Walking speed, unilateral leg loading, and step symmetry in young adults

Changes in Navigation Controls and Field-of-View Modes Affect Cybersickness Severity and Spatiotemporal Gait Patterns After Exposure to Virtual Environments

OBJECTIVE

To examine the effects of navigation controls and field-of-view modes on cybersickness severity and gait dynamics after cessation of exposure to a virtual environment (VE).

BACKGROUND

The applications of virtual reality are increasing in various fields; however, whether changes in interaction techniques and visual contents could mitigate the potential gait disturbance following VE exposure remains unclear.

METHOD

Thirty healthy adults wore a head-mounted display to complete six sessions of 12-min run-and-gun tasks using different navigation controls (gamepad, head, natural) and field-of-view modes (full, restricted). Forward and backward walking tasks were performed before and after VE exposure. The degrees of cybersickness and presence were evaluated using questionnaires, along with the in-session task performance. Spatiotemporal gait measures and their variabilities were calculated for each walking task.

RESULTS

The participants experienced less cybersickness with the head and natural controls than with the gamepad. Natural control, based on matching body movements, was associated with the highest degree of presence and best performance. VE navigation using the gamepad showed reduced cadences and increased stride times during postexposure forward-walking tasks. When the VE was presented via the restricted field-of-view mode, increased gait variabilities were observed from backward-walking tasks after VE exposure.

CONCLUSION

Body movement-based navigation controls may alleviate cybersickness. We observed gait adaptation during both ambulation tasks, which was influenced by the navigation control method and field-of-view mode.

APPLICATION

This study provides the first evidence for gait adaptation during balance-demanding tasks after VE exposure, which is valuable for designing guidelines for virtual reality interactions.

Examination of the prediction of the planar piecewise continuous lumped muscle parameter model for walking gait with ankle-foot orthosis

GOAL

This work examines the use of a previously described piecewise continuous lumped muscle parameter (PPCLMP) model for predicting selected gait parameters for walking without and with ankle-foot orthoses (AFOs) of varying stiffnesses.

METHODS

Two AFOs with low (3.4 Nm/deg) and high (6.9 Nm/deg) stiffnesses were tested on the left leg of six healthy subjects to examine the model prediction on the influence of different AFO stiffnesses on gait.

RESULTS

The model prediction errors ranged from 0 % to 70 % for step lengths with root mean square error (RMSE) of 0.15 m and ranged from 0 % to 67 % for swing time with RMSE of 0.07 s. The prediction precision of step length was more consistent among subjects than of swing time.

DISCUSSIONS AND CONCLUSIONS

The model predicts the observed shortened step lengths and swing times, but there were significant differences between predicted and observed swing times and step lengths. The causes of these differences might be differences in the lumped muscle parameters taken from the literature and those of the subjects tested. Also, the model assumption that muscle stiffness is proportional to joint angle may not be corrected.

Validity and reliability of a commercial wearable sensor system for measuring spatiotemporal gait parameters in a post-stroke population: the effects of walking speed and asymmetry

Objective.Commercial wearable sensor systems are a promising alternative to costly laboratory equipment for clinical gait evaluation, but their accuracy for individuals with gait impairments is not well established. Therefore, we investigated the validity and reliability of the APDM Opal wearable sensor system to measure spatiotemporal gait parameters for healthy controls and individuals with chronic stroke.Approach.Participants completed the 10 m walk test over an instrumented mat three times in different speed conditions. We compared performance of Opal sensors to the mat across different walking speeds and levels of step length asymmetry in the two populations.Main results. Gait speed and stride length measures achieved excellent reliability, though they were systematically underestimated by 0.11 m s-1and 0.12 m, respectively. The stride and step time measures also achieved excellent reliability, with no significant errors (median absolute percentage error <6.00%,p> 0.05). Gait phase duration measures achieved moderate-to-excellent reliability, with relative errors ranging from 4.13%-21.59%. Across gait parameters, the relative error decreased by 0.57%-9.66% when walking faster than 1.30 m s-1; similar reductions occurred for step length symmetry indices lower than 0.10.Significance. This study supports the general use of Opal wearable sensors to obtain quantitative measures of post-stroke gait impairment. These measures should be interpreted cautiously for individuals with moderate-severe asymmetry or walking speeds slower than 0.80 m s-1.

Effect of unilateral ankle loading on gait symmetry in young adults

BACKGROUND

Walking requires constant adjustments to the changing environment. An asymmetrical perturbation can affect the gait symmetry, cause gait adaptations, and potentially induce retention of the adapted gait after removal of the perturbation. A unilateral ankle load has the potential to create asymmetry and facilitate the emergence of new gait patterns. However, few studies have examined the effect of unilateral loading on muscular adjustments during walking. The purpose of this study was to investigate gait adaptations and muscular adjustments after unilaterally loading or unloading the ankle.

RESEARCH QUESTION

What are the effects of unilateral loading and unloading on gait spatiotemporal parameters and muscle activation in young adults?

