Stride-dependent changes in gait of older people

Société de Biomécanique young investigator award 2022: Effects of applying functional electrical stimulation to ankle plantarflexor muscles on forward propulsion during walking in young healthy adults

The triceps surae muscle, composed of the gastrocnemius and soleus muscles, plays a major role in forward propulsion during walking. By generating positive ankle power during the push-off phase, these muscles produce the propulsive force required for forward progression. This study aimed to test the hypothesis that applying functional electrical stimulation (FES) to these muscles (soleus, gastrocnemius or the combination of the two) during the push-off phase would increase the ankle power generation and, consequently, enhance forward propulsion during walking in able-bodied adults. Fifteen young adults walked at their self-selected speed under four conditions: no stimulation, with bilateral stimulation of the soleus, gastrocnemius, and both muscles simultaneously. Muscles were stimulated just below the discomfort threshold during push-off, i.e., from heel-off to toe-off. FES significantly increased ankle power (+22 to 28 % depending on conditions), propulsive force (+15 to 18 %) and forward progression parameters such as walking speed (+14 to 20 %). Furthermore, walking speed was significantly higher (+5%) for combined soleus and gastrocnemius stimulation compared with gastrocnemius stimulation alone, with no further effect on other gait parameters. In conclusion, our results demonstrate that applying FES to the gastrocnemius and soleus, separately or simultaneously during the push-off phase, enhanced ankle power generation and, consequently, forward propulsion during walking in able-bodied adults. Combined stimulation of the soleus and gastrocnemius provided the greatest walking speed enhancement, without affecting other propulsion parameters. These findings could be useful for designing FES-based solutions for improving gait in healthy people with propulsion impairment, such as the elderly.

Do Postural and Walking Stabilities Change over a Decade by Aging? A Longitudinal Study

BACKGROUND

Previous studies have demonstrated that the center of gravity (COG) is more unstable in the elderly than in young people. However, it is unclear whether aging itself destabilizes the COG. This study aimed to investigate changes in COG sway and gait kinematics over time by a longitudinal study of middle-aged and elderly adults.

METHODS

This study included 198 healthy middle-aged and elderly people who underwent stabilometry at ten-year intervals. The participants' mean age at baseline was 62.9 ± 6.5 years, and 77 (39%) of them were male. The results of stabilometry (mean velocity, sway area, postural sway center in the medial-lateral direction [X center], and postural sway center in the anterior-posterior direction [Y center]), and results of exercise tests (the height-adjusted maximum stride length [HMSL] and the 10 m walk test [10MWT]) were analyzed. The destabilized group with 11 participants, whose mean velocity exceeded 3 cm/s after 10 years, was compared with the stable group with 187 participants, whose mean velocity did not exceed 3 cm/s.

RESULTS

Mean velocity increased significantly over ten years (open-eye, from 1.53 ± 0.42 cm to 1.86 ± 0.67 cm, p < 0.001); however, the sway area did not change significantly. X center showed no significant change, whereas Y center showed a significant negative shift (open-eye, from -1.03 ± 1.28 cm to -1.60 ± 1.56 cm, p < 0.001). Although the results of 10MWT and initial HMSL did not differ significantly, the HMSL in the destabilized group at ten years was 0.64, which was significantly smaller than the 0.72 of others (p = 0.019).

CONCLUSIONS

The ten-year changes in COG sway in middle-aged and elderly adults were characterized by a significant increase in mean velocity but no significant difference in sway area. Because the destabilized group had significantly smaller HMSL at ten years, instability at the onset of movement is likely to be affected by COG instability.

Differential spatiotemporal gait effects with frequency and dopaminergic modulation in STN-DBS

Objective

The spatiotemporal gait changes in advanced Parkinson's disease (PD) remain a treatment challenge and have variable responses to L-dopa and subthalamic deep brain stimulation (STN-DBS). The purpose of this study was to determine whether low-frequency STN-DBS (LFS; 60 Hz) elicits a differential response to high-frequency STN-DBS (HFS; 180 Hz) in spatiotemporal gait kinematics.

Methods

Advanced PD subjects with chronic STN-DBS were evaluated in both the OFF and ON medication states with LFS and HFS stimulation. Randomization of electrode contact pairs and frequency conditions was conducted. Instrumented Stand and Walk assessments were carried out for every stimulation/medication condition. LM-ANOVA was employed for analysis.

Results

Twenty-two PD subjects participated in the study, with a mean age (SD) of 63.9 years. Significant interactions between frequency (both LFS and HFS) and electrode contact pairs (particularly ventrally located contacts) were observed for both spatial (foot elevation, toe-off angle, stride length) and temporal (foot speed, stance, single limb support (SLS) and foot swing) gait parameters. A synergistic effect was also demonstrated with L-dopa and both HFS and LFS for right SLS, left stance, left foot swing, right toe-off angle, and left arm range of motion. HFS produced significant improvement in trunk and lumbar range of motion compared to LFS.

Conclusion

The study provides evidence of synergism of L-dopa and STN-DBS on lower limb spatial and temporal measures in advanced PD. HFS and LFS STN-DBS produced equivalent effects among all other tested lower limb gait features. HFS produced significant trunk and lumbar kinematic improvements.

Influence of the Hawthorne effect on spatiotemporal parameters, kinematics, ground reaction force, and the symmetry of the dominant and nondominant lower limbs during gait

The Hawthorne effect is a change in behavior resulting from awareness of being observed or evaluated. This study aimed to determine whether awareness of being evaluated or presence of an observer influence gait. Twenty-one young women were asked to walk in three conditions. In the first condition (unawareness of evaluation; UE), participants were aware that it was a practice trial, and there was no observer. In the second condition (awareness of evaluation; AE), participants were aware that their gait was being evaluated. The third condition (AE + researcher observation; RO) was similar to the second condition except that an additional researcher observed the participant' gait. The spatiotemporal, kinematic, ground reaction forces, and ratio index (symmetry of both lower limbs) were compared among the three conditions. A higher ratio index indicated a relative increase in the value on left versus right. Gait speed (P = 0.012) and stride length (right and left; P = 0.006 and 0.007, respectively) were significantly increased in the AE + RO than in UE. Range of motion of the right hip and left ankle was significantly greater in AE than in UE (P = 0.039 and 0.012, respectively). The ratio index of ground reaction force during push-off was significantly higher in AE and AE + RO conditions than in UE (P < 0.001 and P = 0.004, respectively). The Hawthorne effect (awareness of being evaluated or presence of an observer) potentially influences gait. Thus, factors that influence gait analysis should be considered when evaluating normal gait.

Effects of aging on arm coordination at different walking speeds

BACKGROUND

Previous work has shown that the mean continuous relative phase and coordination variability of lower limbs are modified in older adults when walking.

RESEARCH QUESTION

Here, we propose to understand the extent to which such control mechanisms for upper limbs are present during gait. Specifically, we seek to understand if aging and gait speed constraints influence the interjoint control of upper limbs during walking.

METHODS

This observational study evaluated thirty-three participants, divided into older (n = 20, age 66.4 ± 4.3 years; mass: 77.2 ± 14.2 kg; height: 165 ± 9.20 cm) and young adults (n = 13, age 29.5 ± 4.7 years; mass 75.5 ± 9.6 kg; height: 172 ± 6.24 cm) were asked to walk at 0.28, 0.83, 1.38 m.s^-1 on a level treadmill while their segmental movements were simultaneously registered with 3D motion capture system. We calculated the mean continuous relative phase and coordination variability (continuous relative phase variability) in elbow-shoulder and shoulder-hip pairs, and a generalized estimating equation was used to test the main and interaction effects of age and speed.

RESULTS

Older adults had a reduced continuous relative phase (more in-phase coordination) of upper limbs at whole stance for elbow-shoulder, at loading response for shoulder-hip, at mid-stance and terminal stance for elbow-shoulder and shoulder-hip in comparison to young adults at different speeds (p < 0.05). The coordination variability of upper limbs was greater (higher continuous relative phase variability) in older than young adults at 0.28 and 1.38 m.s^-1.

SIGNIFICANCE

These findings substantiate the altered motor control role of upper limbs in gait aging, suggesting that lower self-selected speed may be related to the reduced ability to control arm movement during the intermediate phases of gait.

A normative study of the gait features measured by a wearable inertia sensor in a healthy old population

BACKGROUND

Gait function impairments are associated with the risk of various medical conditions in older adults. As gait function declines with advancing age, normative data are required for proper interpretation of gait function in older adults.

