Wearing an ultrasound probe during walking does not influence lower limb joint kinematics in adolescents with cerebral palsy and typically developing peers.

BACKGROUND: Enhancing traditional three-dimensional gait analysis with a portable ultrasound device at the lower-limb muscle-tendon level enables direct measurement of muscle and tendon lengths during walking. However, it is important to consider that the size of the ultrasound probe and its attachment on the lower limb may potentially influence gait pattern. RESEARCH QUESTION: What is the effect of wearing an ultrasound probe at the lower limb in adolescents with cerebral palsy and typically developing peers? METHODS: Eleven individuals with cerebral palsy and nine age-matched typically developing peers walking barefoot at their self-selected speed were analyzed. Data collection occurred under three conditions: the reference condition (GAIT), and two conditions involving placement of the ultrasound probe over the distal medial gastrocnemius-Achilles tendon junction (MTJ) and over the medial gastrocnemius mid-belly to capture fascicles (FAS). Data processing included calculating differences between conditions using root mean square error (RMSE) for joint kinematics and comparing them to the overall mean difference. Additionally, Spearman correlations were calculated to examine the relationship between kinematic RMSEs and walking speed. RESULTS: No significant differences in stance phase duration or walking speed were observed among the three conditions. Average RMSEs were below 5° for all parameters and condition comparisons in both groups. In both the TD and CP groups, RMSE values during the swing phase were higher than those during the stance phase for all joints. No significant correlations were found between height or body mass and swing phase RMSEs. In the CP group, there was a significant correlation between joint kinematics RMSEs and differences in walking speed at the hip, knee and ankle joints when comparing the MTJ condition with the GAIT condition. SIGNIFICANCE: This study confirms joint kinematics alterations are smaller than 5° due to wearing to the leg an ultrasound probe during walking.

The effects of an upper limb exoskeleton on gait performance and stability.

Upper limb exoskeletons (ULEs) are emerging as workplace tools to alleviate workload and prevent work-related musculoskeletal disorders during lifting tasks. However, their introduction raises concerns about potential instability and increased fall risk for workers. This study investigates gait performance and stability parameters implications of ULE use. Fifteen participants performed a carrying task with different loads (0, 5, 10, 15 kg), both with and without the use of an ULE. Spatiotemporal gait parameters, Required Coefficient of Friction (RCoF), Minimum Foot Clearance (MFC), and Margin of Stability (MoS) were analysed. The findings indicate that while the ULE does not significantly alter most gait parameters or slip risk, it may negatively impact trip risk. Furthermore, while mediolateral stability remains unaffected, anteroposterior stability is compromised by ULE usage. These insights are critical for ensuring the safe implementation of ULEs in occupational settings.

Neuro-orthopaedic check-up and walking in people with multiple sclerosis: toward a more specific assessment to improve rehabilitation results.

The rehabilitation process of people with multiple sclerosis (PwMS) is a challenge, and decision-making requires a thorough assessment to increase the chances of success in rehabilitation planning. The aim of this study was to investigate the importance of the neuroorthopaedic check-Up (NOChU) for gait prognosis. Participated in the study 105 PwMS with different levels of impairment. The NOChU includes measurements of passive range of motion (ROM), muscle strength, and spasticity. Additionally, was carried out the spatial-temporal analysis of the walking, Timed Up and Go test, and 6-min walk test. ROM remained relatively preserved to perform daily life activities except for ankle dorsiflexion. Muscle strength was also relatively preserved. Spasticity affected especially the ankle muscles, clearly the sural triceps. Among the NOChU measurements the catch seemed to have the most impact on walking on its different phases and on other activities. Accurate NOChU measurements play a crucial role in clinical settings, guiding informed decisions in rehabilitation planning. Future research endeavours could focus on exploring the correlations between NOChU deficiencies and the decline in walking capabilities among PwMS, with the goal of proposing personalized treatment strategies that address their specific requirements.