METHODS

Twenty young adults (10 M/10 F) walked on a treadmill at their preferred walking speeds in 3 conditions: 1) a 2-minute baseline trial; 2) three 5-minute trials with a load (3 % of bodyweight) on the dominant ankle (Loading); and 3) one 5-minute trial with the load removed (Unloading). Inertial measurement units (IMUs) and electromyography sensors (EMGs) were used for data collection. Early and late adaptation and post-adaptation were assessed using the first 5 strides and the last 30 strides of loading and unloading conditions. Outcome measures included symmetry index (SI) of spatiotemporal parameters, range-of-motion (ROM) of the lower body joints, and EMG integrals of leg muscles. Repeated measures ANOVA was conducted for statistical analysis (α = 0.05).

RESULTS

SI of swing phase percentage demonstrated rapid adaptation after unilateral loading or unloading. Stride length demonstrated an aftereffect following unloading. Young adults reduced ankle ROMs bilaterally in early adaptation and increased loaded-side knee and hip ROMs in late adaptation. Additionally, they increased the tibialis anterior activity bilaterally immediately after unilateral loading.

SIGNIFICANCE

Young adults showed an aftereffect in some variables after unilateral unloading, signifying that unilateral ankle loading can induce short term learning of a new gait pattern.

A Pilot Study of Intensive Locomotor-Related Skill Training and Transcranial Direct Current Stimulation in Chronic Spinal Cord Injury

BACKGROUND AND PURPOSE

Improved walking function is a priority among persons with motor-incomplete spinal cord injury (PwMISCI). Accessibility and cost limit long-term participation in locomotor training offered in specialized centers. Intensive motor training that facilitates neuroplastic mechanisms that support skill learning and can be implemented in the home/community may be advantageous for promoting long-term restoration of walking function. Additionally, increasing corticospinal drive via transcranial direct current stimulation (tDCS) may enhance training effects. In this pilot study, we investigated whether a moderate-intensity motor skill training (MST) circuit improved walking function in PwMISCI and whether augmenting training with tDCS influenced outcomes.

METHODS

Twenty-five adults (chronic, motor-incomplete spinal cord injury) were randomized to a 3-day intervention of a locomotor-related MST circuit and concurrent application of sham tDCS (MST+tDCS sham ) or active tDCS (MST+tDCS). The primary outcome was overground walking speed. Secondary outcomes included walking distance, cadence, stride length, and step symmetry index (SI).

RESULTS

Analyses revealed significant effects of the MST circuit on walking speed, walking distance, cadence, and bilateral stride length but no effect on interlimb SI. No significant between-groups differences were observed. Post hoc analyses revealed within-groups change in walking speed (ΔM = 0.13 m/s, SD = 0.13) that app-roached the minimally clinically important difference of 0.15 m/s.

DISCUSSION AND CONCLUSIONS

Brief, intensive MST involving locomotor-related activities significantly increased walking speed, walking distance, and spatiotemporal measures in PwMISCI. Significant additive effects of tDCS were not observed; however, participation in only 3 days of MST was associated with changes in walking speed that were comparable to longer locomotor training studies.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A386 ).

Varying Joint Patterns and Compensatory Strategies Can Lead to the Same Functional Gait Outcomes: A Case Study

This paper analyses joint-space walking mechanisms and redundancies in delivering functional gait outcomes. Multiple biomechanical measures are analysed for two healthy male adults who participated in a multi-factorial study and walked during three sessions. Both participants employed varying intra- and inter-personal compensatory strategies (e.g., vaulting, hip hiking) across walking conditions and exhibited notable gait pattern alterations while keeping task-space (functional) gait parameters invariant. They also preferred various levels of asymmetric step length but kept their symmetric step time consistent and cadence-invariant during free walking. The results demonstrate the importance of an individualised approach and the need for a paradigm shift from functional (task-space) to joint-space gait analysis in attending to (a)typical gaits and delivering human-centred human-robot interaction.

The Short-Term Effects of Rhythmic Vibrotactile and Auditory Biofeedback on the Gait of Individuals After Weight-Induced Asymmetry

BACKGROUND

Biofeedback (BFB), the practice of providing real-time sensory feedback has been shown to improve gait rehabilitation outcomes. BFB training through rhythmic stimulation has the potential to improve spatiotemporal gait asymmetries while minimizing cognitive load by encouraging a synchronization between the user's gait cycle and an external rhythm.

OBJECTIVE

The purpose of this work was to evaluate if rhythmic stimulation can improve the stance time symmetry ratio (STSR) and to compare vibrotactile to auditory stimulation. Gait parameters including velocity, cadence, stride length, double support time, and step length symmetry, were also examined.

