Development and decline of upright gait stability

In-Shoe Sensor Measures of Loading Asymmetry during Gait as a Predictor of Frailty Development in Community-Dwelling Older Adults

Clinical walk tests may not predict the development of frailty in healthy older adults. With advancements in wearable technology, it may be possible to predict the development of frailty using loading asymmetry parameters during clinical walk tests. This prospective cohort study aimed to test the hypothesis that increased limb loading asymmetry predicts frailty risk in community-living older adults. Sixty-three independently ambulant community-living adults aged ≥ 65 years were recruited, and forty-seven subjects completed the ten-month follow-up after baseline. Loading asymmetry index of net and regional (forefoot, midfoot, and rearfoot) plantar forces were collected using force sensing insoles during a 10 m walk test with their maximum speed. Development of frailty was defined if the participant progressed from baseline at least one grading group of frailty at the follow-up period using the Kihon Checklist. Fourteen subjects developed frailty during the follow-up period. Increased risk of frailty was associated with each 1% increase in loading asymmetry of net impulse (Odds ratio 1.153, 95%CI 1.001 to 1.329). Net impulse asymmetry significantly correlated with asymmetry of peak force in midfoot force. These results indicate the feasibility of measuring plantar forces of gait during clinical walking tests and underscore the potential of using load asymmetry as a tool to augment frailty risk assessment in community-dwelling older adults.

Cognitive Reserve, Physical Reserve, and Cognitive Efficiency of Older People Living in the Sardinian Blue Zone. An Exploratory Study

This study mainly intended to disentangle the role played by physical reserve as a mediator of the relationship between cognitive reserve and global cognitive functioning in older people aging well. A sample of 120 67-101-year-old community-dwellers was recruited in the Sardinian Blue Zone, an area characterized by the extreme longevity of its inhabitants. Each respondent completed a battery of tests examining cognitive functioning, perceived physical health, cognitive reserve, and physical reserve (objectively assessed through accelerometric-derived measures). Significant associations were found among measures of cognitive reserve, physical reserve, perceived physical health, and cognition. Besides, two mediational analyses pointed out that physical reserve and distinct indexes of cognitive reserve explained 18% and 32% of the variance associated with global cognitive functioning. In conclusion, the combination of high cognitive reserve and more preserved motor functioning seems to contribute to the maintenance of healthy cognition in older people aging well.

Reduced center of mass acceleration during regular walking with electromyography biofeedback

BACKGROUND

Regular walking in healthy adults is known to be kinematically stable, but it is unclear how to further kinematically stabilize regular walking. Electromyography biofeedback (EMG-BF) during walking improves walking ability in patients. However, the effect of EMG-BF on walking stability in healthy adults is unknown. Therefore, this study aimed to investigate whether EMG-BF enhances the stability of regular walking in healthy adults.

RESEARCH QUESTION

Does the EMG-BF enhance the stability of regular walking in healthy adults?

METHODS

Auditory biofeedback of single muscle activity was given to twelve participants during regular walking. The target muscles were the ankle plantar flexor, ankle dorsiflexor, and knee flexor. We compared the root mean square of the center of mass acceleration (RMS-CoMacc), which represents walking smoothness, between biofeedback conditions.

RESULTS

We found that EMG-BF during regular walking partially reduced the RMS-CoMacc (p = 0.01). In particular, biofeedback of the ankle plantar flexor muscle reduced the RMS-CoMacc in both the anteroposterior and vertical directions. In the mediolateral RMS-CoMacc, no significant difference was found (p = 0.24).

SIGNIFICANCE

Our study is novel because it is the first study to reveal the impact of EMG-BF on the stability of walking among healthy adults. It identifies the key muscles for EMG-BF, potentially leading to the development of a more effective EMG-BF system in the rehabilitation. Especially, biofeedback of the ankle plantar flexor muscle could improve walking stability in both the anteroposterior and vertical directions. The effect of EMG-BF for reducing the RMS-CoMacc during regular walking might depend on the target muscles of biofeedback.

Sensorimotor and proprioceptive exercise programs to improve balance in older adults: a systematic review with meta-analysis

The primary aim of this study was to systematically review and meta-analyze the impact of sensorimotor and proprioceptive exercises on balance in older adults. We also sought to define how researchers describe proprioceptive and sensory-motor training and their respective protocols. The review was conducted following the PRISMA guidelines, with searches performed in March 2023. Both authors carried out independent searches using the PubMed and PEDro databases. From a total of 320 identified records, 12 studies were deemed eligible for meta-analysis after screening and removal of duplicates. The average PEDro score was 5.11 ± 1.11 indicating overall fair quality of studies.  Common outcome measures included the Berg balance scale, Timed up and go test, Tinetti balance scale, Functional reach test and various single-leg stance tests. All outcomes were significantly improved by the interventions (standard mean difference = 0.65 - 1.29), with little difference between proprioceptive and sensorimotor training. However, the quality of evidence ranged from "very low" to "low" based on GRADE guidelines, suggesting further high-quality studies are needed. This review underscores the potential benefits of sensorimotor and proprioceptive exercises for enhancing balance in older adults, while also highlighting the ambiguity and inconsistency regarding the usage of the terms proprioceptive and sensorimotor training.

Back geometry and mobility function changes in cerebral palsy children after backward walking training: arandomized controlled trial

AIM

To compare the effects of backward (BW) and forward (FW) walking training on back geometry and mobility function in children with hemiparetic cerebral palsy (CP).

METHODS

Fifty-five children with hemiparetic CP participated in this study. They were randomly assigned into two groups. For 12 weeks, both groups got a conventional physical therapy program three days/week. Groups A and B got a specifically developed FW walking training (25 minutes/session) and a specially designed BW walking training (25 minutes/session), respectively.

RESULTS

The trunk imbalance, lateral deviation, pelvic tilting, pelvic torsion, surface motion, and dynamic gait index of group B improved significantly more than group A (p < .05). Both groups showed significant improvements in all measured variables (p < .05).

CONCLUSION

BW walking training might be considered as an effective therapy modality for improving back geometry and mobility function in hemiparetic CP children compared with FW walking training combined with a typical program.

Lightweight and compact smart walking cane

Devices such as canes and wheelchairs, used to assist locomotion, have remained mostly unchanged for centuries. Recent advances in robotics have the potential to develop smart versions of these devices that can offer better support and living conditions to their users. This is the underlying objective of this project. The existing devices, used during recovery and rehabilitation phases where gait stability is key, are often bulky and cannot be easily migrated from hospital to domestic environments, where maneuvering space tends to be restricted. This article discusses a compact, lightweight and minimally invasive, robotic cane to assist locomotion. The device can assist users with mild locomotion disabilities, e.g., in the final stages of rehabilitation, to maintain and recover their balance in standing and walking situations. This extends previous experiments with alternative control strategies, merged with indicators (based on the Gini index) able to recognize differences between users. Several experiments, with a range of users possessing different mobility impairments, confirm the viability of the robotic cane, with users comfortably using the cane after three minutes, on average, proving its ease of use and low intrusiveness, and with constant support offered during the whole movement. Furthermore, the real-time tuning of the controller gains, via the Gini inequality index, enables adjustment to the user's movement.

