Self-selected Comfortable Pace Research Articles

Increased Metabolic Demand During Nighttime Walking in Hilly Forest Terrain While Wearing Night Vision Goggles.

Foot-borne soldiers sometimes carry out nighttime operations. It has previously been reported an elevated metabolic demand and impaired walking economy during outdoor walking on a gravel road in darkness wearing night vision goggles (NVG), compared with wearing a headlamp. The aim of the present study was to evaluate the effect of wearing NVG while walking in a hilly forest terrain and compare the results between experienced and inexperienced NVG users. At nighttime, two different groups, inexperienced (five men and six women) and experienced (nine men) NVG users, walked 1.1 km at a self-selected comfortable pace in a hilly forest. Part I was mainly uphill, and Part II was mainly downhill. Walks were performed wearing a headlamp (light), monocular NVG (mono), binocular NVG (bino), or mono with a 25 kg extra weight (backpack). Walking economy calculated from oxygen uptake in relation to body mass and covered distance (V̇O2 (mL/[kg · km])), heart rate, gait, and walking speed were measured. In both groups, walking economy was deteriorated in all three conditions with limited vision (mono, bino, and backpack) compared to the light condition, both during Part I (mono/bino, experienced: +26/+25%, inexperienced: +34/+28%) and Part II (mono/bino, experienced: +44/+46%, inexperienced: +63/+49%). In the backpack condition, the relative change of walking economy was greater for the inexperienced group than the experienced group: Part I (experienced: +46%, inexperienced: +70%), Part II (experienced: +71%, inexperienced: +111%). Concurrently, the step length was shorter in all three conditions with limited vision during Part I (mono/bino/backpack, experienced: -7/-7/-15%, inexperienced: -12/-12/-19%) and Part II (mono/bino/backpack; experienced: -8/-8/-14%, inexperienced: -17/-15/-24%) than in the light condition. The experienced NVG users walked faster during all conditions, but there was no difference in heart rate between groups. Despite that foveal vision using NVG is adequate, it appears that the mechanical efficiency during nighttime walking in hilly terrain was markedly lower while wearing NVG than with full vision, regardless of whether the soldier was an experienced or inexperienced NVG user. Moreover, the walking economy was even more affected when adding the 25-kg extra weight. It is probable that the deteriorated mechanical efficiency was partly due to the shorter step length in all three conditions with limited vision.

Sex differences in the acute effect of stair-climbing on postprandial blood glucose levels: A randomized controlled trial

Backgrounds and aimsSingle, short stair climbing and descending (SCD) bouts of low to moderate intensity effectively lower postprandial blood glucose but previous reports have found conflicting results on interactions by sex during exercise. We hypothesize that SCD at a self-selected intensity will be equally effective at lowering postprandial blood glucose in males and females. Methods and Results: Thirty subjects (age: 23.8 (3.0) years) performed 0, 1, 3, and 10 min of SCD following consumption of a mixed meal. SCD was performed at a self-selected comfortable pace and all bouts ended at minute 28. Postprandial blood glucose was measured every 15 min for 1 h and analyzed as glucose over time, area under the curve (AUC), and incremental AUC (iAUC) using mixed-design ANOVAs with repeated measures. Although there was no interaction between sex and condition or time (p = .129 to .541) for glucose over time, AUC, or iAUC, there was a main effect for sex for glucose over time (p = .004) and AUC (p = .006), but not iAUC (p = .125). Females had higher blood glucose throughout each trial (22% (13 to 31%), p = .004) but both males' and females’ postprandial blood glucose was lowered following 10 min of SCD relative to the seated control condition. Conclusions: Males and females benefited equally from single, short SCD bouts of low to moderate intensity despite females having higher blood glucose at all time points. Previous findings of sex differences in the attenuating effect of exercise on postprandial blood glucose are likely due to the use of absolute workloads leading to varying relative intensities.

Characterizing Pelvic Floor Muscle Activity During Walking and Jogging in Continent Adults: A Cross-Sectional Study.

