Footswitch System Research Articles

Validation of Linear and Nonlinear Gait Variability Measures Derived From a Smartphone System Compared to a Gold-Standard Footswitch System During Overground Walking.

Smartphones, with embedded accelerometers, may be a viable method to monitor gait variability in the free-living environment. However, measurements estimated using smartphones must first be compared to known quantities to ensure validity. This study assessed the validity and reliability of smartphone-derived gait measures compared to a gold-standard footswitch system during overground walking. Seventeen adults completed three 8-minute overground walking trials during 3 separate visits. The stride time series was calculated as the time difference between consecutive right heel contact events within the footswitch and smartphone-accelerometry signals. Linear (average stride time, stride time standard deviation, and stride time coefficient of variation) and nonlinear (fractal scaling index, approximate entropy, and sample entropy) measures were calculated for each stride time series. Bland-Altman plots with 95% limits of agreement assessed agreement between systems. Intraclass correlation coefficients assessed reliability across visits. Bland-Altman plots revealed acceptable limits of agreement for all measures. Intraclass correlation coefficients revealed good-to-excellent reliability for both systems, except for fractal scaling index, which was moderate. The smartphone system is a valid method and performs similarly to gold-standard research equipment. These findings suggest the development and implementation of an inexpensive, easy-to-use, and ubiquitous telehealth instrument that may replace traditional laboratory equipment for use in the free-living environment.

Concurrent validity of the ZeroWire® footswitch system for the measurement of temporal gait parameters

BackgroundIn contrast to wearable tools (like in-shoe) sensors, lab-based gait assessment (using pressure-sensitive mats or cameras) only acquire data over short distances in non-ecological environments. Research questionTo examine the concurrent validity of a wearable ZeroWire® footswitch system (Aurion Srl, Milan, Italy) vs. the GAITRite® walkway (CIR systems Inc., NJ, USA) for recording temporal gait parameters. MethodsWe included 40 healthy participants in a prospective, single-center study. Temporal gait parameters were recorded simultaneously with the ZeroWire® and GAITRite® systems while each participant walked at three different speeds (slow (60steps/min), comfortable and maximum). To measure the validity, we calculated the interclass correlation coefficient (ICC) and the coefficient of variation (CV) for each parameter (gait cadence, stride time, step time, stance time, and single-support and double-support times). We also performed a graphical analysis using the Bland and Altman method. ResultsThe footswitch system showed moderate-to-excellent concurrent validity vs. the GAITRite mat. The degree of agreement between the two assessments was greatest at the maximum gait velocity showed, with very good validity (ICC > 0.91) seen for most parameters, whereas agreement ranged from moderate to very good for the other speeds. Independently of the gait speed, the highest levels of agreement were recorded for gait velocity, cadence, stride time, step time, and stance time. According to the CVs, both systems showed the same accuracy and double-support time was the more variable parameter. SignificanceThe ZeroWire® footswitch system appears to be valid for assessing temporal gait parameters (and particularly gait cadence and stride, step and stance times in healthy participants). It is likely to be well suited to the assessment of gait parameters under ecological conditions and in dual-task gait paradigms.

Concurrent validity of footswitches analysis for the measurement of temporal gait parameters

The GAITRite ® system, according to the published data, appears to be an easy to use and validated device for gait analysis. However, it only allows acquisitions on short distances in a nonecological environment. In addition to this device, it could be interesting to use new embarked evaluation tools. The main aim of this study was to examine the concurrent validity of temporal parameters recorded by the portable Zero Wire, AURION ® footswitch system in comparison to the GAITRite ® mat. In a single center prospective study, 40 healthy subjects were included. Each subject had to walk at three different speeds (slow, normal, max) and temporal gait parameters were recorded at the same time by each system. To measure the validity of the footswitch system, we calculated inter class correlation coefficient (ICC) for each temporal parameter (step and cycle time, cadence, % of stance, % of single support, % of swing). Gait parameters recorded at maximum gait velocity showed the best concordance between the two assessments, with a majority of parameters demonstrating a very good validity (ICC > 0.91). At slow speed, the analysis revealed excellent results for gait cadence and step and cycle times, whereas validity was good (ICC > 0.71) to moderate (ICC > 0.51) for the other parameters. The validity profile was a little worse at normal speed, especially for % of swing and % of stance. The Zero Wire, AURION ® , portable footswitch system, is a valid for temporal gait parameters assessment, particularly considering raw parameters. It provides the opportunity to assess gait parameters and variability in ecological conditions, particularly in dual-task gait protocols.

