B. Graham, Patrick A. Costigan — 2009-11-18

Abstract: Introduction: Principal component analysis (PCA) has been used to reduce the volume of gait data and can also be used to identify the differences between populations. This approach has not been used on stair climbing gait data. Our objective was to use PCA to compare the gait patterns between young and older adults during stair climbing.Methods: The knee joint mechanics of 30 healthy young adults (23.9±2.6 years) and 32 healthy older adults (65.5±5.2 years) were analyzed while they ascended a custom 4-step staircase. The three-dimensional net knee joint forces, moments, and angles were calculated using typical inverse dynamics. PCA models were created for the knee joint forces, moments and angles about the three axes. The principal component scores (PC scores) generated from the model were analyzed for group differences using independent samples t-tests. A stepwise discriminant procedure determined which principal components (PCs) were most successful in differentiating the two groups.Results: The number of PCs retained for analysis was chosen using a 90% trace criterion. Of the scores generated from the PCA models nine were statistically different (p<.0019) between the two groups, four of the nine PC scores could be used to correctly classify 95% of the original group.Conclusions: The PCA and discriminant function analysis applied in this investigation identified gait pattern differences between young and older adults. Identification of stair gait pattern differences between young and older adults could help in understanding age-related changes associated with the performance of the locomotor task of stair climbing.

Frontal plane alignment: An imageless method to predict the mechanical femoral–tibial angle (mFTA) based on functional determination of joint centres and axes

2009-11-18

Abstract: Lower limb alignment is important for the internal loading conditions in the knee. In this study, we aimed to evaluate a new imageless, non-invasive method for quantifying frontal plane alignment by direct comparison against CT. To determine the mechanical femoral–tibial angle (mFTA), functional posture analysis was performed in 15 limbs (13 individuals) using previously published methods for the minimisation of skin marker artefact together with the functional identification of joints, and compared against a published regression method.Whilst the average Functional-mFTA (1.3±2.3) was not significantly different (p>0.25) from the CT-mFTA (1.5±2.1), the Regression-mFTA (4.7±5.6) showed a significant error (p<0.01). The Functional-mFTA correlated significantly (R=0.91; p<0.0001), with a small bias (0.3°) and agreed better with the CT-mFTA than the Regression-mFTA (R=0.76; p<0.001), which had a bias of 3.4°. The results demonstrate that the mFTA can be quantified accurately using an imageless, non-invasive functional approach, which also offers greater accuracy over regression methods.These new techniques could provide an accurate, non-invasive approach for quantifying frontal plane alignment, particularly in cases where X-rays may not be available.

Kinematic analysis of the braking and propulsion phases during the support time in sprint running

Simone Ciacci, Rocco Di Michele, Franco Merni — 2009-11-19

Abstract: The contact time (CT) and the ratio between the duration of braking (BP) and propulsion phase (PP) during the support are two mechanical parameters that are relevant for the performance in sprinting. Several different kinematic methods have been used to estimate the BP–PP transition point, with some disagreements among studies. The purpose of this study was to compare three criteria to individuate that point: the maximum knee flexion (KNEEFLEX), the maximum fall of the COM (COMVERT) and the horizontal COM acceleration (COMHORIZ). It was hypothesized that these three events would take place in different instants, representing different moments of the step cycle. The kinematic analysis was performed through stereophotogrammetry on seven male middle-level sprinters (mean±SD height: 180±5 cm; body mass: 75±11 kg; personal best on 100m: 10.96±0.45s).The COMVERT expressed as percentage of CT (mean±SD 31.73±8.29%) was on average strongly anticipated compared to both KNEEFLEX (45.07±3.60%, p<0.01) and COMHORIZ (56.86±8.56%, p<0.01). The ∼12% difference between KNEEFLEX and COMHORIZ was also statistically significant (p<0.01). The 40–60% relative proportion of BP and PP considered to be optimal in the literature, was reflected in this study only by the KNEEFLEX criterion. Given the importance of BP time as a reference parameter to assess the training status and efficacy of training interventions, it looks necessary both from a scientific and applied perspective to consider a standardized criterion to identify the BP–PP transition point.