IntroductionThe pelvic floor muscles (PFM) are active during motor tasks that increase intra-abdominal pressure, but little is known about how the PFM respond to dynamic activities, such as gait. The purpose of this study was to characterize and compare PFM activity during walking and jogging in continent adults across the entire gait cycle.Methods17 able-bodied individuals (8 females) with no history of incontinence participated in this study. We recorded electromyography (EMG) from the abdominal muscles, gluteus maximus (GM), and PFM while participants performed attempted maximum voluntary contractions (aMVC) of all muscles and completed 60–70 strides in four gait conditions: slow walk (1 km/h); regular walk (self-selected comfortable pace); transition walk (self-selected fastest walking pace); jog (same speed as transition walking). We quantified activity throughout the whole gait cycle (%aMVCGC) and during periods of bursting (%aMVCBR) for each participant, and analyzed the timing of PFM bursting periods to explore when the PFM were most active in the gait cycle. We also conducted a phase metric analysis on the PFM and GM burst timings. We performed a Spearman's rank-order correlation to examine the effect of speed on %aMVCGC, %aMVCBR, and phase metric score, and used the Wilcoxon Signed-Rank test to evaluate the effect of gait modality, matched for speed (walking vs. jogging), on these variables.ResultsThe PFM were active throughout the gait cycle, with bursts typically occurring during single-leg support. The PFM and GM were in phase for 44–69% of the gait cycle, depending on condition. There was a positive correlation between gait speed and both %aMVCGC and %aMVCBR (p < 0.001). Phase metric scores were significantly higher during jogging than transition walking (p = 0.005), but there was no difference between gait modality on %aMVCGC or %aMVCBR (p = 0.059). Where possible we disaggregated data by sex, although were unable to make statistical comparisons due to low sample sizes.ConclusionThe PFM are active during walking and jogging, with greater activity at faster speeds and with bursts in activity around single-leg support. The PFM and GM co-activate during gait, but are not completely in phase with each other.

Gait Analysis with Wearables Can Accurately Classify Fallers from Non-Fallers: A Step toward Better Management of Neurological Disorders.

Falls are the leading cause of mortality, morbidity and poor quality of life in older adults with or without neurological conditions. Applying machine learning (ML) models to gait analysis outcomes offers the opportunity to identify individuals at risk of future falls. The aim of this study was to determine the effect of different data pre-processing methods on the performance of ML models to classify neurological patients who have fallen from those who have not for future fall risk assessment. Gait was assessed using wearables in clinic while walking 20 m at a self-selected comfortable pace in 349 (159 fallers, 190 non-fallers) neurological patients. Six different ML models were trained on data pre-processed with three techniques such as standardisation, principal component analysis (PCA) and path signature method. Fallers walked more slowly, with shorter strides and longer stride duration compared to non-fallers. Overall, model accuracy ranged between 48% and 98% with 43–99% sensitivity and 48–98% specificity. A random forest (RF) classifier trained on data pre-processed with the path signature method gave optimal classification accuracy of 98% with 99% sensitivity and 98% specificity. Data pre-processing directly influences the accuracy of ML models for the accurate classification of fallers. Using gait analysis with trained ML models can act as a tool for the proactive assessment of fall risk and support clinical decision-making.

Ankle–foot orthosis with dorsiflexion resistance using spring-cam mechanism increases knee flexion in the swing phase during walking in stroke patients with hemiplegia

