Preferred Gait Speed Research Articles

Gait characteristics, balance performance and falls in ambulant adults with cerebral palsy: An observational study

The relationship between spatiotemporal gait parameters, balance performance and falls history was investigated in ambulant adults with cerebral palsy (CP). Participants completed a single assessment of gait using an instrumented walkway at preferred and fast speeds, balance testing (Balance Evaluation Systems Test; BESTest), and reported falls history. Seventeen ambulatory adults with CP, mean age 37 years, participated. Gait speed was typically slow at both preferred and fast speeds (mean 0.97 and 1.21m/s, respectively), with short stride length and high cadence relative to speed. There was a significant, large positive relationship between preferred gait speed and BESTest total score (ρ=0.573; p<0.05) and fast gait speed and BESTest total score (ρ=0.647, p<0.01). The stride lengths of fallers at both preferred and fast speeds differed significantly from non-fallers (p=0.032 and p=0.025, respectively), with those with a prior history of falls taking shorter strides. Faster gait speed was associated with better performance on tests of anticipatory and postural response components of the BESTest, suggesting potential therapeutic training targets to address either gait speed or balance performance. Future exploration of the implications of slow walking speed and reduced stride length on falls and community engagement, and the potential prognostic value of stride length on identifying falls risk is recommended.

Local Dynamic Stability of the Knee is Maximal for Walking Overground at the Preferred Speed

While humans can walk at a range of speeds, they reveal a tendency to adopt a particular individual preferred gait speed. Given the preference for this speed, we may expect the movement trajectory to be more dynamically stable than faster or slower speeds. However, research on treadmill walking has found that local dynamic stability (quantified inversely as the maximum Lyapunov exponent, λMAX) increases with decreasing speed. Recent research on the stride frequency of overground walking suggests that use of a treadmill may have influenced these findings. Knowledge of the local dynamic stability of overground walking at different speeds promises to contribute to our understanding of the preferred gait speed of not only healthy individuals, but also those with movement disorders through aging or disease. PURPOSE: To determine the impact of gait speed on local dynamic stability of knee motion when walking overground. METHODS: The preferred gait speed of 12 young healthy adults was determined from each individual’s average speed of three walking trials across a GAITRite© instrumented mat. The task required walking 65 m overground in a straight line at 5 different target speeds of: 50, 75, 100, 125 and 150% of the preferred gait speed. Only trials performed within ±10% of each target gait speed were considered valid, and participants were required to complete 3 valid walking trials at each speed. Sagittal plane knee motion of both knees was measured using electrogoniometers. λMAX was quantified from each electrogoniometer time series. The relationship between λMAX and gait speed was statistically assessed using hierarchical linear modeling. RESULTS: Walking speed (s) had a large significant quadratic effect on λMAX for both knees, with minima at the preferred speed (right: λMAX = 0.00016s^2 - 0.033s + 2.75, p=.000, r^2 = .39; left: λMAX = 0.00013s^2 - 0.026s + 2.39, p= .000, r^2= .48). CONCLUSIONS: Walking overground at the preferred speed maximizes local dynamic stability (minimizes λMAX) of knee motion in gait. Walking at faster or slower speeds reduces local dynamic stability of the knee motion, which has been correlated with increased risk of falling.

Physical fitness training for stroke patients.