METHODOLOGY

An experimental rhythmic stimulation system was developed, and twelve healthy adults (5 males), age 28.42 ± 10.93 years, were recruited to participate in walking trials. A unilateral ankle weight was used to induce a gait asymmetry to simulate asymmetry as commonly exhibited by individuals with lower limb amputation and other clinical disorders. Four conditions were evaluated: 1) No ankle weight baseline, 2) ankle weight without rhythmic stimulation, 3) ankle weight + rhythmic vibrotactile stimulation (RVS) using alternating motors and 4) ankle weight + rhythmic auditory stimulation (RAS) using a singletone metronome at the participant's self-selected cadence.

FINDINGS

As expected the STSR became significantly more asymmetrical with the ankle weight (i.e. induced asymmetry condition). STSR improved significantly with RVS and RAS when compared to the ankle weight without rhythmic stimulation. Cadence also significantly improved with RVS and RAS compared to ankle weight without rhythmic stimulation. With the exception of double support time, the other gait parameters were unchanged from the ankle weight condition. There were no statistically significant differences between RVS and RAS.

CONCLUSION

This study found that rhythmic stimulation can improve the STSR when an asymmetry is induced. Moreover, RVS is at least as effective as auditory stimulation in improving STSR in healthy adults with an induced gait asymmetry. Future work should be extended to populations with mobility impairments and outside of laboratory settings.

Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals

Background

Ankle-targeting resistance training for improving plantarflexion function during walking increases rehabilitation intensity, an important factor for motor recovery after stroke. However, understanding of the effects of resisting plantarflexion during stance on joint kinetics and muscle activity—key outcomes in evaluating its potential value in rehabilitation—remains limited. This initial study uses a unilateral exosuit that resists plantarflexion during mid-late stance in unimpaired individuals to test the hypotheses that when plantarflexion is resisted, individuals would (1) increase plantarflexor ankle torque and muscle activity locally at the resisted ipsilateral ankle, but (2) at higher forces, exhibit a generalized response that also uses the unresisted joints and limb. Further, we expected (3) short-term retention into gait immediately after removal of resistance.

Methods

Ten healthy young adults walked at 1.25 m s⁻¹ for four 10-min discrete bouts, each comprising baseline, exposure to active exosuit-applied resistance, and post-active sections. In each bout, a different force magnitude was applied based on individual baseline ankle torques. The peak resistance torque applied by the exosuit was 0.13 ± 0.01, 0.19 ± 0.01, 0.26 ± 0.02, and 0.32 ± 0.02 N m kg⁻¹, in the LOW, MED, HIGH, and MAX bouts, respectively.

Results

(1) Across all bouts, participants increased peak ipsilateral biological ankle torque by 0.13–0.25 N m kg⁻¹ (p < 0.001) during exosuit-applied resistance compared to corresponding baselines. Additionally, ipsilateral soleus activity during stance increased by 5.4–11.3% (p < 0.05) in all but the LOW bout. (2) In the HIGH and MAX bouts, vertical ground reaction force decreased on the ipsilateral limb while increasing on the contralateral limb (p < 0.01). Secondary analysis found that the force magnitude that maximized increases in biological ankle torque without significant changes in limb loading varied by subject. (3) Finally, peak ipsilateral plantarflexion angle increased significantly during post-exposure in the intermediate HIGH resistance bout (p < 0.05), which corresponded to the greatest average increase in soleus activity (p > 0.10).

Conclusions

Targeted resistance of ankle plantarflexion during stance by an exosuit consistently increased local ipsilateral plantarflexor effort during active resistance, but force magnitude will be an important parameter to tune for minimizing the involvement of the unresisted joints and limb during training.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00966-5.

The Effect of Rhythm Abilities on Metronome-Cued Walking with an Induced Temporal Gait Asymmetry in Neurotypical Adults

ABSRACT. Human gait is inherently rhythmical, thus walking to rhythmic auditory stimulation is a promising intervention to improve temporal gait asymmetry (TGA) following neurologic injury such as stroke. However, the degree of benefit may relate to an individual's underlying rhythmic ability. We conducted an initial investigation into the relationship between rhythm abilities and responsiveness of TGA when walking to a metronome. TGA was induced in neurotypical young adults with ankle and thigh cuff weights. Participants were grouped by strong or weak rhythm ability based on beat perception and production tests. TGA was induced using a unilateral load affixed to the non-dominant leg. Participants walked under three conditions: uncued baseline, metronome set to 100% of baseline cadence, and metronome set to 90% of baseline cadence. Repeated measures analysis using generalized estimating equations was conducted to determine how rhythm ability affected TGA response in each walking condition. Most participants improved TGA when walking to a metronome at either tempo compared to baseline; however, this improvement did not differ between strong and weak rhythm ability groups. Those who scored worse on the rhythm perception test also were poorer at synchronizing their steps to the beat. The induced TGA is smaller than what is commonly experienced after stroke. A larger induced TGA may be necessary to reveal subtle differences in responsiveness to rhythmical auditory stimulation between those with strong and weak rhythm abilities.