Salient and placebo vibrotactile feedback are equally effective in reducing sway in bilateral vestibular loss patients

Maurice Janssen, Robert Stokroos, Jos Aarts, Rob van Lummel, Herman Kingma — 2009-11-19

Abstract: This study explores the effect of vibrotactile biofeedback on body sway in stance in patients with severe bilateral vestibular losses in a placebo-controlled study. A tilt sensor mounted on the head or trunk is used to detect head or body tilt and activates via a microprocessor 12 small vibrators that are placed around the waist with a mutual distance of 30°. Two positions of the tilt sensor (head and trunk) and three types of biofeedback (normal, full and random) were evaluated, besides no biofeedback. Body sway during stance was assessed in 10 patients with bilateral vestibular areflexia and performance was scored in the seven different conditions. Inter-individual and test–retest variability without biofeedback was assessed in 10 additional patients with bilateral vestibular areflexia. In six patients no significant change in body swaypath was observed using biofeedback. In four patients body swaypath decreased significantly using biofeedback and sensor on the head in all three activation modes, whereas with sensor on the trunk only one patient showed a significant improvement in swaypath in all three activation modes. The patients rated the functionality of the AVBF system and its effect on balance on average 6.5 on a scale from 0 to 10. Thus, body sway improved in 4 out of 10 patients using biofeedback, but the improvement with true biofeedback was only observed in those subjects where an improvement was present in placebo mode as well. The improvement was, at least partially, caused by other effects than biofeedback, like training, increased self-confidence or alertness.

Sagittal plane bending moments acting on the lower leg during running

2009-11-18

Abstract: Sagittal bending moments acting on the lower leg during running may play a role in tibial stress fracture development. The purpose of this study was to evaluate these moments at nine equidistant points along the length of the lower leg (10% point–90% point) during running. Kinematic and ground reaction force data were collected for 20 male runners, who each performed 10 running trials. Inverse dynamics and musculoskeletal modelling techniques were used to estimate sagittal bending moments due to reaction forces and muscle contraction. The muscle moment was typically positive during stance, except at the most proximal location (10% point) on the lower leg. The reaction moment was predominantly negative throughout stance and greater in magnitude than the muscle moment. Hence, the net sagittal bending moment acting on the lower leg was principally negative (indicating tensile loads on the posterior tibia). Peak moments typically occurred around mid-stance, and were greater in magnitude at the distal, compared with proximal, lower leg. For example, the peak reaction moment at the most distal point was −9.61±2.07%Bw.Ht., and −2.73±1.18%Bw.Ht. at the most proximal point. These data suggest that tensile loads on the posterior tibia are likely to be higher toward the distal end of the bone. This finding may explain the higher incidence of stress fracture in the distal aspect of the tibia, observed by some authors. Stress fracture susceptibility will also be influenced by bone strength and this should also be accounted for in future studies.

Apparatus for monitoring load bearing rehabilitation exercises of a transfemoral amputee fitted with an osseointegrated fixation: A proof-of-concept study

2009-11-19

Abstract: The purpose of this proof-of-concept study was to determine the relevance of direct measurements to monitor the load applied on the osseointegrated fixation of transfemoral amputees during static load bearing exercises. The objectives were (A) to introduce an apparatus using a three-dimensional load transducer, (B) to present a range of derived information relevant to clinicians, (C) to report on the outcomes of a pilot study and (D) to compare the measurements from the transducer with those from the current method using a weighing scale. One transfemoral amputee fitted with an osseointegrated implant was asked to apply 10kg, 20kg, 40kg and 80kg on the fixation, using self-monitoring with the weighing scale. The loading was directly measured with a portable kinetic system including a six-channel transducer, external interface circuitry and a laptop. As the load prescribed increased from 10kg to 80kg, the forces and moments applied on and around the antero-posterior axis increased by four-fold anteriorly and 14-fold medially, respectively. The forces and moments applied on and around the medio-lateral axis increased by nine-fold laterally and 16-fold from anterior to posterior, respectively. The long axis of the fixation was overloaded and underloaded in 17% and 83% of the trials, respectively, by up to ±10%. This proof-of-concept study presents an apparatus that can be used by clinicians facing the challenge of improving basic knowledge on osseointegration, for the design of equipment for load bearing exercises and for rehabilitation programs.