BackgroundAnkle–foot orthoses with plantarflexion resistance (AFO-Ps) improve knee flexion in the stance phase on the paretic side in patients with hemiparesis. However, AFO-Ps decrease ankle power generation in the late stance phase and do not improve the knee flexion in the swing phase based on insufficient push-off at the late stance, resulting in lower toe clearance. Research questionThis study sought to investigate the effect of an AFO with dorsiflexion resistance, which was implemented by our developed device with spring–cam mechanism attached to the AFO-P (Gait Solution; Pacific Supply Co., Ltd., Japan), on kinetics and kinematics in the lower limb during gait in patients with hemiparesis. MethodsEleven patients with hemiparesis due to stroke walked on a 7-m walkway at a self-selected comfortable pace in the following conditions: (a) walking using the AFO-P with the proposed device with a spring–cam mechanism (AFO-PCAM), (b) walking using the AFO-P without our device (AFO-P), and (c) walking using no device (barefoot condition). Gait kinematics and kinetics were collected using a three-dimensional motion analysis system and four ground-reaction force plates. Changes in all parameters from the barefoot to AFO-PCAM and AFO-P conditions were compared using the Wilcoxon signed-rank test. ResultsIn the AFO-PCAM condition, decrease in the maximum ankle power generation in the late-stance phase was significantly smaller than that in the AFO-P condition (p = 0.041). We noted a significant higher change in knee flexion in the paretic swing phase in the AFO-PCAM condition relative to that in the AFO-P condition (p = 0.016). The effect size for the comparisons of change was large (r ≧ 0.5). SignificanceOur device facilitated the realization of the ankle plantarflexion power in the late-stance phase because of dorsiflexion resistance, increasing the knee flexion angle during the swing phase.

Altered Vertical Ground Reaction Force Components While Walking in Individuals With Chronic Ankle Instability

Aberrant loading is a mechanism by which individuals with chronic ankle instability (CAI) may negatively impact cartilage health and therefore long-term health outcomes. We aimed to quantify walking vertical ground reaction force (vGRF) component differences between those with and without CAI. Participants (n = 36) walked barefoot overground at a self-selected comfortable pace. Normalized peak vGRF, time to peak vGRF, and normalized loading rate were calculated. Higher normalized loading rates (CAI: 5.69 ± 0.62 N/BW/s; controls: 5.30 ± 0.44 N/BW/s, p = .034) and less time to peak vGRF (CAI: 1.48 ± 0.18 s; controls: 1.62 ± 0.16 s, p = .018) were observed in those with CAI. In conclusion, those with CAI demonstrate a higher normalized loading rate and less time to peak vGRF compared to controls.

Concurrent Validity of the Zeno Walkway for Measuring Spatiotemporal Gait Parameters in Older Adults.

Previous studies have shown that older adults at high fall risk exhibit altered spatiotemporal gait parameters such as lesser gait speed, shorter step length, and greater step width compared with their healthy counterparts. Measurement of these gait parameters for older adults can play a pivotal role in clinical evaluation. While the GAITRite walkway has been previously validated and used extensively for research purposes, the Zeno walkway validity has not been established. Although both walkways use pressure sensor-based technology, comparison of the spatiotemporal gait measurements between the systems for older adults is unknown. Our purpose was to determine the concurrent validity of the Zeno walkway with the gold-standard GAITRite walkway among healthy older adults and those at high fall risk using a cross-sectional study design. Thirty healthy older adults and 17 older adults at high fall risk performed 5 walking trials barefoot on a 16´ × 4´ Zeno walkway and a 14´ × 2´ GAITRite walkway in a quasi-randomized order. Testing on the Zeno walkway was performed in a continuous manner while testing on the GAITRite walkway was performed using 5 discrete trials. Walking trials were done at self-selected comfortable and fast pace conditions. Data from the Zeno walkway were processed using the PKMAS software. Data from the GAITRite were processed using the GAITRite software. For each group and condition, spatiotemporal gait parameters common to both walkways' footfall processing software were compared using a Wilcoxon signed rank test. Concurrent validity was estimated using intraclass correlation coefficient (ICC(2,5)) and Bland-Altman plots. Both groups had significantly greater stride width on the GAITRite walkway during both conditions. During the fast pace condition, both groups walked with greater gait speed, cadence, and stride velocity, lesser step time, stance time, and double-support time, greater percentage of gait cycle spent in single-support phase, and lesser percentage of gait cycle spent in double-support phase on the GAITRite walkway. Differences observed could be attributed to surface textures, software used to process the footfalls, dimensions of the walkways, or the continuous versus discrete protocols used in the current study. The ranges of ICC(2,5) values for healthy older adults and adults at high fall risk walking at a comfortable pace were 0.449 to 0.918 and 0.854 to 0.969 and at a fast pace were 0.784 to 0.964 and 0.850 to 0.976, respectively. These values imply that the concurrent validity was moderate for most temporal parameters when healthy older adults walked at comfortable pace and excellent otherwise. Overall, the concurrent validity between both walkways was acceptable. Concurrent validity for spatiotemporal parameters between the GAITRite walkway and the Zeno walkway was moderate to excellent for older adults dependent on the specific parameter (spatial vs temporal), population (healthy or fall risk), and walking pace (comfortable or fast).