Low-cost piezoelectric footswitch system for measuring temporal parameters during walking

Human walking is one of the most investigated biomechanical events, and gait analysis depends on accurate measurement of heel strike (HS) and toe off (TO). The purpose of this study was to construct and validate a low-cost footswitch system for the measurement of temporal gait parameters. Ten young healthy subjects participated of the validation and test of the footswitch system with two different footwear, Bland-Altman analysis showed 98% and 95% of validation data within the limits of agreement, for HS and TO respectively (mean difference of 16ms1ms and 20ms9ms) and the temporal parameters measured during treadmill walking at a speed of 4.5km.h-1 showed results similar to those found in the literature for normal walking. The outcomes confirm low CoVs for the instrumented athletic and instability shoe, respectively: (1.520.61)% and (1.900.73)% for contact time, (2.170.95)% and (2.570.95)% for balance time, (0.840.28)% and (1.120.53)% for stride time. The low-cost footswitch system described and validated in the present study has an important practical applicability, mostly for emerging and developing countries biomechanics labs. Keywords: Footswitch System, Gait Analysis, Locomotion, Low-Cost, Walk.

Gait control and executive dysfunction in early schizophrenia

Dysexecutive functioning, which is described as an enduring core feature of schizophrenia, has been associated with gait disorders. However, few studies have reported gait disorders in schizophrenia patients. The objective of this study was to examine the association between executive dysfunction and gait performance in recent-onset schizophrenia patients using the dual task paradigm. Thirty-two subjects participated to the study: 17 with recent-onset schizophrenia and 15 healthy age-matched controls. Executive functions were evaluated using the Frontal Assessment Battery, Stroop and Trail-Making tests. Mean values and coefficients of variation (CV) of the temporal gait parameters while single tasking (just walking) and while dual tasking (walking and forward counting, walking and backward counting, walking and verbal fluency) were measured using the SMTEC(®)-footswitch system. We focused on the CV of stride time as this measure has been shown to be the most representative parameter of higher gait control. A strong effect of the stride time was found in the group factor for the verbal fluency dual-task when compared to controls (Cohen's d mean=1.28 and CV=1.05). The effect was lower in the other dual tasks, and insignificant in the single task of walking. This study shows that patients exhibit higher stride-to-stride variability while dual tasking than controls. It also shows a stronger impact of verbal fluency on gait regularity compared to the other dual tasks revealing a relationship between the executive dysfunction and gait modification. Those results are in line with the idea that schizophrenia implies not only cognitive but also motor functioning and coordination impairment.

Higher Gait Variability is Associated with Decreased Parietal Gray Matter Volume Among Healthy Older Adults

The objectives of this study were to examine the association of stride time variability (STV) with gray and white matter volumes in healthy older adults, and to determine the specific location of any parenchymal loss associated with higher STV. A total of 71 participants (mean age 69.0 ± 0.8 years; 59.7 % female) were included in this study. All participants had a 1.0 Tesla 3D T1-weighted MRI of the brain to measure gray and white matter volumes. STV was measured at steady-state self-selected walking speed using an electronic footswitch system. We found an association between higher STV and lower gray matter volume in the right parietal lobe (e.g., angular gyrus, Brodmann area 39, cluster corrected pFWE = 0.035). There were no significant associations between STV and higher gray matter volume or change in white matter volume. To the best of our knowledge this study is the first to identify a significant association of higher STV with lower right parietal gray matter volume in healthy older adults.

