Gait Stability Research Articles

Nonlinear Gait Variability Increases with Age in Children from 2–10 Years Old

Background: Linear methods of analysis of variability are concerned with the magnitude of variability and often consider deviations from a central mean as errors. The utilization of nonlinear tools to examine variability allows for the exploration and measurement of the patterns of variability displayed by the system. This methodology explores the deterministic properties of biological signals, in this case, gait, or how previous iterations within the gait cycle influence subsequent and future iterations. The nonlinear analysis of gait variability of the joint angle time series has not been investigated in developing children. Methods: We collected 3 min of treadmill walking data for 28 children between the ages of 2 and 10 years old and analyzed their joint angle time series using nonlinear methods of analysis (sample entropy, largest Lyapunov exponent, and recurrence quantification analysis). Results: Our results indicate that the nonlinear variability of children’s gait increases as children age. Interestingly, this contrasts with the findings from our previous work that showed a decrease in linear variability as children age. The combination of a decrease in linear variability, or a refined and improved stability of gait, as well as an increase in nonlinear variability, or an increase in the sophistication and quality of movement patterns, suggest an overall maturation of the neuromuscular system. Conclusions: Our study indicate that there is a refining of gait with age and motor maturation. This refining speaks to the overall multifaceted organization of systems that defines the maturation of gait.

The effect of run duration, gait variable and Lyapunov exponent algorithm on the inter-session reliability of local dynamic stability in healthy young people.

Local dynamic stability (LDS) of gait has been used to differentiate between healthy and injured populations, establishing its potential as an indicator of healthy gait and a new objective measure to assess gait function following injury. For LDS to be a reliable assessment tool of healthy gait progression during rehabilitation, it must provide consistent and sensitive inter-session measures. Methodological factors such as trial duration, gait variable, and Lyapunov Exponent (LyE) algorithm can influence LDS estimation and its reliability. Young people are a high-risk population for sport-related injuries, and running is a key activity during rehabilitation and is regularly assessed. Therefore, the effects of run duration, gait variable, and LyE algorithm choice on the reliability and sensitivity of inter-session LDS measures in young people were investigated. Sixteen healthy participants ran on a treadmill on two separate sessions (difference of 7±5days). LDS was calculated using both the Rosenstein and Wolf algorithm for durations of 1-, 2-, 3-, 4- and 5-min of knee flexion angle and medio-lateral acceleration of the pelvis and thorax from each session. The relative and absolute reliability between sessions was calculated using the intraclass correlation coefficient and standard error of measurement. The sensitivity of inter-session LDS change was quantified by the minimal detectable change. Results showed that longer run durations produced higher relative reliability and a minimum run duration of 4min is recommended to achieve moderate-to-good inter-session reliability across all gait variables and LyE algorithms. However, shorter durations of 2-3min may still be sufficient when using medio-lateral pelvis acceleration or knee flexion angle, particularly with the Rosenstein algorithm, which also improves sensitivity to change. These findings provide practical guidance for methodological choices when calculating LDS in young people during running and support their potential use as reliable tools for monitoring gait function and tracking rehabilitation progress in young people following injury.

Acute effects of voluntary breathing patterns on postural control during walking.

Breathing and postural control is reported to be both neuromuscularly and mechanically interdependent. To date, the effects of voluntary abdominal and thoracic breathing (VAB and VTB) on the EMG activity of muscles involved in both respiratory and postural functions, as well as gait biomechanics related to these breathing patterns, have not been investigated in young, healthy adults. The aim of the study was to evaluate the EMG responses of neck and trunk muscles, as well as the kinematic, stability, and kinetic parameters of gait induced by VAB and VTB compared to involuntary breathing (INB). Twenty-four healthy, physically active participants (12 men and 12 females) were required to complete three two-minute walking sessions on an instrumented treadmill (e.g. devices with capacitive sensors embedded beneath the running belt) at 5.0kmh-1, first with INB and then alternatively with VAB and VTB. A respiratory inductive plethysmography unit was used to provide real-time visual feedback of the breathing pattern performed by each participant. The EMG activity of the sternocleidomastoid (SCM), upper trapezius (UT), thoracic and lumbar erector spinae (TES and LES), as well as spatiotemporal (step width, stride length, stride time, stance phase, swing phase, and cadence), stability (anteroposterior and mediolateral center of pressure trajectory), and dynamic gait parameters (vertical ground reaction forces, vGRF) were recorded during each testing condition. Our findings revealed that both voluntary breathing patterns significantly affected the EMG activity of the SCM (p<0.01) and UT (p<0.05), with the activity between these muscles, as expressed by the SCM:UT ratio, being more balanced during VAB (0.94) and VTB (1.05) compared to INB (0.73). Additionally, VAB walking led to a narrower step width (p<0.01) and reduced vGRF over the forefoot (p<0.01) compared to INB walking. Neither VAB nor VTB influenced the activation levels of the LES and TES, nor did they affect other spatiotemporal, stability, or dynamic gait parameters (p>0.05). Our findings suggest that certain gait parameters (e.g. step width, forefoot vGRFs) are primarily influenced by VAB compared to INB, likely due to the more balanced activation of the SCM and UT muscles. This balanced activation may enhance head stability and control during walking, thereby contributing to improved postural control.