Levels of physical fitness are low after stroke. It is unknown whether improving physical fitness after stroke reduces disability. To determine whether fitness training after stroke reduces death, dependence, and disability and to assess the effects of training with regard to adverse events, risk factors, physical fitness, mobility, physical function, quality of life, mood, and cognitive function. Interventions to improve cognitive function have attracted increased attention after being identified as the highest rated research priority for life after stroke. Therefore we have added this class of outcomes to this updated review. We searched the Cochrane Stroke Group Trials Register (last searched February 2015), the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 1: searched February 2015), MEDLINE (1966 to February 2015), EMBASE (1980 to February 2015), CINAHL (1982 to February 2015), SPORTDiscus (1949 to February 2015), and five additional databases (February 2015). We also searched ongoing trials registers, handsearched relevant journals and conference proceedings, screened reference lists, and contacted experts in the field. Randomised trials comparing either cardiorespiratory training or resistance training, or both (mixed training), with usual care, no intervention, or a non-exercise intervention in stroke survivors. Two review authors independently selected trials, assessed quality and risk of bias, and extracted data. We analysed data using random-effects meta-analyses. Diverse outcome measures limited the intended analyses. We included 58 trials, involving 2797 participants, which comprised cardiorespiratory interventions (28 trials, 1408 participants), resistance interventions (13 trials, 432 participants), and mixed training interventions (17 trials, 957 participants). Thirteen deaths occurred before the end of the intervention and a further nine before the end of follow-up. No dependence data were reported. Diverse outcome measures restricted pooling of data. Global indices of disability show moderate improvement after cardiorespiratory training (standardised mean difference (SMD) 0.52, 95% confidence interval (CI) 0.19 to 0.84; P value = 0.002) and by a small amount after mixed training (SMD 0.26, 95% CI 0.04 to 0.49; P value = 0.02); benefits at follow-up (i.e. after training had stopped) were unclear. There were too few data to assess the effects of resistance training.Cardiorespiratory training involving walking improved maximum walking speed (mean difference (MD) 6.71 metres per minute, 95% CI 2.73 to 10.69), preferred gait speed (MD 4.28 metres per minute, 95% CI 1.71 to 6.84), and walking capacity (MD 30.29 metres in six minutes, 95% CI 16.19 to 44.39) at the end of the intervention. Mixed training, involving walking, increased preferred walking speed (MD 4.54 metres per minute, 95% CI 0.95 to 8.14), and walking capacity (MD 41.60 metres per six minutes, 95% CI 25.25 to 57.95). Balance scores improved slightly after mixed training (SMD 0.27, 95% CI 0.07 to 0.47). Some mobility benefits also persisted at the end of follow-up. The variability, quality of the included trials, and lack of data prevents conclusions about other outcomes and limits generalisability of the observed results. Cardiorespiratory training and, to a lesser extent, mixed training reduce disability during or after usual stroke care; this could be mediated by improved mobility and balance. There is sufficient evidence to incorporate cardiorespiratory and mixed training, involving walking, within post-stroke rehabilitation programmes to improve the speed and tolerance of walking; some improvement in balance could also occur. There is insufficient evidence to support the use of resistance training. The effects of training on death and dependence after stroke are still unclear but these outcomes are rarely observed in physical fitness training trials. Cognitive function is under-investigated despite being a key outcome of interest for patients. Further well-designed randomised trials are needed to determine the optimal exercise prescription and identify long-term benefits.

Visual afference mediates head and trunk stability in vestibular hypofunction

Humans must maintain head and trunk stability while walking. The purpose of this study was to compare the kinematics of healthy controls and patients with vestibular hypofunction (VH) when walking and making head rotations of different frequencies in both light and dark conditions. We recruited eight individuals with VH and nine healthy control subjects to perform four tasks at their preferred gait speed, being normal walk, walking and making yaw head rotations at 1.5Hz and 2Hz, and walking in the dark and making yaw head rotations at 1.5Hz. Linear kinematics as well as head, trunk, and pelvis angular velocities were captured using the Vicon motion analysis system (Vicon Motion Systems, Oxford, UK). We found no difference in walking velocities for any of the four walking conditions across groups. The lateral displacement of the center of mass was increased in VH patients. In the dark, patients had more head instability in pitch (larger amplitudes and velocities) even though they were walking and making active yaw head rotations. Patients also had a smaller relative phase angle (mean 3.50±standard deviation 2.13°) than controls (mean 10.31±standard deviation 2.70°) (p<0.01). Our data suggest that patients with VH have difficulty walking with a straight trajectory when turning their head. Additionally, patients with VH have an abnormal excursion of spontaneous pitch head rotation while walking and making active yaw head turns, which is dependent on vision. Rehabilitation for these patients should consider applying unique head rotation frequencies when training gait with head turns as well as alternating their exposure to light.