RESEARCH PURPOSE

This study aimed to construct age-stratified normative data of non-dimensionally normalized temporal and spatial gait features in healthy older adults.

METHODS

We recruited 320 community-dwelling healthy adults aged 65 years or older from two prospective cohort studies. We stratified them into four age groups (65-69, 70-74, 75-79, and 80-84 years). Each age group comprised 40 men and 40 women. We obtained six gait features (cadence, step time, step time variability, step time asymmetry, gait speed, and step length) using a wearable inertia measurement unit attached on the skin overlying L3-L4 on the back. To mitigate the influence of body shape, we non-dimensionally normalized the gait features into unitless values using height and gravity.

RESULT

The effect of age group was significant in all raw gait features (p < 0.001 for step time variability, speed and step length; p < 0.05 for cadence, step time and step time asymmetry), and that of sex was significant in the five raw gait features, except for step time asymmetry(p < 0.001 for cadence, step time, speed, and step length; p < 0.05 for step time asymmetry). When gait features were normalized, the effect of age group remained (p < 0.001 for all gait features), whereas that of sex disappeared (p > 0.05 for all gait features).

SIGNIFICANCE

Our dimensionless normative data on gait features may be useful in comparative studies of gait function between sexes or ethnicities with different body shapes.

The effect of rocker sole shoes on ground reaction force in the elderly

Aging is associated with decreases in gait performance and mobility. Toe-only rocker sole is prescribed as a common shoe modification in restricted foot and ankle joints mobility. Therefore, this study aimed to determine the effect of toe-only rocker sole shoes on the ground reaction force (GRF) in the elderly. Twenty-one older adults walked on a walkway equipped with one force plate under six different conditions including barefoot (BF), normal shoe (NS), and four types of toe-only rocker sole shoes (RS) with various degrees of rocker angle (RS10, RS20, RS30, and RS40). The peaks of the GRFs in three planes were obtained. Different rocker angles could affect GRF parameters. The first peak of GRF (FZ1) significantly increased with both RS30 and RS40 compared to BF, NS, RS10, and RS20. FZ1 significantly decreased with RS30 compared to RS40. The braking force (FX1) was significantly lower with NS compared to RS30 and RS40. FX1 was significantly higher with RS40 compared to the other shoe conditions. The propulsive force (FX2) significantly decreased during walking with BF compared to NS, RS20, RS30, and RS40. A higher FX2 was observed in RS40 than the other shoe conditions except RS30. Also, FX2 was significantly lower with RS10 compared to RS30. Increasing rocker angle may result in an increase in the peak magnitude of FZ1, FX1, FX2 in the elderly without any improvement in walking speed.

Integrated Gait Triggered Mixed Reality and Neurophysiological Monitoring as a Framework for Next-Generation Ambulatory Stroke Rehabilitation

Brain stroke affects millions of people in the world every year, with 50 to 60 percent of stroke survivors suffering from functional disabilities, for which early and sustained post-stroke rehabilitation is highly recommended. However, approximately one third of stroke patients do not receive early in hospital rehabilitation programs due to insufficient medical facilities or lack of motivation. Gait triggered mixed reality (GTMR) is a cognitive-motor dual task with multisensory feedback tailored for lower-limb post-stroke rehabilitation, which we propose as a potential method for addressing these rehabilitation challenges. Simultaneous gait and EEG data from nine stroke patients was recorded and analyzed to assess the applicability of GTMR to different stroke patients, determine any impacts of GTMR on patients, and better understand brain dynamics as stroke patients perform different rehabilitation tasks. Walking cadence improved significantly for stroke patients and lower-limb movement induced alpha band power suppression during GTMR tasks. The brain dynamics and gait performance across different severities of stroke motor deficits was also assessed; the intensity of walking induced event related desynchronization (ERD) was found to be related to motor deficits, as classified by Brunnstrom stage. In particular, stronger lower-limb movement induced ERD during GTMR rehabilitation tasks was found for patients with moderate motor deficits (Brunnstrom stage IV). This investigation demonstrates the efficacy of the GTMR paradigm for enhancing lower-limb rehabilitation, explores the neural activities of cognitive-motor tasks in different stages of stroke, and highlights the potential for joining enhanced rehabilitation and real-time neural monitoring for superior stroke rehabilitation.

Standard Error of the Mean and Minimal Detectable Change of Gait Speed in Older Adults Using Japanese Long-Term Care Insurance System

Evaluation of motor function, such as gait ability, can accurately predict the subsequent occurrence of disability in older adults. There are no reports of standard error of the mean (SEM) or minimal detectable change (MDC) with respect to gait in Japanese long-term care insurance-certified individuals. The purpose of this study was to investigate the values of preferred gait, fast gait, and the timed up and go (TUG) test. This study included 46 participants using the Japanese long-term care insurance system. (age 86.5 ± 6.6 years, 12 men, 34 women). The duration of three gait were measured twice using a stopwatch. The SEM was 0.07 for preferred gait, 0.09 for fast gait and 2.59 for TUG. The MDC was 0.19 for preferred gait, 0.26 for fast gait, and 7.17 for TUG. The SEM and MDC values of preferred gait, fast gait, and TUG in this study corroborated with those of previous studies, whereas others were different. Considering that gait speed differs with the country, it may be difficult to compare it among different population groups. We obtained the results of gait speed of Japanese long-term care insurance-certified individuals, which is a new finding

The influence of net ground reaction force orientation on mediolateral stability during walking

BACKGROUND

Previous work has linked the eccentricity of the net ground reaction force (GRF_net) to increased mediolateral instability during single-step voluntary and compensatory stepping responses. The present work sought to understand the extent to which such control mechanisms for mediolateral stability are present during gait.

RESEARCH QUESTION

How do gait velocity and step width constraints influence the kinetic control of mediolateral stability control among healthy participants?

METHODS

25 participants performed three walking conditions - normal walking with self-selected speed and foot-placement, fast walking with self-selected foot-placement, and narrowbase walking - across a 10-meter walkway. Lateral instability was quantified by the mediolateral margin of stability (MoS_ML). The frontal-plane eccentricity of the GRF_net was calculated as the difference between GRF_net vector orientation and that of a line joining the coordinates of COP_net and COM. Two discrete time-points (P1 and P2) following foot-contact were examined, as they have been suggested to be indicative of proactive and reactive COM control, respectively. Task-related differences in the magnitude and timing of kinematic and kinetic outcome variables were analysed using one-way ANOVAs with repeated-measures.

RESULTS

With constraints on step-width in narrow-base walking, participants exhibited reduced stability as evidenced by reduced MoS_ML, alongside reductions in the peak GRF_net eccentricity (θ_d) at P1. Participants exhibited no reduction in stability during fast walking, as revealed by the MoS_ML in part because of a similar onset of P1 within the gait cycle. P2 magnitude was larger in narrow-base walking relative to fast-walking, and occurred at an earlier point in the gait cycle.

SIGNIFICANCE

Findings suggest proactive mechanisms (i.e. P1) may predominantly regulate mediolateral stability during walking. Reactive mechanisms (i.e. P2), however, may be capable of offsetting instability in situations where proactive mechanisms are insufficient.

A Scoping Review on Minimum Foot Clearance: An Exploration of Level-Ground Clearance in Individuals with Abnormal Gait

Background: Falls are a major health concern, with one in three adults over the age of 65 falling each year. A key gait parameter that is indicative of tripping is minimum foot clearance (MFC), which occurs during the mid-swing phase of gait. This is the second of a two-part scoping review on MFC literature. The aim of this paper is to identify vulnerable populations and conditions that impact MFC mean or median relative to controls. This information will inform future design/maintenance standards and outdoor built environment guidelines. Methods: Four electronic databases were searched to identify journal articles and conference papers that report level-ground MFC characteristics. Two independent reviewers screened papers for inclusion. Results: Out of 1571 papers, 43 relevant papers were included in this review. Twenty-eight conditions have been studied for effects on MFC. Eleven of the 28 conditions led to a decrease in mean or median MFC including dual-task walking in older adults, fallers with multiple sclerosis, and treadmill walking. All studies were conducted indoors. Conclusions: The lack of standardized research methods and covariates such as gait speed made it difficult to compare MFC values between studies for the purpose of defining design and maintenance standards for the outdoor built environment. Standardized methods for defining MFC and an emphasis on outdoor trials are needed in future studies.