Perceptions of an over-ground induced temporal gait asymmetry by healthy young adults

Nearly 60% of individuals with stroke walk with temporal gait asymmetry (TGA; a phase inequality between the legs during gait). About half of individuals with TGA are unable to correctly identify the presence or direction of their asymmetry. If patients are unable to perceive their gait errors, it will be harder to correct them to improve their gait pattern. Perception of gait pattern error may be affected by the stroke itself; therefore, the objectives of this study were to determine how the gait of neurotypical individuals changes with an induced temporal asymmetry, and how perception of that TGA compares to actual asymmetry both before and after 15-min of exposure to the induced asymmetry. After baseline symmetry (measured as symmetry index (SI)) was assessed with a pressure sensitive mat, participants (n = 29) walked for 15 min over-ground with cuff weights (7.5% of body weight) on their non-dominant leg to induce TGA. Presence, direction, and magnitude of TGA was measured at five time points: 1) baseline, 2) immediately after unilateral loading (early adaptation (EA)), 3) at the end of 15 min of walking (late adaptation (LA)), 4) immediately after load removal (early deadaptation (EDA)), and 5) after the participant indicated that their gait had returned to baseline symmetry (late deadaptation (LDA). Presence, direction, and magnitude of perceived TGA was measured by self-report. Measured and perceived TGA changes over time were assessed with separate one-way repeated measures analyses of variance. Agreement between measured and perceived TGA was assessed. During EA, all participants walked asymmetrically, spending more time on the non-loaded limb compared to baseline (-12.67 [95%CI -14.56, -10.78], p < 0.0001). All but one participant perceived this TGA, however only fifteen (52%) correctly perceived both TGA presence and direction. At LA, the group remained asymmetric (-9.22 [95%CI -11.32, -7.12], p < 0.0001), but only 9 participants (31%) correctly perceived both the presence and direction of their TGA. Visual inspection of the data at each time point revealed most participants perceived TGA magnitude as greater than actual TGA. Overall, we find that TGA can be induced and maintained in neurotypical young adults. Perception of TGA direction is inaccurate and perception of TGA magnitude is grossly overestimated. Perceptions of TGA do not improve after a period of exposure to the new walking pattern. These preliminary findings indicate that accurately perceiving an altered gait pattern is a difficult task even for healthy young adults.

Spatio-temporal gait parameters obtained from foot-worn inertial sensors are reliable in healthy adults in single- and dual-task conditions

Inertial measurement units (IMUs) are increasingly popular and may be usable in clinical routine to assess gait. However, assessing their intra-session reliability is crucial and has not been tested with foot-worn sensors in healthy participants. The aim of this study was to assess the intra-session reliability of foot-worn IMUs for measuring gait parameters in healthy adults. Twenty healthy participants were enrolled in the study and performed the 10-m walk test in single- and dual-task ('carrying a full cup of water') conditions, three trials per condition. IMUs were used to assess spatiotemporal gait parameters, gait symmetry parameters (symmetry index (SI) and symmetry ratio (SR)), and dual task effects parameters. The relative and the absolute reliability were calculated for each gait parameter. Results showed that spatiotemporal gait parameters measured with foot-worn inertial sensors were reliable; symmetry gait parameters relative reliability was low, and SR showed better absolute reliability than SI; dual task effects were poorly reliable, and taking the mean of the second and the third trials was the most reliable. Foot-worn IMUs are reliable to assess spatiotemporal and symmetry ratio gait parameters but symmetry index and DTE gait parameters reliabilities were low and need to be interpreted with cautious by clinicians and researchers.

Muscle Co-Activation around the Knee during Different Walking Speeds in Healthy Females

The purpose of this study was to examine the changes in co-activation around the knee joint during different walking speeds in healthy females using the co-activation index. Ten healthy females (age: 21.20 ± 7.21 years, height: 164.00 ± 4.00 cm, mass: 60.60 ± 4.99 kg) participated in this study and performed three walking speeds (slow, normal, and fast). A Qualisys 11-camera motion analysis system sampling at a frequency of 200 Hz was synchronized with a Trigno EMG Wireless system operating at a 2000 Hz sampling frequency. A significant decrease in the co-activation index of thigh muscles was observed between the slow and fast, and between the normal and fast, walking speeds during all walking phases. A non-significant difference was observed between the slow and normal walking speeds during most walking phases, except the second double support phase, during which the difference was significant. A negative relationship was found between walking speed and the co-activation index of thigh muscles in all speeds during walking phases: first double support (r = −0.3386, p < 0.001), single support (r = −0.2144, p < 0.01), second double support (r = −0.4949, p < 0.001), and Swing (r = −0.1639, p < 0.05). In conclusion, the results indicated high variability of thigh muscle co-activation in healthy females during the different walking speeds, and a decrease in the co-activation of the thigh muscles with the increase of speed.

Unicompartmental knee arthroplasty results in a better gait pattern than total knee arthroplasty: Gait analysis with a smartphone application

OBJECTIVES

The aim of this study was to compare the smartphone- based gait analysis data of patients who underwent total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA).