Regional neuromuscular regulation within human rectus femoris muscle during gait in young and elderly men

Recently, we demonstrated region-specific electromyography (EMG) responses along the rectus femoris (RF) muscle during gait in healthy young men (Watanabe et al., 2014b). For the RF muscle, regional EMG response should be tested to characterize neuromuscular control and/or to assess its dysfunction and/or pathology during gait. We aimed to identify spatial distribution of EMG pattern within the RF muscle in elderly during gait. Seven young men (age: 20.4±1.0 years) and 8 elderly men (age: 73.8±5.9 years) walked on treadmill with three different speed: slow (preferred −1km/h), preferred, and fast (preferred +1km/h). The spatial distribution of surface EMG was tested by central locus activation (CLA), which is calculated from 18 surface electrodes along the longitudinal line of the muscle. CLA were not different between the groups for slow and preferred gait speed (p>0.05) during a gait cycle. In fast gait speed, CLA at 80% of a gait cycle (swing phase) for the elderly were significantly located at more distal site than the young group (p<0.05) (13.0±2.1cm and 10.2±2.2cm from most proximal electrodes for the elderly and young). This difference in CLA reflected a significantly lower EMG activity at the proximal regions in the elderly group (p<0.05). These results suggest the elderly manifest characteristic regional EMG responses within the RF muscle for leg swing movement of fast speed gait.

What type, or combination of exercise can improve preferred gait speed in older adults? A meta-analysis.

BackgroundImproved preferred gait speed in older adults is associated with increased survival rates. There are inconsistent findings in clinical trials regarding effects of exercise on preferred gait speed, and heterogeneity in interventions in the current reviews and meta-analyses.Objective: to determine the meta-effects of different types or combinations of exercise interventions from randomized controlled trials on improvement in preferred gait speed.MethodsData sources: A literature search was performed; the following databases were searched for studies from 1990 up to 9 December 2013: PubMed, EMBASE, EBSCO (AMED, CINAHL, ERIC, Medline, PsycInfo, and SocINDEX), and the Cochrane Library.Study eligibility criteria: Randomized controlled trials of exercise interventions for older adults ≥ 65 years, that provided quantitative data (mean/SD) on preferred gait speed at baseline and post-intervention, as a primary or secondary outcome measure in the published article were included. Studies were excluded when the PEDro score was ≤4, or if participants were selected for a specific neurological or neurodegenerative disease, Chronic Obstructive Pulmonary Disease, cardiovascular disease, recent lower limb fractures, lower limb joint replacements, or severe cognitive impairments. The meta-effect is presented in Forest plots with 95 % confidenceStudy appraisal and synthesis methods: intervals and random weights assigned to each trial. Homogeneity and risk of publication bias were assessed.ResultsTwenty-five studies were analysed in this meta-analysis. Data from six types or combinations of exercise interventions were pooled into sub-analyses. First, there is a significant positive meta-effect of resistance training progressed to 70-80 % of 1RM on preferred gait speed of 0.13 [CI 95 % 0.09-0.16] m/s. The difference between intervention- and control groups shows a substantial meaningful change (>0.1 m/s). Secondly, a significant positive meta-effect of interventions with a rhythmic component on preferred gait speed of 0.07 [CI 95 % 0.03-0.10] m/s was found. Thirdly, there is a small significant positive meta-effect of progressive resistance training, combined with balance-, and endurance training of 0.05 [CI 95 % 0.00-0.09] m/s. The other sub-analyses show non-significant small positive meta-affects.ConclusionsProgressive resistance training with high intensities, is the most effective exercise modality for improving preferred gait speed. Sufficient muscle strength seems an important condition for improving preferred gait speed. The addition of balance-, and/or endurance training does not contribute to the significant positive effects of progressive resistance training. A promising component is exercise with a rhythmic component. Keeping time to music or rhythm possibly trains higher cognitive functions that are important for gait.Limitations: The focus of the present meta-analysis was at avoiding as much heterogeneity in exercise interventions. However heterogeneity in the research populations could not be completely avoided, there are probably differences in health status within different studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s12877-015-0061-9) contains supplementary material, which is available to authorized users.

Balance during walking on an inclined instrumented pathway following incomplete spinal cord injury.