A Home-Based, Music-Cued Movement Program Is Feasible and May Improve Gait in Progressive Supranuclear Palsy.

Objectives: To understand the benefits and feasibility of using supervised, home-based, music-cued training to improve gait speed and stability in community-dwelling people with Progressive Supranuclear Palsy.Design: Feasibility trial incorporating a single group repeated-measures design.Setting: Human movement laboratory and participants' homes.Interventions:Two training sessions per week, conducted by experienced physiotherapists over 4 weeks. Each home training session consisted of a range of activities in standing or walking, with, and without auditory cues. Rhythmic auditory cues were played via a portable digital music player and consisted of metronome beats and individually chosen, commercially available rhythmic music tracks.Main Outcome Measures: Spatiotemporal gait measures were recorded using an 8 m long GAITRite® mat. Participants walked without cues at self-selected comfortable pace. The Progressive Supranuclear Palsy and Unified Parkinson's Disease Rating Scales were administered at baseline. Addenbrooke's Cognitive Examination-III, Geriatric Depression Scale, Assessment of Personal Music Preference Scale, and Physiological Profile Assessment were administered at baseline and retest.Results: At baseline, two of the five community-dwelling participants with Progressive Supranuclear Palsy walked with normal speed and low gait variability. Of the remainder who walked with slower, more variable patterns, two walked faster at retest, one by a clinically meaningful amount. Four participants reduced their timing variability at retest and three reduced step length variability. All participants reported high satisfaction levels with the program.Conclusions: When delivered at home with the support of caregivers, music-cued gait training can provide a feasible approach to improving disorders of gait stability in people with this rare, degenerative condition. Movement to music is engaging and enjoyable which can facilitate adherence to therapy.Clinical Trial Registration : ANZCTR 12616000851460. http://www.anzctr.org.au/

An examination of treadmill running familiarisation in barefoot and shod conditions in healthy men

ABSTRACTRunning on a treadmill is an activity that is novel to many people. Thus, a familiarisation period may be required before reliable and valid determinations of biomechanical parameters can be made. The current study investigated the time required for treadmill familiarisation under barefoot and shod running conditions. Twenty-six healthy men, who were inexperienced in treadmill running, were randomly allocated to run barefoot or shod for 20 minutes on a treadmill at a self-selected comfortable pace. Sagittal-plane kinematics for the ankle, knee and hip, and ground reaction force and spatio-temporal data were collected at two-minute intervals. For the barefoot condition, temporal differences were observed in peak hip flexion and peak knee flexion during swing. For the shod condition, temporal differences were observed for peak vertical ground reaction force. No temporal differences were observed after 8 minutes for either condition. Reliability analysis revealed high levels of consistency (ICC > 0.90) across all consecutive time-points for all dependent variables for both conditions after 8 minutes with the exception of maximal initial vertical ground reaction force loading rate. Participants in both barefoot and shod groups were therefore considered familiarised to treadmill running after 8 minutes.

