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

Quantifying Human Gait Symmetry During Blindfolded Treadmill Walking

Bilateral gait symmetry is an essential requirement for normal walking since asymmetric gait patterns increase the risk of falls and injuries. While human gait control heavily relies on the contribution of sensory inputs, the role of sensory systems in producing symmetric gait has remained unclear. This study evaluated the influence of vision as a dominant sensory system on symmetric gait production. Ten healthy adults performed treadmill walking with and without vision. Twenty-two gait parameters including ground reaction forces, joint range of motion, and other spatial-temporal gait variables were evaluated to quantify gait symmetry and compared between both visual conditions. Visual block caused increased asymmetry in most parameters of ground reaction force, however mainly in the vertical direction. When vision was blocked, symmetry of the ankle and knee joint range of motion decreased, but this change did not occur in the hip joint. Stance and swing time symmetry decreased during no-vision walking while no significant difference was found for step length symmetry between the two conditions. This study provides a comprehensive analysis to reveal how the visual system influences bilateral gait symmetry and highlights the important role of vision in gait control. This approach could be applied to investigate how vision alters gait symmetry in patients with disorders to help better understand the role of vision in pathological gaits.

A Machine Learning Pipeline for Gait Analysis in a Semi Free-Living Environment

This paper presents a novel approach to creating a graphical summary of a subject's activity during a protocol in a Semi Free-Living Environment. Thanks to this new visualization, human behavior, in particular locomotion, can now be condensed into an easy-to-read and user-friendly output. As time series collected while monitoring patients in Semi Free-Living Environments are often long and complex, our contribution relies on an innovative pipeline of signal processing methods and machine learning algorithms. Once learned, the graphical representation is able to sum up all activities present in the data and can quickly be applied to newly acquired time series. In a nutshell, raw data from inertial measurement units are first segmented into homogeneous regimes with an adaptive change-point detection procedure, then each segment is automatically labeled. Then, features are extracted from each regime, and lastly, a score is computed using these features. The final visual summary is constructed from the scores of the activities and their comparisons to healthy models. This graphical output is a detailed, adaptive, and structured visualization that helps better understand the salient events in a complex gait protocol.

Machine Learning-Based Predicted Age of the Elderly on the Instrumented Timed Up and Go Test and Six-Minute Walk Test

A decrease in dynamic balance ability (DBA) in the elderly is closely associated with aging. Various studies have investigated different methods to quantify the DBA in the elderly through DBA evaluation methods such as the timed up and go test (TUG) and the six-minute walk test (6MWT), applying the G-Walk wearable system. However, these methods have generally been difficult for the elderly to intuitively understand. The goal of this study was thus to generate a regression model based on machine learning (ML) to predict the age of the elderly as a familiar indicator. The model was based on inertial measurement unit (IMU) data as part of the DBA evaluation, and the performance of the model was comparatively analyzed with respect to age prediction based on the IMU data of the TUG test and the 6MWT. The DBA evaluation used the TUG test and the 6MWT performed by 136 elderly participants. When performing the TUG test and the 6MWT, a single IMU was attached to the second lumbar spine of the participant, and the three-dimensional linear acceleration and gyroscope data were collected. The features used in the ML-based regression model included the gait symmetry parameters and the harmonic ratio applied in quantifying the DBA, in addition to the features of description statistics for IMU signals. The feature set was differentiated between the TUG test and the 6MWT, and the performance of the regression model was comparatively analyzed based on the feature sets. The XGBoost algorithm was used to train the regression model. Comparison of the regression model performance according to the TUG test and 6MWT feature sets showed that the performance was best for the model using all features of the TUG test and the 6MWT. This indicated that the evaluation of DBA in the elderly should apply the TUG test and the 6MWT concomitantly for more accurate predictions. The findings in this study provide basic data for the development of a DBA monitoring system for the elderly.

Identifying the Effects of Age and Speed on Whole-Body Gait Symmetry by Using a Single Wearable Sensor

Studies on gait symmetry in healthy population have mainly been focused on small range of age categories, neglecting Teenagers (13–18 years old) and Middle-Aged persons (51–60 years old). Moreover, age-related effects on gait symmetry were found only when the symmetry evaluation was based on whole-body acceleration than on spatiotemporal parameters of the gait cycle. Here, we provide a more comprehensive analysis of this issue, using a Symmetry Index (SI) based on whole-body acceleration recorded on individuals aged 6 to 84 years old. Participants wore a single inertial sensor placed on the lower back and walked for 10 m at comfortable, slow and fast speeds. The SI was computed using the coefficient of correlation of whole-body acceleration measured at right and left gait cycles. Young Adults (19–35 years old) and Adults (36–50 years old) showed stable SI over the three speed conditions, while Children (6–12 years old), Teenagers (13–18 years old), Middle-Aged persons and Elderly (61–70 and 71–84 years old) exhibited lower SI values when walking at fast speed. Overall, this study confirms that whole-body gait symmetry is lower in Children and in Elderly persons over 60 years of age, showing, for the first time, that asymmetries appear also during teenage period and in Middle-Aged persons (51–60 years old).

Foot contact forces can be used to personalize a wearable robot during human walking

Individuals with below-knee amputation (BKA) experience increased physical effort when walking, and the use of a robotic ankle-foot prosthesis (AFP) can reduce such effort. The walking effort could be further reduced if the robot is personalized to the wearer using human-in-the-loop (HIL) optimization of wearable robot parameters. The conventional physiological measurement, however, requires a long estimation time, hampering real-time optimization due to the limited experimental time budget. This study hypothesized that a function of foot contact force, the symmetric foot force-time integral (FFTI), could be used as a cost function for HIL optimization to rapidly estimate the physical effort of walking. We found that the new cost function presents a reasonable correlation with measured metabolic cost. When we employed the new cost function in HIL ankle-foot prosthesis stiffness parameter optimization, 8 individuals with simulated amputation reduced their metabolic cost of walking, greater than 15% (p < 0.02), compared to the weight-based and control-off conditions. The symmetry cost using the FFTI percentage was lower for the optimal condition, compared to all other conditions (p < 0.05). This study suggests that foot force-time integral symmetry using foot pressure sensors can be used as a cost function when optimizing a wearable robot parameter.

Effect of limited range of motion of the hip joint and leg-length discrepancy on gait trajectory: an experiment to reproduce the asymmetric gait that occurs in patients with osteoarthritis of the hip joint

PURPOSE

Although some symptoms that often occur with hip joint osteoarthritis (OA) may be involved in the appearance of gait disturbance, the main cause has not been identified. We hypothesised that the abnormalities in gait trajectory of patients with hip joint OA are mainly caused by limited range of motion of the hip joint or the presence of leg-length discrepancy, or both. To investigate this hypothesis, we examined whether the abnormal gait trajectory in patients with hip joint OA can be reproduced in healthy individuals by asking them to wear a hip orthosis and shoe orthotic (insole).

METHODS

We recruited 2 groups of participants: patients with hip joint OA (OA group, 38 patients) and healthy individuals who imitated patients with OA of the hip joint by wearing a hip orthosis or shoe orthotic (10-mm or 20-mm insole) or both (simulated OA group, 6 individuals). For gait analysis, we used a portable, wearable gait analyser with inertial sensors to evaluate 3-dimensional (3D) changes in gait trajectory.