Quantifying the dose-response relationship between exercise and health-related quality of life in patients undergoing haemodialysis: A meta-analysis.

Objective: This meta-analysis aims to explore the dose-response relationship of aerobic exercise or aerobic combined resistance exercise on cardiopulmonary function in maintenance hemodialysis（MHD）, with the goal of aiding in the formulation of precise exercise prescriptions. Methods: A literature search up to August 18, 2023, was conducted in databases including Web of Science, among others, focusing on the effects of exercise interventions on cardiopulmonary function in hemodialysis patients.Two researchers independently conducted literature screening, data extraction, and an assessment of study methodology quality. A dose-response meta-analysis was carried out using a one-stage cubic spline mixed-effects model, followed by stratified analyses based on intervention period, intervention method, and exercise environment. Results: A nonlinear dose-response relationship was observed between exercise and 6-minute walk test (6WMT) as well as peak oxygen uptake (VO2Peak) in hemodialysis patients. The optimal exercise dose for the 6WMT across the full exposure range was 922 METs-min/week, with VO2Peak increasing with the dose. The effects were influenced by the type of exercise, intervention period, and exercise environment. An exercise dose of 500 METs-min/week and 619 METs-min/week was found sufficient to achieve the minimal clinically important differences (MCID) for 6WMT and VO2Peak, respectively. Conclusion: There is a significant association between the dose of exercise and its effects. With appropriate adjustment of variables, even low-dose exercise can lead to clinically significant improvements in cardiopulmonary function.

Investigation of intersegmental coordination patterns in human walking.

BACKGROUND: Intersegmental coordination between thigh, shank, and foot plays a crucial role in human gait, facilitating stable and efficient human walking. Limb elevation angles during the gait cycle form a planar manifold describes the by the planar covariation law, a recognized fundamental aspect of human locomotion. RESEARCH QUESTION: How does the walking speed, age, BMI, and height, affect the size and orientation of the intersegmental coordination manifold and covariation plane? METHODS: This study introduces novel metrics for quantifying intersegmental coordination, including the mean radius of the manifold, rotation of the manifold about the origin, and the orientation of the plane with respect to the coordinate planes. A statistical investigation is conducted on a publicly available human walking dataset for subjects aged 19-67 years, walking at speeds between 0.18 and 2.3 m s-1 to determine correlations of the proposed quantities. We used two sample t-test and ANOVA to find statistical significance of changes in the metrics with respect to gender and walking speed, respectively. Regression analysis was used to establish relationships between the introduced metrics and walking speed. RESULTS: High correlations are observed between walking speed and the computed metrics, highlighting the sensitivity of these metrics to gait characteristics. Conversely, negligible correlations are found for demographic parameters like age, body mass index (BMI), and height. Male and female groups exhibit no practically significant differences in any of the considered metrics. Additionally, metrics tend to increase in magnitude as walking speed increases. SIGNIFICANCE: This study contributes numerical metrics to characterize ISC of lower limbs with respect to walking speed along with regression models to estimate these metrics and related kinematic quantities. These findings hold significance for enhancing clinical gait analysis, generating optimal walking trajectories for assistive devices, prosthetics, or rehabilitation, aiming to replicate natural gaits and improve the functionality of biomechanical devices.

Ankle movement alterations during gait in children with acute lymphoblastic leukemia with suspected peripheral mononeuropathy. A cross-sectional study.