To study the postural adaptations of subjects with incomplete spinal cord injury (iSCI) and non-injured subjects during overground walking on level and inclined surfaces. Six subjects with iSCI and seven non-injured subjects walked on an inclined surface (slope: 15%) and a level surface at their natural gait speed and at a slow gait speed (non-injured subjects only). Maximal stabilizing and minimal destabilizing forces were calculated to quantify dynamic balance during walking. Correlational analysis identified the variables that influence these stabilizing and destabilizing forces. Subjects with iSCI and good sensorimotor recovery were similar to non-injured subjects with respect to maximal stabilizing and minimal destabilizing forces when they walked at the same speed. The MaxSF was mainly explained by the center of pressure speed and step length, whereas the minimal destabilizing force was moderately correlated with body mass and height. The influence of gait speed on balance should be considered with a group comparison. With regard to dynamic balance, highly functioning subjects with iSCI do not seem to be sufficiently challenged while walking at their preferred gait speed. Asking individuals with subtle impairments to walk faster following an iSCI may reveal postural adaptations and have an effect on balance abilities.

Temporo-spatial gait parameters during street crossing conditions: A comparison between younger and older adults

Most traffic accidents involving pedestrians happen during street crossing. Safe street crossing by older adults requires complex planning and imposes high cognitive demands. Understanding how street crossing situations affect younger and older adults’ gait is important to create evidence-based policies, education and training. The objective of this study was to develop and test a method to evaluate temporo-spatial gait parameters of younger and older adults during simulated street crossing situations. Twenty-two younger (25±2 years old) and 22 older adults (73±6 years old) who lived independently in the community completed 3 walking trials at preferred gait speed and during simulated street crossing with regular and with reduced time. There were significant differences between groups (p<0.001) and conditions (p<0.001). Older adults’ street crossing walking speed was higher than their preferred speed (p<0.001). Gait during simulated street crossing resulted in significant and progressive gait changes. The methods developed and tested can be used to (1) evaluate if people are at risk of falls and accidents during street crossing situations, (2) to compare among different groups, and (3) to help establish appropriate times for older pedestrians to cross streets safely. The current time to cross streets is too short even for healthy older adults.

Slow gait speed - an indicator of lower cerebral vasoreactivity in type 2 diabetes mellitus.

Objective: Gait speed is an important predictor of health that is negatively affected by aging and type 2 diabetes. Diabetes has been linked to reduced vasoreactivity, i.e., the capacity to regulate cerebral blood flow in response to CO2 challenges. This study aimed to determine the relationship between cerebral vasoreactivity and gait speed in older adults with and without diabetes.Research design and methods: We studied 61 adults with diabetes (65 ± 8 years) and 67 without diabetes (67 ± 9 years) but with similar distribution of cardiovascular risk factors. Preferred gait speed was calculated from a 75 m walk. Global and regional perfusion, vasoreactivity and vasodilation reserve were measured using 3-D continuous arterial spin labeling MRI at 3 Tesla during normo-, hyper- and hypocapnia and normalized for end-tidal CO2.Results: Diabetic participants had slower gait speed as compared to non-diabetic participants (1.05 ± 0.15 m/s vs. 1.14 ± 0.14 m/s, p < 0.001). Lower global vasoreactivity (r2adj = 0.13, p = 0.007), or lower global vasodilation reserve (r2adj = 0.33, p < 0.001), was associated with slower walking in the diabetic group independently of age, BMI and hematocrit concentration. For every 1 mL/100 g/min/mmHg less vasodilation reserve, for example, gait speed was 0.05 m/s slower. Similar relationships between vasodilation reserve and gait speed were also observed regionally within the cerebellum, frontal, temporal, parietal, and occipital lobes (r2adj = 0.27–0.33, p < 0.0001). In contrast, vasoreactivity outcomes were not associated with walking speed in non-diabetic participants, despite similar vasoreactivity ranges across groups.Conclusion: In the diabetic group only, lower global vasoreactivity was associated with slower walking speed. Slower walking in older diabetic adults may thus hallmark reduced vasomotor reserve and thus the inability to increase perfusion in response to greater metabolic demands during walking.