RESULTS

In the OA group, the patterns of gait trajectories that were drawn on the 3 planes (coronal, sagittal, and horizontal planes) could be roughly divided into 3 types. The gait trajectories that were drawn when wearing a hip orthosis in the simulated OA group were very similar to 1 of the 3 patterns of gait trajectory that occurs in the OA group.

CONCLUSIONS

We were able to reproduce the abnormal gait trajectory that is observed in ⅓ of patients with hip OA in healthy individuals, so we propose that an extreme reduction in hip joint ROM is 1 of the causes of abnormal gait pattern in patients with OA of the hip joint. A difference in leg length of 20 mm alone has little effect on gait trajectory.

The effect of peripheral arterial disease and intermittent claudication on gait regularity and symmetry

Peripheral arterial disease (PAD) affects 20-30% of older adults and is associated with intermittent claudication (IC), which is walking-induced pain. This study compared the regularity and symmetry of gait between healthy older adults and adults with PAD, and between IC and non-IC conditions in the PAD group. Eighteen control (70.7 ± 6.3 years) and 11 PAD participants (67.0 ± 10.1 years) walked overground at a continuous, self-selected speed. A waist-mounted accelerometer determined step time, stride time, gait speed and mediolateral (ML), vertical (V) and anteroposterior (AP) gait regularity (step/stride) and symmetry. Correlations between ankle-brachial index (ABI) scores and PAD gait regularity/symmetry were also investigated. PAD step and stride times were greater (p < 0.01), while gait speed, ML and AP step regularity and ML and V stride regularity were significantly less than the controls (p < 0.05). There were no significant differences in gait symmetry. Within the PAD group, post-IC step/stride time and speed increased and decreased, respectively, (p < 0.05), while post-IC step and stride regularity were significantly less in all three directions (p < 0.01). Similarly, ML and V post-IC gait asymmetry increased significantly (p < 0.05). ABI was significantly correlated with pre-and post-IC vertical stride regularity (p < 0.01), and with pre- and post-IC ML gait symmetry (p < 0.05). The results demonstrate that gait regularity decreases as a result of PAD and IC. The association between gait regularity/symmetry and ABI should be investigated further, as it may have clinical application to the assessment of PAD severity.

Sex differences in the regularity and symmetry of gait in older adults with and without knee osteoarthritis

BACKGROUND

Three-dimensional (3D) motion measured at the lower back during walking can describe the regularity and symmetry of gait that may be related to osteoarthritis (OA) and functional status. However, gait speed and inherent sex differences, regardless of the presence of OA, may confound these measures. Therefore, there is a need to understand the effect of OA separately among males and females, without the confounding influence of gait speed.

OBJECTIVE

To investigate the difference in 3D gait regularity and symmetry measures between gait speed-matched males and females with and without knee OA.

METHOD

Gait regularity and symmetry were computed as autocorrelations of pelvic accelerations during treadmill walking in four groups of older adults: healthy asymptomatic females (AsymF; n = 44), healthy asymptomatic males (AsymM; n = 45), females diagnosed with knee OA (OAF; n = 44), and males diagnosed with knee OA (OAM; n = 45). Data were obtained from a larger research database, allowing for the matching of gait speed between groups. The main effect of OA, sex, and interaction effect between them was examined for the 3D gait regularity and symmetry measures at an alpha level of 0.05.

RESULTS

There was no main effect of OA on any variable, but there was a significant main effect of sex on mediolateral and anteroposterior gait regularity measures. Specifically, females demonstrated significantly greater gait regularity, most notably in the mediolateral directions compared to males.

CONCLUSION

Older adult females were found to display significantly greater mediolateral gait regularity as compared to males, regardless of the presence of OA. Further, this difference exists among matched gait speeds, suggesting it is not the result of gait speed. Overall, these results highlight the importance of sex-specific analyses and considering gait speed when examining gait acceleration patterns near the center of mass for both cross sectional and longitudinal gait assessments.

Impact of walking states, self-reported daily walking amount and age on the gait of older adults measured with a smart-phone app: a pilot study

BACKGROUND

Smartphones provide a cost-effective avenue for gait assessment among older adults in the community. The purpose of this study is to explore the impact of walking state, self-reported daily walking amount, and age on gait quality, using a smartphone application.

METHODS

One hundred older adult individuals from North China, aged 73.0 ± 7.7 years, voluntarily participated in this study. They performed three walking tests: normal walking, fast walking, and visually impaired walking. Three-dimensional acceleration data for gait were obtained using the smartphone app Pocket Gait. This study used multivariate analysis of variance (MANOVA) to explore the effects of the walking state, self-reported daily walking amount, and age on the step frequency, root mean square (RMS) acceleration, step time variability, regularity, and symmetry.

RESULTS

The walking state, self-reported daily walking amount, and age had statistically significant effects on gait quality. Compared with normal walking, the step frequency, RMS acceleration, variability, and regularity were greater in the fast-walking state, and simulated visually impaired walking did not significantly affect gait quality. Relatively older individuals had a significant decline in gait quality compared to (relatively) younger older adult individuals. Compared with older adults who walked less than 1 km a day, older adults who walked more had better gait quality.

CONCLUSIONS

The walking state, self-reported daily walking amount, and age have a significant effect on the gait quality of older adults. Walking with pigmented sunglasses can be used as a training intervention to improve gait performance. Older adult people who walk less than 1 km/day have worse gait quality compared with their counterparts.

Backward vs. Forward Gait Symmetry Analysis Based on Plantar Pressure Mapping

Symmetry is one of the factors analysed in normal and pathological gaits. Backward gait is an area of interest to scientists, in terms of its physiology and therapeutic possibilities. This study aimed to analyse the symmetry of the pressure parameters of backward gait in comparison to forward gait using different symmetry indices. Eighty-one healthy people aged between 19 and 84 years took part in the study. Foot pressure distribution was analysed during forward and backward gaits at self-selected speeds. Mean and maximum pressure values were calculated after dividing the foot into four or ten areas. Delta, Ratio Index, Robinson Index, Gait Asymmetry, and Symmetry Angle were calculated for each area, separately for both forward and backward gaits. Higher ratios of asymmetry were found during backward than during forward gait. Larger ratios of asymmetry were found within toes II–V, forefoot, metatarsals I, II, and III, medial and lateral heel areas. No significant correlation between symmetry indices and age or BMI was found. Results suggested that the lower symmetry of backward gait is caused by a higher number of corrective movements that allow for the maintenance of body balance and global symmetry of gait. This can be realised by increased cortical control of the backward gait, which was a new movement task for all participants.

Predicting Sarcopenia of Female Elderly from Physical Activity Performance Measurement Using Machine Learning Classifiers

Purpose

Sarcopenia is a symptom in which muscle mass decreases due to decreasing in the number of muscle fibers and muscle cross-sectional area as aging. This study aimed to develop a machine learning classification model for predicting sarcopenia through a inertial measurement unit (IMU)-based physical performance measurement data of female elderly.