BACKGROUND: Peripheral neuropathy due to chemotherapeutic drugs causes alterations in ankle movement during gait. This study aimed to describe the spatiotemporal parameters and ankle kinematics during gait in schoolchildren with acute lymphoblastic leukemia with clinically suspected peripheral neuropathy. METHODS: In children with acute lymphoblastic leukemia in the maintenance phase, we calculated spatiotemporal and kinematic parameters of the ankle during gait using Kinovea® software. Furthermore, we identified alterations in the parameters obtained considering the values of the normality data from a stereophotogrammetry system as the reference values. Finally, we represented the kinematic parameters of the ankles calculated with Kinovea® compared to the normality values of the stereophotogrammetry. FINDINGS: We evaluated 25 schoolchildren; 13 were male (52.0%) with a median age of 88.0months and a median of 60.0 weeks in the maintenance phase, and 54.8% were classified as standard risk. Spatiotemporal parameters: cadence (steps/min), bilateral step length (m), and average gait speed (m/s) in ALL children were significantly lower than reference values (p < 0.001). Except for right mid-stance and bilateral foot strike, initial swing showed that both ankles maintained plantar flexion values during gait, significantly lower in ALL patients (p < 0.05). INTERPRETATION: We identified spatiotemporal and kinematics alterations in schoolchildren with acute lymphoblastic leukemia during all phases of the gait suggestive of alteration in ankle muscles during movement, probably due to peripheral neuropathy; nevertheless, our results should be taken with caution until the accuracy and reliability of Kinovea® software as a diagnostic test compared to the stereophotogrammetric system in children with ALL and healthy peers is proven.

Impact of distinct cognitive domains on gait variability in individuals with mild cognitive impairment and dementia.

BACKGROUND: Gait variability is a common feature in neurodegenerative diseases and has been linked to cognitive impairment. Despite this link, the influence of specific cognitive domains, such as memory, visual spatial skills, executive function, and verbal function on gait variability is not well-understood. OBJECTIVE: To investigate the predictive value of these specific cognitive domains on gait variability in people with mild cognitive impairment (MCI) and dementia during preferred and dual task walking. METHOD: One hundred and two participants with either MCI or dementia underwent a comprehensive cognitive assessment and completed preferred and dual-task walking trials on a pressure-sensing walkway. Gait variability was assessed using the PKMAS software. Lower extremity function was evaluated with a self-reported validated scale. RESULTS: Our findings indicate that only visual spatial abilities had a moderate predictive value on gait variability [F (1, 78) = 17.30, p < 0.01, r = 0.43], both in preferred pace walking (70% direct effect) and dual-task walking (90% direct effect) (p's < 0.05). Additionally, lower extremity functional skills had a significant indirect effect (30%) on gait variability in preferred walking contexts. CONCLUSION: For individuals diagnosed with MCI or dementia, increased gait variability may be driven by deficits in visual spatial processing. An increased understanding of the role of visual spatial processing in gait variability can aid in the assessment and management of individuals with MCI or dementia, potentially leading to targeted interventions to improve mobility and safety.

Effect of Protein Supplementation Combined With Resistance Training in Gait Speed in Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: We aimed to evaluate the effectiveness of the combination of protein supplementation and resistance training (RT), compared with RT alone or combined with a placebo, in improving gait speed. METHODS: We searched PubMed, Web of Science, Cochrane Library, and SPORTDiscus databases, and 18 randomized controlled trials with 1,147 older participants were included for meta-analysis. Data were pooled as the effect sizes (Hedges' g) with 95% confidence interval (CI) of the gait speed (in meters per second). The random-effect meta-analysis, subgroup analyses, meta-regression, and sensitivity analysis were conducted. RESULTS: The combination of protein supplementation and RT significantly improved gait speed (Hedges' g: 0.52 m/s, 95% confidence interval [0.17, 0.86], p = .005; I2 = 86.5%) compared with the RT alone. The subgroup analyses revealed that the significant improvement in gait speed postprotein intervention plus RT was observed only in participants who consumed protein after RT (Hedges' g: 0.90 m/s, 95% confidence interval [0.46, 1.33], p = .001; I2 = 79.6%). The pooled result did not significantly change after excluding any single study at one time or excluding smaller studies with large effect sizes. CONCLUSIONS: Protein supplementation combined with RT could significantly improve the gait speed of older adults compared with RT alone. This positive effect is more pronounced in people who consume protein after RT.

The clinical characteristics of cerebral small vessel disease patients with motoric cognitive risk syndrome during single- and dual-task walking.