The capacity of action observation to drag the trainees' motor pattern toward the observed model

Action Observation Training (AOT) promotes the acquisition of motor abilities. However, while the cortical modulations associated with the AOT efficacy are well known, few studies investigated the AOT peripheral neural correlates and whether their dynamics move towards the observed model during the training. We administered seventy-two participants (randomized into AOT and Control groups) with training for learning to grasp marbles with chopsticks. Execution practice was preceded by an observation session, in which AOT participants observed an expert performing the task, whereas controls observed landscape videos. Behavioral indices were measured, and three hand muscles' electromyographic (EMG) activity was recorded and compared with the expert. Behaviorally, both groups improved during the training, with AOT outperforming controls. The EMG trainee-model similarity also increased during the training, but only for the AOT group. When combining behavioral and EMG similarity findings, no global relationship emerged; however, behavioral improvements were "locally" predicted by the similarity gain in muscles and action phases more related to the specific motor act. These findings reveal that AOT plays a magnetic role in motor learning, attracting the trainee's motor pattern toward the observed model and paving the way for developing online monitoring tools and neurofeedback protocols.

Estimability study on the age of toddlers' gait development based on gait parameters

In the first few years of toddlers' locomotion, various gait parameters improve gradually and dynamically with gait development. Therefore, in this study, we hypothesized that the age of gait development, or the level of gait development with age as its indicator, can be estimated from several gait parameters related to gait development, and investigated its estimability. In total, 97 healthy toddlers aged about 1-3 years participated in the study. All five selected gait parameters showed a moderate or higher correlation with age, but the duration with a large change and the strength of the association with gait development varied for each gait parameter. Multiple regression analysis was performed using age as the objective variable and five selected gait parameters as explanatory variables, and an estimation model (R² = 0.683, adjusted R² = 0.665) was created. The estimation model was verified using a test dataset separate from the training dataset (R² = 0.82, p < 0.001). It was suggested that the age of gait development could be estimated from gait alone. Gait analysis based on empirical observations may reduce the need for skilled observers and their potential variability.

Evaluating the immediate effect of the speed alteration task on walking stability using the Timed Up and Go test

[Purpose] This study aimed to investigate how the speed alteration task, which gradually increases or conversely decreases walking speed, affected walking stability. [Participants and Methods] Thirteen healthy young adults performed two walking tasks as follows: the speed alteration task, in which the walking speed was gradually increased or decreased, and the speed constant task, in which the walking speed was maintained at a comfortable level. Before and after each task, the Timed Up and Go test was performed to analyze time, walking speed, and trajectory. The overall score of the Timed Up and Go test, as well as the scores of the three major segments (i.e., forward, turning around, and return), and nine subsegments, were calculated and analyzed. [Results] During the speed alteration task, parameters including time and walking speed of the Timed Up and Go test were significantly improved. Also, the same parameters increased significantly in the forward and return segments. These increases were also observed in the first subsegment of the forward segment and the second subsegment of the return segment. [Conclusion] The speed alteration task improved walking stability, so it could be used in gait training to improve walking stability.

Motor proficiency as a correlate of coping in late adult lifespan. An exploratory study

BACKGROUND AND OBJECTIVES

A body of studies suggests that coping resources may represent a protective factor against functional and cognitive losses associated with advanced ageing. This study intended to examine the contributions of global cognition, functional mobility, and muscular strength on self-reported coping strategies in late adulthood.

METHODS

One hundred and thirty-seven community-based older individuals (M_age = 77.2 years, SD = 5.8 years, age range: 63-92 years), 48 males and 89 females with and without signs of cognitive decline completed a battery of tools assessing global cognitive function, problem-focused coping, muscular strength (assessed by handgrip strength, HGS) and functional mobility (assessed using the instrumented Timed-Up-and-Go test).

RESULTS

Significant associations were found between problem-focused coping, global cognitive function, HGS, functional mobility parameters, age, and education. Moreover, when the effects of education and gender were controlled for, HGS, functional mobility, and global cognitive function scores accounted for 44% of the variance in coping.

CONCLUSIONS

In clinical practice, the use of functional mobility and muscular strength measures to screen the physical health of older individuals should be encouraged.

Changes in kinematic synergy in older adults during walking: A two-year follow-up study

BACKGROUND

A well-controlled center of mass (CoM) in a coordinated segmental manner is required during gait. A synergy index that quantifies the strength of the synergistic control of the body segments that control the CoM can be evaluated using uncontrolled manifold (UCM) analysis. Several studies have compared the synergy index between older and younger adults; however, contradictory results have been found regarding age-related changes in the synergy index. Moreover, no study has investigated these changes longitudinally.

RESEARCH QUESTION

To evaluate age-related changes in the synergy index to control the CoM during gait in a longitudinal study.

METHODS

Twenty-five older adults participated at a baseline visit. The gait task at the two-year follow-up was completed by 16 older adults. Participants walked on a 6-m walkway at baseline and the two-year follow-up, and kinematic data were collected. Using UCM analysis, the synergy indices controlling CoM in the mediolateral and vertical directions were evaluated at baseline and follow-up. We also evaluated the Timed Up and Go (TUG) test and the strength of the knee extensor at both periods.

RESULTS

We found that TUG was significantly slower at follow-up; however, no difference was found in muscle strength. The synergy index in the mediolateral direction increased significantly after two years; such increases were found in individuals with decreased gait speed.

SIGNIFICANCE

This study showed that changes in gait patterns, including decreasing gait speed and increasing segmental coordination, may be important for gait with appropriate postural control relative to the environment and dynamic stability of the body in individuals with low functional mobility.

The Role of Walking Experience in the Emergence of Gait Harmony in Typically Developing Toddlers

The ability to walk without support usually develops in the first year of a typically developing toddler’s life and matures further in the following years. Mature walking is characterized by the correct timing of the different gait phases that make up a full gait cycle formed by stance, swing, and double support phases. The harmony of mature walking is given by a specific self-similar structure of the ratios between the durations of these phases (stride/stance, stance/swing, swing/double support), that in adults all converge to the golden ratio (phi, about 1.618). The aim of this longitudinal, prospective, experimental study was to investigate the evolution of this gait harmonic structure in the transition from supported to independent walking. In total, 27 children were recruited and recorded at various stages of locomotor development, ranging from neonatal stepping up to an independent walking experience of about six months. Differently from walking speed that progressively increased with age, the gait phase ratios started to converge to golden value only after the first independent steps, suggesting a relation to the maturation of the walking experience. The independent walking experience seems to represent a trigger for the evolution of a locomotor harmonic pattern in toddlers learning to walk.

Segmental contribution to whole-body angular momentum during stepping in healthy young and old adults

Recent evidence suggests that during volitional stepping older adults control whole-body angular momentum (H) less effectively than younger adults, which may impose a greater challenge for balance control during this task in the elderly. This study investigated the influence of aging on the segment angular momenta and their contributions to H during stepping. Eighteen old and 15 young healthy adults were instructed to perform a series of stepping at two speed conditions: preferred and as fast as possible. Full-body kinematics were recorded to compute angular momenta of the trunk, arms and legs and their contributions to total absolute H on the entire stepping movement. Results indicated that older adults exhibited larger angular momenta of the trunk and legs in the sagittal plane, which contributed to a higher sagittal plane H range during stepping compared to young adults. Results also revealed that older adults had a greater trunk contribution and lower leg contribution to total absolute H in the sagittal plane compared to young adults, even though there was no difference in the other two planes. These results stress that age-related changes in H control during stepping arise as a result of changes in trunk and leg rotational dynamics.