Patients and Methods

Seventy-eight female subjects from an elderly population (aged: 78.8±5.7 years) volunteered to participate in this study. To evaluate the physical performance of the elderly, the experiment conducted timed-up-and-go test (TUG) and 6-minute walk test (6mWT) with worn a single IMU. Based on literature review, 132 features were extracted from collected data. Feature selection was performed through the Kruskal–Wallis test, and features datasets were constructed according to feature selection. Three major machine learning-based classification algorithms classified the sarcopenia group in each dataset, and the performance of classification models was compared.

Results

As a result of comparing the classification model performance for sarcopenia prediction, the k-nearest neighborhood algorithm (kNN) classification model using 40 major features of TUG and 6mWT showed the best performance at 88%.

Conclusion

This study can be used as a basic research for the development of self-monitoring technology for sarcopenia.

A Novel Tool for Gait Analysis: Validation Study of the Smart Insole PODOSmart®

The new smart insole PODOSmart^®, is introduced as a new tool for gait analysis against high cost laboratory based equipment. PODOSmart^® system measures walking profile and gait variables in real life conditions. PODOSmart^® insoles consists of wireless sensors, can be fitted into any shoe and offer the ability to measure spatial, temporal, and kinematic gait parameters. The intelligent insoles feature several sensors that detect and capture foot movements and a microprocessor that calculates gait related biomechanical data. Gait analysis results are presented in PODOSmart^® platform. This study aims to present the characteristics of this tool and to validate it comparing with a stereophotogrammetry-based system. Validation was performed by gait analysis for eleven healthy individuals on a six-meters walkway using both PODOSmart^® and Vicon system. Intraclass correlation coefficients (ICC) were calculated for gait parameters. ICC for the validation ranged from 0.313 to 0.990 in gait parameters. The highest ICC was observed in cadence, circumduction, walking speed, stride length and stride duration. PODOSmart^® is a valid tool for gait analysis compared to the gold standard Vicon. As PODOSmart^®, is a portable gait analysis tool with an affordable cost it can be a useful novel tool for gait analysis in healthy and pathological population.

Signatures of Gait Movement Variability in CKD Patients Scheduled for Hemodialysis Indicate Pathological Performance Before and After Hemodialysis: A Prospective, Observational Study

Background: The frailty status of hemodialysis patients is well-known, but the role of the therapy in the frailty process is not yet clear. Nowadays gait analysis in nephrology is neglected, although gait performance is known to be related to frailty and kidney function. We hypothesized that gait quality and physical activity level is already affected before, and does not change because of the start of hemodialysis.

Methods: Fourteen patients (72.3 ± 5.7 years old) in a pre-dialysis program underwent an instrumental gait analysis and their physical activity was monitored for a week. This protocol was repeated 3, 6, 12, and 24 months after the first hemodialysis session.

Results: At baseline, our sample showed a conservative gait with pathologic gait variability, high dual-task cost, and a sedentary lifestyle. No statistically significant change was found in any parameter in the analyzed period, but there was a tendency toward an improvement of gait quality and physical activity in the first year of treatment, and a decline in the second year.

Conclusion: Elderly patients in the pre-dialysis stage show a conservative gait, however variability was in a pathological range and did not change post-hemodialysis. This hints toward changes in the central nervous system due to the kidney disease. This finding suggests the importance of gait analysis in the early stages of renal disease in the diagnosis of changes in the nervous system due to kidney failure that affect gait. Early detection of these changes would potentially allow a prevention program tailored to this population to be developed.

Relationship of the sacral slope with early gait derangements in robust older women

BACKGROUND

Trunk pelvic dissociation is fundamental to the compensatory mechanism for muscle weakness during body bending. We carried out an early investigation of gait changes in a sample of community-dwelling women ≥60 years without gait complaints. The primary objective was to correlate spine and pelvic angles with performance tests and accelerometry parameters. The secondary objective was to correlate performance tests with accelerometry.

METHODS

In this cross-sectional study, 54 community-dwelling women ≥60 years were subjected to Falls Efficacy Scale-International (FES-I), performance tests (Berg Balance Scale, Timed Up and Go, and Gait analysis), and radiographic analysis of sagittal alignment (Thoracic and Lumbar Cobb, Pelvic Incidence, Sacral Slope, and Pelvic Tilt angles). Gait speed was assessed in a 10-m comfortable walk, and accelerometry parameters were obtained in a 30-m walk distance.

RESULTS

The sample, aged 72 ± 6 years, exhibited moderate correlation between Sacral Slope and Step Length (+ 0.615). Sacral Slope weakly correlated with FES-I (- 0.339), Berg Balance Scale (+ 0.367), and with further accelerometry data in the AP plane: RMS, (+ 0.439) and Stride Regularity (+ 0.475), p < 0.05, all. Lumbar Cobb weakly correlated with the following accelerometry data in the AP plane: Step Length (+ 0.405), RMS, (+ 0.392), and Stride Regularity (+ 0.345), p < 0.05, all. Additionally, Stride Regularity in AP moderately correlated with FES-I (0,561, p < 0.05), among other weak correlations between performance tests and accelerometry data in AP.

CONCLUSIONS

Early alterations in Sacral Slope and gait abnormalities in the AP plane may provide understanding of the early gait changes in robust older women.

Acceleration Gait Measures as Proxies for Motor Skill of Walking: A Narrative Review

In adults 65 years or older, falls or other neuromotor dysfunctions are often framed as walking-related declines in motor skill; the frequent occurrence of such decline in walking-related motor skill motivates the need for an improved understanding of the motor skill of walking. Simple gait measurements, such as speed, do not provide adequate information about the quality of the body motion's translation during walking. Gait measures from accelerometers can enrich measurements of walking and motor performance. This review article will categorize the aspects of the motor skill of walking and review how trunk-acceleration gait measures during walking can be mapped to motor skill aspects, satisfying a clinical need to understand how well accelerometer measures assess gait. We will clarify how to leverage more complicated acceleration measures to make accurate motor skill decline predictions, thus furthering fall research in older adults.

Gait regularity assessed by wearable sensors: Comparison between accelerometer and gyroscope data for different sensor locations and walking speeds in healthy subjects

Inertial measurement units (IMU), including accelerometers and gyroscopes, can support the assessment of gait regularity, relevant for an effective walking. Gait regularity is typically quantified by an autocorrelation analysis of trunk/pelvis accelerations. A methodological upgrade fosters a multi-sensor approach including upper and lower limbs. Very few studies dealt with gait regularity using gyroscope data and no comparison between the two inertial sensors has been published. Therefore, this study compares gait regularity assessment by autocorrelation analyses performed on accelerometer and gyroscope data simultaneously acquired. Twenty-five adult healthy subjects walked steady-state on treadmill at three speeds (3.6, 5.0, 6.4 km/h), with rest between. Four IMUs were firmly attached on the trunk, pelvis, wrist and ankle. The autocorrelation method was applied to time-windows of the signal vector magnitude and resulted, on average for each trial, in its regularity index (RI) and periodicity index (PI), i.e. the stride time. Results showed that both sensors identified the same PI (Spearman correlation coefficient = 0.999), and evidenced that, for matched sensor locations and gait speeds, the accelerometer-based RI was larger/equal to the gyroscope-based RI on 86.3% of all conditions (overall median of gyroscope-to-accelerometer RI ratio was 91.1%). The two sensors gave always statistically different RI, with the exception of the ankle at the lowest speed and wrist at higher speeds. Such results help remove potential confounders from analyses performed with different sensors and support the use of accelerometers for gait regularity assessment, not excluding that gyroscopes may be more suitable for other human movements.