PATIENTS AND METHODS

Between January 2016 and April 2019, a total of 51 patients (3 males, 48 females; mean age: 60.92 years; range, 51 to 70 years) who were operated with UKA or TKA in our clinic were retrospectively analyzed. The patients were divided into two groups according to the type of procedure as the UKA group (n=17) and unilateral TKA group (n=34). Gait analysis was made via a smartphone application (Gait Analyzer software version 0.9.95.0) with data acquired from the accelerometer of the smartphone. This analysis was performed using data collected from the Acceleration Sensor LSM6DSO into the Samsung Galaxy Note 10 Plus phone. Gait velocity, step time, step length, cadence, step time symmetry, step length symmetry, and vertical COM (vert-COM) parameters were measured.

RESULTS

There were no statistically significant differences between the groups in respect of age, sex, body mass index, operated side, and follow-up duration. Compared to the TKA group, the UKA patients showed a better gait pattern in gait velocity (p=0.03), step time symmetry (p=0.005), and step length symmetry (p=0.024). No significant difference was detected in step time (p=0.807), step length (p=0.302), cadence (p=0.727) and vert-COM parameters (p=0.608).

CONCLUSION

The gait of UKA patients is closer to the physiological pattern with a better gait velocity, step time symmetry, and step length symmetry than TKA patients. The surgical treatment option of UKA for knee medial compartment osteoarthritis leads to a better gait pattern than TKA.

The Effect of Increased Gait Speed on Asymmetry and Variability in Children With Cerebral Palsy

Gait of children and adolescents with cerebral palsy (CP) is often reported to be more asymmetric and variable than gait of typically developing (TD) peers. As this may lead to less stable and less efficient gait, a relevant clinical question is how asymmetry may be improved and variability reduced in this population. The main objective of the current study was to investigate whether higher walking speed would affect gait symmetry and gait variability in children and adolescents with CP. Data from clinical gait analyses of 43 children and adolescents (29 males and 14 females) with unilateral (n = 28) or bilateral (n = 15) CP were included. Mean age was 11.3 ± 3.4 years, with level I (n = 26) or level II (n = 17) according to the Gross Motor Function Classification System (GMFCS). Corresponding data from 20 TD peers, matched in age and gender, were included as reference. Step time, step length, single support, and stance phase were studied at two different gait speeds: preferred and fast walking speed. Symmetry index and coefficient of variation were used as measures of asymmetry and variability, respectively. Results indicated that all participants managed to increase gait speed when instructed to do so. Overall, increased speed did not result in a more asymmetrical or variable gait, except for an increase in step length asymmetry and a difference in response between GMFCS levels I and II in variability. This implies that manipulation of gait speed may be useful clinically without necessarily making gait more unstable. However, some increase in step length asymmetry may be inevitable when gait speed is increased in people with CP.

Quantitative analysis of the bilateral coordination and gait asymmetry using inertial measurement unit-based gait analysis

Inertial measurement unit (IMU)-based gait analysis can be used to quantitatively analyze the bilateral coordination and gait asymmetry (GA). The purpose of this study was to investigate changes in bilateral coordination and GA due to gait speed using an IMU based gait analysis and identify spatiotemporal factors affecting bilateral coordination and GA. Eighty healthy adults (40 men and 40 women) participated in the study. The mean age was 26.2 years, and the mean body mass index was 22.8 kg/m2. Three different walking speeds (80%, 100%, and 120% of preferred walking speed) on a treadmill were applied for 1 min of continuous level walking using a shoe-type IMU-based gait analysis system. The phase coordination index (PCI) and GA were calculated on three different walking speeds. Several variables (gait speed, height, body mass index, cadence, and step length) were analyzed as possible factors affecting the PCI and GA. Bilateral coordination and GA improved during fast walking (p = 0.005 and p = 0.019, respectively) and deteriorated during slow walking (p<0.001 and p = 0.008, respectively), compared with the participants' preferred walking speeds. The correlation analysis revealed that PCI was negatively correlated with step length at each walking condition and lower gait speed was negatively correlated with PCI and GA during slow walking. Both bilateral coordination and GA had a negative linear relationship with gait speed, showing an improvement in the fast walking condition and deterioration in the slow walking condition. Step length was the factor associated with the change in the bilateral coordination.

Walking Gait Before and After Chiropractic Care Following Fifth Metatarsal Fractures: A Single Case Kinetic and Kinematic Study

Objectives

The purpose of this report is to describe the kinetic and kinematic analysis of walking gait following healed left proximal fifth metatarsal fractures.

Clinical Features

A 62-year-old female presented at a chiropractic clinic with concerns that recent metatarsal fractures had not fully resolved and reported abnormal gait due to pain and several weeks use of a "walking boot." The patient's walking gait was evaluated with a force-sensor treadmill and an inertial measurement unit motion capture system. Recordings were made before, at midpoint, and post-chiropractic care (11 visits total). Data were analyzed for spatio-temporal gait parameters, vertical ground reaction forces, and ranges of motion of the hip, knee, and ankle.