Higher Levels of Serum Leptin Are Linked with a Reduction in Gait Stability: A Sex-Based Association

Gait stability prevents falls and injuries during physical activities. Muscle strength, aging, and co-existing chronic diseases are factors that affect gait stability. Leptin is an adipokine with pro-inflammatory properties. Several reports demonstrated an association between serum leptin and a reduction in muscle strength. Given the above relationships, we hypothesized that serum leptin could be associated with gait stability. To test this, 146 apparently healthy university students were recruited. Data collection involved anthropometric measurements, physical activity (PA) data, gait parameters, and serum leptin levels. A gait instability index was derived from the percentages of double support time and walking asymmetry (WA) collected from smartphones. Females demonstrated higher leptin levels and WA despite a lower body mass index (BMI). Lower PA levels were also observed among females. Leptin levels were negatively correlated with WA, step count, and vigorous PA (p &lt; 0.05). These correlations remained significant following correction for leptin by BMI. Using logistic regression, a higher leptin-to-BMI ratio was associated with high gait instability (OR = 9.97, 95%CI: 4.17−23.84, p &lt; 0.001). After stratification by sex, this association was only evident among females (OR = 6.09, 95%CI: 1.04−35.56, p = 0.045). These findings suggest a sex-based association between serum leptin and gait stability among apparently healthy students.

How knee muscles and ground reaction forces shape knee buckling and ankle push-off in neuromuscular simulations of human walking

Ankle push-off is important for efficient, human-like walking, and many prosthetic devices mimic push-off using motors or elastic elements. The knee is extended throughout the stance phase and begins to buckle just before push-off, with timing being crucial. However, the exact mechanisms behind this buckling are still unclear. We use a predictive neuromuscular simulation to investigate whether active muscles are required for knee buckling and to what extent ground reaction forces (GRFs) drive it. In a systematic parameter search, we tested how long the knee muscles vastus (VAS), gastrocnemius (GAS), and hamstrings could be deactivated while maintaining a stable gait with impulsive push-off. VAS deactivation up to 35% of the gait cycle resulted in a dynamic gait with increased ankle peak power. GAS deactivation up to 20% of the gait cycle was detrimental to gait efficiency and showed reduced ankle peak power. At the start of knee buckling, the GRF vector is positioned near the knee joint’s neutral axis, assisting in knee flexion. However, this mechanism is likely not enough to drive knee flexion independently. Our findings contribute to the biomechanical understanding of ankle push-off, with applications in prosthetic and bipedal robotic design, and fundamental research on human gait mechanics.

Step Width Haptic Feedback for Gait Stability in Spinocerebellar Ataxia: Preliminary Results.

Wider step width and lower step-to-step variability are linked to improved gait stability and reduced fall risk. It is unclear if patients with spinocerebellar ataxia (SCA) can learn to adjust these aspects of gait to reduce fall risk. The aims were to examine the possibility of using wearable step width haptic biofeedback to enhance gait stability and reduce fall risk in individuals with SCA. Thirteen people with SCA type 3 performed step width training (single session) using real-time feedback. Step width increased post-training (19.3 cm, interquartile range [IQR] 16.3-20.2 cm) and at retention (16.6 cm, IQR 16.2-21.1 cm), compared to baseline (11.0 cm, IQR 5.2-15.2 cm; P < 0.001). Step width variability decreased during post-training (19.7%, IQR 17.4%-26.2%) and at retention (22.3%, IQR 18.6%-30.2%), compared to baseline (44.5%, IQR 28.5%-71.2%; P < 0.001). Crossover steps, another mark of instability, decreased after training (P < 0.031). These pilot results suggest that patients with SCA can use a novel, wearable biofeedback system to improve their gait stability. © 2025 International Parkinson and Movement Disorder Society.