Accelerometer Measurement of Trunk Lateral Fluctuation During Walking Following Total Knee Arthroplasty in Patients With Osteoarthritis

This study aimed to clarify the effect of total knee arthroplasty (TKA) on trunk fluctuation and regularity of gait in patients with knee osteoarthritis by an accelerometer. The participants included 18 patients with knee osteoarthritis undergoing TKA. The gait at a comfortable velocity was assessed pre- and post-TKA by a triaxial accelerometer attached to the neck and lumbar regions. Measurement post-TKA was performed 4 weeks after surgery. Trunk fluctuation was estimated by the root mean square (RMS) of acceleration and RMS ratio (the ratio of RMS in each direction to the total RMS). Regularity of gait was estimated using the autocorrelation function. The results showed that TKA significantly decreased the RMS ratio in mediolateral acceleration of the neck and lumbar regions and reduced gait regularity. TKA appears to reduce compensatory trunk motion through the improvement of knee function. An assessment of trunk fluctuation using an accelerometer is useful for the clinical assessment of patients with knee osteoarthritis pre- and post-TKA.

Reliability of gait parameters in male and female healthy adults during self-paced treadmill-based walking

Background/aims

The purpose of this study was to examine the intra-rater reliability of the Gait Real-time Analysis Interactive Laboratory system during self-paced mode, in repeated gait analysis of healthy individuals.

Methods

A total of 10 healthy men (age: 35.4 ± 13.3 years; body mass index: 25.2 ± 4.3) and 10 healthy women (age: 41.1 ± 16.4 years; body mass index: 24.5 ± 2.6) were split into two groups according to sex. They walked on a split-belt, self-paced treadmill. Each participant completed two gait assessments separated by an average of 7 ± 3 days. Key gait kinematic, kinetic and spatial-temporal parameters were analysed. The interclass correlation coefficient, standard error of measurement and minimum detectable change were calculated to evaluate the reliability of these gait parameters.

Results

There was a high repeatability of spatial temporal and excellent repeatability of kinematic and kinetic parameters in both groups.

Conclusions

The findings suggest that the Gait Real-time Analysis Interactive Laboratory system in self-paced mode is a good instrument to evaluate gait parameters for women as well as men.

Lower Limb Joint Kinetics During Walking in Middle-Aged Runners With Low or High Lifetime Running Exposure

Aging is associated with a distal-to-proximal shift in joint kinetics during walking. This plasticity of gait is amplified rather than attenuated in old adults with high physical capacity. Because running is associated with greater kinetic demands at the ankle, older individuals with more versus less lifetime running exposure may retain a larger proportion of their ankle kinetics. The purpose of the study was to compare lower-extremity joint kinetics during walking between middle-aged runners with high and low lifetime running exposure. Eighteen middle-aged runners (9 per group) participated. Joint kinetics were calculated from kinematic and ground reaction force data during overground walking at 1.3 m·s-1 and compared between groups. High exposure runners produced 50% greater positive hip work (P = .03; Cohen d = 1.02) during walking compared with low exposure runners, but ankle kinetics were not different between groups. No other differences in joint kinetics or kinematics were observed between groups. These findings suggest that the age-related increase in hip joint kinetics during walking could be a compensatory gait strategy that is not attenuated by lifetime running exposure alone. Finally, the amount of lifetime running exposure did not affect ankle kinetics during walking in middle-aged runners.

Can shank acceleration provide a clinically feasible surrogate for individual limb propulsion during walking?

Aging and many pathologies that affect gait are associated with reduced ankle power output and thus trailing limb propulsion during walking. However, quantifying trailing limb propulsion requires sophisticated measurement equipment at significant expense that fundamentally limits clinical translation for diagnostics or gait rehabilitation. As a component of joint power, our purpose was to determine if shank acceleration estimated via accelerometers during push-off can serve as a clinically feasible surrogate for ankle power output and peak anterior ground reaction forces (GRF) during walking. As hypothesized, we found that young adults modulated walking speed via changes in peak anterior GRF and peak ankle power output that correlated with proportional changes in shank acceleration during push-off, both at the individual subject (R² ≥ 0.80, p < 0.01) and group average (R² ≥ 0.74, p < 0.01) levels. In addition, we found that unilateral deficits in trailing limb propulsion induced via a leg bracing elicited unilateral and relatively proportional reductions in peak anterior GRF, peak ankle power, and peak shank acceleration. These unilateral leg bracing effects on peak shank acceleration correlated with those in peak ankle power (braced leg: R² = 0.43, p = 0.028) but those effects in both peak shank acceleration and peak ankle power were disassociated from those in peak anterior GRF. In conclusion, our findings in young adults provide an early benchmark for the development of affordable and clinically feasible alternatives for assessing and monitoring trailing limb propulsion during walking.

Decomposition of a Multiscale Entropy Tensor for Sleep Stage Identification in Preterm Infants

Established sleep cycling is one of the main hallmarks of early brain development in preterm infants, therefore, automated classification of the sleep stages in preterm infants can be used to assess the neonate’s cerebral maturation. Tensor algebra is a powerful tool to analyze multidimensional data and has proven successful in many applications. In this paper, a novel unsupervised algorithm to identify neonatal sleep stages based on the decomposition of a multiscale entropy tensor is presented. The method relies on the difference in electroencephalography(EEG) complexity between the neonatal sleep stages and is evaluated on a dataset of 97 EEG recordings. An average sensitivity, specificity, accuracy and area under the receiver operating characteristic curve of 0.80, 0.79, 0.79 and 0.87 was obtained if the rank of the tensor decomposition is selected based on the age of the infant.

Deterioration of specific aspects of gait during the instrumented 6-min walk test among people with multiple sclerosis

Prolonged walking is typically impaired among people with multiple sclerosis (pwMS), however, it is unclear what the contributing factors are or how to evaluate this deterioration. We aimed to determine which gait features become worse during sustained walking and to examine the clinical correlates of gait fatigability in pwMS. Fifty-eight pwMS performed the 6-min walk test while wearing body-fixed sensors. Multiple gait domains (e.g., pace, rhythm, variability, asymmetry and complexity) were compared across each minute of the test and between mild- and moderate-disability patient groups. Associations between the decline in gait performance (i.e., gait fatigability) and patient-reported gait disability, fatigue and falls were also determined. Cadence, stride time variability, stride regularity, step regularity and gait complexity significantly deteriorated during the test. In contrast, somewhat surprisingly, gait speed and swing time asymmetry did not change. As expected, subjects with moderate disability (n = 24) walked more poorly in most gait domains compared to the mild-disability group (n = 34). Interestingly, a group × fatigue interaction effect was observed for cadence and gait complexity; these measures decreased over time in the moderate-disability group, but not in the mild group. Gait fatigability rate was significantly correlated with physical fatigue, gait disability, and fall history. These findings suggest that sustained walking affects specific aspects of gait, which can be used as markers for fatigability in MS. This effect on gait depends on the degree of disability, and may increase fall risk in pwMS. To more fully understand and monitor correlates that reflect everyday walking in pwMS, multiple domains of gait should be quantified.

