Michiel Punt

Effect of arm swing strategy on local dynamic stability of human gait

INTRODUCTION Falling causes long term disability and can even lead to death. Most falls occur during gait. Therefore improving gait stability might be beneficial for people at risk of falling. Recently arm swing has been shown to influence gait stability. However at present it remains unknown which mode of arm swing creates the most stable gait. AIM To examine how different modes of arm swing affect gait stability. METHOD Ten healthy young male subjects volunteered for this study. All subjects walked with four different arm swing instructions at seven different gait speeds. The Xsens motion capture suit was used to capture gait kinematics. Basic gait parameters, variability and stability measures were calculated. RESULTS We found an increased stability in the medio-lateral direction with excessive arm swing in comparison to normal arm swing at all gait speeds. Moreover, excessive arm swing increased stability in the anterior-posterior and vertical direction at low gait speeds. Ipsilateral and inphase arm swing did not differ compared to a normal arm swing. DISCUSSION Excessive arm swing is a promising gait manipulation to improve local dynamic stability. For excessive arm swing in the ML direction there appears to be converging evidence. The effect of excessive arm swing on more clinically relevant groups like the more fall prone elderly or stroke survivors is worth further investigating. CONCLUSION Excessive arm swing significantly increases local dynamic stability of human gait.

Characteristics of daily life gait in fall and non fall-prone stroke survivors and controls

BackgroundFalls in stroke survivors can lead to serious injuries and medical costs. Fall risk in older adults can be predicted based on gait characteristics measured in daily life. Given the different gait patterns that stroke survivors exhibit it is unclear whether a similar fall-prediction model could be used in this group. Therefore the main purpose of this study was to examine whether fall-prediction models that have been used in older adults can also be used in a population of stroke survivors, or if modifications are needed, either in the cut-off values of such models, or in the gait characteristics of interest.MethodsThis study investigated gait characteristics by assessing accelerations of the lower back measured during seven consecutive days in 31 non fall-prone stroke survivors, 25 fall-prone stroke survivors, 20 neurologically intact fall-prone older adults and 30 non fall-prone older adults. We created a binary logistic regression model to assess the ability of predicting falls for each gait characteristic. We included health status and the interaction between health status (stroke survivors versus older adults) and gait characteristic in the model.ResultsWe found four significant interactions between gait characteristics and health status. Furthermore we found another four gait characteristics that had similar predictive capacity in both stroke survivors and older adults.ConclusionThe interactions between gait characteristics and health status indicate that gait characteristics are differently associated with fall history between stroke survivors and older adults. Thus specific models are needed to predict fall risk in stroke survivors.

Responses to gait perturbations in stroke survivors who prospectively experienced falls or no falls

BACKGROUND Steady-state gait characteristics appear promising as predictors of falls in stroke survivors. However, assessing how stroke survivors respond to actual gait perturbations may result in better fall predictions. We hypothesize that stroke survivors who fall have a diminished ability to adequately adjust gait characteristics after gait is perturbed. This study explored whether gait characteristics of perturbed gait differ between fallers and non fallers. METHOD Chronic stroke survivors were recruited by clinical therapy practices. Prospective falls were monitored over a six months follow up period. We used the Gait Real-time Analysis Interactive Lab (GRAIL, Motekforce Link B.V., Amsterdam) to assess gait. First we assessed gait characteristics during steady-state gait and second we examined gait responses after six types of gait perturbations. We assessed base of support gait characteristics and margins of stability in the forward and medio-lateral direction. FINDINGS Thirty eight stroke survivors complete our gait protocol. Fifteen stroke survivors experienced falls. All six gait perturbations resulted in a significant gait deviation. Forward stability was reduced in the fall group during the second step after a ipsilateral perturbation. INTERPRETATION Although stability was different between groups during a ipsilateral perturbation, it was caused by a secondary strategy to keep up with the belt speed, therefore, contrary to our hypothesis fallers group of stroke survivors have a preserved ability to cope with external gait perturbations as compared to non fallers. Yet, our sample size was limited and thereby, perhaps minor group differences were not revealed in the present study.