Mobility and cognition: End points for dietary interventions in aging

BACKGROUND: Healthy aging is associated with functional declines in mobility and cognition among both humans and non-human animals. OBJECTIVE: This study combines human measures of mobility and cognition to develop a test battery for evaluating the effects of dietary supplements among older adults. Selected measures parallel behavior tasks used to assess the efficacy of dietary interventions in rodent models of aging. METHODS: Seventy six healthy adults, between the ages of 21 and 75, completed a 1 hour mobility and cognition assessment. Postural sway and spatiotemporal gait parameters were measured using a Zebris ™ instrumented treadmill system. A computerbased virtual water maze and the trail-making test were used to assess spatial memory and executive function, respectively. RESULTS: Sway velocity during quiet standing increased with age. Preferred gait speed declined with age and changes in the gait cycle reveal an age-related increase in total double support during normal walking. In the virtual water maze, latency to locate a hidden or visible platform increased with age; meanwhile, probe test performance declined with age. CONCLUSIONS: Healthy adults show age-related declines in measures of mobility and cognition. These measures are a useful tool for translating research on dietary interventions to older adults.

Physical fitness training for stroke patients.

Levels of physical fitness are low after stroke. It is unknown whether improving physical fitness after stroke reduces disability. To determine whether fitness training after stroke reduces death, dependence, and disability. The secondary aims were to determine the effects of training on physical fitness, mobility, physical function, quality of life, mood, and incidence of adverse events. We searched the Cochrane Stroke Group Trials Register (last searched January 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 12: searched January 2013), MEDLINE (1966 to January 2013), EMBASE (1980 to January 2013), CINAHL (1982 to January 2013), SPORTDiscus (1949 to January 2013), and five additional databases (January 2013). We also searched ongoing trials registers, handsearched relevant journals and conference proceedings, screened reference lists, and contacted experts in the field. Randomised trials comparing either cardiorespiratory training or resistance training, or both, with no intervention, a non-exercise intervention, or usual care in stroke survivors. Two review authors independently selected trials, assessed quality, and extracted data. We analysed data using random-effects meta-analyses. Diverse outcome measures limited the intended analyses. We included 45 trials, involving 2188 participants, which comprised cardiorespiratory (22 trials, 995 participants), resistance (eight trials, 275 participants), and mixed training interventions (15 trials, 918 participants). Nine deaths occurred before the end of the intervention and a further seven at the end of follow-up. No dependence data were reported. Diverse outcome measures made data pooling difficult. Global indices of disability show a tendency to improve after cardiorespiratory training (standardised mean difference (SMD) 0.37, 95% confidence interval (CI) 0.10 to 0.64; P = 0.007); benefits at follow-up and after mixed training were unclear. There were insufficient data to assess the effects of resistance training.Cardiorespiratory training involving walking improved maximum walking speed (mean difference (MD) 7.37 metres per minute, 95% CI 3.70 to 11.03), preferred gait speed (MD 4.63 metres per minute, 95% CI 1.84 to 7.43), walking capacity (MD 26.99 metres per six minutes, 95% CI 9.13 to 44.84), and Berg Balance scores (MD 3.14, 95% CI 0.56 to 5.73) at the end of the intervention. Mixed training, involving walking, increased preferred walking speed (MD 4.54 metres per minute, 95% CI 0.95 to 8.14), walking capacity (MD 41.60 metres per six minutes, 95% CI 25.25 to 57.95), and also pooled balance scores but the evidence is weaker (SMD 0.26 95% CI 0.04 to, 0.49). Some mobility benefits also persisted at the end of follow-up. The variability and trial quality hampered the assessment of the reliability and generalisability of the observed results. The effects of training on death and dependence after stroke are unclear. Cardiorespiratory training reduces disability after stroke and this may be mediated by improved mobility and balance. There is sufficient evidence to incorporate cardiorespiratory and mixed training, involving walking, within post-stroke rehabilitation programs to improve the speed and tolerance of walking; improvement in balance may also occur. There is insufficient evidence to support the use of resistance training. Further well-designed trials are needed to determine the optimal content of the exercise prescription and identify long-term benefits.