Objective: We aimed to (1) identify neuroimaging biomarkers of distinguishing motoric cognitive risk syndrome (MCRS) risk among older Chinese adults with cerebral small vessel disease (CSVD) and (2) detect differences in gait parameters and neuroimaging biomarkers between CSVD individual with and without MCRS, especially during dual-task walking (DTW). Methods: We enrolled 126 inpatients with CSVD who were divided into two groups according to MCRS status. Data on basic parameters, variability, asymmetry, and coordination were collected during single-task walking (STW) and DTW. Neuroimaging features (white matter hyperintensities, lacunes, and microbleeds) and total disease burden were calculated. Analysis of variance and logistic regression analyses were applied to assess the role of STW, DTW, and neuroimaging biomarkers in MCRS. Results: In total, 126 consecutive inpatients with CSVD were included (84 and 42 patients were classified as MCRS-negative and MCRS-positive, respectively). The MCRS-positive group showed poorer performance for nearly all gait parameters compared with the MCRS-negative group during cognitive DTW. Meanwhile, all gait parameters except asymmetry were assessed in participants with MCRS for significant deterioration during cognitive DTW compared with that during STW. However, only basic parameters differed between STW and cognitive DTW in participants without MCRS. A significant independent association between total CSVD scores and MCRS was also detected. Conclusions: For CSVD patients, with higher total CSVD burden rather than any single neuroimaging marker, was linked to a greater risk of MCRS. In addition, CSVD individuals with MCRS had higher variability and phase coordination index (PCI), especially in cognitive DTW. Thus, they should concentrate more on their gait variability or coordination and reduce secondary task loads while walking in daily life, especially in cognitive secondary tasks.

Psoas force recruitment in full-body musculoskeletal movement simulations is restored with a geometrically informed cost function weighting.

Simulations of musculoskeletal models are useful for estimating internal muscle and joint forces. However, predicted forces rely on optimization and modeling formulations. Geometric detail is important to predict muscle forces, and greater geometric complexity is required for muscles that have broad attachments or span many joints, as in the torso. However, the extent to which optimized muscle force recruitment is sensitive to these geometry choices is unclear. We developed level, uphill and downhill sloped walking simulations using a standard (uniformly weighted, "fatigue-like") cost function with lower limb and full-body musculoskeletal models to evaluate hip muscle recruitment with different geometric representations of the psoas muscle under walking conditions with varying hip moment demands. We also tested a novel cost function formulation where muscle activations were weighted according to the modeled geometric detail in the full-body model. Total psoas force was less and iliacus, rectus femoris, and other hip flexors' force was greater when psoas was modeled with greater geometric detail compared to other hip muscles for all slopes. The proposed weighting scheme restored hip muscle force recruitment without sacrificing detailed psoas geometry. In addition, we found that lumbar, but not hip, joint contact forces were influenced by psoas force recruitment. Our results demonstrate that static optimization dependent simulations using models comprised of muscles with different amounts of geometric detail bias force recruitment toward muscles with less geometric detail. Muscle activation weighting that accounts for differences in geometric complexity across muscles corrects for this recruitment bias.

Evaluation of a walking school bus program: a cluster randomized controlled trial.

BACKGROUND: The purpose of this study was to investigate the effects of a walking school bus intervention on children's active commuting to school. METHODS: We conducted a randomized controlled trial (RCT) in Houston, Texas (Year 1) and Seattle, Washington (Years 2-4) from 2012 to 2016. The study had a two-arm, cluster randomized design comparing the intervention (walking school bus and education materials) to the control (education materials) over one school year October/November - May/June). Twenty-two schools that served lower income families participated. Outcomes included percentage of days students' active commuting to school (primary, measured via survey) and moderate-to-vigorous physical activity (MVPA, measured via accelerometry). Follow-up took place in May or June. We used linear mixed-effects models to estimate the association between the intervention and outcomes of interest. RESULTS: Total sample was 418 students [Mage=9.2 (SD = 0.9) years; 46% female], 197 (47%) in the intervention group. The intervention group showed a significant increase compared with the control group over time in percentage of days active commuting (ß = 9.04; 95% CI: 1.10, 16.98; p = 0.015) and MVPA minutes/day (ß = 4.31; 95% CI: 0.70, 7.91; p = 0.02). CONCLUSIONS: These findings support implementation of walking school bus programs that are inclusive of school-age children from lower income families to support active commuting to school and improve physical activity. TRAIL REGISTRATION: This RCT is registered at clinicaltrials.gov (NCT01626807).

