Age and walking speed effects on muscle recruitment in gait termination

During gait termination at normal walking speed, older adults more frequently employ two-step responses, increasing their stopping distance and stopping time more than younger controls. This study investigated ageing effects on lower limb muscle recruitment patterns during stopping at three walking speeds. Twelve young male (26±3.7 years, range 19–30) and 12 gender-matched older participants (72±4.3 years, range 65–82) terminated walking at normal, medium and maximum speed. A visual stopping stimulus was presented 10 ms following either left or right heel-contact with no stimulus (catch) on 30% of trials. Electromyographic (EMG) activity was recorded from the tibialis anterior (TA), soleus (SOL), biceps femoris (BF), vastus lateralis (VL) and gluteus medius (GM). Older males more frequently (46% of trials) took two-steps to stop than young males (20%). The stance leg muscles responded significantly faster than the swing leg, and with increased speed, fewer swing limb muscles contributed to stopping. Older males were slower to respond with the stance leg, at 215 ms following the stimulus compared with 176 ms for the younger group. They also recruited fewer swing leg muscles with less frequent activation of the soleus and gluteus medius. Failure to activate muscles would provide less extensor torque to maintain the centre of gravity anterior to the forward base of support. This would decrease the total force opposing horizontal velocity in order to bring the body to rest and, as a consequence, encourage an additional step prior to stopping.

Passenger walking speed data for Australian domestic airports

The data covers the speed at which passengers walk through Australian domestic airport terminals, based on their group size.

Individual calibration for estimating free-living walking speed using the MTI monitor

Purpose : This study was conducted to devise a new individual calibration method to enhance MTI accelerometer estimation of free-living level walking speed.

Method : Five female and five male middle-aged adults walked 400 m at 3.5, 4.5, and 5.5 km·h-1, and 800 m at 6.5 km·h-1 on an outdoor track, following a continuous protocol. Lap speed was controlled by a global positioning system (GPS) monitor. MTI counts-to-speed calibration equations were derived for each trial, for each subject for four such trials with each of four MTI, for each subject for the average MTI, and for the pooled data. Standard errors of the estimate (SEE) with and without individual calibration were compared. To assess accuracy of prediction of free-living walking speed, subjects also completed a self-paced, "brisk" 3-km walk wearing one of the four MTI, and differences between actual and predicted walking speed with and without individual calibration were examined.

Results : Correlations between MTI counts and walking speed were 0.90 without individual calibration, 0.98 with individual calibration for the average MTI, and 0.99 with individual calibration for a specific MTI. The SEE (mean ± SD) was 0.58 ± 0.30 km·h-1 without individual calibration, 0.19 ± 0.09 km·h-1 with individual calibration for the average MTI monitor, and 0.16 ± 0.08 km·h-1 with individual calibration for a specific MTI monitor. The difference between actual and predicted walking speed on the "brisk" 3-km walk was 0.06 ± 0.25 km·h-1 using individual calibration and 0.28 ± 0.63 km·h-1 without individual calibration (for specific accelerometers).

Conclusion : MTI accuracy in predicting walking speed without individual calibration might be sufficient for population-based studies but not for intervention trials. This individual calibration method will substantially increase precision of walking speed predicted from MTI counts.

Validity of treadmill- and track-based individual calibration methods for estimating free-living walking speed and VO2 using the Actigraph accelerometer

BACKGROUND: For many patients clinical prescription of walking will be beneficial to health and accelerometers can be used to monitor their walking intensity, frequency and duration over many days. Walking intensity should include establishment of individual specific accelerometer count, walking speed and energy expenditure (VO2) relationships and this can be achieved using a walking protocol on a treadmill or overground. However, differences in gait mechanics during treadmill compared to overground walking may result in inaccurate estimations of free-living walking speed and VO2. The aims of this study were to compare the validity of track- and treadmill-based calibration methods for estimating free-living level walking speed and VO2 and to explain between-method differences in accuracy of estimation.

METHODS: Fifty healthy adults [32 women and 18 men; mean (SD): 40 (13) years] walked at four pre-determined speeds on an outdoor track and a treadmill, and completed three 1-km self-paced level walks while wearing an Actigraph monitor and a mobile oxygen analyser. Speed- and VO2-to-Actigraph count individual calibration equations were computed for each calibration method. Between-method differences in calibration equation parameters, prediction errors, and relationships of walking speed with VO2 and Actigraph counts were assessed. RESULTS: The treadmill-calibration equation overestimated free-living walking speed (on average, by 0.7 km · h(-1)) and VO2 (by 4.99 ml · kg(-1) · min(-1)), while the track-calibration equation did not. This was because treadmill walking, from which the calibration equation was derived, produced lower Actigraph counts and higher VO2 for a given walking speed compared to walking on a track. The prediction error associated with the use of the treadmill-calibration method increased with free-living walking speed. This issue was not observed when using the track-calibration method. CONCLUSIONS: The proposed track-based individual accelerometer calibration method can provide accurate and unbiased estimates of free-living walking speed and VO2 from walking. The treadmill-based calibration produces calibration equations that tend to substantially overestimate both VO2 and speed.