The relationship between trunk acceleration parameters and kinematic characteristics during walking in patients with stroke

[Purpose] Limited literature has investigated the relationships between acceleration-based gait characteristics and kinematic information from motion analysis systems in gait analysis. The purpose of this study is to determine whether acceleration-based gait characteristics were associated with gait characteristics by motion analysis systems in patients with stroke. [Participants and Methods] Seventeen patients with stroke walked along a 10-m-long walkway at their comfortable speed. Trunk acceleration was measured with an accelerometer. Several reflective markers over bony landmarks on the lower extremities were used to capture movements. We evaluated the correlations of variables calculated between the trunk accelerometers and the motion analysis system. [Results] Walking speed was positively correlated with harmonic ratios along the anteroposterior axis and stride regularity along the vertical and anteroposterior axes. Harmonic ratios were associated with the stance phase percent on the unaffected side. Stride regularity was associated with the stance phase percent on both sides. Smaller interstride variability was associated with smaller peak ankle plantarflexion during both phases and greater peak ankle dorsiflexion during swing phase. Stride regularity is positively associated with maximal knee flexion during swing phase. [Conclusion] Relationships with spatiotemporal and joint kinematic parameters from the motion analysis system support the potential use of accelerometers.

Two-year changes in gait variability in community-living older adults

BACKGROUND

Increases in stride-to-stride fluctuations (gait variability) are common among older adults, but little is known about the natural progression of gait variability with increasing age.

RESEARCH QUESTION

Does gait variability change with increasing age in a group of community-living older adults?

METHODS

The participants were community-living volunteers between 70-81 years, who were tested with a two-year interval between tests. They walked 6.5 m under four different conditions: At preferred speed, at fast speed, during a dual task condition and on an uneven surface. Trunk accelerations in the anteroposterior (AP), mediolateral (ML) and vertical (V) direction were captured using a body-worn sensor worn at the lower back. Gait variability was estimated using an autocorrelation procedure, where coefficients tending towards 1.0 indicated low variability and 0.0 as high variability. To estimate change, we used an ANOVA-procedure with baseline gait speed as a covariate.

RESULTS

At baseline, 85 older adults were tested, and data for 56 of these were available for analysis over a two-year period of time. The average age at inclusion was 75.8 years (SD 3.43) and 60% were women. During preferred speed walking, variability increased in the AP direction (mean difference 0.05, p = .038), during fast speed walking it increased in the V direction (mean difference 0.04, p = .037) and during dual task-walking, it increased in the ML and V directions (mean differences 0.03, p = .032 and 0.09, p = .020 respectively).

SIGNIFICANCE

The findings from this study could be helpful for discriminating between normal and pathological progression of gait variability in older adults.

Development and validation of Comprehensive Gait Assessment using InerTial Sensor score (C-GAITS score) derived from acceleration and angular velocity data at heel and lower trunk among community-dwelling older adults

Background

Although some gait parameters from inertial sensors have been shown to be associated with important clinical issues, because of controversial results, it remains uncertain which parameters for which axes are clinically valuable. Following the idea that a comprehensive score obtained by summing various gait parameters would sensitively reflect declines in gait performance, we developed a scoring method for community-dwelling older adults, the Comprehensive Gait Assessment using InerTial Sensor score (C-GAITS score). The aim of this study was to examine the internal consistency and the construct validity of this method.

Methods

In this cross-sectional study, the gait performance of 378 community-dwelling older people (mean age = 71.7 ± 4.2 years, 210 women) was assessed using inertial sensors attached to the heel and lower trunk. Participants walked along a 15-m walkway, and accelerations, angular velocity, and walking time were measured. From these data, walking speed, mean stride time, coefficients of variation of stride time and swing time, and autocorrelation coefficients and harmonic ratios of acceleration in vertical, mediolateral, and anteroposterior directions at the lower trunk were calculated. Scoring was performed based on quartile by gender (i.e., scored from 0 to 3) for each of the 10 gait parameters. The C-GAITS score was the sum of these scores (range: 0–30). Lower extremity strength, balance function, fall history, and fear of falling were also assessed.

Results

An exploratory factor analysis revealed that the C-GAITS score yielded four distinct factors explaining 57.1% of the variance. The Cronbach’s alpha coefficient was 0.77. A single linear regression analysis showed a significant relationship between total C-GAITS score and walking speed (adjusted R² = 0.28). Results from bivariate comparisons using unpaired t-tests showed that the score was significantly related to age (p = 0.002), lower extremity strength (p = 0.007), balance function (p <  0.001), fall history (p = 0.04), and fear of falling (p <  0.001).

Conclusions

Good internal consistency and appropriate construct validity of the C-GAITS score were confirmed among community-dwelling older adults. The score might be useful in clinical settings because of ease of use and interpretation and capability of capturing functional decline.

The Effect of Treadmill Walking on Gait and Upper Trunk through Linear and Nonlinear Analysis Methods

Treadmills are widely used to recover walking function in the rehabilitation field for those patients with gait disorders. Nevertheless, the ultimate goal of walking function recovery is to walk on the ground rather than on the treadmill. This study aims to determine the effect of treadmill walking on gait and upper trunk movement characteristics using wearable sensors. Eight healthy male subjects are recruited to perform 420-m straight overground walking (OW) and 5 min treadmill walking (TW), wearing 3 inertial measurement units and a pair of insole sensors. In addition to common linear features, nonlinear features, which contains sample entropy, maximal Lyapunov exponent and fractal dynamic of stride intervals (detrended fluctuation analysis), are used to compare the difference between TW and OW condition. Canonical correlation analysis is also used to indicate the correlation between upper trunk movement characteristics and gait features in the aspects of spatiotemporal parameters and gait dynamic features. The experimental results show that the treadmill can cause a shorter stride length, less stride time and worsen long-range correlation of stride intervals. And the treadmill can significantly increase the stability for both gait and upper trunk, while it can significantly reduce gait regularity during swing phase. Canonical correlation analysis results show that treadmill can reduce the correlation between gait and upper trunk features. One possible interpretation of these results is that people tend to walk more cautiously to prevent the risk of falling and neglect the coordination between gait and upper trunk when walking on the treadmill. This study can provide fundamental insightful information about the effect of treadmill walking on gait and upper trunk to support future similar studies.