Psychophysiological effects of walking in forests and urban built environments with disparate road traffic noise exposure: study protocol of a randomized controlled trial.

BACKGROUND: Stress is a widespread phenomenon and reality of everyday life, entailing negative consequences for physical and psychological wellbeing. Previous studies have indicated that exposure to greenspaces and nature-based interventions are promising approaches to reducing stress and promoting restoration. However, an increasing percentage of the population lives in urban regions with limited opportunities to spend time in greenspaces. In addition, urban settings typically feature increased levels of noise, which represents a major environmental stressor. Although various studies have compared the effects of exposure to greenspaces versus urban built environments, evidence of the effects of noise in this context is very limited. Psychophysiological benefits of exposure to greenspaces compared to urban built environments reported in earlier studies might be less (or at least not only) due to features of the greenspaces than to additional stressors, such as road traffic noise in the urban built environment. Hence, differences in the effects attributed to greenness in previous studies may also be due to potentially detrimental noise effects in comparison settings. This paper reports the study protocol for a randomized, controlled intervention study comparing the effects of walking in forest versus urban built environments, taking road traffic noise exposure during walks in the respective settings into account. METHODS: The protocol envisages a field study employing a pretest-posttest design to compare the effects of 30-min walks in urban built environments and forests with different road traffic noise levels. Assessments will consist of self-reported measures, physiological data (salivary cortisol and skin conductance), an attention test, and noise, as well as greenness measurements. The outcomes will be restoration, stress, positive and negative affect, attention, rumination, and nature connectedness. DISCUSSION: The results will inform about the restorative effect of walking in general, of exposure to different types of environments, and to different noise levels in these sites. The study will provide insights into the benefits of walking and nature-based interventions, taking into account the potential detrimental effects of noise exposure. It will thus facilitate a better understanding of low-threshold interventions to prevent stress and foster wellbeing. TRIAL REGISTRATION: ISRCTN48943261 ; Registered 23.11.2023.

Association between walking pace and risks of major chronic diseases in individuals with hypertension based on a prospective study in UK Biobank: Involvement of inflammation.

OBJECTIVE: Walking pace is associated with risks of major chronic diseases including cancer, cardiovascular disease (CVD) and diabetes mellitus type 2 (T2DM) in the general population. However, whether increasing walking pace could reduce risks of major chronic diseases in individuals with hypertension remains to be explored, and the underlying mechanism potentially mediated by low-grade inflammation is also unclear. METHODS: A total of 160,470 participants with hypertension were included based on the UK Biobank. The relationships of the walking pace and low-grade inflammation with risks of major chronic diseases in individuals with hypertension were assessed by the Cox proportional hazards model. Mediation analyses were performed to investigate the contribution of low-grade inflammation to the association between walking pace and risks of major chronic diseases. RESULTS: Individuals with hypertension at the brisk walking pace had decreased risks of overall cancer and site-specific cancers (liver, lung, and endometrial cancers), all CVD events (angina, atrial fibrillation, heart failure, myocardial infarction, peripheral vascular disease and stroke), and T2DM (hazard ratios: 0.42-0.91). Increasing low-grade inflammation was associated with higher risks of aforementioned diseases except liver cancer and atrial fibrillation. Furthermore, low-grade inflammation partially mediated associations of the walking pace with risks of lung cancer, T2DM, and all CVD events (except atrial fibrillation), with mediation proportion of 2.0%-9.8%. CONCLUSIONS: Brisk walking pace was linked to reduced risks of major chronic diseases in individuals with hypertension, partially mediated by low-grade inflammation. Improving walking pace may be beneficial for health in individuals with hypertension.