Ageing effects on visual reaction time in a single task condition and when treadmill walking

Visual reaction time (RT) was measured in 10 older men (mean age, 71.1 years) and gender-matched controls (mean age, 26.3 years) when standing (single task) and when walking on a motor-driven treadmill (dual task). There were 90 quasirandomly presented trials over 15 min in each condition. Longer mean and median RTs were observed in the dual task compared to the single task. Older males had significantly slower mean and median RTs (315 and 304 ms, respectively) than the younger group (273 and 266 ms, respectively) in both task conditions. There were no age or condition effects on with in-subject variability. Both groups showed a trend of increasing RT over the 90 single task trials but when walking only the younger group slowed. These novel findings demonstrate high but sustained attention by older adults when walking. It is proposed that the motor task's attentional demands might contribute to their slower preferred walking speed.

Control of lead and trail limbs during obstacle crossing following stroke

Background and Purpose. Obstacle crossing is compromised following stroke. The purpose of this study was to quantify modifications during obstacle clearance following stroke.

Subjects. Twelve subjects with stroke and 12 subjects without stroke participated in the study.

Methods. Kinematic variables were measured while participants crossed a 4-cm-high obstacle. Subjects with stroke walked at a self-selected speed; subjects without stroke walked at a comparable speed and at a self-selected speed.

Results. Several modifications were observed following stroke with both groups walking at self-selected speeds. The affected lead limb was positioned closer to the obstacle before crossing. Affected trail-limb clearance over the obstacle was reduced. Both affected and unaffected lead and trail limbs landed closer to the obstacle after clearance. Swing time was increased in the affected lead limb after obstacle clearance. Fewer modifications were detected at matched walking speed; the trail limb still landed closer to the obstacle.

Discussion and Conclusion. Modifications during obstacle crossing following stroke may be partly related to walking speed. The findings raise issues of safety because people with stroke demonstrated reduced clearance of a 4-cm obstacle and limb placement closer to the obstacle after clearance.

Psychometric properties of the modified Emory functional ambulation profile in stroke patients

Objective: To examine the test – retest reliability, convergent and predictive validity and responsiveness of the modified Emory Functional Ambulation Profile (mEFAP) in assessing gait function in stroke patients undergoing rehabilitation. Subjects: Forty subacute stroke inpatients were enrolled in the validity and responsiveness study. Twenty chronic patients participated in the reliability study. Setting: Rehabilitation department of a medical centre. Design: In the validity and responsiveness study, patients were tested using the mEFAP, 10-m walking speed test, Barthel Index and Rivermead Mobility Index at admission and at discharge. For the reliability study, the patients completed the mEFAP twice one week apart. Results: The patients' performances on the mEFAP were moderately to highly correlated with results of the 10-m walking speed test and Rivermead Mobility Index (absolute correlation coefficients ≥ 0.67), indicating good convergent validity. Patients' performance on the mEFAP at admission was moderately correlated with the Barthel Index and Rivermead Mobility Index scores at discharge (Spearman's rank correlation coefficients = -0.52 and -0.78, respectively), indicating good predictive validity. The standardized response mean of the mEFAP was 1.1 (P < 0.0001), suggesting good responsiveness. The intraclass correlation coefficient ICC(3,1) for the mEFAP was 0.997, indicating excellent test – retest reliability. Conclusions: Our results provide strong evidence that the mEFAP has good reliability, validity and responsiveness for assessing stroke patients undergoing rehabilitation. The mEFAP is a useful scale for measuring walking function and recovery in stroke patients.