Immediate effect of insoles on balance in older adults

BACKGROUND

In recent years, fall prevention in older adults has received considerable attention in healthcare. Among many interventions, insoles are considered cost-effective and easily adopted tools to improve balance in older people. Numerous studies have verified the immediate effects of insoles on balance in older adults. However, there is still lack of consensus regarding the immediate benefits of using insoles on balance improvement.

RESEARCH QUESTION

Given this, a meta-analysis was conducted to provide more conclusive evidence about the immediate effect of insoles on balance in older adults and answer the question: "Do insoles influence balance in older people?"

METHODS

PubMed, NDSL, Medline, Google Scholar, and Web of Science were searched from March to August 2018. The key terms were "insole", "elderly", "gait", "balance", "shoe", "foot", and "postural". Finally, seven primary studies were selected for this meta-analysis. The balance related outcomes were coded to compute effect sizes and the overall effect size of the standardized mean differences was analyzed. Moderating variables included kinematic variables of balance, static and dynamic balance, and type of insole.

RESULTS

The overall effect size of insoles was medium (d = 0.618), which suggests that insoles are beneficial for older adults for improving balance. More specifically, this study revealed that textured and vibration insoles were the most effective types of insoles.

SIGNIFICANCE

This finding supports the idea that augmented tactile and mechanical sensory input from insoles can enhance the postural control mechanisms in older adults with age-related deterioration of sensory mechanisms. The use of insoles may lead to a reduction in the rate of falls which are related to decreased quality of life in older adults.

12-Week Exercise Training of Knee Joint and Squat Movement Improves Gait Ability in Older Women

This study analyzed the effects of an exercise training program consisting of a knee joint complex exercise device (leg-link system) with digitally controlled active motion function and squat movement on physical fitness and gait ability of elderly women aged 70 or above. Fifty four (54) elderly women aged 70 or above were divided into three groups as control group (n = 18), aerobic training group (n = 18), and combined training group with resistance and aerobic exercise (n = 18). Health-related physical fitness, gait ability-related physical fitness, and the temporal and spatial parameters of gait ability were compared. The health-related physical fitness after the 12-week training was not significantly altered in control group, whereas combined training group showed significant increase in all factors (p < 0.05) and aerobic training group showed significant increase (p < 0.05) only in the physical efficiency index. The gait ability-related physical fitness and all items of the temporal and spatial parameters of gait were found to have significantly increased (p < 0.05) in combined training group after the 12-week exercise training; however, in aerobic training group, only the factors related to muscular endurance and balance showed significant increase (p < 0.05). This study suggested that the exercise training consisting of knee joint complex exercise with digitally controlled active motion function and squat exercise for strengthening lower extremities and core muscles had positive effects on enhancing the ambulatory competence in elderly women.

Effects of using cane and vestibular rehabilitation on the walking function in elderly patients with dizziness

OBJECTIVE

Adults over the age of 65 years with balance disorders are at about twice the risk of falls, compared with those without balance disorders. Falls contribute to about 74% of the proximal femoral fractures commonly seen in the elderly. Since balance disorders are more prevalent in older adults than in younger adults, it is important to deal with balance disorders in older adults to prevent falls and the resulting deterioration in their ADL (activity of daily living). In this study, we investigated the effects of vestibular rehabilitation (VR) and cane use on improving gait and balance in patients aged over 65 years with balance disorder.

METHODS

Patients aged over 65 years presenting to the Department of Otolaryngology at St. Marianna University School of Medicine between July 1 and November 1, 2018, with symptoms of dizziness for ≥ 3 months and a Japanese translation of the Dizziness Handicap Inventory score of ≥ 26 were included in the study. We quantitatively analyzed their gait before and after VR, and with and without the use of a cane.

RESULTS

A total of 21 patients participated in the study (14 women; mean age 73.9 ± 6.9 years). Before VR, using a cane made no difference to step length or walking speed. After VR, using a cane increased step length from 50.5 cm (95% confidence interval [CI], 47.4-53.7 cm) to 52.0 cm (95% CI, 48.9-55.1 cm) (p = 0.039). There was no change in walking speed. A comparison of walking assessment results while using a cane before and after VR showed that step length increased from 49.9 cm (95% CI, 46.6-53.2 cm) to 52.0 cm (95% CI, 48.9-55.1 cm) (p = 0.005), and walking speed increased from 90.5 cm/s (95% CI, 82.7-98.4 cm/s) to 96.1 cm/s (95% CI, 88.3-103.9 cm/s) (p = 0.005).

CONCLUSIONS

Walking speed and step length with the use of a cane significantly improved following VR. VR and cane use may act synergistically to improve walking.

Gender-based age differences in hip and knee kinematics of Chinese adults during walking and running

BACKGROUND

Many studies have presented lower limb kinematics in Western countries, but few have concentrated on gender and age differences for Chinese populations.

OBJECTIVES

The purpose of this study was to investigate three-dimensional hip and knee kinematics especially for elderly Chinese during walking and running, as well as to analyze age differences.

MATERIALS AND METHODS

Sixty healthy volunteers, including 40 young and 20 elderly adults, were divided into two groups by gender and instructed to perform walking and running in a comfortable manner. The hip and knee kinematics were obtained with 3D Motion Capture System. Normalization was used to avoid the body size effect. Age differences were tested with independent t-test (p< 0.05).

RESULTS

In non-sagittal planes, the hip and knee ranges of motion of young males are larger during running, but smaller during walking than those of elderly males. Young females reveal smaller non-sagittal planes hip and knee ranges of motion than elderly females, regardless of whether they are walking or running. There are also significant age differences in the peak hip and knee angles especially in frontal plane during running. Young adults reveal greatly higher peak hip and knee adduction angles than elderly adults.

CONCLUSIONS

Walking speed and the hip and knee ROM for Chinese are different from Westerners. These kinematic differences can be used for reference to design better joint prostheses to meet various Chinese people's needs.

Gait Stability in Older Adults During Level-Ground Walking: The Attentional Focus Approach

OBJECTIVES

The objective of this study was to investigate the effect of attentional focus instructions on gait stability during level-ground walking among older adults.

METHODS

We recruited 140 community-dwelling older adults (mean age = 70.3 years, SD = 4.7 years) from elderly community centers in Hong Kong. The experiment included assessments on participant's characteristics and walking trials. During walking trials, each participant was invited to walk at a self-selected pace along a 6-m walkway. Internal focus instructions (Internal condition), external focus instructions (External condition), or no instruction (Control condition) were given in a randomized order for three trials per condition, giving a total of nine walking trials. Spatial and temporal gait parameters were measured.

RESULTS

Results showed significantly higher body sway and variability of swing and stance time under Internal condition relative to External and Control conditions. Moreover, reduced velocity and shorter steps were demonstrated under Internal condition relative to External and Control conditions.

DISCUSSION

External focus instructions did not improve gait stability in older adults when compared to Control condition. Internal focus instructions appear to compromise gait stability. Future research should investigate if walking instructions that refer to body movements explicitly compromise gait rehabilitation for older adults in clinical settings.

Corticomuscular control of walking in older people and people with Parkinson's disease

Changes in human gait resulting from ageing or neurodegenerative diseases are multifactorial. Here we assess the effects of age and Parkinson’s disease (PD) on corticospinal activity recorded during treadmill and overground walking. Electroencephalography (EEG) from 10 electrodes and electromyography (EMG) from bilateral tibialis anterior muscles were acquired from 22 healthy young, 24 healthy older and 20 adults with PD. Event-related power, corticomuscular coherence (CMC) and inter-trial coherence were assessed for EEG from bilateral sensorimotor cortices and EMG during the double-support phase of the gait cycle. CMC and EMG power at low beta frequencies (13–21 Hz) was significantly decreased in older and PD participants compared to young people, but there was no difference between older and PD groups. Older and PD participants spent shorter time in the swing phase than young individuals. These findings indicate age-related changes in the temporal coordination of gait. The decrease in low-beta CMC suggests reduced cortical input to spinal motor neurons in older people during the double-support phase. We also observed multiple changes in electrophysiological measures at low-gamma frequencies during treadmill compared to overground walking, indicating task-dependent differences in corticospinal locomotor control. These findings may be affected by artefacts and should be interpreted with caution.