Stride-time variability and sensorimotor cortical activation during walking

The time it takes between consecutive foot contacts from the same leg is referred to as the stride-time interval. Several investigations have shown that the variations that are present in the stride time intervals are linked to walking balance. In this study, functional near infrared spectroscopy (fNIRS) was utilized to evaluate whether activation in the medial sensorimotor cortices reflects the amount of variations seen in the stride-time intervals. Thirteen healthy adults (Age=23.7 ± 1.4 yrs.) walked forwards and backwards on a programmable treadmill. Each walking condition consisted of two sessions, with each being comprised of five alternating blocks of standing still or walking at 0.45 m/s. Activation in the medial sensorimotor cortices was measured using an fNIRS system, which consisted of a 4 × 4 grid of infrared optode emitter/detector pairs. The optodes were positioned on the participant's head using the International 10/20 system with Cz located beneath the center of the front two rows of optodes. We evaluated the block-wise changes in the amount of oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb) in the channels that were located over the supplementary motor area, pre-central gyrus, post-central gyrus and superior parietal lobule. Throughout the experiment, a footswitch system was used to concurrently measure the amount of variation present in the stride-time intervals. Our results showed that oxyHb was greater in the supplementary motor area, pre-central gyrus, and superior parietal lobule when participants walked backwards rather than forwards, which suggests that backward walking presents more of a challenge to the nervous system as it controls the stepping pattern. Additionally, there was a significant decrease in the amount of deoxyHb present in the supplementary motor area while walking backward. Consistent with previous investigations, we noted that the amount of variability present in the stride-time intervals was greater during backward walking compared to forward walking. In addition, the amount of variation in the stride-time intervals while walking forward was positively correlated with the maximum oxyHb response found in the pre-central gyrus and supplementary motor area, which has not been previously shown. This neurobehavioral relationship supports the notion that the subtle variations found in the stride-time intervals are partly associated with processing demands by the motor cortices for regulating the forward temporal kinematics.

Frontotemporal dementia: Pathology of gait?

The main diagnostic criteria of the behavioural variant of frontotemporal degeneration (bvFTD) include neurobehavioral and dysexecutive syndromes, but not specific gait characteristics although strong relationship between gait and prefrontal functions are increasingly recognized. Accordingly, we tested the hypothesis that patients with bvFTD would have more gait changes than older healthy controls and demented patients with Alzheimer's disease (AD). Sixty subjects were included in the study: 19 with bvFTD, 19 with AD and 22 healthy controls. Mean values and coefficients of variation (CV) of stride time while just walking (i.e., single tasking) and while walking with backward counting (i.e., dual tasking) were measured using the SMTEC-footswitch system. Stride time, mean value, and CV were significantly increased in both patient groups compared with healthy controls during single task or walking alone (P < 0.001) and during dual tasking (P < 0.001). After adjusting for age, Mini-mental examination, psychoactive drugs, gender, and history of previous fall, only the patients with bvFTD group was associated with an increase of CV of stride time during single walking (P < 0.001) and dual tasking (P < 0.001). These data suggest that gait instability during single and dual tasking could represent a supportive argument for bvFTD. In clinical practice, such a diagnosis should be at least considered in any demented patient with gait instability.

Reliability and Validity of Bilateral Thigh and Foot Accelerometry Measures of Walking in Healthy and Hemiparetic Subjects

Objective. Measures of walking ability in large clinical trials are usually limited to a timed short-distance walk and the distance walked in a fixed time. A new integrated system of 5 accelerometers was tested for reliability and compared to a footswitch system to determine if the accelerometers offered a practical option for the acquisition of spatiotemporal gait parameters. Methods. Leg accelerations and decelerations were defined in relation to simultaneous kinematic and electromyographic data acquired from a healthy subject. Eight healthy adults and 6 independent ambulators with hemiparetic stroke walked 15 m at 2 different speeds wearing both the accelerometers and footswitches. Twelve healthy subjects walked at 5 different speeds repeated 3 times on each of 2 days wearing the accelerometers. Walking speed, cadence, stride length, and single- and double-limb support, swing, and stance times were calculated. Results. No differences (t test, P > 0.2) were found between footswitch and accelerometer variables when comparing all left or right legs in healthy subjects and all paretic or unaffected legs in stroke subjects. A 2-way nested ANOVA model (speed, left and right legs, trial, and session) with the accelerometers at walking speeds from 0.5 to 1.8 m/s revealed high reproducibility of all measures. Conclusions. The accelerometry system provided reliable and valid spatiotemporal measures of gait for the upper range of speeds likely to be targeted for rehabilitation interventions in ambulatory subjects.