Clinical assessment of gait and functional mobility in Italian healthy and cognitively impaired older persons using wearable inertial sensors

AIM

The main purpose of the present study was to verify the feasibility of wearable inertial sensors (IMUs) in a clinical setting to screen gait and functional mobility in Italian older persons. In particular, we intended to verify the capability of IMUs to discriminate individuals with and without cognitive impairments and assess the existence of significant correlations between mobility parameters extracted by processing trunk accelerations and cognitive status.

METHODS

This is a cross-sectional study performed on 213 adults aged over 65 years (mean age 77.0 ± 5.4; 62% female) who underwent cognitive assessment (through Addenbrooke's Cognitive Examination Revised, ACE-R) instrumental gait analysis and the Timed Up and Go (TUG) test carried out using a wearable IMU located in the lower back.

RESULTS

Individuals with cognitive impairments exhibit a peculiar gait pattern, characterized by significant reduction of speed (- 34% vs. healthy individuals), stride length (- 28%), cadence (- 9%), and increase in double support duration (+ 11%). Slight, but significant changes in stance and swing phase duration were also detected. Poorer performances in presence of cognitive impairment were observed in terms of functional mobility as overall and sub-phase TUG times resulted significantly higher with respect to healthy individuals (overall time, + 38%, sub-phases times ranging from + 22 to + 34%), although with some difference associated with age. The severity of mobility alterations was found moderately to strongly correlated with the ACE-R score (Spearman's rho = 0.58 vs. gait speed, 0.54 vs. stride length, 0.66 vs. overall TUG time).

CONCLUSION

The findings obtained in the present study suggest that wearable IMUs appear to be an effective solution for the clinical assessment of mobility parameters of older persons screened for cognitive impairments within a clinical setting. They may represent a useful tool for the clinician in verifying the effectiveness of interventions to alleviate the impact of mobility limitations on daily life in cognitively impaired individuals.

Artificial Neural Network Analyzing Wearable Device Gait Data for Identifying Patients With Stroke Unable to Return to Work

A potential dramatic effect of long-term disability due to stroke is the inability to return to work. An accurate prognosis and the identification of the parameters inflating the possibility of return to work after neurorehabilitation are crucial. Many factors may influence it, such as mobility and, in particular, walking ability. In this pilot study, two emerging technologies have been combined with the aim of developing a prognostic tool for identifying patients able to return to work: a wearable inertial measurement unit for gait analysis and an artificial neural network (ANN). Compared with more conventional statistics, the ANN showed a higher accuracy in identifying patients with respect to healthy subjects (90.9 vs. 75.8%) and also in identifying the subjects unable to return to work (93.9 vs. 81.8%). In this last analysis, the duration of double support phase resulted the most important input of the ANN. The potentiality of the ANN, developed also in other fields such as marketing on social networks, could allow a powerful support for clinicians that today should manage a large amount of instrumentally recorded parameters in patients with stroke.

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.

Slow walking synergies reveal a functional role for arm swing asymmetry in healthy adults: A principal component analysis with relation to mechanical work

INTRODUCTION

The purpose of this study was to reveal a functional role for arm-swing asymmetry during gait in healthy adults. To this end, the primary aim was to investigate the role of neuromuscular control on the asymmetry of propulsive and collision joint work at either end of the double-support phase (W_DS) in the context of sidedness. The secondary aim was to investigate the effect of neuromuscular control on propulsive and collision joint work at either end of the single-support phase (W_SS) in the context of arm-swing asymmetry.

METHODS

Slow -walking trials of 25 participants were analysed using principal component analysis to generate movement synergies (PM_k). Independent variables included the tightness of neuromuscular control (N₁) formulated from the first PM_k and the directional Arm-swing asymmetry index (dASI). Dependent variables included the difference between double-support collision and propulsive joint work (W_DS) and a ratio consisting of the difference between single-support collision and propulsive work of both sides (W_SS). A linear mixed-effects model was utilized for aim 1 while a multiple linear regression analysis was undertaken for aim 2.

RESULTS

Healthy adult gait was accompanied by a left-side dominant arm-swing on average. For aim 1, N₁ demonstrated a significant negative effect on W_DS while sidedness had a negative direct effect and positive indirect effect through N₁ on W_DS. The most notable finding was the interaction between dASI and N₁ which demonstrated a highly significant positive effect on W_SS.

INTERPRETATION

Evidence was put forward that arm-swing asymmetry during gait is related to footedness among healthy adults. Future studies should look to formally confirm this finding.

Functional Electrical Stimulation for Foot Drop in Post-Stroke People: Quantitative Effects on Step-to-Step Symmetry of Gait Using a Wearable Inertial Sensor

The main purpose of the present study was to assess the effects of foot drop stimulators (FDS) in individuals with stroke by means of spatio-temporal and step-to-step symmetry, harmonic ratio (HR), parameters obtained from trunk accelerations acquired using a wearable inertial sensor. Thirty-two patients (age: 56.84 ± 9.10 years; 68.8% male) underwent an instrumental gait analysis, performed using a wearable inertial sensor before and a day after the 10-session treatment (PRE and POST sessions). The treatment consisted of 10 sessions of 20 min of walking on a treadmill while using the FDS device. The spatio-temporal parameters and the HR in the anteroposterior (AP), vertical (V), and mediolateral (ML) directions were computed from trunk acceleration data. The results showed that time had a significant effect on the spatio-temporal parameters; in particular, a significant increase in gait speed was detected. Regarding the HRs, the HR in the ML direction was found to have significantly increased (+20%), while those in the AP and V directions decreased (approximately 13%). Even if further studies are necessary, from these results, the HR seems to provide additional information on gait patterns with respect to the traditional spatio-temporal parameters, advancing the assessment of the effects of FDS devices in stroke patients.

Stair Gait in Older Adults Worsens With Smaller Step Treads and When Transitioning Between Level and Stair Walking

Older people have an increased risk of falling during locomotion, with falls on stairs being particularly common and dangerous. Step going (i.e., the horizontal distance between two consecutive step edges) defines the base of support available for foot placement on stairs, as with smaller going, the user's ability to balance on the steps may become problematic. Here we quantified how stair negotiation in older participants changes between four goings (175, 225, 275, and 325 mm) and compared stair negotiation with and without a walking approach. Twenty-one younger (29 ± 6 years) and 20 older (74 ± 4 years) participants negotiated a 7-step experimental stair. Motion capture and step-embedded force platform data were collected. Handrail use was also monitored. From the motion capture data, body velocity, trunk orientation, foot clearance and foot overhang were quantified. For all participants, as stair going decreased, gait velocity (ascent p_A = 0.033, descent p_D = 0.003) and horizontal step clearance decreased (p_A = 0.001), while trunk rotation (p_D = 0.002) and foot overhang increased (p_A,D < 0.001). Compared to the younger group, older participants used the handrail more, were slower across all conditions (p_A < 0.001, p_D = 0.001) and their foot clearance tended to be smaller. With a walking approach, the older group (Group x Start interaction) showed a larger trunk rotation (p_A = 0.011, p_D = 0.015), and smaller lead foot horizontal (p_A = 0.046) and vertical clearances (p_D = 0.039) compared to the younger group. A regression analysis to determine the predictors of foot clearance and amount of overhang showed that physical activity was a common predictor for both age groups. In addition, for the older group, medications and fear of falling were found to predict stair performance for most goings, while sway during single-legged standing was the most common predictor for the younger group. Older participants adapted to smaller goings by using the handrails and reducing gait velocity. The predictors of performance suggest that motor and fall risk assessment is complex and multifactorial. The results shown here are consistent with the recommendation that larger going and pausing before negotiating stairs may improve stair safety, especially for older users.