Abnormal Gait Recognition Using 3D Joint information of Multiple Kinects System and RNN-LSTM

Gait is an important indicator for specific diseases. Abnormal gait patterns are caused by various factors such as physical, neurological, and sensory problems. If it is possible to recognize abnormal gait patterns in the early stage of the related disease, patients can receive proper treatment early and prevent secondary accidents such as falls caused by unbalanced gait. In this paper, we propose a gait recognition system that can recognize 5 abnormal gait patterns. Our system using 3D joint information obtained by using multiple Kinect v2 sensors and RNN-LSTM. In particular, abnormal gaits caused by physical problems such as injury, weakness of muscle, and joint problems are targeted for recognition. The purpose of this paper is to find optimal condition for gait recognition when using the multiple Kinect v2 sensors. Experiments were conducted by comparing the test accuracies on 14 combinations of human joint. Through this experiment, we selected optimal joints to show outstanding results so that our gait recognition model performs optimally. Results show that Ankles, Wrists, and the Head are the most influential joints on RNN-LSTM model. We applied 25-joint information of the human body to recognize gait patterns and achieved an accuracy over 97%.

Walking-speed estimation using a single inertial measurement unit for the older adults

Background

Although walking speed is associated with important clinical outcomes and designated as the sixth vital sign of the elderly, few walking-speed estimation algorithms using an inertial measurement unit (IMU) have been derived and tested in the older adults, especially in the elderly with slow speed. We aimed to develop a walking-speed estimation algorithm for older adults based on an IMU.

Methods

We used data from 659 of 785 elderly enrolled from the cohort study. We measured gait using an IMU attached on the lower back while participants walked around a 28 m long round walkway thrice at comfortable paces. Best-fit linear regression models were developed using selected demographic, anthropometric, and IMU features to estimate the walking speed. The accuracy of the algorithm was verified using mean absolute error (MAE) and root mean square error (RMSE) in an independent validation set. Additionally, we verified concurrent validity with GAITRite using intraclass correlation coefficients (ICCs).

Results

The proposed algorithm incorporates the age, sex, foot length, vertical displacement, cadence, and step-time variability obtained from an IMU sensor. It exhibited high estimation accuracy for the walking speed of the elderly and remarkable concurrent validity compared to the GAITRite (MAE = 4.70%, RMSE = 6.81 𝑐𝑚/𝑠, concurrent validity (ICC (3,1)) = 0.937). Moreover, it achieved high estimation accuracy even for slow walking by applying a slow-speed-specific regression model sequentially after estimation by a general regression model. The accuracy was higher than those obtained with models based on the human gait model with or without calibration to fit the population.

Conclusions

The developed inertial-sensor-based walking-speed estimation algorithm can accurately estimate the walking speed of older adults.

Is the walk ratio a window to the cerebellum in multiple sclerosis? A structural magnetic resonance imaging study

BACKGROUND AND PURPOSE

Existing research studies have demonstrated a relationship between magnetic resonance imaging (MRI) neuroimaging measures and walking speed in people with multiple sclerosis (PwMS). However, to date there are no data as to the brain structures involved in gait coordination and control in PwMS. Therefore, the aim of our study was to investigate the association between walk ratio, an indicator of gait coordination, and related brain structures in PwMS.

METHODS

A brain MRI was performed by a 3.0-T MR scanner in conjunction with a volumetric analysis based on three-dimensional T1-weighted images. Regions of interest were volumes of the hippocampus, amygdala, putamen, caudate, pallidum, thalamus, cerebellum and the corpus callosum regions. Walking speed and walk ratio, defined as step length divided by step rate, was measured whilst walking on an electronic walkway.

RESULTS

In all, 343 PwMS (41.1 ± 13.4 years, 69.1% female, median Expanded Disability Status Scale 2.5) were included in the study. A significant association was found between the left cerebellum volume and walk ratio after controlling for age, gender, total cranial volume and disability; R²  = 0.379, P = 0.002. A similar association was found between the right cerebellum volume and walk ratio, R²  = 0.364, P = 0.002. No correlations were observed between walk ratio and the thalamus, basal ganglia, hippocampus, amygdala and the corpus callosum volumes. No association was found between walking speed and all brain measures.

CONCLUSIONS

The walk ratio should be considered when evaluating and assessing PwMS presenting with ataxia. Furthermore, it is also hypothesized that a low walk ratio indicates a lower cerebellum volume in the MS population.

Effects of High-Frequency Proprioceptive Training on Single Stance Stability in Older Adults: Implications for Fall Prevention

Single-limb stance instability is a major risk factor for falls in older adults. Thus, improvement of stance stability could play an important role in fall prevention. This study aimed to determine whether high-frequency proprioceptive training (HPT) could significantly improve single stance stability (SSS) in older adults, by increasing proprioceptive control and optimizing the contribution of vision. Sixty-one subjects (30 men, 31 women) aged 65-85 years were investigated. The subjects were randomly assigned to three intervention groups, i.e., HPT, treadmill, and no intervention, stratifying by gender and proprioceptive control at baseline. Stability tests and HPT, consisting of 12 sessions (6 weeks), were performed with computerized postural stations. Pre-post analysis showed that HPT significantly improved SSS by increasing proprioceptive control (p<0.001) and postural control (p<0.01). The treadmill and no intervention groups did not show any significant change. The results showed that different levels of proprioceptive control may activate, inhibit, or minimize the stabilizing intervention of vision. Given that HPT significantly reduced ankle sprains and low back pain in professional athletes (previous study), we discuss the hypothesis that the risk of falls in older adults and the risk of recurrent injuries in athletes would have a common origin: lack of proprioceptive control consequent to reduced interaction with uneven ground. The findings suggest that HPT may be a powerful activator of refined proprioceptive control, which allows increased SSS, safer interaction with the ground, and mitigation of other risk factors.

Real-World Gait Speed Estimation Using Wrist Sensor: A Personalized Approach

Gait speed is an important parameter to characterize people's daily mobility. For real-world speed measurement, inertial sensors or global navigation satellite system (GNSS) can be used on wrist, possibly integrated in a wristwatch. However, power consumption of GNSS is high and data are only available outdoor. Gait speed estimation using wrist-mounted inertial sensors is generally based on machine learning and suffers from low accuracy because of the inadequacy of using limited training data to build a general speed model that would be accurate for the whole population. To overcome this issue, a personalized model was proposed, which took unique gait style of each subject into account. Cadence and other biomechanically derived gait features were extracted from a wrist-mounted accelerometer and barometer. Gait features were fused with few GNSS data (sporadically sampled during gait) to calibrate the step length model of each subject through online learning. The proposed method was validated on 30 healthy subjects where it has achieved a median [Interquartile Range] of root mean square error of 0.05 [0.04-0.06] (m/s) and 0.14 [0.11-0.17] (m/s) for walking and running, respectively. Results demonstrated that the personalized model provided similar performance as GNSS. It used 50 times less training GNSS data than nonpersonalized method and achieved even better results. This parsimonious GNSS usage allowed extending battery life. The proposed algorithm met requirements for applications which need accurate, long, real-time, low-power, and indoor/outdoor speed estimation in daily life.

The Relationship between Walking Speed and Step Length in Older Aged Patients

Compared with elderly people who have not experienced falls, those who have were reported to have a shortened step length, large fluctuations in their pace, and a slow walking speed. The purpose of this study was to elucidate the step length required to maintain a walking speed of 1.0 m/s in patients aged 75 years or older. We measured the 10 m maximum walking speed in patients aged 75 years or older and divided them into the following two groups: Those who could walk 1.0 m/s or faster (fast group) and those who could not (slow group). Step length was determined from the number of steps taken during the 10 m-maximum walking speed test, and the step length-to-height ratio was calculated. Isometric knee extension muscle force (kgf), modified functional reach (cm), and one-leg standing time (s) were also measured. We included 261 patients (average age: 82.1 years, 50.6% men) in this study. The fast group included 119 participants, and the slow group included 142 participants. In a regression logistic analysis, knee extension muscle force (p = 0.03) and step length-to-height ratio (p < 0.01) were determined as factors significantly related to the fast group. As a result of ROC curve analysis, a step length-to-height ratio of 31.0% could discriminate between the two walking speed groups. The results suggest that the step length-to-height ratio required to maintain a walking speed of 1.0 m/s is 31.0% in patients aged 75 years or older.