Can people with Parkinson's disease improve dual tasking when walking?

Sandra G. Brauer, Meg E. Morris — 2009-12-07

Abstract: Background: Gait disorders in people with Parkinson's disease (PD) are accentuated when they perform another task simultaneously. This study examines whether practice enables people with PD to walk with large steps while performing added tasks, and to determine if training people with PD to walk with added working memory tasks leads to improvements in gait when walking and performing other tasks simultaneously.Methods: Walking patterns were recorded pre and post a 20min dual task training session in 20 people with PD. Participants performed a series of 10m walking trials under seven conditions: gait only, and with six different added tasks varying by task type (e.g. motor, cognitive), domain (e.g. postural, manual manipulation, language, calculation, auditory, visuospatial), and difficulty level. Dual task training aimed to improve step length while simultaneously undertaking a variety of language and counting working memory tasks that were different to those used in assessment.Results: Following training, step length increased when performing five of the six added tasks, indicating transfer of dual task training when walking occurred across task types and domains. Improvements in gait speed occurred in three of the six added tasks. When other gait variables were examined, such as step length variability, few improvements with training were found.Conclusions: Training can lead to larger steps when walking under dual task conditions in people with PD. The gait variable emphasised during dual task training appears to be an important factor in enabling the transfer of training improvements across tasks.

One year follow-up after operative ankle fractures: A prospective gait analysis study with a multi-segment foot model

2009-11-27

Abstract: Ankle fractures are one of the most common lower limb traumas. Several studies reported short- and long-term post-operative results, mainly determined by radiographic and subjective functional evaluations. Three-dimensional gait analysis with a multi-segment foot model was used in the current study to quantify the inter-segment foot motions in 18 patients 1 year after surgically treated ankle fractures. Data were compared to that from gender- and age-matched healthy controls. The correlations between Olerud/Molander ankle score and kinematics were also evaluated. Patients with ankle fractures showed less plantarflexion and smaller range of motion in the injured talocrural joint, which were believed to be a sign of residual joint stiffness after surgery and immobilization. Moreover, the forefoot segment had smaller sagittal and transverse ranges of motion, less plantarflexion and the hallux segment had less dorsiflexion and smaller sagittal range of motion. The deviations found in the forefoot segment may contribute to the compensation mechanisms of the injured ankle joint. Findings of our study show that gait analysis with a multi-segment foot model provides a quantitative and objective way to perform the dynamic assessment of post-operative ankle fractures, and makes it possible to better understand not only how the injured joint is affected, but also the surrounding joints.

Evaluation of gait symmetry after stroke: A comparison of current methods and recommendations for standardization

2009-11-23

Abstract: Symmetry is a gait characteristic that is increasingly measured and reported, particularly in the stroke patient population. However, there is no accepted standard for assessing symmetry making it difficult to compare across studies and establish criteria to guide clinical decision making. This study compares the most common expressions of spatiotemporal gait symmetry to describe post-stroke gait and makes recommendations regarding the most suitable measure for standardization. The following symmetry equations were compared: symmetry ratio, symmetry index, gait asymmetry and symmetry angle using step length, swing time, stance time, double support time and an intra-limb ratio of swing: stance time. Comparisons were made within a group of 161 community-dwelling, ambulatory individuals with stroke and 81 healthy adults as a reference group. Our analysis supports the recommendations of the symmetry ratio as the equation for standardization and step length, swing time and stance time as the gait parameters to be used in the equation. Future work should focus on establishing the intra-individual variability of these measures and linking them to mechanisms of gait dysfunction.

Continual use of augmented low-Dye taping increases arch height in standing but does not influence neuromotor control of gait