Motor Skill Learning-Induced Functional Plasticity in the Primary Somatosensory Cortex: A Comparison Between Young and Older Adults

While in young adults (YAs) the underlying neural mechanisms of motor learning are well-studied, studies on the involvement of the somatosensory system during motor skill learning in older adults (OAs) remain sparse. Therefore, the aim of the present study was to investigate motor learning-induced neuroplasticity in the primary somatosensory cortex (S1) in YAs and OAs. Somatosensory evoked potentials (SEPs) were used to quantify somatosensory activation prior and immediately after motor skill learning in 20 right-handed healthy YAs (age range: 19–35 years) and OAs (age range: 57–76 years). Participants underwent a single session of a 30-min co-contraction task of the abductor pollicis brevis (APB) and deltoid muscle. To assess the effect of motor learning, muscle onset asynchrony (MOA) between the onsets of the contractions of both muscles was measured using electromyography monitoring. In both groups, MOA shortened significantly during motor learning, with YAs showing bigger reductions. No changes were found in SEP amplitudes after motor learning in both groups. However, a correlation analysis revealed an association between baseline SEP amplitudes of the N20/P25 and N30 SEP component and the motor learning slope in YAs such that higher amplitudes are related to higher learning. Hence, the present findings suggest that SEP amplitudes might serve as a predictor of individual motor learning success, at least in YAs. Additionally, our results suggest that OAs are still capable of learning complex motor tasks, showing the importance of motor training in higher age to remain an active part of our society as a prevention for care dependency.

Magnitude, symmetry and attenuation of upper body accelerations during walking in women: The role of age, fall history and walking surface

OBJECTIVES

The present experiment examined the role of age and fall history in upper body accelerations when walking on an even and on an uneven surface.

STUDY DESIGN

An observational cross-sectional study.

MAIN OUTCOME MEASURES

The magnitude (root mean square [RMS]), symmetry (harmonic ratio) and attenuation (attenuation coefficient) of upper body accelerations were quantified as primary outcomes; gait spatiotemporal parameters were measured as secondary outcomes.

METHODS

Twenty young adults (mean ± SD age: 29.00 ± 4.51 yrs), 20 older non-fallers (66.60 ± 5.43 yrs) and 20 older fallers (68.55 ± 4.86 yrs) walked on an even and on an uneven surface, while wearing four accelerometers attached to the forehead, pelvis, right and left shanks.

RESULTS

Older fallers exhibited increased RMS acceleration in the mediolateral direction at the pelvis level compared with young adults when walking on the even surface (0.18 ± 0.04 vs. 0.14 ± 0.02, respectively), whereas walking on an uneven surface was associated with reduced magnitude of acceleration in older fallers (0.19 ± 0.04) compared with non-fallers (0.23 ± 0.04) and young adults (0.22 ± 0.03). Among other changes, walking on the uneven surface diminished pelvis-to-head attenuation in the mediolateral direction in older fallers (38.07 ± 14.51) compared with non-fallers (50.96 ± 11.03) and young adults (62.62 ± 8.21; all ps<0.05).

CONCLUSIONS

Reduced mediolateral accelerations in older fallers when walking on the uneven surface can be interpreted as a compensatory mechanism to preserve stability through increased body stiffness. Reduced postural flexibility in the frontal plane compromises the central role of the trunk in minimizing the impact of gait-related oscillations to the head, as evidenced by reduced mediolateral attenuation in older fallers.

Smoothness of Gait in Healthy and Cognitively Impaired Individuals: A Study on Italian Elderly Using Wearable Inertial Sensor

The main purpose of the present study was to compare the smoothness of gait in older adults with and without cognitive impairments, using the harmonic ratio (HR), a metric derived from trunk accelerations. Ninety older adults aged over 65 (age: 78.9 ± 4.8 years; 62% female) underwent instrumental gait analysis, performed using a wearable inertial sensor and cognitive assessment with the Mini Mental State Examination (MMSE) and Addenbrooke’s Cognitive Examination Revised (ACE-R). They were stratified into three groups based on their MMSE performance: healthy controls (HC), early and advanced cognitive decline (ECD, ACD). The spatio-temporal and smoothness of gait parameters, the latter expressed through HR in anteroposterior (AP), vertical (V) and mediolateral (ML) directions, were derived from trunk acceleration data. The existence of a relationship between gait parameters and degree of cognitive impairment was also explored. The results show that individuals with ECD and ACD exhibited significantly slower speed and shorter stride length, as well as reduced values of HR in the AP and V directions compared to HC, while no significant differences were found between ECD and ACD in any of the investigated parameters. Gait speed, stride length and HR in all directions were found to be moderately correlated with both MMSE and ACE-R scores. Such findings suggest that, in addition to the known changes in gait speed and stride length, important reductions in smoothness of gait are likely to occur in older adults, owing to early/prodromal stages of cognitive impairment. Given the peculiar nature of these metrics, which refers to overall body stability during gait, the calculation of HR may result in being useful in improving the characterization of gait patterns in older adults with cognitive impairments.

Observer-Agent Kinematic Similarity Facilitates Action Intention Decoding

It is well known that the kinematics of an action is modulated by the underlying motor intention. In turn, kinematics serves as a cue also during action observation, providing hints about the intention of the observed action. However, an open question is whether decoding others’ intentions on the basis of their kinematics depends solely on how much the kinematics varies across different actions, or rather it is also influenced by its similarity with the observer motor repertoire. The execution of reach-to-grasp and place actions, differing for target size and context, was recorded in terms of upper-limb kinematics in 21 volunteers and in an actor. Volunteers had later to observe the sole reach-to-grasp phase of the actor’s actions, and predict the underlying intention. The potential benefit of the kinematic actor-participant similarity for recognition accuracy was evaluated. In execution, both target size and context modulated specific kinematic parameters. More importantly, although participants performed above chance in intention recognition, the similarity of motor patterns positively correlated with recognition accuracy. Overall, these data indicate that kinematic similarity exerts a facilitative role in intention recognition, providing further support to the view of action intention recognition as a visuo-motor process grounded in motor resonance.

The light is red: Uncertainty behaviours displayed by pedestrians during illegal road crossing

Road accidents involving pedestrians are a reality of urban life. Pedestrian risk is now well known and documented from the perspective of drivers. However, pedestrian behaviour plays a central role in road accidents, notably in terms of illegal road crossing at signalized intersections. This study focuses on pedestrians crossing illegally at a signal light, and specifically investigates uncertainty behaviour, also referred to as hesitation, which occurs when a pedestrian slows down or stops his/her crossing movement then (1) abandons the crossing by returning to the kerb or (2) accelerates to cross the road more quickly. We sought to understand the causes of this behaviour in France and Japan, two countries where interesting differences have already been demonstrated in the way pedestrians behave. The results show a longer period of uncertainty for pedestrians in Japan compared to France. Japanese pedestrians also hesitated longer when they were alone. This study demonstrates a tendency to speed up if there are a number of pedestrians already crossing the road, but abandoning behaviours were more frequently observed than acceleration. This study confirms that pedestrians may misevaluate the moment to cross and hesitate when they realise that they have made a mistake, thus increasing the risk of an accident. These results could help to find solutions that prevent illegal and dangerous road-crossing behaviours.