A randomized controlled trial to reduce falls in people with Parkinson's Disease

Background. Falls are common and disabling in people with Parkinson's disease (PD). There is a need to quantify the effects of movement rehabilitation on falls in PD. Objective. To evaluate 2 physical therapy interventions in reducing falls in PD. Methods. We randomized 210 people with PD to 3 groups: progressive resistance strength training coupled with falls prevention education, movement strategy training combined with falls prevention education, and life-skills information (control). All received 8 weeks of out-patient therapy once per week and a structured home program. The primary end point was the falls rate, recorded prospectively over a 12 month period, starting from the completion of the intervention. Secondary outcomes were walking speed, disability, and quality of life. Results. A total of 1547 falls were reported for the trial. The falls rate was higher in the control group compared with the groups that received strength training or strategy training. There were 193 falls for the progressive resistance strength training group, 441 for the movement strategy group and 913 for the control group. The strength training group had 84.9% fewer falls than controls (incidence rate ratio [IRR] = 0.151, 95% CI 0.071-0.322, P < .001). The movement strategy training group had 61.5% fewer falls than controls (IRR = 0.385, 95% CI 0.184-0.808, P = .012). Disability scores improved in the intervention groups following therapy while deteriorating in the control group. Conclusions. Rehabilitation combining falls prevention education with strength training or movement strategy training reduces the rate of falls in people with mild to moderately severe PD and is feasible.

Additional weekend therapy may reduce length of rehabilitation stay after stroke: a meta-analysis of individual patient data

QUESTIONS: Among people receiving inpatient rehabilitation after stroke, does additional weekend physiotherapy and/or occupational therapy reduce the length of rehabilitation hospital stay compared to those who receive a weekday-only service, and does this change after controlling for individual factors? Does additional weekend therapy improve the ability to walk and perform activities of daily living, measured at discharge? Does additional weekend therapy improve health-related quality of life, measured 6 months after discharge from rehabilitation? Which individual, clinical and hospital characteristics are associated with shorter length of rehabilitation hospital stay? DESIGN: This study pooled individual data from two randomised, controlled trials (n=350) using an individual patient data meta-analysis and multivariate regression. PARTICIPANTS: People with stroke admitted to inpatient rehabilitation facilities. INTERVENTION: Additional weekend therapy (physiotherapy and/or occupational therapy) compared to usual care (5 days/week therapy). OUTCOME MEASURES: Length of rehabilitation hospital stay, independence in activities of daily living measured with the Functional Independence Measure, walking speed and health-related quality of life. RESULTS: Participants who received weekend therapy had a shorter length of rehabilitation hospital stay. In the un-adjusted analysis, this was not statistically significant (MD -5.7 days, 95% CI -13.0 to 1.5). Controlling for hospital site, age, walking speed and Functional Independence Measure score on admission, receiving weekend therapy was significantly associated with a shorter length of rehabilitation hospital stay (β=7.5, 95% CI 1.7 to 13.4, p=0.001). There were no significant between-group differences in Functional Independence Measure scores (MD 1.9 points, 95% CI -2.8 to 6.6), walking speed (MD 0.06 m/second, 95% CI -0.15 to 0.04) or health-related quality of life (SMD -0.04, 95% CI -0.26 to 0.19) at discharge. DISCUSSION: Modest evidence indicates that additional weekend therapy might reduce rehabilitation hospital length of stay.

Shortest equals fastest : upper primary children`s pre-conceptions of speed

An understanding of speed as distance travelled per unit time is fundamental to the development of the more complex conception of acceleration. This paper examines the opportunities provided for upper primary children to reveal and modify their pre-conceptions of speed through a walking activity developed as part of the Practical Mechanics in Primary Mathematics project.

Drifting or walking? colonisation routes used by different instars and species of lotic, macroinvertebrate filter feeders

Many views of stream invertebrate populations centre on drift as the major route of larval dispersal, but few studies have presented unambiguous information about the role of drift. We present the results from an experiment designed to determine whether the major route of colonisation of substrata by hydropsychid larvae (commonly found in the drift) is by drifting directly onto substrata or by walking along the stream bottom. The experimental design contained four treatments: substrata open to drifters and walkers; fenced substrata open to drifters only; and two treatments open to drifters and walkers that provided forms of fence controls. Fifteen replicates of each treatment were set out at random locations within a riffle at each of three sites, with each site on a different river (the Little River, the Steavenson River and the Acheron River) in the Acheron River catchment. The experiment was run twice, once during autumn (April 1999) and once during early summer (January 2000). Both experiments were colonised by three species of hydropsychids, Asmicridea sp. AV1, and Smicrophylax sp. AV1 and AV2. We found that 2nd/3rd instars of Asmicridea sp. AV1 walked as well as drifted, whereas all others primarily drifted. No relation between numbers of recruits and water speed was found when substrata were open only to drifters, whereas substrata open also to walkers gained more recruits in faster flows. Additionally, larvae more frequently abandoned nets in slow than fast flows, indicating that drifting into unfavourable flow environments may result in mortality or redispersal of larvae. These findings demonstrate that, although drift is important, it is not necessarily the only method used by hydropsychids to colonise substrata. Larvae may have more capacity to choose substrata in fast flows when they colonise substrata by walking. Spot measures of hydropsychid distribution cannot distinguish between these explanations. The finding that walkers can sometimes comprise significant numbers of recruits raises the prospect that hydropsychids can be sourced locally and have not inevitably drifted in from upstream locations.