Melinda Franettovich, Andrew Chapman, Peter Blanch, Bill Vicenzino — 2009-11-30

Abstract: This study investigated the effect of continual use of augmented low-Dye (ALD) taping on neuromotor control of the lower limb during gait, as well as foot posture and mobility. Twenty-eight females were randomly allocated to wear ALD tape continuously or a no-tape control for a mean 12±2 days. Electromyographic activity from 12 lower limb muscles, three-dimensional motion at the ankle, knee, hip and pelvis (i.e., measures of neuromotor control) and foot posture and mobility was measured before and after the tape or control interventions. For the tape group, arch height ratio (=arch height/distance from heel to first metatarsophalangeal joint line) was greater by 0.006 (95% confidence interval: 0.0002–0.01, p=0.04) following the intervention period, whereas no change was observed for the control group (−0.003 (−0.01–0.004), p=0.36). The difference between groups (0.009 (0.0004–0.02), p=0.04) equated to a 0.16cm increase in arch height for the tape group following continual use of ALD tape. There was no change in neuromotor control of gait following continual use of ALD taping (p>0.05). Continual use of ALD tape for approximately 12 days produced a small change in foot posture, but no alteration in neuromotor control. Previous literature suggests that this increase in arch height is likely to be clinically relevant and may be one factor that contributes to the known efficiency of ALD tape in the treatment of lower extremity pain and injury.

Relationships between segmental foot mobility and plantar loading in individuals with and without diabetes and neuropathy

Smita Rao, Charles L. Saltzman, H. John Yack — 2009-11-19

Abstract: The purpose of our study was to examine dynamic foot function during gait as it relates to plantar loading in individuals with DM (diabetes mellitus and neuropathy) compared to matched control subjects. Foot mobility during gait was examined using a multi-segment kinematic model, and plantar loading was measured using a pedobarograph in subjects with DM (N=15), control subjects (N=15). Pearson product moment correlation was used to assess the relationship between variables of interest. Statistical significance and equality of correlations were assessed using approximate tests based on Fisher's Z transformation (α=0.05). In individuals with DM, first metatarsal sagittal plane excursion during gait was negatively associated with pressure time integral under the medial forefoot (r=−0.42 and −0.06, DM and Ctrl, P=0.02). Similarly, lateral forefoot sagittal plane excursion during gait was negatively associated with pressure time integral under the lateral forefoot (r=−0.56 and −0.11, DM and Ctrl, P=0.02). Frontal plane excursion of the calcaneus was negatively associated with medial (r=−0.57 and 0.12, DM and Ctrl, P<0.01) and lateral (r=−0.51 and 0.13, DM and Ctrl, P<0.01) heel and medial forefoot pressure time integral (r=−0.56 and −0.02, DM and Ctrl, P<0.01). The key findings of our study indicate that reductions in segmental foot mobility were accompanied by increases in local loading in subjects with DM. Reduction in frontal plane calcaneal mobility during walking serves as an important functional marker of loss of foot flexibility in subjects with DM.

Arm swing magnitude and asymmetry during gait in the early stages of Parkinson's disease

Michael D. Lewek, Roxanne Poole, Julia Johnson, Omar Halawa, Xuemei Huang — 2009-11-30

Abstract: The later stages of Parkinson's disease (PD) are characterized by altered gait patterns. Although decreased arm swing during gait is the most frequently reported motor dysfunction in individuals with PD, quantitative descriptions of gait in early PD have largely ignored upper extremity movements. This study was designed to perform a quantitative analysis of arm swing magnitude and asymmetry that might be useful in the assessment of early PD. Twelve individuals with early PD (in “off” state) and eight controls underwent gait analysis using an optically-based motion capture system. Participants were instructed to walk at normal and fast velocities, and then on heels (to minimize push-off). Arm swing was measured as the excursion of the wrist with respect to the pelvis. Arm swing magnitude for each arm, and inter-arm asymmetry, were compared between groups. Both groups had comparable gait velocities (p=0.61), and there was no significant difference between the groups in the magnitude of arm swing in all walking conditions for the arm that swung more (p=0.907) or less (p=0.080). Strikingly, the PD group showed significantly greater arm swing asymmetry (asymmetry angle: 13.9±7.9%) compared to the control group (asymmetry angle: 5.1±4.0%; p=0.003). Unlike arm swing magnitude, arm swing asymmetry unequivocally differs between people with early PD and controls. Such quantitative evaluation of arm swing, especially its asymmetry, may have utility for early and differential diagnosis, and for tracking disease progression in patients with later PD.