Age-Related Changes in Mobility Evaluated by the Timed Up and Go Test Instrumented through a Single Sensor

Mobility across people with a large range of age was evaluated, for the first time, by using an instrumented timed up and go test (iTUG) based on signals acquired by a single wearable inertial sensor. Eighty healthy participants, from childhood to old age, performed the test, covering walking distances of 3 m and 7 m. Total time, temporal, and velocity parameters of linear and turning subcomponents of the test were quantified. While children, adults, and senior adults exhibited similar values for all the parameters, older adults showed increases in duration and reductions in velocity during the turning phases when compared with the other groups. an increase in velocity was observed during mid turning when the test was performed along the longer distance. Similarity across children, adults, and senior adults indicates that healthy individuals develop the abilities performed in the iTUG early, while the slowing down shown during the turning phases by the older adults may reflect the need to implement adaptive adjustments to face changes of direction. These results emphasize the idea that reducing equipment to a single sensor provides an appropriate quantification when the iTUG is used to investigate a broader age range or different levels of complexity.

Gait Asymmetry Post-Stroke: Determining Valid and Reliable Methods Using a Single Accelerometer Located on the Trunk

Asymmetry is a cardinal symptom of gait post-stroke that is targeted during rehabilitation. Technological developments have allowed accelerometers to be a feasible tool to provide digital gait variables. Many acceleration-derived variables are proposed to measure gait asymmetry. Despite a need for accurate calculation, no consensus exists for what is the most valid and reliable variable. Using an instrumented walkway (GaitRite) as the reference standard, this study compared the validity and reliability of multiple acceleration-derived asymmetry variables. Twenty-five post-stroke participants performed repeated walks over GaitRite whilst wearing a tri-axial accelerometer (Axivity AX3) on their lower back, on two occasions, one week apart. Harmonic ratio, autocorrelation, gait symmetry index, phase plots, acceleration, and jerk root mean square were calculated from the acceleration signals. Test-retest reliability was calculated, and concurrent validity was estimated by comparison with GaitRite. The strongest concurrent validity was obtained from step regularity from the vertical signal, which also recorded excellent test-retest reliability (Spearman's rank correlation coefficients (rho) = 0.87 and Intraclass correlation coefficient (ICC21) = 0.98, respectively). Future research should test the responsiveness of this and other step asymmetry variables to quantify change during recovery and the effect of rehabilitative interventions for consideration as digital biomarkers to quantify gait asymmetry.

Decision-Making Processes Underlying Pedestrian Behaviors at Signalized Crossing: Part 1. The First to Step off the Kerb

Pedestrians are ideal subjects for the study of decision-making, due to the inter-individual variation in risk taking. Many studies have attempted to understand which environmental factors influence the number of times pedestrians broke the rules at road-crossings, very few focused on the decision-making process of pedestrians according to the different conditions of these variables, that is to say their perception and interpretation of the information they receive. We used survival analyses and modeling to highlight the decision-making process of pedestrians crossing the road at signalized crossings in France and in Japan. For the first pedestrians to step off the kerb, we showed that the probability to cross the road follows three different processes: one at the red signal, one just before the pedestrian signal turns green, and one after the signal has turned green. Globally, the decision of the first pedestrian to cross, whether he or she does so at the green or at the red signal, is influenced by their country of residence. We identify the use of cognitive processes such as risk sensitivity and temporal discounting, and propose new concepts based on the results of this study to decrease the incidence of rule-breaking by pedestrians.

Age-Related Changes in Smoothness of Gait of Healthy Children and Early Adolescents

In this study, we acquired and processed trunk accelerations during level walking in 85 children aged 8-13 years to calculate spatio-temporal parameters and Harmonic Ratio (HR), which is a metrics representative of gait smoothness and step-to-step symmetry. The results show that while spatio-temporal parameters remain unchanged once normalized considering individuals' anthropometry, significantly higher values of HR for both the antero-posterior and vertical directions were found in participants aged 12-13 with respect to those of 8-9. This indicates an improvement of gait symmetry, which suggests that the gait maturation process is still ongoing for the age ranges tested here.

Postural Instability in Parkinson's Disease: A Review

Parkinson’s disease (PD) is a heterogeneous progressive neurodegenerative disorder, which typically affects older adults; it is predicted that by 2030 about 3% of the world population above 65 years of age is likely to be affected. At present, the diagnosis of PD is clinical, subjective, nonspecific, and often inadequate. There is a need to quantify the PD factors for an objective disease assessment. Among the various factors, postural instability (PI) is unresponsive to the existing treatment strategies resulting in morbidity. In this work, we review the physiology and pathophysiology of postural balance that is essential to treat PI among PD patients. Specifically, we discuss some of the reported factors for an early PI diagnosis, including age, nervous system lesions, genetic mutations, abnormal proprioception, impaired reflexes, and altered biomechanics. Though the contributing factors to PI have been identified, how their quantification to grade PI severity in a patient can help in treatment is not fully understood. By contextualizing the contributing factors, we aim to assist the future research efforts that underpin posturographical and histopathological studies to measure PI in PD. Once the pathology of PI is established, effective diagnostic tools and treatment strategies could be developed to curtail patient falls.

Contribution of vision and its age-related changes to postural stability in obstacle crossing during locomotion

BACKGROUND

Obstacle crossing requires sufficient toe clearance for trip and fall prevention for which postural stability is a prerequisite. It is thought that the upper visual field plays an important role in the maintenance of postural stability, but its influence and age-dependence have not been investigated yet.

RESEARCH QUESTION

What is the role of the visual fields in maintaining postural stability during crossing an obstacle in young and older adults?.

METHODS

This study included 14 young adults and 14 older adults. The participants, wearing an accelerometer and liquid crystal shutter goggles, were asked to cross an obstacle under the following three conditions (i) full vision; (ii) total visual field occlusion at two steps before the obstacle, and (iii) lower visual field occlusion at two steps before the obstacle. The root mean square ratio in the mediolateral direction (RMSR_ML) for the three sections (i.e., approach to the obstacle, lead limb crossing, and trail limb crossing), as well as the root mean square in the mediolateral direction (RMS_ML) for each section were calculated.

RESULTS

RMS_ML during lead limb crossing was significantly increased in older adults compared to young adults (p < 0.01). There was no significant main effect of visual condition and age group on RMSR_ML for the three steps.

SIGNIFICANCE

The study results suggest postural lateral instability in older adults with poor balance ability during lead limb crossing. Regardless of age, the peripheral visual information appears to contribute minimally to the maintenance of postural lateral stability at least from two steps before the obstacle, when the participants perceived the surrounding environment and the size of the obstacle while approaching it.