Intervention and Outcome

Pre-care, the patient's self-rated disability in walking was 50 out of 80 on a Lower Extremity Functional Scale, which improved to 80 out of 80, post-care. Her self-selected preferred walking speed increased, as did step length, cadence, and single support time. Increased symmetry was seen in timing of peak ground reaction forces, stance phase percentages of loading and pre-swing, and ranges of motion for hip and knee flexion and extension.

Conclusions

The patient recovered completely, and the post-injury kinematic and kinetic data allowed for quantification of gait patterns and changes in the clinical environment.

Muscle activation pattern during self-propelled treadmill walking

[Purpose] To examine muscular demands during self-propelled treadmill walking to provide a potential option for fitness training. [Participants and Methods] Eleven healthy college students were recruited. Participants walked under three conditions: over-ground walking at a self-selected speed, treadmill walking at a self-selected speed, and treadmill walking at a speed comparable to that of over-ground walking. Step lengths and lower extremity muscle activations were recorded while participants walked under the three conditions. [Results] Step lengths were significantly shorter when participants walked on a self-propelled treadmill than when walking over-ground. The spatiotemporal and muscle activations of the gaits varied among the different walking conditions. Muscular demands at the moment of heel-strike were higher around the hip and knee when walking on the self-propelled treadmill than when walking over-ground. [Conclusion] During heel-strike, the lower extremity extensors were activated more on the self-propelled treadmill with an incline, especially at faster speeds, than during over-ground walking. A low-cost, self-propelled treadmill may be a modality for training specific muscles.

Modulation of plantar pressure and gastrocnemius activity during gait using electrical stimulation of the tibialis anterior in healthy adults

High plantar flexor moment during the stance phase is known to cause high plantar pressure under the forefoot; however, the effects on plantar pressure due to a change of gastrocnemius medialis (GM) activity during gait, have not been investigated to date. Reciprocal inhibition is one of the effects of electrical stimulation (ES), and is the automatic antagonist alpha motor neuron inhibition which is evoked by excitation of the agonist muscle. The aim of this study was to investigate the influences of ES of the tibialis anterior (TA) on plantar pressure and the GM activity during gait in healthy adults. ES was applied to the TAs of twenty healthy male adults for 30 minutes at the level of intensity that causes a full range of dorsiflexion in the ankle (frequency; 50 Hz, on-time; 10 sec, off-time; 10 sec). Subjects walked 10 meters before and after ES, and we measured the peak plantar pressure (PP), pressure time integral (PTI), and gait parameters by using an F-scan system. The percentage of integrated electromyogram (%IEMG), active time, onset time, peak time, and cessation time of TA and GM were calculated. PP and PTI under the forefoot, rear foot, and total plantar surface significantly decreased after the application of ES. Meanwhile, changes of gait parameters were not observed. %IEMG and the active time of both muscles did not change; however, onset time and peak time of GM became significantly delayed. ES application to the TA delayed the timing of onset and peak in the GM, and caused the decrease of plantar pressure during gait. The present results suggest that ES to the TA could become a new method for the control of plantar pressure via modulation of GM activity during gait.

Comparing the effects of adapting to a weight on one leg during treadmill and overground walking: A pilot study

BACKGROUND

Locomotor adaptation has been suggested as a way to improve gait symmetry in individuals post-stroke. Most perturbation methods utilize costly, specialized equipment. The use of a unilateral leg weight may provide a low cost, clinically translatable alternative. Furthermore, previous studies have suggested that adaptation context may affect movement outcomes. The purpose of this study was to assess the ability of a unilaterally applied ankle weight to drive locomotor adaptation and determine the effect of context (treadmill versus overground) in young, non-disabled participants.

METHODS

Eighteen young non-disabled adults were randomly assigned to receive 10min of walking on a treadmill with a weight (TG), overground with a weight (OG) or as a control on a treadmill/overground without a weight (CG). Outcomes measured before, during and after adaptation were: step length symmetry, single limb support symmetry and gait speed.

RESULTS

After adding the weight, single limb support immediately became asymmetrical for all participants without changes in step length symmetry. After walking for 10min, TG step length became asymmetrical. After weight removal, both TG and OG had increased step length asymmetry. TG decreased single limb support asymmetry while OG did not. After walking overground without the weight, walking parameters eventually returned to baseline in both weighted groups. The control group showed no changes.

CONCLUSION

A unilaterally applied ankle weight appears able to cause gait adaptation in young, non-disabled participants. However different adaptive changes in the gait pattern are made by the nervous system when the perturbation is applied in different contexts.