Long-term dance training alters the likelihood of slips and trips

Prior studies have suggested that dance may mitigate fall risks by enhancing muscular strength; despite its apparent safety, compelling evidence substantiating its efficacy in fall prevention remains scarce. The objective of this study was to examine whether individuals with prolonged dance training demonstrate distinct biomechanical responses to fall risk in contrast to those without dance experience. Methods: Thirty-two participants were recruited internally from a university setting (comprising 8 non-dancers, 8 ballet dancers, 8 korean dancers, and 8 modern dancers) for this investigation. Kinematic and kinetic data were scrutinized using Visual-3D software, and subsequent analyses involved data normalization, with One-way ANOVA conducted using SPSS 23.0 software. Results: Ballet dancers and modern dancers displayed longer stride lengths, narrower step widths, and quicker walking speeds compared to non-dancers; Korean dancers exhibited shorter stride lengths, narrower step widths, slower walking speeds, and higher gait symmetry. Modern dancers demonstrated the highest MTC during swing phase, while korean dancers showed the smallest HCV, thus yielding the lowest RCOF. Conclusion: Korean dancers demonstrated the lower risks of falls and trips; rigorous professional training in dancers fosters distinctive, stable gaits, superior joint control, and robust body balance, all contributing to a decrease of the likelihood of risks of falls and trips. Conversely, while modern dancers similarly showed the reduced risks, the varied styles in modern dance may be introducing some uncertainty in mitigating risks of falls and trips.

Association Between Lower Limb Strength Asymmetry and Gait Asymmetry: Implications for Gait Variability in Stroke Survivors.

Background: Gait disturbances characterized by asymmetries in lower limb strength and gait patterns are frequently observed in stroke patients, which increases gait variability and fall risk. However, the extent to which lower limb strength asymmetry influences gait asymmetry and variability in this population remains unclear. Methods: This cross-sectional study included 84 participants, comprising stroke survivors and age- and sex-matched healthy older adults. A portable dynamometer was used to assess lower limb strength, and inertial measurement units to analyze gait parameters. Asymmetry indices were used to quantify strength and gait asymmetries. Statistical analyses included Pearson correlations and stepwise regression to examine the relationships among lower limb strength asymmetry, gait asymmetry, and gait variability. Results: Stroke survivors exhibited significantly greater lower limb strength and gait asymmetries than healthy older adults (p < 0.001). Knee extension (KE) strength asymmetry was a significant predictor of increased gait variability in stroke survivors (R2 = 0.448, p < 0.001) but not in healthy controls. Moreover, longer poststroke duration was associated with greater asymmetry in KE strength (r = 0.42, p < 0.05) and double support time (r = 0.45, p < 0.05). Conclusions: Lower limb strength asymmetry, specifically in knee extensors, is a critical determinant of gait asymmetry and variability in stroke survivors. The association between poststroke duration and increased asymmetry indicates the progressive nature of these impairments. These findings emphasize the importance of targeted interventions to reduce strength asymmetry and address chronic impairments in poststroke rehabilitation to improve gait stability and reduce fall risk.

Gait instability and compensatory mechanisms in Parkinson's disease with camptocormia: An exploratory study.

Camptocormia has been considered to contribute to vertical gait instability and, at times, may also lead to forward instability in experimental settings in Parkinson's disease (PD). However, these aspects, along with compensatory mechanisms, remain largely unexplored. This study comprehensively investigated gait instability and compensatory strategies in PD patients with camptocormia (PD+CC). Ten PD+CC, 30 without camptocormia (PD-CC), and 27 healthy controls (HCs) participated. Self-paced gait tasks were analyzed using three-dimensional motion capture systems to assess gait stability, spatiotemporal, and kinematic parameters. Unique cases with pronounced forward gait stability or instability were first identified, followed by group comparisons. Correlation analysis was performed to examine associations between trunk flexion angles (lower/upper) and gait parameters. Significance level was set at 0.05. Excluding one unique case, the PD+CC group showed a significantly lower vertical center of mass (COM) position (p=0.019), along with increased mediolateral COM velocity (p=0.004) and step width (p=0.013), compared to PD-CC group. Both PD groups showed higher anterior-posterior margin of stability than HCs (p<0.001). Significant correlations were found between lower/upper trunk flexion angles and a lower vertical COM position (r=-0.690/-0.332), as well as increased mediolateral COM velocity (r=0.374/0.446) and step width (r=0.580/0.474). Most PD+CC patients exhibited vertical gait instability, increasing fall risk, and adopted compensatory strategies involving greater lateral COM shift and wider base of support, with these trends intensifying as trunk flexion angles increased. These findings may guide targeted interventions for gait instability in PD+CC.