Upper body accelerations during level walking in transtibial amputees

BACKGROUND:

The observation of upper body movement is gaining interest in the gait analysis community. Recent studies involved the use of body-worn motion sensors, allowing translation of laboratory measurements to real-life settings in the context of patient monitoring and fall prevention.

OBJECTIVES:

It was shown that amputee persons demonstrate altered acceleration patterns due to the presence of prosthetic components, while no information is available on how accelerations propagate upwards to the head during level walking. This descriptive study aims to fill this gap.

STUDY DESIGN:

Original research report.

METHODS:

Twenty definitive prosthesis users with transtibial amputation and 20 age-matched able-bodied individuals participated in the study. Three magneto-inertial measurement units were placed at head, sternum and pelvis level to assess acceleration root mean square. Three repetitions of the 10-m walking test were performed at a self-selected speed.

RESULTS:

Acceleration root mean square was significantly larger at pelvis and head level in individuals with amputation than in able-bodied participants, mainly in the transverse plane ( p < 0.05). Differences were also observed in how accelerations propagate upwards, highlighting that a different motor strategy is adopted in amputee persons gait to compensate for increased instability.

CONCLUSION:

The obtained parameters allow an objective mobility assessment of amputee persons that can integrate with the traditional clinical approach.

CLINICAL RELEVANCE

Transtibial amputees exhibit asymmetries due to the sound limb's support prevalence during gait: this is evidenced by amplified accelerations on the transverse plane and by related differences in upper body movement control. Assessing these accelerations and their attenuations upwards may be helpful to understand amputee's motor strategies and to improve prosthetic training.

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.

Inertial sensors versus standard systems in gait analysis: a systematic review and meta-analysis

INTRODUCTION

The increasing popularity of inertial sensors in clinical practice is not supported by precise information on their reliability or guidelines for their use in rehabilitation. The authors investigated the state of the literature concerning the use of inertial sensors for gait analysis in both healthy and pathological adults comparing traditional systems. Furthermore, trying to define directions for clinicians.

EVIDENCE ACQUISITION

In accordance with the PRISMA statement, authors searched in PubMed, Web of Science and Scopus all paper published from January 1st, 2005 until December 31st, 2017. They included both healthy and pathological adults' subjects as population, wearable or inertial sensors used for gait analysis and compared with classical gait analysis performed in a Motion Lab as intervention and comparison, gait parameters as outcomes. Considering the methodological quality, authors focused on: sample; description of the study; type of gait analysis used for comparison; type of sensor; sensor placement on the body; gait task requested.

EVIDENCE SYNTHESIS

From a total of 888 articles, 16 manuscripts were selected and 7 of them were considered for meta-analysis for different gait parameters. Demographic data, tested devices, reference systems, test procedures and outcomes were analyzed.

CONCLUSIONS

Our results show a good agreement between inertial sensors and classical gait analysis for some gait parameters, supporting their use as a solution for capturing kinematic information over an extended space and time and even outside a laboratory in real-life conditions. Authors can support the use of portable inertial sensors for a practical gait analysis in clinical setting with good reliability. It will then be the experience of the clinician to direct the decision-making process.

Clinical features of patients who might benefit more from walking robotic training

BACKGROUND

Robotic walking training improves probability to reach an autonomous walking in non-ambulant patients affected by subacute stroke. However, little information is available regarding the prognostic factors for identifying best responder patients. The purpose of the present study is therefore to investigate the clinical features of patients with subacute stroke that might benefit more from robotic walking therapy.

METHODS

One hundred subacute inpatients randomized in robotic or conventional gait training were assessed at baseline and after 4 weeks of training performed 5 times per week. Forward Binary Logistic Regression was performed using functional ambulation category (FAC) as dependent variable and as independent variables: trunk function (trunk control test), global ability (Barthel Index), age, sex, time from stroke and beginning of rehabilitation, side and type of stroke, and in the first analysis also type of treatment.

RESULTS

The parameters that have a significant effect on the FAC-score at discharge were a higher BI-score at admission, a higher TCT-score at admission, a short time from the ictus and a robotic therapy. The variance explained by these four factors was 78%. When the two groups were separately analysed for type of treatment, a higher BI-score and a short time from stroke resulted in good prognosis for conventional therapy, whereas only a high TCT-score improved efficacy of robotic training.

CONCLUSION

Efficacy of robotic walking training was not associated with global ability at admission. Hence, more severely disabled patients may obtain greater benefit from robotic training, independently by other factors, except the need of a residual trunk control that was identified as a good prognostic factor for robotic walking training.

Usefulness of Magnetoinertial Wearable Devices in Neurorehabilitation of Children with Cerebral Palsy

Background

Despite the increasing use of wearable magnetoinertial measurement units (MIMUs) for gait analysis, the efficacy of MIMU-based assessment for planning rehabilitation has not been adequately documented yet.

Methods

The usefulness of a MIMU-based assessment was evaluated comparing the data acquired by three MIMUs located at the pelvis, sternum, and head levels in 12 children with cerebral palsy (CP, age: 2–9 years) and 12 age-matched children with typical development (TD). Gait stability was quantified in terms of acceleration attenuation coefficients from pelvis to head, pelvis to sternum, and sternum to head. Children with CP were randomly divided in two groups: in the first group (CPI), MIMU-based parameters were used by therapists for planning patient-tailored rehabilitation programs, whereas in the second group (CPB), therapists were blind to the MIMU-based assessment results. Both CPI and CPB were tested before and after the relevant neurorehabilitation program. Ad hoc questionnaires were also administered to therapists of the CPI group to assess the degree of usefulness perceived about the information provided by the MIMU-based assessment.

Results

Significant differences were found between children with CP and those with TD for the acceleration attenuation coefficient from pelvis to head (p = 0.048) and from pelvis to sternum (p = 0.021). After neurorehabilitation, this last parameter increased more in CPI (35%) than in CPB (6%, p = 0.017 for the interaction group per time). The results of the questionnaires showed that therapists agreed with the usability (100% judged it as “easy to use”) and usefulness of the MIMU-based assessment in defining patient-oriented interventions (87%).

Conclusions

There is a large debate in literature about the efficacy of classical gait analysis that should be enlarged to new technological approaches, such as that based on MIMUs. This study is a first proof of concept about the efficacy of this approach for neurorehabilitation of children with CP.

Watch your step! Who can recover stair climbing independence after stroke?

BACKGROUND

After discharge, most patients who have suffered a stroke remain with some limitations in their stair climbing ability. This is a critical factor in order to be independent in real-life mobility. Although there are several studies on prognostic factors for gait recovery, few of them have focused on the recovery of stair climbing.

AIM

The aim of this study was to identify prognostic risk factors for the recovery of stair climbing ability in a large sample of subjects with subacute stroke.

DESIGN

Observational study.

SETTING

Neurorehabilitation Inpatient Unit.

POPULATION

Subjects within the first month after stroke that had been admitted to an inpatient rehabilitation unit and discharged after an intensive inpatient rehabilitation.

METHODS

Demographical and clinical data were collected. Barthel Index (BI), Trunk Control Test and Motricity Index (MI) scores were recorded at admission and at discharge. Patients received two daily 40-minute sessions of motor rehabilitation, six days per week, during approximately two months. Forward Binary Logistic regressions were used to identify the role of risk factors, using as dependent variables the recovery of stair climbing ability and walking ability at discharge. As independent variables we used age, gender, onset-to-admission interval, side of hemiparesis, trunk control, Motricity Index (MI), presence of obesity, presence of neglect, presence of depression, classification of cerebral infarction (total anterior circulation, partial anterior circulation, posterior circulation or lacunar infarcts), degree of independence in activities of daily living, and cognitive state, all assessed at admission.