A novel tool for the assessment of dynamic balance in healthy individuals

Nejc Šarabon, Boštjan Mlaker, Goran Markovic — 2009-11-30

Abstract: The purpose of this study was to evaluate the intra- and inter-session reliability of a newly developed portable electronic balance measurement system (Clever Balance Board; CBB). In the first experiment, 36 male athletes performed three trials of the Sharpened-Romberg test, single limb stance test, and the CBB test in a randomized order. In the second experiment, eight physically active men and 12 women performed the CBB test in two sessions separated by 48h. The first experiment revealed a large trial-to-trial improvement for the Sharpened-Romberg test (46%) and single limb stance test (21%), while the same effect was relatively small for the three CBB scores (5–7%). The second experiment revealed a minimal improvement in the CBB scores between two sessions (0.6–2.3%). The observed intraclass correlation coefficients (ICC) and coefficients of variation (CV) suggested an acceptable retest correlation (ICC=0.85 and 0.76), but very large within-individual variation (CV=42.1% and 45.7%) of the Sharpened-Romberg test and the single limb stance test. Regarding the CBB scores, the corresponding retest correlation coefficients and within-individual variations were ICC=0.90–0.96 and CV=6.9–16.2%, respectively. Finally, inter-session reliability coefficients proved that the CBB scores had high retest correlation and an acceptable within-individual variation (ICC=0.77–0.90 and CV=8.4–13.9%). These results generally suggest that the CBB could be a reliable tool for dynamic balance assessment in healthy and physically active individuals.

Changes in standing postural control during acquisition of a sequential reaching task

Anne K. Galgon, Patricia A. Shewokis, Carole A. Tucker — 2009-12-04

Abstract: Postural control acquired during learning functional reaching movements has not been well examined. Fourteen healthy adults practiced a serial reaching task 300 times. Task acquisition was examined considering two types of action-goals : hand accuracy and consistency as the focal action-goals and control of equilibrium as the postural action-goal . Hand accuracy and consistency were measured as absolute constant error and variable error. Postural control was measured by time to boundary (TtB). Improvements were expected in the focal goals and postural goal; however the timing of improvements might reflect explicit and implicit learning processes. Practice effects resulted in improvements for hand task accuracy, consistency and an increase in TtB values. Changes in postural control may reflect improved efficiency or improved perception-action coupling by the postural system within task performance.

A body-fixed-sensor-based analysis of power during sit-to-stand movements

2009-12-07

Abstract: This study presents an analysis of power exertion for lifting the body's centre of mass (CoM) during rising from a chair. Five healthy young (21–44 years) and 12 healthy older (70–79 years) subjects performed sit-to-stand (STS) movements while data were measured with force-plates underneath chair and feet and motion sensors attached to different locations on the upper and lower trunk. Force-plate-data were used to determine the timing of STS movements and the vertical power for lifting the CoM from a sitting to a standing position. Data of three-dimensional hybrid motion sensors, consisting of accelerometers, gyroscopes and earth-magnetic-field sensors, were used to determine vertical accelerations and power. The comparison of sensor-based estimations of peak power with peak power calculated from force-plate-data demonstrated fair to excellent linear relationships for all sensor locations on the trunk. The best approximation of peak power was obtained by a weighted combination of data measured at different trunk locations. Results of the older subjects were consistent with those of the young subjects performing slow, normal and fast STS movements. The presented approach is relevant for monitoring fall risk and assessment of mobility in older people. Similar approaches for assessing power may be developed for other mobility related activities, such as stair walking, or sports related activities such as jumping.