Mobility related physical and functional losses due to aging and disease - a motivation for lower limb exoskeletons

BACKGROUND

Physical and functional losses due to aging and diseases decrease human mobility, independence, and quality of life. This study is aimed at summarizing and quantifying these losses in order to motivate solutions to overcome them with a special focus on the possibilities by using lower limb exoskeletons.

METHODS

A narrative literature review was performed to determine a broad range of mobility-related physical and functional measures that are affected by aging and selected cardiovascular, respiratory, musculoskeletal, and neurological diseases.

RESULTS

The study identified that decreases in limb maximum muscle force and power (33% and 49%, respectively, 25-75 yrs) and in maximum oxygen consumption (40%, 20-80 yrs) occur for older adults compared to young adults. Reaction times more than double (18-90 yrs) and losses in the visual, vestibular, and somatosensory systems were reported. Additionally, we found decreases in steps per day (75%, 60-85 yrs), maximum walking speed (24% 25-75 yrs), and maximum six-minute and self-selected walking speed (38% and 21%, respectively, 20-85 yrs), while we found increases in the number of falls relative to the number of steps per day (800%), injuries due to falls (472%, 30-90 yrs) and deaths caused by fall (4000%, 65-90 yrs). Measures were identified to be worse for individuals with impaired mobility. Additional detrimental effects identified for them were the loss of upright standing and locomotion, freezing in movement, joint stress, pain, and changes in gait patterns.

DISCUSSION

This review shows that aging and chronic conditions result in wide-ranging losses in physical and sensory capabilities. While the impact of these losses are relatively modest for level walking, they become limiting during more demanding tasks such as walking on inclined ground, climbing stairs, or walking over longer periods, and especially when coupled with a debilitating disease. As the physical and functional parameters are closely related, we believe that lost functional capabilities can be indirectly improved by training of the physical capabilities. However, assistive devices can supplement the lost functional capabilities directly by compensating for losses with propulsion, weight support, and balance support.

CONCLUSIONS

Exoskeletons are a new generation of assistive devices that have the potential to provide both, training capabilities and functional compensation, to enhance human mobility.

Neurologic examination in the elderly

Clinical evaluation of neurologic disorders in the elderly requires seeking a thorough history and performing an age-appropriate neurologic examination with special attention to changes that occur with normal aging. The history should be obtained from the patient as well as collateral sources close to the patient to ensure accuracy and should include contextual elements such as medical history, social, economic, and psychological background, as well as an assessment of current functional state beyond activities of daily living. The safety of the patient, including the presence of physical, psychological, and financial threats, should be addressed during the interview. The neurological examination in older adults may need to be modified to circumvent disabilities such as hearing and visual impairment. Some elements of the neurological examination are expected to be affected by the process of aging, including pupillary reactivity, presbyopia, difficulty with ocular pursuit and up-gaze, reduced or absent distal reflexes, slower motor speed, and reduced ability to tandem walk, among others. In addition to a screening neurological assessment, evaluation of older adults with a particular complaint may require additional interview queries and examination manoeuvres. Common symptoms in the elderly include cognitive difficulties, balance and gait disorders, tremors, and neuropathy. A specialized approach to patients with cognitive difficulties must include assessment of each cognitive domain, including attention, executive function, learning and memory, perceptual-motor function, and social cognition. Balance and gait are essential parts of the neurological examination, and in patients with a history of falls or mobility issues, should become a central part of the evaluation. In patient with tremors, careful observation of the tremor quality (amplitude, frequency, and alleviating/exacerbating factors such as rest, movement, and posture) can aid diagnosis. Evaluation of neuropathy includes determining modality (numbness, tingling, pain, and weakness) and the distribution of symptoms in order to localize the site of nerve injury, which can be supplemented with nerve conduction studies/electromyography, to guide further diagnostic workup and treatment. A combination of detailed history and examination often will suggest a likely underlying neurodegenerative disorder and guide further diagnostic workup to establish a specific diagnosis.

Design of Instrumented Shoes for Gait Characterization: A Usability Study With Healthy and Post-stroke Hemiplegic Individuals

Ambulation is a fundamental requirement of human beings for enjoying healthy community life. A neurological disorder such as stroke can significantly affect one's gait thereby restricting one's active community participation. To quantify one's gait, spatiotemporal gait parameters are widely used in clinical context with different tests such as 10 meter walk test, 6 min walk test, etc. Though these conventional observation-based methods are powerful, yet they often suffer from subjectivity, a scarcity of adequately trained therapists and frequent clinical visits for assessment. Researchers have been exploring the technology-assisted solutions for gait characterization. There are laboratory-based stereophotogrammetric methods and walk mats that are powerful tools as far as gait characterization is concerned. However, these suffer from issues with portability, accessibility due to high cost, labor-intensiveness, etc. Faced with these issues, our present research tries to investigate and quantify the gait abnormalities in individuals with neurological disorder by using a portable and cost-effective instrumented shoes (Shoes_FSRhenceforth). The in-house developed Shoes_FSR comprised of a pair of shoes instrumented with Force Sensing Resistors (FSR) and a wireless data acquisition unit. The real-time FSR data was acquired wirelessly and analyzed by a central console to offer quantitative indices of one's gait. Studies were conducted with 15 healthy participants and 9 post-stroke survivors. The spatiotemporal gait parameters of healthy participants measured using Shoes_FSR were validated with standard methods such as stereophotogrammetric system and paper-based setup. Statistical analysis showed good agreement between the gait parameters measured using Shoes_FSR and the standard methods. Specifically, the mean absolute error of the spatial parameters measured by the Shoes_FSR, in the worst case, was 1.24% and that for the temporal parameters was 1.12% with that measured by standard methods for healthy gait. This research shows the potential of the Shoes_FSR to quantify gait abnormality of post-stroke hemiplegic patients. In turn, the results show a promise for the future clinical use of the Shoes_FSR.

Gait Mechanics Differences Between Healthy Controls and Patients With Peripheral Artery Disease After Adjusting for Gait Velocity Stride Length and Step Width

Patients with peripheral artery disease (PAD) experience significant leg dysfunction. The effects of PAD on gait include shortened steps, slower walking velocity, and altered gait kinematics and kinetics, which may confound joint torques and power measurements.

Spatiotemporal parameters, joint torques and powers were calculated and compared between 20 patients with PAD and 20 healthy controls using independent t-tests. Separate ANCOVA models were used to evaluate group differences after independently adjusting for gait velocity, stride length and step width. Compared to healthy controls, patients with PAD exhibited reduced peak extensor and flexor torques at the knee, and hip. After adjusting for all covariates combined, differences between groups remained for ankle power generation in late stance, and knee flexor torque. Reduced walking velocity observed in subjects affected by PAD was closely connected with reductions in joint torques and powers during gait. Gait differences remained, at the knee and ankle, after adjusting for the combined effect of spatiotemporal parameters. Improving muscle function through exercise or with the use of assistive devices needs to be a key tool in the development of interventions that aim to enhance the ability of PAD patients to restore spatiotemporal gait parameters.

Effects of 14 days of bed rest and following physical training on metabolic cost, mechanical work, and efficiency during walking in older and young healthy males

In this study, we investigated: i) the effects of bed rest and a subsequent physical training program on metabolic cost (Cw), mechanical work and efficiency during walking in older and young men; ii) the mechanisms underlying the higher Cw observed in older than young men.Twenty-three healthy male subjects (N = 16 older adults, age 59.6±3.4 years; N = 7 young, age: 23.1±2.9 years) participated in this study. The subjects underwent 14 days of bed rest followed by two weeks of physical training (6 sessions). Cw, mechanical work, efficiency, and co-contraction time of proximal muscles (vastus lateralis and biceps femoris) and distal muscles (gastrocnemius medialis and tibialis anterior) were measured during walking at 0.83, 1.11, 1.39, 1.67 m·s-1 before bed rest (pre-BR), after bed rest (post-BR) and after physical training (post-PT).No effects of bed rest and physical training were observed on the analysed parameters in either group. Older men showed higher Cw and lower efficiency at each speed (average +25.1 and -20.5%, P<0.001, respectively) compared to young. Co-contraction time of proximal and distal muscles were higher in older than in young men across the different walking speeds (average +30.0 and +110.3%, P<0.05, respectively).The lack of bed rest and physical training effects on the parameters analyzed in this study may be explained by the healthy status of both young and older men, which could have mitigated the effects of these interventions on walking motor function. On the other hand, the fact that older adults showed greater Cw, overall higher co-contraction time of antagonist lower limb muscles, and lower efficiency compared to the young cohort throughout a wide range of walking speed may suggest that older adults sacrificed economy of walking to improve stability.