Systemic Effects of Molar and Incisor Biting on Walking Direction With and Without Visual Feedback

Gait stability and walking direction control are conventionally attributed to coordination among somatosensory, visual, and vestibular systems. Recent evidence of functional interdependence between masticatory and neuromuscular systems indicates that the stomatognathic system is neurologically integrated with various body systems relevant to movement planning and execution. This study investigated the effects of unilateral molar biting and incisor biting on walking with and without visual feedback. A cohort of 31 healthy young adults aged 21 to 30 years (average age of 23.93 ± 1.89) participated in this study. Three types of errors in walking direction (angle error, position error, and curve error) were computed. Our findings indicate that, in right-handed individuals, irrespective of visual feedback, unilateral biting caused systematic deviations toward the biting side from initiation to termination of walking. The consistent deviation in walking, particularly during unilateral right biting conditions in right-handed individuals, may indicate a complex interplay between masticatory function and gait control mechanism, potentially influenced by handedness and motor lateralization within the cortex. This study establishes a foundation for future research exploring the interrelation between bite location, visual feedback, and motor control in diverse populations. This research may provide insight for more efficient interventions for gait-related disorders.

Temporal characteristics of foot rollover of amputee walking gait when using an Energy Storage and Return prosthesis.

Energy Storage and Return (ESAR) prosthetic feet provide improved walking when compared with previous designs. However, it may not mimic the unimpaired smooth and progressive movement of the foot on the floor (foot rollover). To characterize the temporal foot rollover of participants with unilateral transtibial amputation using an ESAR prosthetic foot. Cross-sectional. Plantar pressure data were collected from 11 participants with unilateral transtibial amputation using ESAR prostheses (2 females, mean age 37 ± 10 years, activity levels K2-K4) and 9 unimpaired participants (3 females, mean age 33 ± 10 years). The Initial Contact, Final Contact, and Total Contact times of 7 areas of the feet (unimpaired, intact, and prosthetic feet) were studied together with the duration of the Heel Rocker, Ankle Rocker, and Forefoot Rocker. Results were compared using a mixed analysis of the variance test. Statistical analysis revealed an interaction (P < 0.05) between foot and areas. The contact times were different (P < 0.05) between unimpaired and prosthetic feet for most foot areas. Furthermore, the prosthetic foot showed the longest duration of Heel Rocker (21.1 ± 8.5% of stance phase vs. 17.7 ± 10.2% for the intact foot and 15.7 ± 8.8% for the unimpaired feet, P < 0.05) and the shortest duration of Ankle Rocker (43.8 ± 18.1% vs. 47.2 ± 16.9% for the intact foot and 50.0 ± 13.4% for the unimpaired feet, P < 0.05). Results suggest that the ESAR foot does not mimic the unimpaired foot rollover, especially in the contact pattern and the heel and ankle rockers. This might have an impact on efficiency and stability of gait.

The Effects of Ankle and Foot Exercises on Ankle Strength, Balance, and Falls in Older People: A Systematic Review and Meta-Analysis.