Are perceptions of the physical and social environment associated with mothers' walking for leisure and for transport? A longitudinal study

Objective
The role local neighbourhood environments play in influencing purpose-specific walking behaviors has not been well-explored in prospective studies. This study aimed to cross-sectionally and prospectively examine whether local physical and social environments were associated with mothers' walking for leisure and for transport.

Methods
In 2004, 357 mothers from Melbourne, Australia, provided information on their local physical and social neighbourhood environments, and in 2004 and 2006 reported weekly time spent walking for leisure and for transport. Environmental predictors of high levels of walking and increases in walking were examined using log binomial regression.

Results
Public transport accessibility and trusting many people in the neighbourhood were predictive of increases in walking for leisure, while connectivity, pedestrian crossings, a local traffic speed were predictive of increases in transport-related walking. Satisfaction with local facilities was associated with increasing both types of walking, and the social environment was important for maintaining high levels of both leisure- and transport-related walking.

Conclusion
The findings provide evidence of a longitudinal relationship between physical and social environments and walking behaviors amongst mothers. Enhancing satisfaction with local facilities and giving consideration to ‘walkability’, safety and public transport accessibility during environment planning processes may help mothers to increase walking.

Street characteristics preferred for transportation walking among older adults: a choice-based conjoint analysis with manipulated photographs

BACKGROUND: Knowledge about the relationships between micro-scale environmental factors and older adults' walking for transport is limited and inconsistent. This is probably due to methodological limitations, such as absence of an accurate neighborhood definition, lack of environmental heterogeneity, environmental co-variation, and recall bias. Furthermore, most previous studies are observational in nature. We aimed to address these limitations by investigating the effects of manipulating photographs on micro-scale environmental factors on the appeal of a street for older adults' transportation walking. Secondly, we used latent class analysis to examine whether subgroups could be identified that have different environmental preferences for transportation walking. Thirdly, we investigated whether these subgroups differed in socio-demographic, functional and psychosocial characteristics, current level of walking and environmental perceptions of their own street.

METHODS: Data were collected among 1131 Flemish older adults through an online (n = 940) or an interview version of the questionnaire (n = 191). This questionnaire included a choice-based conjoint exercise with manipulated photographs of a street. These manipulated photographs originated from one panoramic photograph of an existing street that was manipulated on nine environmental attributes. Participants chose which of two presented streets they would prefer to walk for transport.

RESULTS: In the total sample, sidewalk evenness had by far the greatest appeal for transportation walking. The other environmental attributes were less important. Four subgroups that differed in their environmental preferences for transportation walking were identified. In the two largest subgroups (representing 86% of the sample) sidewalk evenness was the most important environmental attribute. In the two smaller subgroups (each comprising 7% of the sample), traffic volume and speed limit were the most important environmental attributes for one, and the presence of vegetation and a bench were the most important environmental attributes for the other. This latter subgroup included a higher percentage of service flat residents than the other subgroups.

CONCLUSIONS: Our results suggest that the provision of even sidewalks should be considered a priority when developing environmental interventions aiming to stimulate older adults' transportation walking. Natural experiments are needed to confirm whether our findings can be translated to real environments and actual transportation walking behavior.

Perceived environmental aesthetics and convenience and company are associated with walking for exercise among Australian adults

Background: This study aimed to investigate relationships between environmental aesthetics, convenience, and walking companions and walking for exercise or recreation and to investigate differences in these relationships by sex and by reported physical and mental health.

Methods: Analyses of cross-sectional self-report data from a statewide population survey of 3,392 Australian adults were used.

Results: Men and women reporting a less aesthetically pleasing or less convenient environment were less likely to report walking for exercise or recreation in the past 2 weeks. Those respondents, particularly women, reporting no company or pet to walk with were also less likely to walk for exercise or recreation. Associations with environmental and social influences were observed for men and women reporting both good and poor physical and mental health.

Conclusions: Perceived environmental aesthetics and convenience and walking companions are important correlates of walking for exercise among urban Australians. Acknowledging the cross-sectional nature of these data, findings support a case for evaluation of environmental policies to promote physical activity.