RESULTS

A total of 257 subjects were enrolled. BI-Score, MI-Score and presence of unilateral spatial neglect at admission were able to explain 83% of variance for the recovery of stair climbing ability. Subjects with a BI >40 at admission were about 17 times more likely to be able to climb stairs again than other patients, and those with MI ≥25 were about 9 times more likely than the rest. The presence of unilateral spatial neglect reduced this possibility of recovering stair climbing ability by about 5.5 times. Of these factors, only MI ≥25, together with a score at Trunk Control Test >12, significantly predicted also walking recovery.

CONCLUSIONS

This study highlights the different prognostic factors for recovering stair climbing and walking abilities, with a major role of unilateral spatial neglect in the former.

CLINICAL REHABILITATION IMPACT

There is a need for specific rehabilitation of stair climbing, also for improving the independence in activities of daily living, especially in patients who the clinical staff already knows should manage stairs in their community after being discharged.

Neural predictors of gait stability when walking freely in the real-world

BACKGROUND

Gait impairments during real-world locomotion are common in neurological diseases. However, very little is currently known about the neural correlates of walking in the real world and on which regions of the brain are involved in regulating gait stability and performance. As a first step to understanding how neural control of gait may be impaired in neurological conditions such as Parkinson's disease, we investigated how regional brain activation might predict walking performance in the urban environment and whilst engaging with secondary tasks in healthy subjects.

METHODS

We recorded gait characteristics including trunk acceleration and brain activation in 14 healthy young subjects whilst they walked around the university campus freely (single task), while conversing with the experimenter and while texting with their smartphone. Neural spectral power density (PSD) was evaluated in three brain regions of interest, namely the pre-frontal cortex (PFC) and bilateral posterior parietal cortex (right/left PPC). We hypothesized that specific regional neural activation would predict trunk acceleration data obtained during the different walking conditions.

RESULTS

Vertical trunk acceleration was predicted by gait velocity and left PPC theta (4-7 Hz) band PSD in single-task walking (R-squared = 0.725, p = 0.001) and by gait velocity and left PPC alpha (8-12 Hz) band PSD in walking while conversing (R-squared = 0.727, p = 0.001). Medio-lateral trunk acceleration was predicted by left PPC beta (15-25 Hz) band PSD when walking while texting (R-squared = 0.434, p = 0.010).

CONCLUSIONS

We suggest that the left PPC may be involved in the processes of sensorimotor integration and gait control during walking in real-world conditions. Frequency-specific coding was operative in different dual tasks and may be developed as biomarkers of gait deficits in neurological conditions during performance of these types of, now commonly undertaken, dual tasks.

Harmony as a convergence attractor that minimizes the energy expenditure and variability in physiological gait and the loss of harmony in cerebellar ataxia

BACKGROUND

The harmony of the human gait was recently found to be related to the golden ratio value (ϕ). The ratio between the duration of the stance and that of the swing phases of a gait cycle was in fact found to be close to ϕ, which implies that, because of the fractal property of autosimilarity of that number, the gait ratios stride/stance, stance/swing, swing/double support, were not significantly different from one another. We studied a group of patients with cerebellar ataxia to investigate how the differences between their gait ratios and the golden ratio are related to efficiency and stability of their gait, assessed by energy expenditure and stride-to-stride variability, respectively.

METHODS

The gait of 28 patients who were affected by degenerative cerebellar ataxia and of 28 healthy controls was studied using a stereophotogrammetric system. The above mentioned gait ratios, the energy expenditure estimated using the pelvis reconstructed method and the gait variability in terms of the stride length were computed, and their relationships were analyzed. Matching procedures have also been used to avoid multicollinearity biases.

FINDINGS

The gait ratio values of the patients were farther from the controls (and hence from ϕ), even in speed matched conditions (P=0.011, Cohen's D=0.76), but not when the variability and energy expenditure were matched between the two groups (Cohen's D=0.49). In patients with cerebellar ataxia, the farther the stance-swing ratio was from ϕ, the larger the total mechanical work (R²_adj=0.64). Further, a significant positive correlation was observed between the difference of the gait ratio from the golden ratio and the severity of the disease (R=0.421, P=0.026).

INTERPRETATION

Harmony of gait appears to be a benchmark of physiological gait leading to physiological energy recovery and gait reliability. Neurorehabilitation of patients with ataxia might benefit from the restoration of harmony of their locomotor patterns.

Neural Correlates of Single- and Dual-Task Walking in the Real World

Recent developments in mobile brain-body imaging (MoBI) technologies have enabled studies of human locomotion where subjects are able to move freely in more ecologically valid scenarios. In this study, MoBI was employed to describe the behavioral and neurophysiological aspects of three different commonly occurring walking conditions in healthy adults. The experimental conditions were self-paced walking, walking while conversing with a friend and lastly walking while texting with a smartphone. We hypothesized that gait performance would decrease with increased cognitive demands and that condition-specific neural activation would involve condition-specific brain areas. Gait kinematics and high density electroencephalography (EEG) were recorded whilst walking around a university campus. Conditions with dual tasks were accompanied by decreased gait performance. Walking while conversing was associated with an increase of theta (θ) and beta (β) neural power in electrodes located over left-frontal and right parietal regions, whereas walking while texting was associated with a decrease of β neural power in a cluster of electrodes over the frontal-premotor and sensorimotor cortices when compared to walking whilst conversing. In conclusion, the behavioral “signatures” of common real-life activities performed outside the laboratory environment were accompanied by differing frequency-specific neural “biomarkers”. The current findings encourage the study of the neural biomarkers of disrupted gait control in neurologically impaired patients.

Robot-assisted gait training for stroke patients: current state of the art and perspectives of robotics

In this review, we give a brief outline of robot-mediated gait training for stroke patients, as an important emerging field in rehabilitation. Technological innovations are allowing rehabilitation to move toward more integrated processes, with improved efficiency and less long-term impairments. In particular, robot-mediated neurorehabilitation is a rapidly advancing field, which uses robotic systems to define new methods for treating neurological injuries, especially stroke. The use of robots in gait training can enhance rehabilitation, but it needs to be used according to well-defined neuroscientific principles. The field of robot-mediated neurorehabilitation brings challenges to both bioengineering and clinical practice. This article reviews the state of the art (including commercially available systems) and perspectives of robotics in poststroke rehabilitation for walking recovery. A critical revision, including the problems at stake regarding robotic clinical use, is also presented.

Aging effect on muscle synergies in stepping forth during a forward perturbation

PURPOSE

We explored changes in muscle interactions during healthy aging as a window into neural control strategies of postural preparation to action/perturbation. In particular, we quantified the strength of multi-muscle synergies stabilizing the center of pressure (COP) displacement during the preparation for making a step associated with support surface translations.

METHODS

Young and elderly subjects were required to make a step in response to support surface perturbations. Surface muscle activity of 11 leg and trunk muscles was analyzed to identify sets of 4 muscle modes (M-modes). Linear combinations of M-modes and their relationship to changes in the COP displacement in the anterior-posterior direction were then determined. Uncontrolled manifold analysis was performed to determine variance components in the M-mode space and indices of M-mode synergy stabilizing COP displacement.