Step-by-step variability of swing phase trajectory area during steady state walking at a range of speeds

BACKGROUND

Step kinematic variability has been characterized during gait using spatial and temporal kinematic characteristics. However, people can adopt different trajectory paths both between individuals and even within individuals at different speeds. Single point measures such as minimum toe clearance (MTC) and step length (SL) do not necessarily account for the multiple paths that the foot may take during the swing phase to reach the same foot fall endpoint. The purpose of this study was to test a step-by-step foot trajectory area (SBS-FTA) variability measure that is able to characterize sagittal plane foot trajectories of varying areas, and compare this measure against MTC and SL variability at different speeds. We hypothesize that the SBS-FTA variability would demonstrate increased variability with speed. Second, we hypothesize that SBS-FTA would have a stronger curvilinear fit compared with the CV and SD of SL and MTC. Third, we hypothesize SBS-FTA would be more responsive to change in the foot trajectory at a given speed compared to SL and MTC. Fourth, SBS-FTA variability would not strongly co-vary with SL and MTC variability measures since it represents a different construct related to foot trajectory area variability.

METHODS

We studied 15 nonimpaired individuals during walking at progressively faster speeds. We calculated SL, MTC, and SBS-FTA area.

RESULTS

SBS-FTA variability increased with speed, had a stronger curvilinear fit compared with the CV and SD of SL and MTC, was more responsive at a given speed, and did not strongly co-vary with SL and MTC variability measures.

CONCLUSION

SBS foot trajectory area variability was sensitive to change with faster speeds, captured a relationship that the majority of the other measures did not demonstrate, and did not co-vary strongly with other measures that are also components of the trajectory.

Gait kinematics and kinetics are affected more by peripheral arterial disease than by age

Peripheral arterial disease (PAD) produces abnormal gait and disproportionately affects older individuals. The current study investigated PAD gait biomechanics in younger (<65 yr) and older (>/=65 yr) subjects. The study included 61 patients with PAD (31 younger, age: 57.4 +/- 5.3 yr, and 30 older, age: 71.9 +/- 5.2 yr) and 52 nondisabled age-matched control subjects. Patients with PAD were tested during pain-free walking and compared with control subjects. Joint kinematics and kinetics (torques) were compared using a 2 x 2 analysis of variance (groups: patients with PAD vs control subjects, age: younger vs older). Patients with PAD had significantly increased ankle and decreased hip range of motion during the stance phase as well as decreased ankle dorsiflexor torque compared with control subjects. Gait changes in older individuals are largely constrained to time-distance parameters. Joint kinematics and kinetics are significantly altered in patients with PAD during pain-free walking. Symptomatic PAD produces a consistent ambulatory deficit across ages definable by advanced biomechanical analysis. The most important finding of the current study is that gait, in the absence of PAD and other ambulatory comorbidities, does not decline significantly with age based on advanced biomechanical analysis. Therefore, previous studies must be examined in the context of patients with potential PAD being present in the population, and future ambulatory studies must include PAD as a confounding factor when assessing the gait function of elderly individuals.

Effects of single and dual tasks during walking on spatiotemporal gait parameters of community-dwelling older

[Purpose] This study aimed to investigate the effects of single and dual motor tasks on walking in the elderly. [Subjects and Methods] Data of 308 community-dwelling elderly people were analyzed. Spatiotemporal gait data were obtained using the OPTO Gait system. The gait ability test was conducted under single- and dual-task conditions. [Results] Age and task main effects showed significant difference. Interaction did not show any significant difference. [Conclusion] Our results showed that gait performance decreased during dual task compared to single task. Moreover, we found that the higher the age, the greater the effect on dual tasks. Further research is needed to determine how to improve dual task abilities in older adults.

Comparison in three dimensional gait kinematics between young and older adults on land and in shallow water

This study investigated in three-dimensional space, firstly whether the aquatic medium and secondly ageing, had any effect on the lower limb's joint angles during aquatic-based gait. Three-dimensional joint kinematics of the lower limb of 51 healthy male participants [25 young group (24.6±4.9 years, 172.1±5.5cm, 69.8±10.3kg) and 26 older group (58.5±5.1 years, 167.9±5.1cm, 70.8±12.1kg)] were quantified during land and shallow water walking. Participants walked at their self-selected comfortable speed in both mediums. The results suggested that the properties of water - hydrodynamic drag, and buoyancy - affected the gait kinematics for both groups. Both age groups used more of their hip flexion in the aquatic environment to help them propel forward instead of using the ankle plantarflexion. The effect of age during the aquatic-based gait was identified in ankle adduction angle and knee abduction/adduction angle at initial contact. Only the older group elicited a significantly smaller ankle adduction angle during the aquatic-based gait when compared to the land-based gait. Only the young group elicited a significantly larger knee abduction/adduction angle at initial contact during the aquatic-based gait when compared to the land-based gait. These findings can facilitate professionals in the area of aquatic rehabilitation to better customise aquatic-based walking exercise programmes to suit their client's specific needs.

Mobile Device Accuracy for Step Counting Across Age Groups

Background

Only one in five American meets the physical activity recommendations of the Department of Health and Human Services. The proliferation of wearable devices and smartphones for physical activity tracking has led to an increasing number of interventions designed to facilitate regular physical activity, in particular to address the obesity epidemic, but also for cardiovascular disease patients, cancer survivors, and older adults. However, the inconsistent findings pertaining to the accuracy of wearable devices for step counting needs to be addressed, as well as factors known to affect gait (and thus potentially impact accuracy) such as age, body mass index (BMI), or leading arm.

Objective

We aim to assess the accuracy of recent mobile devices for counting steps, across three different age groups.

Methods

We recruited 60 participants in three age groups: 18-39 years, 40-64 years, and 65-84 years, who completed two separate 1000 step walks on a treadmill at a self-selected speed between 2 and 3 miles per hour. We tested two smartphones attached on each side of the waist, and five wrist-based devices worn on both wrists (2 devices on one wrist and 3 devices on the other), as well as the Actigraph wGT3X-BT, and swapped sides between each walk. All devices were swapped dominant-to-nondominant side and vice-versa between the two 1000 step walks. The number of steps was recorded with a tally counter. Age, sex, height, weight, and dominant hand were self-reported by each participant.

Results

Among the 60 participants, 36 were female (60%) and 54 were right-handed (90%). Median age was 53 years (min=19, max=83), median BMI was 24.1 (min=18.4, max=39.6). There was no significant difference in left- and right-hand step counts by device. Our analyses show that the Fitbit Surge significantly undercounted steps across all age groups. Samsung Gear S2 significantly undercounted steps only for participants among the 40-64 year age group. Finally, the Nexus 6P significantly undercounted steps for the group ranging from 65-84 years.

Conclusions

Our analysis shows that apart from the Fitbit Surge, most of the recent mobile devices we tested do not overcount or undercount steps in the 18-39-year-old age group, however some devices undercount steps in older age groups. This finding suggests that accuracy in step counting may be an issue with some popular wearable devices, and that age may be a factor in undercounting. These results are particularly important for clinical interventions using such devices and other activity trackers, in particular to balance energy requirements with energy expenditure in the context of a weight loss intervention program.

Effects of step length and step frequency on lower-limb muscle function in human gait

The aim of this study was to quantify the effects of step length and step frequency on lower-limb muscle function in walking. Three-dimensional gait data were used in conjunction with musculoskeletal modeling techniques to evaluate muscle function over a range of walking speeds using prescribed combinations of step length and step frequency. The body was modeled as a 10-segment, 21-degree-of-freedom skeleton actuated by 54 muscle-tendon units. Lower-limb muscle forces were calculated using inverse dynamics and static optimization. We found that five muscles - GMAX, GMED, VAS, GAS, and SOL - dominated vertical support and forward progression independent of changes made to either step length or step frequency, and that, overall, changes in step length had a greater influence on lower-limb joint motion, net joint moments and muscle function than step frequency. Peak forces developed by the uniarticular hip and knee extensors, as well as the normalized fiber lengths at which these muscles developed their peak forces, correlated more closely with changes in step length than step frequency. Increasing step length resulted in larger contributions from the hip and knee extensors and smaller contributions from gravitational forces (limb posture) to vertical support. These results provide insight into why older people with weak hip and knee extensors walk more slowly by reducing step length rather than step frequency and also help to identify the key muscle groups that ought to be targeted in exercise programs designed to improve gait biomechanics in older adults.