Using Inertial Sensors to Quantify Postural Sway and Gait Performance during the Tandem Walking Test

Vestibular dysfunction typically manifests as postural instability and gait irregularities, in part due to inaccuracies in processing spatial afference. In this study, we have instrumented the tandem walking test with multiple inertial sensors to easily and precisely investigate novel variables that can distinguish abnormal postural and gait control in patients with unilateral vestibular hypofunction. Ten healthy adults and five patients with unilateral vestibular hypofunction were assessed with the tandem walking test during eyes open and eyes closed conditions. Each subject donned five inertial sensors on the upper body (head, trunk, and pelvis) and lower body (each lateral malleolus). Our results indicate that measuring the degree of balance and gait regularity using five body-worn inertial sensors during the tandem walking test provides a novel quantification of movement that identifies abnormalities in patients with vestibular impairment.

Effects of Gait Strategy and Speed on Regularity of Locomotion Assessed in Healthy Subjects Using a Multi-Sensor Method

The regularity of pseudo-periodic human movements, including locomotion, can be assessed by autocorrelation analysis of measurements using inertial sensors. Though sensors are generally placed on the trunk or pelvis, movement regularity can be assessed at any body location. Pathological factors are expected to reduce regularity either globally or on specific anatomical subparts. However, other non-pathological factors, including gait strategy (walking and running) and speed, modulate locomotion regularity, thus potentially confounding the identification of the pathological factor. The present study’s objectives were (1) to define a multi-sensor method based on the autocorrelation analysis of the acceleration module (norm of the acceleration vector) to quantify regularity; (2) to conduct an experimental study on healthy adult subjects to quantify the effect on movement regularity of gait strategy (walking and running at the same velocity), gait speed (four speeds, lower three for walking, upper two for running), and sensor location (on four different body parts). Twenty-five healthy adults participated and four triaxial accelerometers were located on the seventh cervical vertebra (C7), pelvis, wrist, and ankle. The results showed that increasing velocity was associated with increasing regularity only for walking, while no difference in regularity was observed between walking and running. Regularity was generally highest at C7 and ankle, and lowest at the wrist. These data confirm and complement previous literature on regularity assessed on the trunk, and will support future analyses on individuals or groups with specific pathologies affecting locomotor functions.

Early clinical evaluation of total hip arthroplasty by three-dimensional gait analysis and muscle strength testing

BACKGROUND

As improvement of gait is an important reason for patients to undergo total hip arthroplasty (THA) and they generally tend to evaluate its success based on postoperative walking ability, objective functional evaluation of postoperative gait is important. However, the patient's normal gait before osteoarthritis is unknown and the changes that will occur postoperatively are unclear. We investigated the change in gait and hip joint muscle strength after THA by using a portable gait rhythmograph (PGR) and muscle strength measuring device.

PATIENT AND METHODS

The subjects were 46 women (mean age: 65.9 years) with osteoarthritis of the hip. Gait analysis and muscle strength testing were performed before THA, as well as 3 weeks and 3 months after surgery. We measured the walking speed, step length, and gait trajectory using PGR prospectively. PGR is attached to the patient's waist and records signals at a sampling rate of 100 Hz. Isometric torque of hip flexion and abduction were measured by using a hand-held dynamometer.

RESULTS

There was no improvement at 3 weeks postoperatively, but the walking speed, stride length and muscle strength were clearly showed improvement at 3 months postoperatively. The walking trajectory was not normal preoperatively, since the trajectory was not symmetrical and did not intersect in the midline or form a butterfly pattern, and abnormality of the trajectory tended to persist postoperative 3 months despite resolution of hip joint pain after surgery.

CONCLUSION

Since postoperative improvement of gait is an important consideration for patients undergoing THA, it seems relevant to evaluate changes in the gait after surgery and three-dimensional analysis with a PGR may be useful for this purpose.

Exposure to an extreme environment comes at a sensorimotor cost

Long duration space flight is known to induce severe modifications in the sensorimotor and musculoskeletal systems. While in-flight strategies including physical fitness have been used to prevent the loss of bone and muscle mass using appropriate rehabilitative countermeasures, less attention has been put forth in the design of technologies that can quickly and effectively assess sensorimotor function during missions in space. The aims of the present study were therefore (1) to develop a Portable Sensorimotor Assessment Platform (PSAP) to enable a crewmember to independently and quickly assess his/her sensorimotor function during the NASA's Extreme Environment Mission Operations (NEEMO) and (2) to investigate changes in performance of static posture, tandem gait, and lower limb ataxia due to exposure in an extreme environment. Our data reveal that measuring the degree of upper body balance and gait regularity during tandem walking using PSAP provided a sensitive and objective quantification of body movement abnormalities due to changes in sensorimotor performance over the duration of mission exposure.

Exoskeleton assistance symmetry matters: unilateral assistance reduces metabolic cost, but relatively less than bilateral assistance

BACKGROUND

Many gait impairments are characterized by asymmetry and result in reduced mobility. Exoskeletons could be useful for restoring gait symmetry by assisting only one leg. However, we still have limited understanding of the effects of unilateral exoskeleton assistance. Our aim was to compare the effects of unilateral and bilateral assistance using a within-subject study design.

METHODS

Eleven participants walked in different exoskeleton conditions. In the Unilateral conditions, only one leg was assisted. In Bilateral Matched Total Work, half of the assistance from the Unilateral conditions was applied to both legs such that the bilateral sum was equal to that of the Unilateral conditions. In Bilateral Matched Work Per Leg, the same assistance as in the Unilateral conditions was provided to both legs such that the bilateral sum was the double of that of the Unilateral conditions. In the Powered-Off condition, no assistance was provided. We measured metabolic energy consumption, exoskeleton mechanics and kinematics.

RESULTS

On average, the Unilateral, Bilateral Matched Total Work and Bilateral Matched Work Per Leg conditions reduced the metabolic rate by 7, 11 and 15%, respectively, compared with the Powered-Off condition. A possible explanation for why the Unilateral conditions effectively reduced the metabolic rate could be that they caused only very little asymmetry in gait biomechanics, except at the ankle and in the horizontal center-of-mass velocity. We found the highest ratio of metabolic rate reduction versus positive work assistance with bilateral assistance and low work per leg (Bilateral Matched Total Work). Statistical analysis indicated that assistance symmetry and assistance per leg are more important than the bilateral summed assistance for reducing the metabolic rate of walking.

CONCLUSIONS

These data bridge the gap between conclusions from studies with unilateral and bilateral exoskeletons and inform how unilateral assistance can be used to influence gait parameters, such as center-of-mass velocity.

The impact of Nordic walking training on the gait of the elderly

The purpose of the current study was to define the impact of regular practice of Nordic walking on the gait of the elderly. Thereby, we aimed to determine whether the gait characteristics of active elderly persons practicing Nordic walking are more similar to healthy adults than that of the sedentary elderly. Comparison was made based on parameters computed from three inertial sensors during walking at a freely chosen velocity. Results showed differences in gait pattern in terms of the amplitude computed from acceleration and angular velocity at the lumbar region (root mean square), the distribution (Skewness) quantified from the vertical and Euclidean norm of the lumbar acceleration, the complexity (Sample Entropy) of the mediolateral component of lumbar angular velocity and the Euclidean norm of the shank acceleration and angular velocity, the regularity of the lower limbs, the spatiotemporal parameters and the variability (standard deviation) of stance and stride durations. These findings reveal that the pattern of active elderly differs significantly from sedentary elderly of the same age while similarity was observed between the active elderly and healthy adults. These results advance that regular physical activity such as Nordic walking may counteract the deterioration of gait quality that occurs with aging.