Three-dimensional spring-loaded inverted pendulum walking model considering human moving speed and frequency.

The spring-loaded inverted pendulum (SLIP) model is an effective model to capture the essential dynamics during human walking and/or running. However, most of the existing three-dimensional (3D) SLIP model does not explicitly account for human moving speed and frequency. To address this knowledge gap, this paper develops a new SLIP model which includes roller foot, massless spring and concentrated mass. The governing equations-of-motion for SLIP model during its double support phase are derived. It is noted that in the current formulation, the motion of roller foot is prescribed so only the equations for the concentrated mass needs to be solved. In order to yield model parameters leading to a periodic walking gait, a constrained optimization problem is formulated and solved using gradient-based approach with a global search strategy. The optimization results show that when the attack angle ranges from 68° to 74° the 3D SLIP model can yield a periodic walking gait with walking speeds varying from 0.5 to 2.0 m/s, the predicted human walking data is also compared with published experimental data, finding reasonable accuracy.

Causal associations between sarcopenia-related traits and intervertebral disc degeneration: a two-sample mendelian randomization analysis.

BACKGROUND: Sarcopenia (SP) and intervertebral disc degeneration (IVDD) have a higher incidence in the elderly population. Previous studies have indicated a potential association between SP and IVDD. The objective of this study is to elucidate the potential causal relationship between sarcopenia-related traits and IVDD through Two-sample Mendelian randomization (MR) analysis. METHODS: We utilized a genome-wide association study conducted on the European population to collect aggregated data on sarcopenia and IVDD. Inverse variance weighting was primarily employed, supplemented by MR Egger, weighted median, simple model, and weighted model methods. Additionally, sensitivity analysis was performed to assess the robustness of the findings. RESULTS: Appendicular lean mass is positively associated with "Other intervertebral disc disorders" (OIDD) and "Prolapsed or slipped disc" (POSD) (OIDD: p = 0.002, OR = 1.120; POSD: p < 0.001, OR = 1.003), while grip strength (GS) is positively associated with POSD (left: p = 0.004, OR = 1.008; right: p < 0.001, OR = 1.010). It is worth mentioning that walking pace has significant causal relationship with "Low back pain" (LBP), "Lower back pain or/and sciatica" (LBPOAS), "Sciatica with lumbago" (SWL) and OIDD (LBP: p < 0.001, OR = 0.204; LBPOAS: p < 0.001, OR = 0.278; SWL: p = 0.003, OR = 0.249; OIDD: p < 0.001, OR = 0.256). CONCLUSION: The present study revealed the causal relationship between SP-related traits and IVDD and recommended to prevent and treat sarcopenia as a means of preventing IVDD in clinic practice.

Association of Age with Dual-Task Objective Cognitive Indicators and Gait Parameters in Older Adults.

Background: Early recognition of dementia like Alzheimer's disease is crucial for disease diagnosis and treatment, and existing objective tools for early screening of cognitive impairment are limited. Objective: To investigate age-related behavioral indicators of dual-task cognitive performance and gait parameters and to explore potential objective markers of early cognitive decline. Methods: The community-based cognitive screening data was analyzed. Hierarchical cluster analysis and Pearson correlation analysis were performed on the 9-item subjective cognitive decline (SCD-9) scores, walking-cognitive dual-task performance, walking speed, and gait parameters of 152 participants. The significant differences of indicators that may related to cognitive decline were statistically analyzed across six age groups. A mathematical model with age as the independent variable and motor cognition composite score as the dependent variable was established to observe the trend of motor cognition dual-task performance with age. Results: Strong correlation was found between motor cognitive scores and SCD and age. Gait parameters like the mean value of ankle angle, the left-right difference rate of ankle angle and knee angle and the coefficient of variation of gait cycle showed an excellent correlation with age. Motor cognition scores showed a decreasing trend with age. The slope of motor cognition scores with age after 50 years (k = -1.06) was six times higher than that before 50 years (k = -0.18). Conclusions: Cognitive performance and gait parameters in the walking-cognitive dual-task state are promising objective markers that could characterize age-related cognitive decline.