Evidence for a disorder of locomotor timing in Huntington's disease

Disturbances of walking have been described in people with Huntington's disease (HD), although the nature of the deficits have not yet been well defined. The purpose of this investigation was to determine whether people with HD have a deficit in the regulation of footstep timing during walking. The footstep patterns of 30 people with HD and 30 matched comparisons were measured at self-selected slow, preferred, and fast speeds. Subjects were also instructed to match their footsteps to auditory metronome cues set at 80 and 120 beats per minute. Gait speed, cadence, stride length, and double limb support as a percentage of the gait cycle were measured using a computerized foot-switch system. People with HD demonstrated a disorder in their ability to regulate cadence, manifest as a reduced step frequency when walking at preferred speed and when required to increase their speed. For all walking conditions, people with HD had increased variability of footstep cadence. They also had difficulty synchronizing their footstep timing to an auditory cue. For all walking conditions, people with HD had reduced stride length. Thus, in HD, there is a disorder in the regulation of footstep timing, with increased variability, a restricted cadence range, difficulty synchronizing footsteps to an auditory cue and reduced stride length. The exact neural correlates of this timing disorder are yet to be determined.

Effects of age on balance control during walking

Shkuratova N, Morris ME, Huxham F. Effects of age on balance control during walking. Arch Phys Med Rehabil 2004;85:582–8. Objective To determine the effects of aging on balance control during walking. Design Two-group repeated-measures design. Setting Gait laboratory in Australia. Participants Convenience sample of 20 healthy older subjects (mean age, 72y) and 20 healthy young subjects (mean age, 24y). Interventions Changes in locomotor performance in response to perturbations to balance were quantified for healthy older adults compared with healthy young adults for (1) straight line walking at preferred speed, (2) straight line walking at fast speed, (3) figure-of-eight walking at preferred speed, and (4) figure-of-eight walking while performing a secondary motor task. Main outcome measures Gait speed, stride length, cadence, and double-limb support duration, using a footswitch system. Results Healthy older people screened for pathology had gait patterns comparable to young adults for straight line walking at preferred speed. However, multivariate analysis of variance (MANOVA) showed a significant interaction between age and speed when balance was perturbed by requiring subjects to change from walking at preferred to fast speeds (Pillai-Bartlett trace=.259, F 4,35=3.06, P<.029, partial η 2=.259). This occurred because older people did not increase their speed (F 1,38=7.65, P<.01, partial η 2=.168) or stride length (F 1,38=12.23, P<.01, partial η 2=.243) as much as did the young adults. MANOVAs did not show statistically significant interactions between age and turning conditions or age and dual task conditions, although older people walked more slowly and with shorter steps when turning or performing a secondary task. Conclusions Balance strategies during gait are task specific and vary according to age. In response to challenges to balance imposed by the requirement to change from preferred to fast walking, older people did not increase their speed and stride length to the same extent as did younger adults. This was possibly a strategy to maintain their stability.

Upper body accelerations during walking in healthy young and elderly men

The purpose of the present study was to assess whether any differences existed in the upper body accelerations of young and elderly subjects during natural speed walking. Head and trunk accelerations in eight young subjects (aged 23+/-4 years) and eight healthy elderly subjects (aged 74+/-3 years) were measured during level walking on a 20 m walkway using a pair of tri-axial accelerometers. Heel contact and toe-off events were determined using a footswitch system embedded in the innersole of the right shoe. Gait measures assessed included; stride, stance and swing durations, cadence, gait velocity, step length and 3D head and trunk accelerations. All acceleration variables were normalised to walking speed before statistical analysis. The main findings of this study were: (1) the peak positive anterior-posterior (AP) trunk acceleration associated with push-off was significantly lower for elderly subjects, (2) the peak negative AP head and trunk accelerations following heel contact was significantly higher for elderly subjects, and (3) the time delay between trunk and head accelerations experienced in the AP direction was significantly lower for the elderly compared to the young group. Together, these results suggest that elderly subjects exhibit different patterns of upper body motion in the direction of travel compared to younger subjects. These differences are probably motivated by the need to maximise dynamic stability during critical parts of the gait cycle.