Dual-task related gait changes in individuals with trans-tibial lower extremity amputation

BackgroundThe improvement of gait and mobility are major rehabilitation goals following lower extremity amputations. However, when living in the community many daily activities require the multitasking of motor and cognitive tasks. The dual-task paradigm can be used to evaluate the concurrent performance of mobility and cognitive tasks. Research questionThe purpose of this study was to evaluate the effects of dual-task gait testing in older adults with trans-tibial amputations. MethodsTwenty-four people (15 men, mean age ± SD, 62.72 ± 8.59) with trans-tibial amputation walked on an electronic walkway at i) self-selected comfortable pace and ii) self-selected comfortable pace while counting backwards by threes from a number randomly selected between 100 and 150. Cognitive performance, in the form of corrected response rate, was also evaluated as a single-task. ResultsThe dual-task testing produced poorer performance in velocity (single-task = 58.15 ± 23.16 cm/s, dual-task = 50.92 ± 21.16 cm/s, p = 0.008), cadence (single-task = 76.65 ± 15.84 steps/min, dual-task = 67.85 ± 15.76 steps/min, p = 0.002) and stride time (single-task = 1094 ± 458.28 ms, dual-task = 1241.44 ± 513.73 ms, p = 0.005). Step length, stance time and single limb support time symmetry were also affected, such that less time was spent on the amputated limb during the dual-task testing. SignificanceDual-task testing demonstrated interference resulting in a poor performance in both gait and cognitive performance in trans-tibial amputees. Further research is suggested to evaluate the change in cognition-mobility effects over time and the relationship of this value to future adverse events such as falls and successful outcomes such as community ambulation and reintegration.

Reducing gait speed affects axial coordination of walking turns

Turning is a common feature of daily life and dynamic coordination of the axial body segments is a cornerstone for safe and efficient turning. Although slow walking speed is a common trait of old age and neurological disorders, little is known about the effect of walking speed on axial coordination during walking turns. The aim of this study was to investigate the influence of walking speed on axial coordination during walking turns in healthy elderly adults. Seventeen healthy elderly adults randomly performed 180° left and right turns while walking in their self-selected comfortable pace and in a slow pace speed. Turning velocity, spatiotemporal gait parameters (step length and step time), angular rotations and angular velocity of the head and pelvis, head-pelvis separation (i.e. the angular difference in degrees between the rotation of the head and pelvis) and head-pelvis velocity were analyzed using Wilcoxon signed-rank tests. During slow walking, turning velocity was 15% lower accompanied by shorter step length and longer step time compared to comfortable walking. Reducing walking speed also led to a decrease in the amplitude and velocity of the axial rotation of the head and pelvis as well as a reduced head-pelvis separation and angular velocity. This study demonstrates that axial coordination during turning is speed dependent as evidenced by a more ‘en bloc’ movement pattern (i.e. less separation between axial segments) at reduced speeds in healthy older adults. This emphasizes the need for matching speed when comparing groups with diverse walking speeds to differentiate changes due to speed from changes due to disease.

P183. Effect of nigral stimulation on gait in Parkinson’s disease

Introduction Freezing of gait is a debilitating symptom of Parkinson’s disease with major impact on quality of life. Interleaved stimulation of the subthalamic nucleus (STN-DBS) and the substantia nigra pars reticulata (SNr) may improve otherwise resistant freezing of gait ( Weiss et al., 2013 ), and SNr stimulation was described to modulate presumably axial motor symptoms ( Chastan et al., 2009 ). Methods We performed combined kinematic and electrophysiological (EMG, EEG) analyses in 6 patients with Parkinson’s disease and STN-DBS (5 male, 63 ± 8 years). 5 of these patients were also available for SNr stimulation (lowest electrode contact of the subthalamic lead reaching SNr). Patients were recorded during walking at self-selected comfortable pace on a straight walkway of nine meters. Patients were measured in three conditions: ‘stimulation off’, ’subthalamic stimulation on’, ’nigral stimulation on’. Gait kinematics were recorded by 3 sensors (both left and right ankle, lumbar position) measuring acceleration, angular velocity, and the direction of the magnetic field in three directions. We calculated the gait cycle time and the peak shank angular velocity during the swing phase (angular velocity maximum during the swing phase). Results Our preliminary analyses show that the gait cycle time was similar in all three conditions. The peak shank angular velocity was faster in both subthalamic and nigral stimulation as compared to ‘stimulation off’. Conclusion Both subthalamic and nigral stimulation modulate the peak shank angular velocity in patients with Parkinson’s disease. Additional measurements and correlations to EMG/ EEG analyses are under preparation and will be presented.