Ankle-foot control is essential to maintain balance and gait stability. However, there has been limited evidence on the effect of ankle-foot exercises on balance and falls in older people. This study aimed to summarize the effects of ankle-foot exercises on ankle flexibility and strength, balance, mobility, and falls in older people, and to identify determining factors for ankle-foot exercises to improve balance and mobility. CINAHL, Embase, PubMed, and PEDro were searched to identify randomized controlled trials that studied the effects of ankle-foot exercises on ankle control, balance, and falls in older people. PEDro scale was used to evaluate the methodological quality of the studies. Meta-analyses were done for similar outcomes. The quality of evidence was rated by GRADE. Sixteen papers (n = 651) were included. Meta-analyses showed that ankle-foot exercises significantly improved ankle plantarflexion strength (SMD = 0.35, 95% CI = 0.04 to 0.65, low-quality evidence), ankle flexibility (SMD = 0.48, 95% CI = -0.01 to 0.96, low-quality evidence), and balance in an eyes-open condition (SMD = 0.41, 95% CI = 0.19 to 0.70, low-quality evidence). There was no significant change in ankle dorsiflexion strength (SMD = 0.29, 95% CI = -0.24 to 0.82, very low-quality evidence), balance under eyes-closed condition (SMD = 0.41, 95% CI = -0.1 to 0.92, very low-quality evidence), and gait speed (SMD = 0.36, 95% CI = -0.24 to 0.96, very low-quality evidence). Two studies reported insignificant findings on fear of falling, fall incidence, and risk of falls. Very low to low-quality evidence showed that ankle-foot exercises effectively improve ankle plantarflexion strength, flexibility, and balance with eyes open, whereas no effect on falls was found. Improvements in balance and gait tend to be associated with improvements in ankle strength and flexibility. Toe-strengthening exercise and training 3 times per week appear to be important for improving balance. This review suggested that ankle-foot exercises might improve balance in older people. Determining factors leading to improvement in balance and mobility were identified. It paves the ground for further research to study the effect of ankle-foot exercises on fall prevention.

Effectiveness of unilateral lower-limb exoskeleton robot on balance and gait recovery and neuroplasticity in patients with subacute stroke: a randomized controlled trial

BackgroundImpaired balance and gait in stroke survivors are associated with decreased functional independence. This study aimed to evaluate the effectiveness of unilateral lower-limb exoskeleton robot-assisted overground gait training compared with conventional treatment and to explore the relationship between neuroplastic changes and motor function recovery in subacute stroke patients.MethodsIn this randomized, single-blind clinical trial, 40 patients with subacute stroke were recruited and randomly assigned to either a robot-assisted training (RT) group or a conventional training (CT) group. All outcome measures were assessed at the enrollment baseline (T0), 2nd week (T1) and 4th week (T2) of the treatment. The primary outcome was the between-group difference in the change in the Berg balance scale (BBS) score from baseline to T2. The secondary measures included longitudinal changes in the Fugl-Meyer assessment of the lower limb (FMA-LE), modified Barthel index (mBI), functional ambulation category (FAC), and locomotion assessment with gait analysis. In addition, the cortical activation pattern related to robot-assisted training was measured before and after intervention via functional near-infrared spectroscopy.ResultsA total of 30 patients with complete data were included in this study. Clinical outcomes improved after 4 weeks of training in both groups, with significantly better BBS (F = 6.341, p = 0.018, partial η2 = 0.185), FMA-LE (F = 5.979, p = 0.021, partial η2 = 0.176), FAC (F = 7.692, p = 0.010, partial η2 = 0.216), and mBI scores (F = 7.255, p = 0.042, partial η2 = 0.140) in the RT group than in the CT group. Both groups showed significant improvement in gait speed and stride cadence on the locomotion assessment. Only the RT group presented a significantly increased stride length (F = 4.913, p = 0.015, partial η2 = 0.267), support phase (F = 5.335, p = 0.011, partial η2 = 0.283), and toe-off angle (F = 3.829, p = 0.035, partial η2 = 0.228) on the affected side after the intervention. The RT group also showed increased neural activity response over the ipsilesional motor area and bilateral prefrontal cortex during robot-assisted weight-shift and gait training following 4 weeks of treatment.ConclusionsOverground gait training with a unilateral exoskeleton robot showed improvements in balance and gait functions, resulting in better gait patterns and increased gait stability for stroke patients. The increased cortical response related to the ipsilesional motor areas and their related functional network is crucial in the rehabilitation of lower limb gait in post-stroke patients.