EVALUATION OF GAIT ASYMMETRY USING FORCE PLATES VERSUS ACCELEROMETER

Evaluation of kinetic asymmetry during walking has been important to both researchers and clinicians. Wearable devices such as accelerometers are inexpensive, easily accessible tools provide valuable information in gait analysis and offer the potential to assess asymmetry without restriction to cost-ineffective laboratory settings. The aim of this study is to investigate the feasibility of using an accelerometer in assessment of force asymmetry in gait. To this end, the relationship between asymmetry measured from force platforms and a skin-mounted accelerometer on the lower back was studied during normal walking as well as five different levels of self-induced simulated asymmetry. Results show that there is a positive overall correlation between the asymmetry indices measured by the two methods ([Formula: see text], [Formula: see text]). Future study is needed to investigate factors such as age, gender, and anthropometric properties that can help develop a predictive model.

Age Effects in Postural Control Analyzed via a Principal Component Analysis of Kinematic Data and Interpreted in Relation to Predictions of the Optimal Feedback Control Theory

Optimal feedback control theory suggests that control of movement is focused on movement dimensions that are important for the task's success. The current study tested the hypotheses that age effects would emerge in the control of only specific movement components and that these components would be linked to the task relevance. Fifty healthy volunteers, 25 young and 25 older adults, performed a 80s-tandem stance while their postural movements were recorded using a standard motion capture system. The postural movements were decomposed by a principal component analysis into one-dimensional movement components, PM_k, whose control was assessed through two variables, N_k and σ_k, which characterized the tightness and the regularity of the neuro-muscular control, respectively. The older volunteers showed less tight and more irregular control in PM₂ (N₂: -9.2%, p = 0.007; σ₂: +14.3.0%, p = 0.017) but tighter control in PM₈ and PM₉ (N₈: +4.7%, p = 0.020; N₉: +2.5%, p = 0.043; σ₉: -8.8%, p = 0.025). These results suggest that aging effects alter the postural control system not as a whole, but emerge in specific, task relevant components. The findings of the current study thus support the hypothesis that the minimal intervention principle, as described in the context of optimal feedback control (OFC), may be relevant when assessing aging effects on postural control.

Gait

Gait is one of the keys to functional independence. For a long-time, walking was considered an automatic process involving minimal higher-level cognitive input. Indeed, walking does not take place without muscles that move the limbs and the "lower-level" control that regulates the timely activation of the muscles. However, a growing body of literature suggests that walking can be viewed as a cognitive process that requires "higher-level" cognitive control, especially during challenging walking conditions that require executive function and attention. Two main locomotor pathways have been identified involving multiple brain areas for the control of posture and gait: the dorsal pathway of cognitive locomotor control and the ventral pathway for emotional locomotor control. These pathways may be distinctly affected in different pathologies that have important implications for rehabilitation and therapy. The clinical assessment of gait should be a focused, simple, and cost-effective process that provides both quantifiable and qualitative information on performance. In the last two decades, gait analysis has gradually shifted from analysis of a few steps in a restricted space to long-term monitoring of gait using body fixed sensors, capturing real-life and routine behavior in the home and community environment. The chapter also describes this evolution and its implications.

The Multifeature Gait Score: An accurate way to assess gait quality

PURPOSE

This study introduces a novel way to accurately assess gait quality. This new method called Multifeature Gait Score (MGS) is based on the computation of multiple parameters characterizing six aspects of gait (temporal, amplitude, variability, regularity, symmetry and complexity) quantified with one inertial sensor. According to the aspects described, parameters were aggregated into partial scores to indicate the altered aspect in the case of abnormal patterns. In order to evaluate the overall gait quality, partial scores were averaged to a global score.

METHODS

The MGS was computed for 3 groups namely: healthy adult (10 subjects), sedentary elderly (11 subjects) and active elderly (20 subjects). Data were gathered from an inertial sensor located at the lumbar region during two sessions of 12m walking.

RESULTS

The results based on ANOVA and Tukey tests showed that the partial scores with the exception of those which describe the symmetry aspect were able to discriminate between groups (p<0.05). This significant difference was also confirmed by the global score which shows a significantly lower value for the sedentary elderly group (3.58 ±1.15) compared to the healthy adults (5.19 ±0.84) and active elderly (4.82 ±1.26). In addition, the intersession repeatability of the elaborated global score was excellent (ICC = 0.93, % SEM = 10.81).

CONCLUSION

The results obtained support the reliability and the relevance of the MGS as a novel method to characterize gait quality.

Exoskeleton plantarflexion assistance for elderly

Elderly are confronted with reduced physical capabilities and increased metabolic energy cost of walking. Exoskeletons that assist walking have the potential to restore walking capacity by reducing the metabolic cost of walking. However, it is unclear if current exoskeletons can reduce energy cost in elderly. Our goal was to study the effect of an exoskeleton that assists plantarflexion during push-off on the metabolic energy cost of walking in physically active and healthy elderly. Seven elderly (age 69.3±3.5y) walked on treadmill (1.11ms²) with normal shoes and with the exoskeleton both powered (with assistance) and powered-off (without assistance). After 20min of habituation on a prior day and 5min on the test day, subjects were able to walk with the exoskeleton and assistance of the exoskeleton resulted in a reduction in metabolic cost of 12% versus walking with the exoskeleton powered-off. Walking with the exoskeleton was perceived less fatiguing for the muscles compared to normal walking. Assistance resulted in a statistically nonsignificant reduction in metabolic cost of 4% versus walking with normal shoes, likely due to the penalty of wearing the exoskeleton powered-off. Also, exoskeleton mechanical power was relatively low compared to previously identified optimal assistance magnitude in young adults. Future exoskeleton research should focus on further optimizing exoskeleton assistance for specific populations and on considerate integration of exoskeletons in rehabilitation or in daily life. As such, exoskeletons should allow people to walk longer or faster than without assistance and could result in an increase in physical activity and resulting health benefits.

Accelerometer-Based Step Regularity Is Lower in Older Adults with Bilateral Knee Osteoarthritis

Purpose: To compare the regularity and symmetry of gait between a cohort of older adults with bilateral knee osteoarthritis (OA) and an age and sex-matched control group of older adults with healthy knees.

Methods: Fifteen (8 females) older adults with knee OA (64.7 ± 6.7 years) and fifteen (8 females) pain-free controls (66.1 ± 10.0 years) completed a 9-min. walk at a self-selected, comfortable speed while wearing a single waist-mounted tri-axial accelerometer. The following gait parameters were compared between the two groups according to sex: mean step time, mean stride time, stride and step regularity (defined as the consistency of the stride-to-stride or step-to-step pattern) and the symmetry of gait (defined as the difference between step and stride regularity) as determined by an unbiased autocorrelation procedure that analyzed the pattern of acceleration in the vertical, mediolateral and anteroposterior directions.

Results: Older adults with knee OA displayed significantly less step regularity in the vertical (p < 0.05) and anteroposterior (p < 0.05) directions than controls. Females with knee OA were also found to have significantly less mediolateral step regularity than female controls (p < 0.05), whereas no difference was found between males.