The effects of a concurrent motor task on walking in Alzheimer's disease

The important relationship between cognition and gait in people with dementia has been explored with dual-task studies using added cognitive tasks. Effects of less commonly studied but also attention-dividing motor dual-tasks are important to assess in this group as they are common in everyday function and may affect gait differently from cognitive dual-tasks. They may also be easier to comprehend allowing their application with more severe cognitive impairment. The aim of this study was to evaluate the effects and feasibility of a motor dual-task (MDT) on gait measures in people with Alzheimer's disease (AD). Thirty people (15 men, mean age±SD, 80.2±5.8 years) with a diagnosis of probable AD (MMSE range 8–28) walked on an electronic walkway (i) at self-selected comfortable pace and (ii) at self-selected comfortable pace while carrying a tray and glasses. The MDT produced significant decreases in velocity (Baseline=111.5±26.5cm/s, MDT=96.8±25.7cm/s, p<0.001) and stride length (Baseline=121.4±21.6cm, MDT=108.1±21.0cm, p<0.001) with medium effect sizes, and increased stride time (Baseline=1.11±0.11s, MDT=1.14±0.12s, p=0.001) with small effect size. Measures of spatial (Baseline=3.2±1.0%, MDT=3.9±1.5%, p=0.006) and temporal (Baseline=2.4±0.8%, MDT=2.8±0.8%, p=0.008) variability increased with the motor dual-task, with medium effect sizes. A trend for motor dual-task changes in gait measures to increase with greater disease severity did not reach significance. The tray-carrying task was feasible, even for participants with severe cognitive decline. Further comparison of different types of motor and cognitive dual-tasks may contribute to development of a framework for clinical intervention to improve reduced dual-task walking capacity in people with AD.

Effects of walking direction and cognitive challenges on gait in persons with multiple sclerosis.

Declines in walking performance are commonly seen when undergoing a concurrent cognitive task in persons with multiple sclerosis (MS). The purpose of this study was to determine the effect of walking direction and simultaneous cognitive task on the spatiotemporal gait parameters in persons with MS compared to healthy controls. Ten persons with MS (Median EDSS, 3.0) and ten healthy controls took part in this pilot study. Participants performed 4 walking trials at their self-selected comfortable pace. These trials included forward walking, forward walking with a cognitive task, backward walking, and backward walking with a cognitive task. Walking performance was indexed with measures of velocity, cadence, and stride length for each testing condition. The MS group walked slower with significantly reduced stride length compared to the control group. The novel observation of this investigation was that walking differences between persons with MS and healthy controls were greater during backward walking, and this effect was further highlighted during backward walking with added cognitive test. This raises the possibility that backward walking tests could be an effective way to examine walking difficulties in individuals with MS with relatively minimal walking impairment.

Lower limb and trunk muscles activity when exercising in water

Exercise in a water environment is growing in popularity for a wide range of health, rehabilitation applications. The characteristics of the water environment have been found to create different muscle activation patterns when comparing the land, water based activities of walking, running, knee extension exercises. The aim of this research was to extend this knowledge by comparing other exercise routines, specifically: forward walking, backward walking, jogging, deep-water running, right-side walking, forward walking with long-step, forward walking with kicking, forward walking with knee-up, forward walking with trunk twisting, forward walking with elbow-knee touching, forward walking with knee side-up, backward walking with knee side-up. Ten male adults (age: 27.4 ± 5.9 yr) conducted 20 sec of self-selected comfortable pace exercise for the 12 different forms listed. During each exercise, lower limb, trunk muscles activity of right side Tibialis Anterior, Soleus, Medial Gastrocnemius, Rectus Femoris, Vastus Lateralis, Biceps Femoris, Adductor Longus, Gluteus Medialis, Gluteus Maximus, Rectus Abdomen, Oblique Externus Abdominis, Erector Spine were measured by surface electrodes, sampled at 1,000 Hz. A band-pass filter with 10–500 Hz was applied to the collected data, the root mean square value was calculated for one step cycle, namely right side foot contact to the next right side foot contact. This was averaged across all subjects. The results showed that each form of exercise has its own unique muscle activation pattern. Jogging used lower limb muscles more than the other forms of exercise, deep-water running used the thigh, trunk muscles. Forward walking with kicking, trunk twisting, elbow-knee touching used not only lower limb muscles, but also the trunk muscles, more than the other forms of exercise. The muscle activity of Vastus Lateralis was lower in the forward walking than the all other forms. In comparing each different form of exercise the backward, right-side, the forward walking with knee-up were identified as the lowest intensity form for the lower limb, compared to the other forms. This study identified the different muscle activity activation patterns of lower, trunk muscles with respect to 12 different water based exercises. This new knowledge can guide the exercise prescription protocols for more effective water based exercise routines.