Test–retest reliability of three dimensional gait analysis: Including a novel approach to visualising agreement of gait cycle waveforms with Bland and Altman plots

Background/AimEstimating the measurement error (reliability) of three dimensional gait analysis (3DGA) is crucial to interpretation of gait data. The purpose of this study was to investigate the intra-rater reliability of 3DGA and apply a novel method of visualising reliability of gait cycle waveforms. MethodsA test re-test design was employed. A convenience sample of 30 healthy adults (18F; 12M: mean age 30±6.8 years) participated. Subjects walked along a 10m walkway at their preferred gait speed and 3DGA data were collected using a VICON® 3DGA system. Testing was performed by the same investigator on two separate days within two weeks. Data from 10 trials were averaged and analysed. AnalysisThe intraclass correlation coefficient (ICC), the standard error of measurement (SEM), minimal detectable change (MDC) and limits of agreement were calculated for kinetic and kinematic data. Bland and Altman plots were applied to gait cycle waveforms. ResultsSpatio-temporal parameters such as cadence, step length, velocity, step time and step width were highly repeatable generating ICC's of 0.90 and above and low SEM/MDC. Range of joint movement across the gait cycle was generally more reliable than either minimum or maximum values and higher ICCs were obtained for movement in the sagittal plane. For kinematic data the standard error of measurement was low (≤5̊) for the majority of parameters. Transverse plane measurements showed poor reliablility with lowest ICC's. ICCs for kinetic data ranged from 0.51 to 0.81. ConclusionsReliability of 3DGA has been estimated for our gait laboratory. Bland and Altman plots of gait cycle waveforms provide a useful addition to reliability analysis.

Preliminary Trial of Postural Strategy Training Using a Personal Transport Assistance Robot for Patients With Central Nervous System Disorder

ObjectiveTo examine the efficacy of postural strategy training using a personal transport assistance robot (PTAR) for patients with central nervous system disorders. DesignSingle-group intervention trial. SettingRehabilitation center at a university hospital. ParticipantsOutpatients (N=8; 5 men, 3 women; mean age, 50±13y) with a gait disturbance (mean time after onset, 34±29mo) as a result of central nervous system disorders were selected from a volunteer sample. InterventionsTwo methods of balance exercise using a PTAR were devised: exercise against perturbation and exercise moving the center of gravity. The exercises were performed twice a week for 4 weeks. Main Outcome MeasuresPreferred and tandem gait speeds, Functional Reach Test, functional base of support, center of pressure (COP), muscle strength of lower extremities, and grip strength were assessed before and after the completion of the exercise program. After the exercise program, enjoyment of exercise was investigated via a visual analog scale questionnaire. ResultsAfter the program, statistically significant improvements were noted for tandem gait speeds (P=.009), Functional Reach Test (P=.003), functional base of support (P=.014), and lower extremity muscle strength (P<.001–.042). On the other hand, preferred gait speeds (P=.151), COP (P=.446–.714), and grip power (P=.584) did not change. Finally, subjects rated that this exercise was more enjoyable than traditional balance exercises. ConclusionsDynamic balance and lower extremity muscle strength were significantly improved in response to postural strategy training with the PTAR. These results suggest that postural strategy training with the PTAR may contribute to fall prevention of patients with a balance disorder.

The influence of stride-length on plantar foot-pressures and joint moments

PurposeJoint moments have been acknowledged as key factors in understanding gait abnormalities. Gait velocity is further known to affect joint moments and foot pressures. Keeping gait velocity constant is thus a strategy to cancel out the influence of different preferred gait speed between groups. But even if gait velocity is controlled, individuals can choose different stride length–stride frequency combinations to cope with an imposed gait velocity. ScopeTo understand the influence of stride frequency–stride length on joint moments and plantar pressures. MethodsTwenty healthy young adults had to cross an 8m walkway with a walking speed of 1.3ms−1. The wooden walkway was equipped with a force and a pressure platform. While walking speed was kept constant each participant walked with five different imposed stride lengths (SL): preferred (SL0); with a decrease of 10% (SL−10); with a decrease of 20% (SL−20); with an increase of 10% (SL+10) and with an increase of 20% (SF+20). ResultsAnkle and knee joint moments significantly decreased with a decrease in SL. A significant (p<.05) lower peak pressure was achieved with a decreased SL under the heel, toes and midfoot. Discussion/conclusionThe results showed that a change in stride lengths alters both, joint moments and foot pressures with clinically interesting indications. Redistribution of joint moments in the elderly for example might rather result from decreased SL than from age.