Conclusion: The results showed that the regularity of the step pattern in individuals with bilateral knee OA was less consistent compared to similarly-aged older adults with healthy knees. The findings suggest that future studies should investigate the relationship between step regularity, sex and movement direction as well as the application of these methods to the clinical assessment of knee OA.

The effect of aging on gait parameters in able-bodied older subjects: a literature review

BACKGROUND

Gait disorders are common in the elderly populations, and their prevalence increases with age. Abnormal gait has been associated with greater risk for adverse outcomes in older adults, such as immobility and falls, which in turn lead to loss of functional independence and death.

AIM

The purpose of this review was to evaluate all of the original papers that measured gait parameters in the healthy elderly subjects.

METHOD

The search strategy was based on Population Intervention Comparison Outcome method. A search was performed in Pub Med, Science Direct, Google scholar, ISI web of knowledge databases by using the selected keywords. Forty-two articles were selected for final evaluation. The procedure using the PRISMA method was followed.

RESULTS

Stride lengths of older subjects ranged between 135 and 153 cm, and they preferred to walk with a 41 % increase in step width compared to young subjects. Cadence was reported to be between 103 and 112 steps/min in older adults. They consumed an average of 20-30 % more metabolic energy than younger subjects. All except one study demonstrated that older people have significantly reduced gait symmetry.

CONCLUSION

The progression toward shorter steps and slower walking and increased step width and prolonged double support in older adult, may therefore emerge as a compensatory strategy aimed at increasing stability, avoiding falls, or reducing the energetic cost of mobility.

Wireless Tri-Axial Trunk Accelerometry Detects Deviations in Dynamic Center of Mass Motion Due to Running-Induced Fatigue

Small wireless trunk accelerometers have become a popular approach to unobtrusively quantify human locomotion and provide insights into both gait rehabilitation and sports performance. However, limited evidence exists as to which trunk accelerometry measures are suitable for the purpose of detecting movement compensations while running, and specifically in response to fatigue. The aim of this study was therefore to detect deviations in the dynamic center of mass (CoM) motion due to running-induced fatigue using tri-axial trunk accelerometry. Twenty runners aged 18–25 years completed an indoor treadmill running protocol to volitional exhaustion at speeds equivalent to their 3.2 km time trial performance. The following dependent measures were extracted from tri-axial trunk accelerations of 20 running steps before and after the treadmill fatigue protocol: the tri-axial ratio of acceleration root mean square (RMS) to the resultant vector RMS, step and stride regularity (autocorrelation procedure), and sample entropy. Running-induced fatigue increased mediolateral and anteroposterior ratios of acceleration RMS (p < .05), decreased the anteroposterior step regularity (p < .05), and increased the anteroposterior sample entropy (p < .05) of trunk accelerometry patterns. Our findings indicate that treadmill running-induced fatigue might reveal itself in a greater contribution of variability in horizontal plane trunk accelerations, with anteroposterior trunk accelerations that are less regular from step-to-step and are less predictable. It appears that trunk accelerometry parameters can be used to detect deviations in dynamic CoM motion induced by treadmill running fatigue, yet it is unknown how robust or generalizable these parameters are to outdoor running environments.

Seasonality in physical activity and walking of healthy older adults

BACKGROUND

An increasing number of older adults require improvements in their quality of life. Physical activities, particularly walking ability, are of primary importance for older adults. The influence of season on physical activity has not been sufficiently studied among older adults. Therefore, this report compared the physical activity and walking of older individuals between summer and winter seasons using a longitudinal study design in a community in a mid-latitude area.

METHODS

Participants in the study comprised 39 healthy community-dwelling adults ranging in age from 65 to 80 years. Physical parameters and activities as well as the preferred speed of walking were measured at half-year intervals.

RESULTS

Significant seasonal differences from summer to winter and from winter to summer were detected. Specifically, body fat percentage, single-leg stance, walking speed, cadence, stride length, and trunk and head-trunk pitch ranges were greater in winter than in summer, whereas grip strength and steps per day were greater in summer. Temperature and total activity level were considered to be related to body fat percentage. Grip strength was thought to be affected by outdoor temperature. The possibility of relationships between increased activity per unit time in older adults and increased preferred walking speed, cadence, and stride length in winter temperatures was discussed.

CONCLUSION

The seasonal climatic environment of the geographic area of this study affected the activity level of the participants. These results indicate that seasonality should be considered when analyzing physical activity and walking in older adults.

Bracing of the trunk and neck has a differential effect on head control during gait

During gait, the trunk and neck are believed to play an important role in dissipating the transmission of forces from the ground to the head. This attenuation process is important to ensure head control is maintained. The aim of the present study was to assess the impact of externally restricting the motion of the trunk and/or neck segments on acceleration patterns of the upper body and head and related trunk muscle activity. Twelve healthy adults performed three walking trials on a flat, straight 65-m walkway, under four different bracing conditions: 1) control-no brace; 2) neck-braced; 3) trunk-braced; and 4) neck-trunk braced. Three-dimensional acceleration from the head, neck (C7) and lower trunk (L3) were collected, as was muscle activity from trunk. Results revealed that, when the neck and/or trunk were singularly braced, an overall decrease in the ability of the trunk to attenuate gait-related oscillations was observed, which led to increases in the amplitude of vertical acceleration for all segments. However, when the trunk and neck were braced together, acceleration amplitude across all segments decreased in line with increased attenuation from the neck to the head. Bracing was also reflected by increased activity in erector spinae, decreased abdominal muscle activity and lower trunk muscle coactivation. Overall, it would appear that the neuromuscular system of young, healthy individuals was able to maintain a consistent pattern of head acceleration, irrespective of the level of bracing, and that priority was placed over the control of vertical head accelerations during these gait tasks.

Effects of shoe sole geometry on toe clearance and walking stability in older adults

Thirty-five percent of people above age 65 fall each year, and half of their falls are associated with tripping: tripping, an apparently 'mundane' everyday problem, therefore, significantly impacts on older people's health and associated medical costs. To avoid tripping and subsequent falling, sufficient toe clearance during the swing phase is crucial. We previously found that a rocker-shaped shoe sole enhances toe clearance in young adults, thereby decreasing their trip-risk. This study investigates whether such sole design also enhances older adults' toe clearance, without inadvertently affecting their walking stability. Toe clearance and its variability are reported together with measures of walking stability for twelve older adults, walking in shoes with rocker angles of 10°, 15°, and 20°. Surface inclinations (flat, incline, decline) were chosen to reflect a potential real-world environment. Toe clearance increased substantially from the 10° to the 15° rocker angle (p=0.003) without compromising measures of walking stability (p>0.05). A further increase in rocker angle to 20° resulted in less substantial enhancement of toe clearance and came at the cost of a decrease in gait speed on the decline. The novelty of this investigation lies in the exploration of the trade-off between reduction of trip-risk through footwear design and adverse effects on walking stability on real-life relevant surfaces. Our two studies suggest that the current focus on slip-resistance in footwear design may need to be generalised to include other factors that affect trip-risk.