Changes in hip joint muscle–tendon lengths with mode of locomotion

Patrick O. Riley, Jason Franz, Jay Dicharry, D. Casey Kerrigan — 2009-12-18

Abstract: We have reported that peak hip extension is nearly identical in walking and running, suggesting that anatomical constraints, such as flexor muscle tightness may limit the range of hip extension. To obtain a more mechanistic insight into mobility at the hip and pelvis we examined the lengths of the muscle–tendons units crossing the hip joint. Data defining the three-dimensional kinematics of 26 healthy runners at self-selected walking and running speeds were obtained. These data were used to scale and drive musculoskeletal models using OpenSIM. Muscle–tendon unit (MTU) lengths were calculated for the trailing limb illiacus, rectus femoris, gluteus maximus, and biceps femoris long head and the advancing limb biceps femoris and gluteus maximus. The magnitude and timing of MTU length peaks were each compared between walking and running. The peak length of the right (trailing limb) illiacus MTU, a pure hip flexor, was nearly identical between walking and running, while the maximum length of the rectus femoris MTU, a hip flexor and knee extensor, increased during running. The maximum length of the left (leading limb) biceps femoris was also unchanged between walking and running. Further, the timing of peak illiacus MTU length and peak contralateral biceps femoris MTU length occurred essentially simultaneously during running, at a time during gait when the hamstrings are most vulnerable to stretch injury. This latter finding suggests exploring the role for hip flexor stretching in combination with hamstring stretching to treat and/or prevent running related hamstring injury.

Effect of fatigue and hypohydration on gait characteristics during treadmill exercise in the heat while wearing firefighter thermal protective clothing

Pui W. Kong, Gillian Beauchamp, Joe Suyama, David Hostler — 2009-12-07

Abstract: This study compared the gait characteristics of individuals walking in heat while wearing firefighting equipment in fatigued and non-fatigued states. Nineteen subjects performed a 50-min treadmill protocol in a heated room while gait patterns were recorded using a digital video camcorder. Forty gait cycles were analyzed near the beginning (9min) and at the end (39–49min) of exercise. Spatio-temporal gait variables including step frequency, step length, swing time, stance time, cycle time and double-support time were determined. Gait variability was quantified by the standard deviation (SD) and coefficient of variation (CV) of each variable. Left–right symmetry was calculated using the symmetry index (SI) and symmetry angle (SA). Paired t-tests (α=0.05) were performed to identify difference between the beginning and the end of the protocol for each measured variable. Spatio-temporal gait characteristics did not differ between the beginning and the end of exercise. Gait variability of the double-support time increased at the end as measured by both SD (P=0.037) and CV (P=0.030) but no change was observed for other variables. Left–right symmetry measured using either SI or SA did not differ between sessions. In summary, spatio-temporal gait characteristics and symmetry while wearing firefighting equipment are insensitive to physiological fatigue. Prolonged walking in heat while wearing firefighting equipment may increase gait variability and therefore the likelihood of a fall. Future studies are needed to confirm the potential relationship between fatigue and gait variability and to investigate the possible influence of individual variation.

A functional axis based upper extremity model and associated calibration procedures

B.A. MacWilliams, M.C. Sardelli, R.Z. Tashjian — 2009-11-30

Abstract: An upper extremity model focusing on an accurate and complete description of elbow motion is introduced. Both glenohumeral center of rotation and functional elbow axes are computed and used for anatomical coordinate descriptions. Model results match goniometric measures of the flexed elbow and test–retest analyses of six subjects were repeatable within 5° for most measures. The elbow axis from 25 individuals was located about 12mm distal and anterior to the midpoint of the transepicondylar axis, placing it aligned with the center of the trochlea. Carrying angle of the elbow was determined to be 11° of abduction (valgus) with the arm extended.

Calculation of joint moments following foot contact across two force plates

Andrew Y.C. Wong, Morgan Sangeux, Richard Baker — 2009-12-14

Abstract: This study aimed to quantify the effect of combining the measurements from force plates when a subject's foot comes in contact with more than one force plate. A 3-Dimensional Gait Analysis (3DGA) was performed on a subject walking barefoot. Ten gait trials (good both) were captured where both subject's feet hit a single force plate. Then 20 gait trials (two force plates) were captured where either the right or left subject's foot was in contact with two force plates at a time. Kinematics were computed with VICON® Plugin Gait and kinetics with a BodyLanguage® (VICON, Oxford, UK) model that allowed the combination of force plate measurements. The kinetics traces from both sets of data were compared using variance component analysis. Results suggest that effects of how the moments were calculated were at most a third of those arising from stride to stride variability. This suggests that development of automated systems for determining foot contact coupled with arrays of more and smaller force plates than are commonly used might be useful to ensure the capture of good quality kinetic data in a wide range of patients.

Corrigendum to “The use of rubber foam pads and “sensory ratios” to reduce variability in static posturography assessment” [Gait Posture 29 (2009) 158–160]

2009-12-17

The authors regret the error introduced in the author field. The corrected author field appears above.