Clinimetric properties of a novel feedback device for assessing gait parameters in stroke survivors

IntroductionCommunity-dwelling stroke survivors tend to become less physically active over time. There is no ‘gold standard’ to measure walking activity in this population. Assessment of walking activity generally involves subjective or observer-rated instruments. Objective measuring with an activity monitor, however, gives more insight into actual walking activity. Although several activity monitors have been used in stroke patients, none of these include feedback about the actual walking activity. FESTA (FEedback to Stimulate Activity) determines number of steps, number of walking bouts, covered distance and ambulatory activity profiles over time and also provides feedback about the walking activity to the user and the therapist.AimTo examine the criterion validity and test-retest-reliability of the FESTA as a measure of walking activity in patients with chronic stroke. To target the properties of the measurement device itself and thus exclude effects of behavioral variability as much as possible evaluation was performed in standardized activities.MethodsCommunity-dwelling individuals with chronic stroke were tested twice with a test-retest interval varying from two days to two weeks. They performed a six-minute walk test and a standardized treadmill test at different speeds on both testing days. Walking activity was expressed in gait parameters: steps, mean-step-length and walking distance. Output data of the FESTA on the treadmill was compared with video analysis as the criterion measurement. Intraclass Correlations Coefficients (ICCs) and Mean Relative Root Squared Error (MRRSE) were calculated.ResultsThirty-three patients were tested to determine criterion validity, 27 patients of this group were tested twice for test-retest reliability. ICC values for validity and reliability were high, ranging from .841 to .972.ConclusionThis study demonstrated good criterion validity and test-retest-reliability of FESTA for measuring specific gait parameters in chronic stroke patients. FESTA is a valid and reliable tool for capturing walking activity measurements in stroke, and has applicability to both clinical practice and research.

Virtual obstacle crossing: Reliability and differences in stroke survivors who prospectively experienced falls or no falls

INTRODUCTION Stroke survivors often fall during walking. To reduce fall risk, gait testing and training with avoidance of virtual obstacles is gaining popularity. However, it is unknown whether and how virtual obstacle crossing is associated with fall risk. AIM The present study assessed whether obstacle crossing characteristics are reliable and assessed differences in stroke survivors who prospectively experienced falls or no falls. METHOD We recruited twenty-nine community dwelling chronic stroke survivors. Participants crossed five virtual obstacles with increasing lengths. After a break, the test was repeated to assess test-retest reliability. For each obstacle length and trial, we determined; success rate, leading limb preference, pre and post obstacle distance, margins of stability, toe clearance, and crossing step length and speed. Subsequently, fall incidence was monitored using a fall calendar and monthly phone calls over a six-month period. RESULTS Test-retest reliability was poor, but improved with increasing obstacle-length. Twelve participants reported at least one fall. No association of fall incidence with any of the obstacle crossing characteristics was found. DISCUSSION Given the absence of height of the virtual obstacles, obstacle avoidance may have been relatively easy, allowing participants to cross obstacles in multiple ways, increasing variability of crossing characteristics and reducing the association with fall risk. CONCLUSION These finding cast some doubt on current protocols for testing and training of obstacle avoidance in stroke rehabilitation.

Walking activity and its determinants in free-living ambulatory people in a chronic phase after stroke: a cross-sectional study

Abstract Background: Free-living walking activity and its contributing factors in ambulatory people with stroke is poorly investigated. Objective: Evaluating free-living walking activity and identifying factors associated with free-living walking activity. Methods: In this cross-sectional study, participants wore an accelerometer to measure their level of walking activity. They also completed the Berg Balance Scale (BBS) and the Timed Up and Go test for functional balance, the Falls Efficacy Scale, the 10-Metre Walk Test and the Geriatric Depression Scale to investigate the relation between the performance tests and walking activity. Results: The 38 analyzed participants were on average 62 (±11.4) years old and 66 (IQR 64.8) months post stroke. They took an average of 3048.3 ± 1983.1 steps, had 123.3 ± 61.3 walking bouts a day and walked for 32.5 ± 18.2 min a day. Their average speed was 90.3 ± 13.8 steps a minute. The multivariate linear analysis showed that the BBS was the only determinant that was significantly related to all outcomes, except walking bouts. Conclusion: Free-living walking activity levels in ambulatory people with chronic stroke are low. The BBS is an independent significant predictor of free-living walking activity. Implications for rehabilitation Free-living walking activity can be expressed in different outcomes measured by accelerometry. Free-living walking activity levels in ambulatory people with chronic stroke are low, therefore support to sustain walking in the own environment should be part of the rehabilitation program after stroke. Balance is an important related factor to free-living walking activity which needs attention during rehabilitation after stroke.