Complementary mechanisms for upright balance during walking

Lateral balance is a critical factor in keeping the human body upright during walking. Two important mechanisms for balance control are the stepping strategy, in which the foot placement is changed in the direction of a sensed fall to modulate how the gravitational force acts on the body, and the lateral ankle strategy, in which the body mass is actively accelerated by an ankle torque. Currently, there is minimal evidence about how these two strategies complement one another to achieve upright balance during locomotion. We use Galvanic vestibular stimulation (GVS) to induce the sensation of a fall at heel-off during gait initiation. We found that young healthy adults respond to the illusory fall using both the lateral ankle strategy and the stepping strategy. The stance foot center of pressure (CoP) is shifted in the direction of the perceived fall by ≈2.5 mm, starting ≈247 ms after stimulus onset. The foot placement of the following step is shifted by ≈15 mm in the same direction. The temporal delay between these two mechanisms suggests that they independently contribute to upright balance during locomotion, potentially in a serially coordinated manner. Modeling results indicate that without the lateral ankle strategy, a much larger step width is required to maintain upright balance, suggesting that the small but early CoP shift induced by the lateral ankle strategy is critical for upright stability during locomotion. The relative importance of each mechanism and how neurological disorders may affect their implementation remain an open question.

A wrist sensor and algorithm to determine instantaneous walking cadence and speed in daily life walking

In daily life, a person's gait-an important marker for his/her health status-is usually assessed using inertial sensors fixed to lower limbs or trunk. Such sensor locations are not well suited for continuous and long duration measurements. A better location would be the wrist but with the drawback of the presence of perturbative movements independent of walking. The aim of this study was to devise and validate an algorithm able to accurately estimate walking cadence and speed for daily life walking in various environments based on acceleration measured at the wrist. To this end, a cadence likelihood measure was designed, automatically filtering out perturbative movements and amplifying the periodic wrist movement characteristic of walking. Speed was estimated using a piecewise linear model. The algorithm was validated for outdoor walking in various and challenging environments (e.g., trail, uphill, downhill). Cadence and speed were successfully estimated for all conditions. Overall median (interquartile range) relative errors were -0.13% (-1.72 2.04%) for instantaneous cadence and -0.67% (-6.52 6.23%) for instantaneous speed. The performance was comparable to existing algorithms for trunk- or lower limb-fixed sensors. The algorithm's low complexity would also allow a real-time implementation in a watch.

Spatial and temporal gait characteristics of elderly individuals during backward and forward walking with shoes and barefoot

Backward walking (BW) is an inherent component of mobility and function in daily activities, particularly indoors, when it is more likely that a person is barefoot. No studies to date have compared the spatio-temporal characteristics of BW with and without shoes in elderly individuals. This study compared spatio-temporal measures of BW and forward walking (FW) among elderly individuals while barefoot or wearing shoes. Forty-seven elderly individuals (13 men and 34 women, 76.7±7.7years of age) were evaluated. Participants were requested to walk at a comfortable, self-selected pace across the GAITRite^® walkway for three trials under each of four conditions: walking forward (FW) and BW wearing their own comfortable low-heeled walking shoes and FW and BW walking without shoes. Gait speed, stride length and cadence were significantly reduced in BW versus FW, with an increase in double limb support (DLS), both with and without shoes. Barefoot BW resulted in significantly increased gait speed and cadence, and decreased DLS compared to BW with shoes. BW stride length was not affected by footwear. While barefoot FW was also associated with a significant increase in cadence and decrease in DLS time compared to walking with shoes, it decreased stride length and had no detrimental effect on gait speed. Assessment of the spatio-temporal parameters of walking barefoot and with shoes during FW and BW can contribute to our understanding of the ability of elderly individuals to adapt to changing walking conditions, and should be included in the assessment of functional mobility of elderly individuals.

Altered Functional Performance in Patients with Fibromyalgia

Fibromyalgia is a common chronic pain condition that exerts a considerable impact on patients' daily activities and quality of life.

Objectives: The main objective of the present study was to evaluate kinematic parameters of gait, functional performance, and balance in women with fibromyalgia syndrome.

Methods: The study included 26 female patients with fibromyalgia (49.2 ± 8.0 years) according to the criteria of the American College of Rheumatology, as well as 16 pain-free women (43.5 ± 8.5 years). Gait and balance parameters were extracted from video recordings of participants performing several motor tasks. Non-linear dynamic of body sway time series was also analyzed by computing the Hurst exponent. In addition, functional performance and clinical pain were obtained by using standardized motor tests (Berg's balance scale, 6-min walking test, timed up and go task, Romberg's balance test) and self-report questionnaires (Fibromyalgia Impact Questionnaire).

Results: Walking speed was significantly diminished (p < 0.001) in FM patients as compared to pain-free controls, probably due to significant reductions in stride length (p < 0.001) and cycle frequency (p < 0.001). Analyses of balance also revealed significant differences between fibromyalgia and pain-free controls on body sway in the medial-lateral and anterior-posterior axes (all ps < 0.01). Several parameters of gait and balance were significantly associated with high levels of pain, depression, stiffness, anxiety, and fatigue in fibromyalgia.

Conclusion: Our data revealed that both gait and balance were severely impaired in FM, and that subjective complaints associated with FM could contribute to functional disability in these patients. These findings suggest that optimal rehabilitation and fall prevention in fibromyalgia require a comprehensive assessment of both psychological responses to pain and physical impairments during postural control and gait.

Medidas temporoespaciais indicativas de quedas em mulheres saudáveis entre 50 e 70 anos avaliadas pela análise tridimensional da marcha

RESUMO Objetivou-se comparar e correlacionar medidas temporoespaciais da marcha indicativas de quedas. Participaram do estudo 35 mulheres saudáveis, sem histórico de quedas no ano da avaliação. A análise computadorizada tridimensional da marcha forneceu cinco medidas temporoespaciais de cada participante, dos membros inferiores direito (D) e esquerdo (E). A análise inferencial abordou dois grupos de mulheres: jovens (20 40 anos) e adultas-idosas (50-70 anos). Houve diferença estatística significativa entre os grupos para comprimento da passada D (p=0,003) e E (p=0,002); passo D (p=0,008) e E (p=0,001); tempo de apoio E (p=0,008); tempo de passo D (p=0,049); tempo de apoio duplo E (p=0,003); largura da base E (p=0,005); resposta à carga E (p=0,001); pré-balanço D (p=0,001) e E (p=0,001) e para algumas medidas em percentil do ciclo de marcha: apoio E (p=0,001); balanço E (p=0,001); apoio simples E (p=0,025); resposta à carga E (p=0,00); pré-balanço E (p=0,001) e pré-balanço D (p=0,014). A regressão linear indicou que a variação da idade modificou em média 18% as medidas de comprimento do passo e da passada e em 20% a velocidade da marcha. Com o avanço da idade, as medidas funcionais diminuíram; e, consequentemente, as medidas de estabilidade, como duração dos períodos de apoio, apoio duplo e pré-balanço, aumentaram. Essas modificações indicam risco de queda na faixa etária de 50 a 70 anos. Algumas medidas de marcha podem apresentar alteração em uma faixa etária ainda considerada de baixo risco.

Dynamic margin of stability during gait is altered in persons with multiple sclerosis

Persons with multiple sclerosis (PwMS) have high fall risk due to altered balance. To measure dynamic balance during walking, margin of stability (MoS) examines how the extrapolated center of mass moves relative to the base of support. This study investigates how MoS is affected in PwMS during walking at preferred, slow, and fast speeds, as well as the relationship between MoS and the Expanded Disability Severity Score (EDSS), fall history, and self-report balance confidence questionnaire. MoS was evaluated in PwMS without clinical gait impairment (MS1; n=20), PwMS with clinical gait impairment (MS2; n=20), and age-matched healthy controls (HC) (n=20), in the anterior/posterior (AP) and medial/lateral (ML) direction at heel strike and midstance. In the AP direction, MS2 had a higher MoS than HC (p<0.001) and MS1 (p<0.001) at heel strike and midstance. In the ML direction, MS2 had a higher MoS than HC (p<0.001) at heel strike only. At midstance, slow pace had a lower MoS than preferred pace (p<0.001) and fast pace (p=0.007). Compared to HC, PwMS walk slower which increases their AP MoS. In the ML direction, slow walking causes lower MoS at midstance, so PwMS increase their MoS by taking wider steps. AP MoS correlated with EDSS (p=0.008) and number of falls (p=0.001), and ML MoS correlated with number of falls (p=0.027). Walking slower, with shorter step length, and with wider step widths increases MoS for PwMS but may be a poor adaptive gait strategy since falls still occur.