The Effects of Visual Feedback Distortion with Unilateral Leg Loading on Gait Symmetry

Our prior work provides evidence that visual feedback distortion drives an implicit adaptation; a gradual distortion of visual representation of step length modulated subjects' step lengths away from symmetry. To further explore the effect of the visual feedback distortion on unconscious change in step symmetry, we investigated whether such adaptation would occur even in the presence of altered limb mechanics by adding mass to one side of the leg. 26 subjects performed three 8-min trials (weight only, weight plus visual feedback, and weight plus visual feedback distortion) of treadmill walking. During the weight only trial, the subjects wore a 5 lb mass around the right ankle. The modification of limb inertia caused asymmetric gait. The visual feedback showing right and left step length information as bar graphs was displayed on a computer screen. To add visual feedback distortion, we increased the length of one side of the visual bars by 10% above the actual step length, and the visual distortion was implemented for the side that took longer in response to the added mass. We found that even when adjustments were made to unilateral loading, the subjects spontaneously changed their step symmetry in response to the visual distortion, which resulted in a more symmetric gait. This change may be characterized by sensory prediction errors, and our results suggest that visual feedback distortion has a significant impact on gait symmetry regardless of other conditions affecting limb mechanics. A rehabilitation program employing visual feedback distortion may provide an effective way to restore gait symmetry.

Single-Camera-Based Method for Step Length Symmetry Measurement in Unconstrained Elderly Home Monitoring

OBJECTIVE

single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring. To build unconstrained monitoring environments, we propose a method to measure step length symmetry ratio (a useful gait parameter representing gait symmetry without significant relationship with age) from unconstrained straight walking using a single camera, without strict restrictions on walking directions or routes.

METHODS

according to projective geometry theory, we first develop a calculation formula of step length ratio for the case of unconstrained straight-line walking. Then, to adapt to general cases, we propose to modify noncollinear footprints, and accordingly provide general procedure for step length ratio extraction from unconstrained straight walking.

RESULTS

Our method achieves a mean absolute percentage error (MAPE) of 1.9547% for 15 subjects' normal and abnormal side-view gaits, and also obtains satisfactory MAPEs for non-side-view gaits (2.4026% for 45°-view gaits and 3.9721% for 30°-view gaits). The performance is much better than a well-established monocular gait measurement system suitable only for side-view gaits with a MAPE of 3.5538%.

CONCLUSION

Independently of walking directions, our method can accurately estimate step length ratios from unconstrained straight walking.

SIGNIFICANCE

This demonstrates our method is applicable for elders' daily gait monitoring to provide valuable information for elderly health care, such as abnormal gait recognition, fall risk assessment, etc.

OBJECTIVE

single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring. To build unconstrained monitoring environments, we propose a method to measure step length symmetry ratio (a useful gait parameter representing gait symmetry without significant relationship with age) from unconstrained straight walking using a single camera, without strict restrictions on walking directions or routes.

METHODS

according to projective geometry theory, we first develop a calculation formula of step length ratio for the case of unconstrained straight-line walking. Then, to adapt to general cases, we propose to modify noncollinear footprints, and accordingly provide general procedure for step length ratio extraction from unconstrained straight walking.

RESULTS

Our method achieves a mean absolute percentage error (MAPE) of 1.9547% for 15 subjects' normal and abnormal side-view gaits, and also obtains satisfactory MAPEs for non-side-view gaits (2.4026% for 45°-view gaits and 3.9721% for 30°-view gaits). The performance is much better than a well-established monocular gait measurement system suitable only for side-view gaits with a MAPE of 3.5538%.

CONCLUSION

Independently of walking directions, our method can accurately estimate step length ratios from unconstrained straight walking.

SIGNIFICANCE

This demonstrates our method is applicable for elders' daily gait monitoring to provide valuable information for elderly health care, such as abnormal gait recognition, fall risk assessment, etc.

Kinematic Adaptations of Forward And Backward Walking on Land and in Water

The aim of this study was to compare sagittal plane lower limb kinematics during walking on land and submerged to the hip in water. Eight healthy adults (age 22.1 ± 1.1 years, body height 174.8 ± 7.1 cm, body mass 63.4 ± 6.2 kg) were asked to cover a distance of 10 m at comfortable speed with controlled step frequency, walking forward or backward. Sagittal plane lower limb kinematics were obtained from three dimensional video analysis to compare spatiotemporal gait parameters and joint angles at selected events using two-way repeated measures ANOVA. Key findings were a reduced walking speed, stride length, step length and a support phase in water, and step length asymmetry was higher compared to the land condition (p<0.05). At initial contact, knees and hips were more flexed during walking forward in water, whilst, ankles were more dorsiflexed during walking backward in water. At final stance, knees and ankles were more flexed during forward walking, whilst the hip was more flexed during backward walking. These results show how walking in water differs from walking on land, and provide valuable insights into the development and prescription of rehabilitation and training programs.