RESULTS

Prior to the step initiation, the older subjects showed strong synergies that stabilized COP displacement to forward perturbation of the support surface. However, the synergy indices were significantly lower than those of the young subjects during preparation for making a step. The timings of early postural adjustment (EPA) and anticipatory postural adjustment (APA) were consistently earlier in the young subjects as compared to the older subjects. For both groups, the timing of EPA did not change across tasks, while APA showed delayed timing in response to the support surface translations.

CONCLUSIONS

We infer that changes in the indices of synergies with age may present challenges for the control of postural preparation to external perturbation in older adults. They may lead to excessive muscle co-contractions and low stability of COP displacement. The results reported here could have clinical relevance when identifying the risk of making a step, which has been linked to an increased risk of falls among the elderly.

Adaptations of Prefrontal Brain Activity, Executive Functions, and Gait in Healthy Elderly Following Exergame and Balance Training: A Randomized-Controlled Study

During aging, the prefrontal cortex (PFC) undergoes age-dependent neuronal changes influencing cognitive and motor functions. Motor-learning interventions are hypothesized to ameliorate motor and cognitive deficits in older adults. Especially, video game-based physical exercise might have the potential to train motor in combination with cognitive abilities in older adults. The aim of this study was to compare conventional balance training with video game-based physical exercise, a so-called exergame, on the relative power (RP) of electroencephalographic (EEG) frequencies over the PFC, executive function (EF), and gait performance. Twenty-seven participants (mean age 79.2 ± 7.3 years) were randomly assigned to one of two groups. All participants completed 24 trainings including three times a 30 min session/week. The EEG measurements showed that theta RP significantly decreased in favor of the exergame group [L₍₁₄₎ = 6.23, p = 0.007]. Comparing pre- vs. post-test, EFs improved both within the exergame (working memory: z = -2.28, p = 0.021; divided attention auditory: z = -2.51, p = 0.009; divided attention visual: z = -2.06, p = 0.040; go/no-go: z = -2.55, p = 0.008; set-shifting: z = -2.90, p = 0.002) and within the balance group (set-shifting: z = -2.04, p = 0.042). Moreover, spatio-temporal gait parameters primarily improved within the exergame group under dual-task conditions (speed normal walking: z = -2.90, p = 0.002; speed fast walking: z = -2.97, p = 0.001; cadence normal walking: z = -2.97, p = 0.001; stride length fast walking: z = -2.69, p = 0.005) and within the balance group under single-task conditions (speed normal walking: z = -2.54, p = 0.009; speed fast walking: z = -1.98, p = 0.049; cadence normal walking: z = -2.79, p = 0.003). These results indicate that exergame training as well as balance training positively influence prefrontal cortex activity and/or function in varying proportion.

Stability and Harmony of Gait in Patients with Subacute Stroke

Stroke affects many gait features, such as gait stability, symmetry, and harmony. However, it is still unclear which of these features are directly altered by primary damage, and which are affected by the reduced walking speed. The aim of this study was to analyze the above gait features in patients with subacute stroke with respect to the values observed in age- and speed-matched healthy subjects. A wearable triaxial accelerometer and an optoelectronic device were used for assessing the upright gait stability, symmetry of trunk movements, and harmonic structure of gait phases by means of the root-mean-square (RMS) acceleration of the trunk, harmonic ratio (HR), and gait ratios (GRs), respectively. For healthy subjects, results showed that RMS acceleration increased with speed, HR peaked at a comfortable speed, and GRs tended towards the theoretical value of the golden ratio for speeds >1 m/s. At matched speed conditions, patients showed higher instabilities in the latero-lateral axis (p = 0.001) and reduced symmetry of trunk movements (p = 0.002). Different from healthy subjects, antero-posterior and latero-lateral acceleration harmonics were coupled in patients (R = 0.507, p = 0.023). Conversely, GRs were not more altered in patients than in slow-walking healthy subjects. In conclusion, patients with stroke showed some characteristics similar to those of the elderly when the latter subjects walk slowly, and some altered characteristics, such as increased latero-lateral instabilities coupled with movements performed along the antero-posterior axis.

Postural Control of Elderly Adults on Inclined Surfaces

This study analyzed the postural control of older adults on inclined surfaces, and was conducted in 17 elderly adults and 18 young adults of both genders. Ground reaction forces and moments were collected using two AMTI force platforms, one of which was in a horizontal position (HOR), while the other was inclined 14° in relation to the horizontal plane. Each participant executed three 70 s-trials of bipedal standing with their eyes open and eyes closed in three inclination conditions: the HOR, the inclined position at ankle dorsi-flexion (UP), and the inclined position at ankle plantar-flexion (DOWN). Spectral analysis, global (mean velocity-Velm, ellipse area-Area and F80), and structural stabilometric descriptors (sway density curve-SDC, detrended fluctuation analysis-DFA, sample entropy-SEn) were employed to assess the center of pressure sway. Velm and F80 were greater for the elderly, whereas SDC, DFA, and SEn were smaller for this group. Global, SDC and DFA variables were sensitive to visual deprivation, however the relative difference from the EO to EC condition was higher in young than in elderly. The DOWN condition was more stable than the UP condition for both young and older adults. With regard to the UP condition, the challenge observed is essentially associated with the corresponding biomechanical constraints. In conclusion, the elderly showed significant differences compared to the young, but age per se may not necessarily result in compromised postural control.

Restricted Arm Swing Affects Gait Stability and Increased Walking Speed Alters Trunk Movements in Children with Cerebral Palsy

Observational research suggests that in children with cerebral palsy, the altered arm swing is linked to instability during walking. Therefore, the current study investigates whether children with cerebral palsy use their arms more than typically developing children, to enhance gait stability. Evidence also suggests an influence of walking speed on gait stability. Moreover, previous research highlighted a link between walking speed and arm swing. Hence, the experiment aimed to explore differences between typically developing children and children with cerebral palsy taking into account the combined influence of restricting arm swing and increasing walking speed on gait stability. Spatiotemporal gait characteristics, trunk movement parameters and margins of stability were obtained using three dimensional gait analysis to assess gait stability of 26 children with cerebral palsy and 24 typically developing children. Four walking conditions were evaluated: (i) free arm swing and preferred walking speed; (ii) restricted arm swing and preferred walking speed; (iii) free arm swing and high walking speed; and (iv) restricted arm swing and high walking speed. Double support time and trunk acceleration variability increased more when arm swing was restricted in children with bilateral cerebral palsy compared to typically developing children and children with unilateral cerebral palsy. Trunk sway velocity increased more when walking speed was increased in children with unilateral cerebral palsy compared to children with bilateral cerebral palsy and typically developing children and in children with bilateral cerebral palsy compared to typically developing children. Trunk sway velocity increased more when both arm swing was restricted and walking speed was increased in children with bilateral cerebral palsy compared to typically developing children. It is proposed that facilitating arm swing during gait rehabilitation can improve gait stability and decrease trunk movements in children with cerebral palsy. The current results thereby partly support the suggestion that facilitating arm swing in specific situations possibly enhances safety and reduces the risk of falling in children with cerebral palsy.