Impact of Gait-Synchronized Vibrotactile Sensory Feedback on Gait in Lower Limb Amputees

Background: Research on sensory feedback systems for prosthetic devices aims to enhance sensory capabilities to better meet user needs. Feedback systems for lower limb amputees (LLA) have been shown to reduce cognitive efforts, metabolic cost and phantom limb pain. This study evaluated the effect of a non-invasive, gait-synchronized, vibrotactile feedback system (VTFS) on the gait parameters of LLA. Methods: Four stimulators applied vibrotactile stimulation to the thigh of LLA during walking, corresponding to four pressure sensors located at the fore- and hindfoot embedded in a sock worn on the prosthetic foot. Standardized gait tests, such as the Timed “Up and Go” Test (TUG), the Four Square Step Test (FSST), the 10 Meter Walk Test (10 MWT) and the 2 Minute Walk Test (2 MWT), were performed to assess the risk of falling, coordination, walking speed and endurance before and after intervention. Results: After an average of 61.5 days using the VTFS, gait stability (TUG) improved significantly. Coordination (FSST) improved in 36% of subjects, while 45% showed a clinically relevant increase in gait speed (10 MWT). Conclusions: The results suggest an improved gait performance in the cohort. Though FSST lacked statistical significance, a p-value near 0.05 indicates a trend toward meaningful improvement. Notably, the participant with Targeted Sensory Reinnervation demonstrated the most favorable outcomes.

The effect of arm restriction on dynamic stability and upper-body responses to lateral loss of balance during walking: an observational study.

When losing balance, upper-body movements serve as mechanical aids to regain stability. However, it remains unclear how these movements contribute to dynamic stability during recovery from a lateral loss of balance while walking with arm restriction. We aimed to (i) quantify the effect of arm restriction on gait stability and upper-body velocities and (ii) characterize upper-body kinematic strategies in response to lateral surface translations under different arm restriction conditions. Healthy adults were exposed to lateral surface translations while walking on a computerized treadmill under three conditions: 'free arms', '1-arm restricted' and '2-arms restricted'. Dynamic stability and upper-body velocities for the first step after perturbation onset were extracted. We found decreased dynamic stability in the sagittal plane and increased trunk velocity in the '2-arms restricted' condition compared with the 'free arms' condition. Head and trunk movements in the medio-lateral plane were in opposite directions in 44.31% of responses. Additionally, significant trunk velocities were observed in the opposite direction to the perturbation-induced loss of balance. Our results support the contribution of increased upper-body velocities to balance responses following arm-restricted walking perturbations and suggest that the '2-arms restricted' condition may be utilized as a perturbation-based balance training, focusing on head and trunk responses.

Mechanism-Driven Strategies for Reducing Fall Risk in the Elderly: A Multidisciplinary Review of Exercise Interventions.

Falls among older adults present a major public health challenge, causing significant physical, psychological, and economic consequences. Exercise interventions are a proven strategy to reduce fall risk by targeting biomechanical, physiological, and psychological factors. This review examines evidence from 155 studies published between 2004 and 2024, including systematic reviews, meta-analyses, randomized controlled trials, and cohort studies. Data were rigorously screened and extracted using predefined criteria, with studies sourced from PubMed, MEDLINE, EBSCO (EDS), and additional gray literature identified via Google Scholar. Key findings show that balance and strength training improves postural control, gait stability, and neuromuscular coordination, while resistance training mitigates sarcopenia and enhances joint mobility. Cognitive exercises enhance attention, spatial awareness, decision-making, and psychological benefits like reduced fear of falling and greater social engagement. Multidisciplinary approaches integrating physical, cognitive, and social components deliver the most significant impact. This review underscores the value of evidence-based exercise programs in promoting active aging and enhancing the quality of life for older adults.

Quadruped Robots Gait Planning and Kinematic Analysis

Quadruped robots imitate the gait of animals in nature to achieve flexible and stable movement. Their superior mobility and adaptability have secured an important position in modern robotics. However, quadruped robots still face numerous technical challenges, including complex gait planning. Gait refers to the swinging and supporting movements of the legs and the relative timing of these movements. Different gaits determine various movement forms for quadruped robots, and studying these gaits plays a crucial role in the stable periodic motion of the robot. This paper analyzes three types of gaitsstatic gait, dynamic gait, and quasi-static gaitbased on traditional gait planning methods. Additionally, this paper analyze the movement of the single leg, including the forward and inverse kinematics and the endpoint cycloidal trajectory. Finally, we simulate the stable trot gait in MATLAB, returning the force curve at the foot, joint angles, angular velocity, and angular acceleration curves to complete the verification of the theory.

The effects of age and physical activity status on muscle synergies when walking down slopes.