Coordination dynamics of (a)symmetrically loaded gait

Asymmetries in the resonant frequency of limbs/effectors lead to changes in coordination dynamics, including deviations in relative phase at ϕ = 0 or π rad and reduced stability. These effects have been successfully modeled by the extended Haken-Kelso-Bunz (HKB) coupled oscillator model (Kelso et al. in Attention and performance XIII. Erlbaum, Hillsdale, pp 139-169, 1990), and supported in laboratory tasks of rhythmic limb motions. Efforts to apply the HKB model to walking have supported the predicted deviations in phase, but not the expected decreases in coordination stability. The lack of stability effects arising from asymmetries may be due to the stabilizing influence of a treadmill or may be obscured by the balance requirements and ground impacts in gait. This study examined these possibilities by investigating walking overground with ankle weights of 3 or 6 kg to create asymmetries between the legs, as well as symmetrical loads. Participants walked without a metronome and separately with a metronome to control speed and cadence. Coordination dynamics between the legs were quantified through mean and standard deviation (SD) of ϕ, while individual leg local dynamic stability was calculated as maximum Lyapunov exponent (λ (MAX)). Irrespective of the condition, asymmetrical loads led to deviations in phase from antiphase with the loaded leg lagging behind the other, and both SDϕ and λ (MAX) increased (i.e., stability decreased). Symmetrical loads had no effect on phase deviations, but decreased stability. Overall, these findings indicate that the HKB model captures coordination dynamics in walking, but also highlights limitations in modeling the influence of loads on an individual limb.

Biomechanical characteristics of adults walking forward and backward in water at different stride frequencies

The aim of this study was to examine spatiotemporal characteristics and joint angles during forward and backward walking in water at low and high stride frequency. Eight healthy adults (22.1 ± 1.1 years) walked forward and backward underwater at low (50 pulses) and high frequency (80 pulses) at the xiphoid process level with arms crossed at the chest. The main differences observed were that the participants presented a greater speed (0.58 vs. 0.85 m/s) and more asymmetry of the step length (1.24 vs. 1.48) at high frequency whilst the stride and step length (0.84 vs. 0.7 m and 0.43 vs. 0.35 m, respectively) were lower compared to low frequency (P < 0.05). Support phase duration was higher at forward walking than backward walking (61.2 vs. 59.0%). At initial contact, we showed that during forward walking, the ankle and hip presented more flexion than during backward walking (ankle: 84.0 vs. 91.8º and hip: 22.8 vs. 8.0º; P < 0.001). At final stance, the knee and hip were more flexed at low frequency than at high frequency (knee: 150.0 vs. 157.0º and hip: -12.2 vs. -14.5º; P < 0.001). The knee angle showed more flexion at forward walking (134.0º) than backward walking (173.1º) (P < 0.001). In conclusion, these results show how forward and backward walking in water at different frequencies differ and contribute to a better understanding of this activity in training and rehabilitation.

Combined effects of age and gender on gait symmetry and regularity assessed by autocorrelation of trunk acceleration

BACKGROUND

The gait of a healthy person is believed to be more regular and symmetrical than those of an individual with a disease. Thus, symmetry and regularity are important indicators of human gait.

METHODS

The effects of age and gender on gait symmetry and regularity were investigated in 87 Japanese participants by measuring trunk accelerometry during a 7-m walk. The younger group included 26 female and 21 male students, and the elderly group included 24 females and 16 males. Average age for each group was 20 and 70 years, respectively. Gait symmetry and regularity were evaluated on the basis of autocorrelation functions of trunk accelerations of vertical and anteroposterior axes.

RESULTS

The relationship between age and gait symmetry and regularity was statistically significant for both vertical and anteroposterior axes. Elderly participants showed lower symmetry and regularity in their gait than young participants. A significant gender effect was observed for the symmetry index of both axes but not for the regularity index. Male participants showed lower gait symmetry than females. An interaction effect between age and gender was significant in the symmetry index of anteroposterior acceleration. Gender effect was appeared more clearly in elderly than young participants.

CONCLUSION

Elderly participants showed a more asymmetrical and irregular gait than young participants. In addition to age, a significant gender effect was observed on gait symmetry. However, the effect size of gender was smaller than that of age, and it was not significant for gait regularity. The gait indices obtained by autocorrelation of trunk acceleration can be considered useful to evaluate aging effect on gait.

Harmonic ratios: a quantification of step to step symmetry

The harmonic ratio (HR), derived from the Fourier analysis of trunk accelerations, has been described in various ways as a measure of walking smoothness, walking rhythmicity, or dynamic stability. There is an increasing interest in applying the HR technique to investigate the impact of various pathologies on locomotion; however, explanation of the method has been limited. The aim here is to present a clear description of the mathematical basis of HRs and an understanding of their interpretation. We present harmonic theory, the interpretation of the HR using sinusoidal signals, and an example using actual trunk accelerations and harmonic analyses during limb-loading conditions. We suggest that the HR method may be better defined, not as a measure of rhythmicity or stability, but as a measure of step-to-step symmetry within a stride.