An evaluation of self-administration of auditory cueing to improve gait in people with Parkinson’s disease

Objective: To evaluate a self-administration of auditory cueing on gait difficulties in people with Parkinson’s disease over a one-week period. Design: Single group pre and post test. Setting: Research lab, community. Participants: Twenty-one individuals with Parkinson’s disease. Interventions: Self-application of an auditory pacer set at a rate 25% faster than preferred cadence. Main outcome measures: Self-selected gait speed, cadence, stride length, and double support time with and without the pacer at the initial visit and after one week of pacer use. Results: During the initial visit, the auditory pacer improved gait speed (79.57 (18.13) cm/s vs. 94.02 (22.61) cm/s, P<0.0005), cadence (102.88 (11.34) step/min vs. 109.22 (10.23) steps/min, P=0.036) and stride length (94.33 (21.31) cm vs. 103.5 (22.65) cm, P =0.012). After one week, preferred gait speed was faster than the initial preferred speed (79.57 (18.13) vs. 95.20 (22.23) cm/s, P<0.0005). Stride length was significantly increased (94.33 (21.31) vs. 107.67 (20.01) cm, P =0.001). Double support time was decreased from 21.73 (5.23) to 18.94 (3.59)% gait cycle, P =0.016. Conclusion: Gait performance in people with Parkinson’s disease improved significantly after walking with the auditory pacer for one week.

Relationship between Gait Speed and Physical Activity at Preferred Gait Speeds on Flat Ground and Treadmill

〔目的〕トレッドミル上の快適歩行速度（PST）は，平地での快適歩行速度（PSF）より速く感じる。しかし，実測値はPSTはPSFより遅くなると報告されている。これまでに，その際の身体活動量を加速度計から求めた報告はない。本研究の目的は，PSTとPSFの速度と活動量の相違について，加速度計を用い，比較検討することである。〔対象〕実験1は，若年健康者3名（男性3名：平均年齢20歳），実験2は，若年健康者15名（男性12名，女性3名：平均年齢21歳）を対象とした。〔方法〕トレッドミル上で速度を変化させ，トレッドミル上歩行での酸素摂取量と加速度変化を求めた。また，PSFとPSTの速度と加速度変化の比較も行った。各測定の際，腰背部に装着した小型3軸加速度変換器から快適歩行時の3次元の加速度変化を解析した。加速度変化の積分値（総力積）を求め活動量の指標にした。各条件の比較には1元配置の分散分析（反復測定）を用い有意差を求めた。〔結果〕PSFとその活動量がPSTに比べ有意に高いことが示された。PSFに比べPSTは遅くなるという従来からの報告と同様の結果が得られた。活動量についてもPSFよりPSTが低下し，その差を加速度計より検出できることが確認できた。〔結語〕加速度計から求めた活動量は，平地歩行に対しては臨床上活用できることが示唆された。

Physical Fatigue Affects Gait Characteristics in Older Persons

Fatigue affects self-reported functioning in older persons. Balance and gait problems increase fall risk. The effect of physical fatigue in the elderly population in general, and on balance control during walking in particular is not well known. This study investigates how a repeated sit-to-stand task affects gait control in older persons. Twenty-two persons (mean age 78 years) took part in a fatigue group (FG), and 22 persons (mean age 80 years) in a matched control group (CG). Participants walked back and forth on a walkway at different walking speeds. Gait data were adjusted for pretest-posttest differences in walking speed. The FG participants were physically fatigued by a repeated sit-to-stand task. Trunk data were obtained by a triaxial accelerometer and foot level data by an electronic walkway. There were no group differences in preferred gait speed (p =.96) or in step length (p =.47) following the fatiguing task, but there were significant increases in step width (p =.023) and in mediolateral trunk acceleration amplitude (p =.038) in the FG group. Step-length variability (p =.004) and interstride trunk acceleration variability in the vertical direction (p =.002) increased, and tended to increase in the anteroposterior direction (p =.10) and to decrease in the mediolateral direction (p =.10) in the FG only. Gait changes following a physical fatiguing task agree with changes previously found in older persons at risk of falling, suggesting that physical fatigue may represent a risk factor for falls in elderly persons.