Effectiveness of a passive military exoskeleton in off-loading weight during static and dynamic load carriage: A randomised cross-over study.

BACKGROUND: Load carriage imposes high physical stresses on the human body, increasing the risk of injuries. This study assessed the effectiveness of a passive military exoskeleton in off-loading the weight placed on the body during heavy load carriage under static standing and dynamic walking conditions. METHODS: Eight full-time regular personnel of the Singapore Armed Forces enrolled in the study. Static loading tests included nine trials of 10-s quiet standing while carrying different loads (0-55 kg) with and without the exoskeleton. For dynamic loading, participants walked on a treadmill on flat, inclined, and declined surfaces while carrying two different loads (25 kg, 35 kg) with and without the exoskeleton. In-shoe normal ground reaction forces (GRF) were recorded during quiet standing and treadmill walking. Differences in total force with and without the exoskeleton during static loading were compared using Wilcoxon one-sample signed ranked tests against zero (no weight off-load) as a reference. Statistical parametric mapping test was used to compare the walking in-shoe GRF-time series with and without exoskeleton use for each load and surface condition. RESULTS: Exoskeleton use was effective in off-loading loads of 2.3-13.5 kg during static quiet standing but the response varied substantially across loads and among the participants. Statistical analysis revealed no meaningful differences in the walking in-shoe GRF with and without exoskeleton use. The results were largely consistent across flat, inclined, and declined surfaces, and both 25-kg and 35-kg loads. CONCLUSIONS: The passive military exoskeleton was effective in off-loading some load from the human body during static quiet standing but not dynamic walking on flat and sloped surfaces. The varied response across loads and participants calls for better design and fitting of the military exoskeleton to individual users.

Cognitive-motor interference during walking with modified leg mechanics: a dual-task walking study.

Background: The use of mobile exoskeletons as assistive walking devices has the potential to affect the biomechanics of the musculoskeletal system due to their weight and restricted range of motion. This may result in physical and cognitive load for the user. Understanding how lower extremity loading affects cognitive-motor interference is crucial for the design of wearable devices, including powered exoskeletons, and the development of effective training interventions. Objective: This study aims to examine the effects of modified leg mechanics on cognitive-motor interference in dual-task walking. Gait variability, as an indicator of motor control, was analyzed to investigate its relation to cognitive task difficulty and to determine whether lower extremity loading modifies this relationship. Additionally, the impact on the gait pattern, as represented by the mean values of spatio-temporal gait parameters were investigated. Method: Fifteen healthy young adults walked on a treadmill with and without weight cuffs bilaterally attached to their thighs and shanks while performing a visual-verbal Stroop test (simple task) and a serial subtraction task (difficult task). Dependent variables include mean values and variability (coefficients of variation) of step length, step width, stride time and double support time. Additionally, secondary task performance as correct response rates and perceived workload were assessed. Results: Double support time variability decreased during dual-task walking, but not during walking with modified leg mechanics while performing the difficult secondary task. Walking with modified leg mechanics resulted in increased gait variability compared to normal walking, regardless of cognitive load. During walking with modified leg mechanics, step length, step width, and stride time increased, while double support time decreased. The secondary tasks did not affect the gait pattern. Conclusion: The interplay between an external focus of attention and competition for attentional resources may influence the variability of double support time. The findings suggest that walking with modified leg mechanics could increase cognitive-motor interference for healthy young adults in demanding dual-task situations. Therefore, it is important to analyze the underlying mechanisms of cognitive-motor interference in the context of human-exoskeleton interaction.