Quantifying effects of age on balance and gait with inertial sensors in community-dwelling healthy adults

Although balance and gait deteriorate as a person ages, it is unknown if all balance and gait measures change similarly across the adult age span. We developed the Instrumented Stand and Walk test (ISAW) to provide a quick quantification of key components of balance and walking: postural sway, anticipatory postural adjustments during step initiation, gait, and turning using body-worn, inertial sensors. Our aims were to characterize how different balance and gait measures change with age and to identify key age-related measures of mobility, in a wide age range of healthy, community-dwelling adults. A total of 135 healthy, community-dwelling subjects of age range 21-89years with no history of falls were enrolled. Subjects wore inertial sensors on the wrists, ankles, sternum and lumbar area; 37 reliable and valid measures of postural sway, step initiation, gait and turning were computed. Univariate and multivariate regression analyses were performed to examine how the measures changed with age. Several distinct correlation patterns between age and ISAW measures were observed: linear deterioration, deterioration after plateau, and subtle, or no, worsening. Spatial, but not temporal, measures of gait were age-related. The strongest age correlation was found for centroidal frequency of mediolateral postural sway (r=-0.50, p≤0.001). A hierarchical regression model revealed that age was the most important predictor of mediolateral centroidal frequency, with lower sway frequencies associated with older age, independent of gender, weight, and height. Our results showed that balance and gait represent independent control systems for mobility and not all balance and gait measures deteriorate the same way with age. Postural sway during stance was more strongly related to age than any gait, gait initiation or turning measure.

Bracing the trunk and neck in young adults leads to a more aged-like gait

Older individuals typically walk at slower speeds, with shorter step lengths, greater step widths and spend a larger proportion of the gait cycle in double stance. Changes in neck and trunk mobility may underlie some of the changes in walking seen with increasing age. Consequently, this study was designed to assess whether externally increasing trunk/neck stiffness in young adults leads to similar changes in gait pattern observed with aging. Twelve young adults (20-29 years), sixteen old adults (60-69 years) and fifteen older adults (70-79 years) walked across a 20' pressure sensitive GAITRite© instrumented walkway at their preferred speed. The young adults also walked under three bracing conditions: (1) Neck braced, (2) Trunk braced, and (3) Neck and Trunk braced. The results revealed that the old and older age groups walked significantly slower, with a shorter step length and with a narrower base of support (p's<0.05) compared to the young adults. In young adults, combined neck and trunk bracing led to reduced walking speed, shorter step length, wider base of support and a larger proportion of the gait cycle spent in double stance (p's<0.05). The walking speed and step length of older adults remained less than fully braced young adults (p's<0.05). Overall these results indicate that artificially stiffening the trunk and neck of young individuals leads to systematic gait changes similar to aging. Consequently, age-related changes in mobility of the neck and torso may in part contribute to the decrements in walking seen for older adults.

Construct validity of the walk ratio as a measure of gait control in people with multiple sclerosis without mobility aids

Ambulatory limitations are a key component of disability in people with multiple sclerosis (PwMS). Various tools are employed to assess walking performance in PwMS; however, no ideal measure has as yet been attained. In this situation, a walk ratio might be more advantageous compared with other gait measures. The walk ratio, a simple index for describing temporal and spatial co-ordination, denotes the relationship between step length and cadence during walking. Hence, the primary objective of this study was to determine the relationship between the walk ratio and measures of other theoretically related constructs. The walk ratio was studied using the GAITRite™ system (CIR Systems, Inc. Havertown, USA). The study group included 229 PwMS (143 women) and a mean disease duration of 5.8 (SD=7.1) years. The walk ratio score of the total sample was 5.3 (SD=0.8). Significant differences based on the expanded disability status scale (EDSS) scores (F=11.616, P<0.001) were observed between the neurological disability subgroups. Scores of the very mild (EDSS 0-2.0), mild (EDSS 2.5-4.0) and moderate (EDSS 4.5-5.5) groups were 5.5 (SD=0.7), 5.2 (SD=0.7), 4.9 (SD=0.9), respectively. In terms of fall status, the MS fallers demonstrated a significant lower walk ratio compared to the MS non-fallers; 5.1 (SD=0.8) vs. 5.5 (SD=0.7); P<0.001. Modest significant correlation scores were found between walk ratio and ambulation tests. Scores were slightly higher in the short walking tests, timed 25-foot walk and timed up and go tests (Pearson's rho=0.369, 0.364) compared to the 6 and 2-min walk time tests (Pearson's rho=0.344, 0.308). Collectively, the current study supports the construct validity of the walk ratio index in PwMS without mobility aids.

Acute and Long-Term Effects of Multidirectional Treadmill Training on Gait and Balance in Parkinson Disease

BACKGROUND

Treadmill training has been shown to be a promising rehabilitation strategy for improving gait and balance in persons with Parkinson disease (PD). Most studies have involved only forward walking as an intervention. The effects of multidirectional treadmill (forward, backward, and left and right sideways) on gait and balance have not been reported.

OBJECTIVE

To investigate the acute and long-term effects of multidirectional treadmill training (MDTT) on gait and balance in persons with PD, and to determine the optimal training duration.

DESIGN

Single group, repeated-measures design.

SETTING

Research laboratory in a hospital.

PARTICIPANTS

Ten persons with PD (mean age 65.9 ± 7.4 years; average disease duration 3.90 ± 2.18 years).

INTERVENTIONS

MDTT was used. Participants walked forward, backward, and left and right sideways for 5-7 minutes in each direction at their fastest tolerated speed. The training was 3 days per week continuously for 8 weeks.

MAIN OUTCOME MEASUREMENTS

Gait speed, cadence, and stride length of forward, backward and sideways walks; time and number of steps to turn 360°; and the timed 5-step test and Timed Up-and-Go (TUG) test were performed after the first session of MDTT and every 2 weeks. Effect size of MDTT on each gait and balance variable was measured every 2 weeks for 8 weeks to determine the optimal training duration. Gait and balance variables after the first session of MDTT were compared to the baseline values (pre-MDTT) to study the acute effect of MDTT.

RESULTS

Stride length of forward, backward, and sideways walks improved immediately after 1 session of MDTT (P = .031, .012, and .001, respectively). The number of steps to turn and the timed 5-step test score decreased after the first session (P = .016, and .010, respectively). Six weeks of training was found to yield the largest mean effect size of all gait and balance variables. At 6 weeks of MDTT, gait speed of all walking directions (P = .001-.031), stride length of backward (P < .005) and sideways (P = .001) walks, cadence of sideways walk (P = .036), number of steps to turn (P = .014), and timed 5-step test (P = .033) improved from pre-MDTT measures.

CONCLUSIONS

MDTT immediately improved gait and balance in persons with PD. Six weeks of MDTT might be the optimal training duration to improve gait and balance in the long term.

LEVEL OF EVIDENCE

IV.

Gait analysis and hip extensor function early post total hip replacement

OBJECTIVE

The purpose of this study was to systematically evaluate the sagittal kinematic and kinetic gait patterns in patients in this early post-operative period, to describe them and to better understand the deficiencies in that gait pattern that may help to develop targeted rehabilitation strategies.

METHODS

This study evaluated early gait patterns in 10 patients with isolated unilateral hip osteoarthritis who were post-operative for total hip replacement. Kinetic and kinematic assessments - focusing on sagittal plane abnormalities - were performed at 2 weeks pre-operatively and 8 weeks post-operatively.

RESULTS

Our results demonstrated that while clinical scoring for pain and functional ability significantly improved post-operatively, as did clinical assessment of range of motion passively, this did not translate to the degree of dynamic improvement in gait. Step length and stride length did not improve significantly. Lack of hip extension in terminal stance associated with excessive anterior pelvic tilt persisted and was associated with a worsening in hip extensor power post-operatively.

CONCLUSION

Based on our results, post-operative rehabilitation programmes should include extensor muscle exercises to increase power and to retain the operative gain in passive range of motion, which would help to improve gait patterns.