Effects of extended effortful activity on spatio-temporal parameters of gait in individuals with stroke

Neuromuscular dyscontrol during gait following stroke may be further compromised by increased susceptibility to fatigue. Our purpose was to examine how extended effortful activity affected spatio-temporal gait parameters after stroke. The influence of sub-maximal exercise was assessed among 26 stroke survivors who performed the Six-Minute Walk Test with distance recorded every 2 min. Walking distance decreased 5.8 (S.D. 6.9) m in the second 2-min interval and another 2.3 (S.D. 9.9) m in the final 2 min ( p = 0.0005). Secondly, we evaluated spatio-temporal gait parameters prior to and immediately following a standardized maximal exercise test on a cycle ergometer in 36 stroke survivors. In contrast to the expected reduction in walking speed, maximal exercise led to a 5.5 (S.D. 11.5) cm/s increase in preferred gait speed ( p = 0.007) and a 4.5 (S.D. 7.7) steps/min increase in cadence ( p = 0.0004), but did not affect gait symmetry. Subsequent division of participants by preferred pedaling cadence revealed that individuals with lower preferred cadence had the greatest increase in preferred speed, cadence and paretic leg step length ( p < 0.01). These unexpected results suggest that potential fatigue-induced effects on gait may have been masked by immediate positive influences of movement rate on walking speed. Such activity-specific effects may have clinical applications for stroke patients and other populations with gait deviations.

POWERED ANKLE-FOOT ORTHOSES: EFFICIENCY AT THE EXPENSE OF DECREASED STABILITY?

INTRODUCTION Advances in robotic exoskeletons allow the addition of power at lower extremity joints during locomotion. We previously developed a pair of articulated powered ankle-foot orthoses (PAFOs) that provide external moments at the ankle joint via pneumatic muscle actuators as per similar designs by Ferris [1]. Experiments with this device showed that mechanically augmented PF power resulted in subject’s increasing their preferred gait speed [2]. The additional energy should reduce the metabolic cost necessary to walk. However, force augmentation of all existing powered exoskeletal systems is achieved by positive feedback control; a destabilizing mechanism in dynamic systems.

Do functional walk tests reflect cardiorespiratory fitness in sub-acute stroke?

Background and purposeThe Six-Minute Walk Test (6MWT) has been employed as a measure of functional capacity, but its relationship to cardiorespiratory fitness in stroke is not well established. Gait speed measured over short distances is commonly used as an index of walking competency following stroke. We evaluated the relationship between the 6MWT, aerobic fitness (VO2peak) and walking competency in sub-acute stroke.MethodsThirty-six individuals (mean age ± SD, 64.6 ± 14.4 years; time post-stroke 16.2 ± 13.3 days) were evaluated using the 6MWT (distance, speed, heart rate), a maximal exercise test (VO2peak, heart rate, exercise test duration), and walking competency using a five meter walk (speed, symmetry ratio). Correlation analyses were used to examine the relationships between these outcomes.ResultsThere was a strong correlation between the 6MWT and five meter walk velocity for preferred (r = 0.79) and fast (r = 0.82) speed (p < 0.001). On average, the 6MWT speed was faster than the preferred gait speed (94.9 cm/s vs. 83.8 cm/s, p = 0.003), but slower than the fast-paced walk (115.1 cm/s, p < 0.001). There was significant though more moderate association between 6MWT distance and VO2peak (r = 0.56, p < 0.001) and exercise test duration (r = 0.60, p < 0.001).ConclusionThe speed selected during the 6MWT was strongly related to the velocities selected during the five meter walk distance (intermediate to the selected preferred and fast speeds). Although the 6MWT may be challenging to the cardiorespiratory system, it appears to be more strongly influenced by potential limits to walking speed rather than cardiorespiratory capacity. As a result, this test is not, by itself, an adequate measure of aerobic fitness early after stroke.