Gait & posture最新文献

Background: Human-in-the-loop optimization provides a standardized approach to enhance the effectiveness of assistive technology for gait by tuning devices to the needs of the individual user. Metabolic cost is frequently used as optimization objective. However, the assessment of metabolic cost requires relatively long-lasting physiological steady-state conditions. Subjective user preference could be an interesting alternative optimization objective that could shorten trial duration. We aim to explore whether the measured metabolic cost of walking correlates with the perceived comfort of the user during human-in-the-loop optimization process.

Methods: Ten transtibial amputees underwent an optimization protocol while walking on a treadmill with an experimental prosthetic foot with tuneable stiffness and alignment. We used human-in-the-loop optimization to minimize the metabolic cost of walking by optimizing the stiffness and alignment of the prosthetic foot, using an evolutionary optimization algorithm. The participant's perceived comfort of every optimization trial was determined via the visual analogue comfort scale. To determine the association between metabolic cost and perceived comfort during the optimization period, we performed a repeated measures correlation and a separate Pearson correlation for every individual.

Results: Results showed a moderate negative correlation between metabolic cost and perceived comfort. On an individual level a significant correlation was found in six out of ten cases.

Significance: Perceived comfort allows people to prioritize different optimization objectives simultaneously, and apparently, metabolic cost is prioritized to varying extents.

Introduction: Downhill walking increases fall risk in older adults due to greater balance control demands and postural instability. Steeper inclines amplify gravitational shear forces, requiring precise lower limb coordination to maintain stability. This study investigated the effects of age and slope angle on COM-COP inclination angles (IAs) and rates of change of inclination angles (RCIAs) to better understand age-related adaptations in balance control.

Materials and methods: Fifteen young and fifteen older adults walked at self-selected speeds on level ground and three downhill slopes (5°, 10°, and 15°). Motion capture and force plates recorded gait parameters, from which IAs and RCIAs were calculated. Analysis of covariance (ANCOVA) was used to control for walking speed variations and assess age and slope effects.

Results: As ramp-down angles increased, both groups exhibited reduced walking speed, step length, and single-limb support duration, while double-limb support duration increased. After adjusting for walking speed, significant slope effects were observed for sagittal IA and RCIA at toe-off, as well as for sagittal and frontal RCIA at contralateral heel-strike. Older adults exhibited significantly higher frontal IA and RCIA at contralateral heel-strike, suggesting increased lateral postural demand. These changes may reflect a compensatory effort to maintain stability.

Conclusion: Older adults rely on conservative gait strategies but experience greater lateral instability at contralateral heel-strike, increasing fall risk. These findings highlight the need for targeted balance training and infrastructure modifications to improve safety on sloped surfaces.

Background: Biplanar radiography displays promising results in the production of subject-specific (S.specific) biomechanical models. However, the focus has predominantly centred on methodological investigations in gait analysis. Exploring the influence of such models on the analysis of high range of motion tasks linked to hip pathologies is warranted. The aim of this study is to investigate the effect of S.Specific modelling techniques on the reliability of deep squats kinematics in comparison to generic modelling.

Methods: 8 able-bodied male participants attended 5 motion capture sessions conducted by 3 observers and performed 5 deep squats in each. Prior to each session a biplanar scan was acquired with the reflective-markers attached. Inverse kinematics of pelvis and thigh segments were calculated based on S.specific and Generic model definition. Agreement between the two models femoropelvic orientation in standing was assessed with Bland-Altman plots and paired t- tests. Inter-trial, inter-session, inter-observer variability and observer/trial difference and ratio were calculated for squat kinematic data derived from the two modelling approaches.

Results: Compared to the Generic model, the S.Specific model produced a calibration trial that is significantly offset into more posterior pelvis tilt (-2.8±2.7), hip extension (-2.2±3.8), hip abduction (-1.2±3.6) and external rotation (-13.8±11.4). The S.specific model produced significantly different squat kinematics in the sagittal plane of the pelvis (entire squat cycle) and hip (between 40 % and 60 % of the squat cycle). Variability analysis indicated that the error magnitude between the two models was comparable (difference<2°). The S.specific model exhibited a lower variability in the observer/trial ratio in the sagittal pelvis and hip, the frontal hip, but showed a higher variability in the transverse hip.

Significance: S.specific modelling appears to introduce a calibration offset that primarily translates into an effect in the sagittal plane kinematics. However, the clinical added value of S.specific modelling in terms of reducing experimental sources of kinematic variability was limited.