The aim of the current study was to determine whether gait control (muscle synergies) or gait stability (margin of stability (MoS)) were different between younger and older adults when walking on level or downhill slopes. Further, it sought to determine associations between either age or physical activity with muscle synergy widths. Ten healthy younger (28.1 ± 8.0years) and ten healthy older (69.5 ± 6.3years) adults walked at their preferred walking speed on a treadmill at different slopes (0˚, -4˚ and -8˚). Muscle synergies were extracted using non-negative matrix factorisation and compared between groups and walking slopes. Correlations between the full width at half maximum (FWHM) of the synergies' activations and weekly recreational physical activity minutes and age were also determined. Younger and older adults both walked with similar muscle synergies across all tested slopes, with 4 synergies accounting for > 85% variance of overall muscle activity in both groups across all tested slopes, with high scalar products (≥ 0.86) for each synergy and slope. It was also demonstrated that physical activity and age had different associations with pooled muscle synergies across slopes, as weekly minutes spent in recreational physical activity were associated with the FWHM of a synergy activated at weight acceptance, whereas age was associated with the FWHM of synergies occurring at push off and foot clearance, respectively. Our results suggest that healthy older and younger adults walk with similar muscle synergies on downhill slopes, and that physical activity and age influence different muscle synergies during walking.

Effects of foot–ground friction and age-related gait changes on falls during walking: a computational study using a neuromusculoskeletal model

We used a neuromusculoskeletal model of bipedal walking to examine the effects of foot–ground friction conditions and gait patterns on slip- and trip-induced falls. We developed three two-dimensional neuro-musculoskeletal models in a self-organized manner representing young adults, elderly non-fallers, and elderly fallers. We simulated walking under different foot-ground friction conditions. The static friction coefficient between the foot and the ground was varied from 0.05 to 2.0. Under low friction conditions, the three gait models demonstrated slip-induced falls. The elderly faller model experienced the most slip. This is because the RCOF was higher in the elderly faller model due to its short stride length but much smaller foot clearance. Under high friction conditions, only the elderly faller model demonstrated trip-induced falls. Based on the analysis using the margin of stability, the forward postural stability of the model gradually decreased under high-friction conditions, with the toe of the swing foot contacting the ground and subsequently falling forward. These results imply that there is an optimal coefficient of friction for the ground to prevent slip- and trip-induced falls by people with less stable gaits, which may provide new insights into the design of shoes and floor surfaces for the elderly.

Differences in gait parameters between supervised laboratory and unsupervised daily assessments of healthy adults measured with an in-shoe motion sensor system

This cross-sectional study compared the gait parameters between supervised laboratory and unsupervised daily life assessments in healthy adults. Gait was evaluated in 24 healthy young adults during 72 h of daily life and a 6-min laboratory gait at a comfortable speed. An in-shoe motion sensor system recorded gait data every 2 min, automatically detected stable gait segments by identifying repetitive movement patterns, and calculated the average of three consecutive valid gait cycles during each measurement period. Significant differences were found in walking speed (stride length divided by stride time; laboratory: 4.60 km/h vs. daily-life: 4.38 km/h), maximum (peak) dorsiflexion angle (laboratory: 29.71° vs. daily-life: 26.65°), maximum (peak) plantar flexion angle (laboratory: 74.54° vs. daily-life: 71.91°), roll angle of heel contact (laboratory: 7.46° vs. daily-life: 6.70°), maximum speed during the swing phase (laboratory: 14.49 km/h vs. daily-life: 12.68 km/h), circumduction (lateral displacement during the swing phase; laboratory: 2.68 cm vs. daily-life: 3.69 cm), toe-in/out angle (laboratory: 13.87° vs. daily-life: 15.32°), stance time (laboratory: 0.62 s vs. daily-life: 0.65 s), and pushing time (time between heel leaving and toe leaving the ground; laboratory: 0.20 s vs. daily-life: 0.21 s). The innovative aspect of this study is the comprehensive evaluation of foot-related gait parameters in real-world environments using an in-shoe motion sensor system. This approach provides ecologically valid insights into gait dynamics during daily activities, emphasizing the importance of real-world assessments for accurately evaluating gait performance and predicting adverse events such as falls. Keywords: Gait, Foot, Laboratory, Daily Life, Unsupervised Assessment, Shoe Motion Sensors.