Systematic and random error in repeated measurements of temporal and distance parameters of gait after stroke

Objective: To obtain intersession estimates of error for temporal and distance (TD) parameters of gait in a sample of stroke patients undertaking inpatient rehabilitation. Design: Thirty-one stroke patients were measured with an instrumented footswitch system (after a median of 46 days poststroke; interquartile range = 26 to 63) walking over a 10-meter distance a total of four times on 3 consecutive days. Two familiarization walks provided intrasession retest data. Results: Metric estimates of systematic and random error have been provided for obtained TD parameters. Proportional indices of reliability (ICC [2, 1] and Pearson's r) were generally high, ranging from .72 to .94. Conclusion: By quantifying systematic and random error associated with the process of repeated measurements, criteria have been provided for evaluating change in TD variables during rehabilitation. Although error for gait velocity was small relative to individual differences in the stroke group, it was large relative to levels of change derived from measurements reported during typical periods of rehabilitation. Serial measurements of gait during rehabilitation may be better than two consecutive measurements. This study highlights the need to interpret estimates of error according to the purpose of measurement.

Footswitch system for measurement of the temporal parameters of gait

Gait analysis relies upon accurate measurement of initial and end foot contact times. These times act as a reference point for correlating all other gait data and as a means of distinguishing normal and pathologic gait. We have developed a simple, inexpensive footswitch system that provides accurate estimates of the start and end of stance phase for sequential steps. The estimates of the beginning and end of stance phase do not require custom footwear, extensive calibration, or precise placement of the sensor within the shoe. The system is based on a commercially available transducer and can be readily reproduced for use in a laboratory setting for less than $50. We describe this system, as well as its validation. To assess the accuracy of this footswitch system, we compared footswitch based estimates of initial and end foot contact times with those obtained using a force platform as 10 people took 30 steps (10 each at slow, normal and fast walking rates) across a force platform. Both estimates coincided within ± 10 ms (mean: 0 ± 3 ms; N = 300) for the start of stance phase and within ± 22 ms (mean: −1 ± 8 ms; N = 300) for the end of stance phase. For stance duration, the differences ranged from −24 to 28 ms (mean: 1 ± 10 ms; N = 300). In combination, these measures can be used to estimate stance duration to within 3% of force plate determined values for steps with stance durations ranging from 446 to 1594 ms. Estimates of swing and stride duration also are within 5% of force plate determined values. This system should therefore prove to be a useful tool for augmenting laboratory based investigations of gait.

Retest Reliability of the Temporal and Distance Characteristics of Hemiplegic Gait Using a Footswitch System

Using a footswitch system, the retest reliability of the temporal and distance parameters of gait was investigated within a session for 22 stroke patients in the early phase of rehabilitation. High to very high reliability was found for the temporal and distance parameters of gait, and the temporal symmetry index based on the difference in single-limb support duration between each leg (r = 0.85 to 0.98; intraclass correlation coefficients (ICC)(2,1) = 0.82 to 0.98). Significant differences were found between the two trials for velocity, stride length, and total double support (p < .05). Despite the high reliability coefficients, 95% confidence intervals, which take into account the random and systematic error, were wide for all parameters. These wide confidence intervals indicate that the use of two consecutive measurements for interpreting an individual patient's change would not be a sensitive method for monitoring progress or deterioration during rehabilitation. Strategies that may improve the clinical usefulness of temporal and distance gait measures in stroke rehabilitation are discussed. These include further reducing error sources, increasing data collection per measurement, using serial measurements on each patient, or using less rigorous confidence intervals.