Coordination of Dynamic Balance During Gait Training in People With Acquired Brain Injury

Clark RA, Williams G, Fini N, Moore L, Bryant AL. Coordination of dynamic balance during gait training in people with acquired brain injury. ObjectiveTo investigate movement of the center of mass (COM) during different gait training methods in people with neurologic conditions. DesignCoordination of the gait cycle, represented by mediolateral COM displacement amplitude, timing, and stability, was assessed during a variety of gait training methods performed in a single session. SettingGait laboratory. ParticipantsPeople who were unable to walk unassisted due to an acquired brain injury (n=17) and healthy control subjects (n=25). InterventionsThe participants performed 7 alternative gait training methods in a randomized order. These were therapist manual facilitation, the use of a gait assistive device, treadmill walking with handrail support, and 4 variations of body weight–support treadmill training with combinations of handrail and/or therapist support. Main Outcome MeasuresMediolateral COM movement was analyzed in terms of displacement amplitude (overall range of motion), timing (relative to stride time), and stability (steadiness of the movement). Normative values for these measures were acquired from 25 healthy participants walking at a self-selected comfortable pace. ResultsBody weight–support treadmill training without any additional support resulted in significantly (P<.05) greater amplitude, altered timing, and reduced movement stability compared with nonpathologic gait. Allowing handrail support or therapist facilitation reduced this effect and resulted in treadmill training (± body weight support) having lower movement amplitudes when compared with the other training methods. Therapist manual facilitation most closely matched nonpathologic gait for timing and stability. ConclusionsIn the context of overall dynamic gait coordination, no single method of training provides the optimal stimulus. A training program that uses a variety of techniques may provide a beneficial rehabilitation response.

Effect of treadmill walking on the stride interval dynamics of human gait

Metronomic walking has been found to diminish the statistical persistence intrinsic to the stride interval time series of human gait. Since treadmill walking (TW) possesses a similar form of external pacing, we proposed to study the disruptions in the natural neuromuscular rhythms of gait during TW. Treadmill walking is a widespread rehabilitative tool, however, its effect on an individual’s stride dynamics is not well understood. To better elucidate potential effects, we tested the hypothesis that TW without handrails would diminish the statistical persistence in an individual’s stride interval time series. The scaling exponent ( α ) was employed in this study as a measure of the statistical persistence of the stride interval time series. Sixteen able-bodied young adults (mean age: 23.3 ± 3.3 years) were instructed to walk at a self-selected comfortable pace for 15 min in three different conditions in a randomized order: (1) overground walking, (2) TW without holding a handrail (NoRail) and (3) TW while holding a front handrail (Rail). The α did not differ significantly between the overground and NoRail conditions ( P > 0.5 ). However, the α of the Rail condition ( α = 0.92 ± 0.10 ) differed significantly from both the overground ( α = 0.83 ± 0.06 ; P < 0.015 ) and NoRail conditions ( α = 0.82 ± 0.08 ; P < 0.01 ). In contrast, stride interval variability did not change between walking conditions ( P > 0.5 ) . These findings indicate that comfortable-paced TW does not diminish the intrinsic stride dynamics of human gait.