Gait recovery pattern of unilateral lower limb amputees during rehabilitation

The aim of this study was to determine the rate at which gait recovery as measured by temporal distance factors (velocity and symmetry) occurs in unilateral lower limb amputees. A microcomputer foot switch system was used to record the gait patterns of twenty subjects, mean age 65.1 years. The initial measurement was taken when the subject was capable of walking 6 metres with an interim prosthesis within the parallel bars. The patient sample as a whole was analyzed and subjects were further divided into four groups, depending on ambulatory aid required at discharge. Group A, n = 3 used no aid, Group B, n = 5 used a single stick, Group C, n = 6 used 2 single sticks and Group D, n = 5 required frames. A one way analysis of variance (F = 4.55, p = 0.02) showed a significant difference between the Groups, (A and D, B and D, C and D). The major velocity increase occurs within the first 30 days of the gait training programme. Overall about 55% increase in velocity can be expected within the first fifteen day period followed by an additional 30% between days 15-30. A moderately strong correlation (r = 0.78) was found between initial and discharge velocity. The correlation between initial and discharge symmetry was weaker (r = 0.50).

Pelvic exercise and gait in hemiplegia.

The purpose of this study was to describe and compare the gait of 20 patients with hemiplegia secondary to cerebrovascular accident (CVA) before and after a treatment regimen of resisted pelvic motions. Ten women and 10 men were studied, with a mean age of 48 years and a mean duration post-CVA of two months. Nine subjects (45%) were right hemiplegic, and 11 subjects (55%) were left hemiplegic. Treatment consisted of four sets of five repetitions each of manually resisted pelvic anterior-elevation and posterior-depression movements on the involved side. An insole footswitch system, knee electrogoniometer, and force walking aid were used in gait analysis performed before treatment, immediately after treatment (posttest 1), and 30 minutes after treatment (posttest 2). Results showed significant overall improvement in gait in posttest 1 (p less than .005) compared with the pretest. This improvement, however, was not maintained in posttest 2. Ten patients improved overall in posttest 1; only 4 patients also showed improvement in posttest 2. The major improvements seen immediately after treatment were observed in stance stability and limb advancement in the involved limb. More research is needed to identify an optimum treatment with carry-over using this technique.

A 3—Dimensional approach to assessment to infant crawling kinematics

The purpose of the present study was to assess whether any differences existed in the upper body accelerations of young and elderly subjects during natural speed walking. Head and trunk accelerations in eight young subjects (aged 23±4 years) and eight healthy elderly subjects (aged 74±3 years) were measured during level walking on a 20 m walkway using a pair of tri-axial accelerometers. Heel contact and toe-off events were determined using a footswitch system embedded in the innersole of the right shoe. Gait measures assessed included; stride, stance and swing durations, cadence, gait velocity, step length and 3D head and trunk accelerations. All acceleration variables were normalised to walking speed before statistical analysis. The main findings of this study were: (1) the peak positive anterior–posterior (AP) trunk acceleration associated with push-off was significantly lower for elderly subjects, (2) the peak negative AP head and trunk accelerations following heel contact was significantly higher for elderly subjects, and (3) the time delay between trunk and head accelerations experienced in the AP direction was significantly lower for the elderly compared to the young group. Together, these results suggest that elderly subjects exhibit different patterns of upper body motion in the direction of travel compared to younger subjects. These differences are probably motivated by the need to maximise dynamic stability during critical parts of the gait cycle.

Ankle and subtalar motion during gait in arthritic patients.

The purposes of this study were 1) to document ankle and subtalar motion during gait in 20 healthy subjects and in 25 patients with rheumatoid arthritis (RA) and 2) to determine stride characteristics with and without the use of an extended University of California Biomechanics Laboratory orthosis in RA patients with painful ankle and hindfoot deformity. An insole foot-switch system and ankle and subtalar electrogoniometers measured stride characteristics and dynamic range of motion (ROM). Arthritic patients demonstrated less ROM than healthy subjects except for ROM of hindfoot valgus. Arthritic patients also had slower gait velocity and less single limb support (SLS) time. In five new and five current orthotic wearers, a significant increase (p less than .01) in velocity and SLS time occurred with shoes and a further significant increase (p less than .01) occurred with the orthosis. Nine of 10 patients reported a decrease in ankle and hindfoot pain after using the orthosis. This study demonstrates the value of an orthosis for the treatment of arthritic patients with ankle and hindfoot pain and deformity.