The effects of constraining eye movements on visually evoked steering responses during walking in a virtual environment

We have previously shown that participants who step in place while viewing a moving scene that simulates walking towards and turning a corner demonstrate anticipatory sequential reorientation of axial body segments with timing characteristics similar to those seen during real turning. We propose that the coordination of axial body segments during steering represents a robust pre-programmed postural synergy triggered by gaze realignment in the desired direction of travel. The primary aim of the current study was to test this hypothesis by studying the effects of constraining eye movement on visually evoked steering responses exhibited by participants stepping in place in a virtual environment. We predicted that preventing participants from generating anticipatory gaze shifts would significantly attenuate or eliminate visually evoked postural responses. A secondary aim was to investigate the nature of the visual cues that trigger the coordinated eye and whole body response by testing whether spatial (distance from the corner) or temporal (time to contact with corner) parameters modulated with the speed of the visual scene (normal, half speed and double speed). Six university graduate student (27.8 +/- 5.0 years) participants were asked to step in place at a self-selected comfortable pace while immersed in a virtual environment which simulated walking down a hallway and turning a corner. In half of the trials participants were required to maintain gaze direction on a static target placed in the middle of the viewing screen. Whole body kinematics and gaze behaviour were recorded. In support of our hypothesis, gaze fixation on a stationary target resulted in the suppression of anticipatory steering responses. Although postural adjustments were still observed during constrained gaze trials, they were reactive rather than anticipatory in nature and were significantly smaller than trials in which gaze was unconstrained. Our results further suggest that the time of eye and body reorientation is dependent on the temporal rather than spatial visual cues, i.e. visually specified estimation time to contact with the virtual corner. These results indicate that gaze redirection is a prerequisite for the initiation of a pre-programmed steering synergy and suggest that these robust postural responses are intimately linked to the oculomotor control processes within the central nervous system.

The reaction strategy of lower extremity muscles when slips occur to individuals with trans-femoral amputation

The aim of this study is to investigate the surface electromyography (sEMG) responses of lower extremity muscles for both healthy people and individuals with trans-femoral amputation (TFA), when slip events occur during level walking. Six male individuals with unilateral TFA and five healthy subjects participated in this study. Each subject was required to walk at a self-selected comfortable pace along a 5 m plastic walkway, and to perform walking trials on dry and oily conditions respectively. The sEMG signals of muscles on legs and around waist were recorded in each trial and the normalized instantaneous muscle power (IMP) values were employed to quantify the response intensity. The IMP profiles of each muscle in oily-surface walking trials were compared quantitatively with that in dry-surface trials. There are three main findings in this study. (1) Different muscle reaction strategies are employed in slip events by the healthy persons and the individuals with TFA, respectively. Moreover, when the slip event occurs on the prosthetic leg and the intact leg of the individuals with TFA respectively, the muscle reaction strategies are also different. (2) The individuals with TFA face higher risks of fall than the healthy persons no mater slips occur on the prosthetic side or the intact side. (3) The hip muscles, especially the gluteus maximus (GMA) muscles, always enormously contribute to posture adjustment and balance recovery in slip events.

Stump-socket forces in the syme prosthesis

The data in this paper are related to the research articles entitled “Kinetics of transfemoral amputees with osseointegrated fixation performing common activities of daily living” (Lee et al., Clinical Biomechanics, 2007.22(6). p. 665–673) and “Magnitude and variability of loading on the osseointegrated implant of transfemoral amputees during walking” (Lee et al., Med Eng Phys, 2008.30(7). p. 825–833). This article contains the overall and individual loading characteristics applied on screw-type osseointegrated implant generated by transfemoral bone-anchored prostheses fitted with basic components during daily activities at self-selected comfortable pace. Overall and individual data was presented for the (A) spatio-temporal characteristics, (B) loading patterns, (C) loading boundaries and (D) the loading local extremum during level walking, ascending and descending ramp and stairs. Inter-participant variability of these new datasets with basic components is critical to improve the efficacy and safety of prosthetic components as well as the design of future automated algorithms and clinical trials. Online repository contains the files: https://data.mendeley.com/datasets/hh8rjjh73w/1.