Biology subjects

Abdikadirova, B.

Publications and source records attributed to Abdikadirova, B..

6 recordsLinked to original sources

bioRxiv2025

Adjustable Compliance Footwear Technology to Investigate Gait Adaptation

Kinetic asymmetries in gait caused by neurological impairments are a major factor in mobility deficiency. Gait perturbation training has shown promise for rehabilitating neurological gait asymmetry, but the transfer of benefits from treadmill training to overground walking is limited. To enable kinetic gait perturbation training on treadmills and overground, we developed novel adjustable compliance footwear technology. The system consists of a wearable pneumatic actuation module which controls the pressure of custom air pockets embedded in a soft lattice midsole, and is capable of independently and wirelessly adjusting the midsole compliance under each foot from 300 kN/m and 60% energy absorption to 18 kN/m and 75% energy absorption in under 4 seconds. Hindfoot and forefoot sole deflection data are measured via Hall effect sensors and paired magnets characterized to 1.7 mm accuracy. To demonstrate the experimental capability of the system, we successfully triggered multiple compliance changes during overground walking and recorded ground reaction forces and embedded sensor values during a prolonged asymmetric compliance walking bout on a treadmill. Future work will include a full experimental study of gait adaptation to asymmetric footwear compliance perturbations.

bioengineering↗

bioRxiv2024

Forward Simulations of Walking on Surfaces with Asymmetric Mechanical Impedance: Insights for Gait Rehabilitation

Gait asymmetry, prevalent in stroke survivors and various other neurological and musculoskeletal conditions, leads to abnormal joint loading, increased fall risk, and reduced walking efficiency. Traditional rehabilitation methods often fail to consistently reduce weight-bearing gait asymmetry, necessitating innovative approaches. This study explores the potential of an adjustable mechanical impedance treadmill to amplify weight-bearing asymmetries, leveraging the "error amplification" technique akin to split-belt treadmill training. We developed a 2D optimal control gait model in OpenSim to simulate walking on a rigid platform with one leg and a compliant platform, with adjustable stiffness and damping, with the other. We simulated 112 unique mechanical impedance conditions of the compliant platform and analyzed the effects of these conditions on stance time, ground reaction forces (GRFs), and muscle activations. Our results identified specific impedance parameters that can be utilized to amplify propulsion asymmetries, providing a potential new approach for gait rehabilitation post-stroke. Future work should validate these results in experimental settings and further explore optimal impedance parameters for effective gait therapy of various gait impairments.

bioengineering↗

bioRxiv2024

AdjuSST: An Adjustable Surface Stiffness Treadmill

Humans have the remarkable ability to manage foot-ground interaction seamlessly across terrain changes despite the high dynamic complexity of the task. Understanding how adaptation in the neuromotor system enables this level of robustness in the face of changing interaction dynamics is critical for developing more effective gait retraining interventions. We developed an adjustable surface stiffness treadmill (AdjuSST) to trigger these adaptation mechanisms and enable studies to better understand human adaptation to changing foot-ground dynamics. The AdjuSST system makes use of fundamental beam-bending principles; it controls surface stiffness by controlling the effective length of a cantilever beam. The beam acts as a spring suspension for the transverse endpoint load applied through the treadmill. The system is capable of enforcing a stiffness range of 15-300kN/m within 340 ms, deflecting linearly downwards up to 10 cm, and comfortably accommodating two full steps of travel along the belt. AdjuSST offers significant enhancements in effective walking surface length compared to similar systems, while also maintaining a useful stiffness range and responsive spring suspension. These improvements enhance our ability to study locomotor control and adaptation to changes in surface stiffness, as well as provide new avenues for gait rehabilitation.

bioengineering↗

bioRxiv2023

Gait adaptation to asymmetric hip stiffness applied by a robotic exoskeleton

Wearable exoskeletons show significant potential for improving gait impairments, such as interlimb asymmetry. However, a more profound understanding of whether exoskeletons are capable of eliciting neural adaptation is needed. This study aimed to characterize how individuals adapt to bilateral asymmetric joint stiffness applied by a hip exoskeleton, similar to split-belt treadmill training. Thirteen unimpaired individuals performed a walking trial on the treadmill while wearing the exoskeleton. The right side of the exoskeleton acted as a positive stiffness torsional spring, pulling the thigh towards the neutral standing position, while the left acted as a negative stiffness spring pulling the thigh away from the neutral standing position. The results showed that this intervention applied by a hip exoskeleton elicited adaptation in spatiotemporal and kinetic gait measures similar to split-belt treadmill training. These results demonstrate the potential of the proposed intervention for retraining symmetric gait.

neuroscience↗

bioRxiv2023

Bilateral asymmetric hip stiffness applied by a robotic hip exoskeleton elicits kinematic and kinetic adaptation

Wearable robotic exoskeletons hold great promise for gait rehabilitation as portable, accessible tools. However, a better understanding of the potential for exoskeletons to elicit neural adaptation--a critical component of neurological gait rehabilitation--is needed. In this study, we investigated whether humans adapt to bilateral asymmetric stiffness perturbations applied by a hip exoskeleton, taking inspiration from asymmetry augmentation strategies used in split-belt treadmill training. During walking, we applied torques about the hip joints to repel the thigh away from a neutral position on the left side and attract the thigh toward a neutral position on the right side. Six participants performed an adaptation walking trial on a treadmill while wearing the exoskeleton. The exoskeleton elicited time-varying changes and aftereffects in step length and propulsive/braking ground reaction forces, indicating behavioral signatures of neural adaptation. These responses resemble typical responses to split-belt treadmill training, suggesting that the proposed intervention with a robotic hip exoskeleton may be an effective approach to (re)training symmetric gait.

neuroscience↗

bioRxiv2021

Forward simulations of walking on a variable surface-impedance treadmill: A comparison of two methods

Recent experiments with a variable stiffness tread-mill (VST) suggest that modulating foot-ground contact dynamics during walking may offer an effective new paradigm for gait rehabilitation. How gait adapts to extended perturbations of asymmetrical surface stiffness is still an open question. In this study, we simulated human gait with prolonged asymmetrical changes in ground stiffness using two methods: (1) forward simulation of a muscle-reflex model and (2) optimal control via direct collocation. Simulation results showed that both models could competently describe the biomechanical trends observed in human experiments with a VST which altered the walking surface stiffness for one step. In addition, the simulations revealed important considerations for future experiments studying the effect of asymmetric ground stiffness on gait behavior. With the muscle-reflex model, we observed that although subtle, there was a difference between gait biomechanics before and after the prolonged asymmetric stiffness perturbation, showing the behavioral signature of an aftereffect despite the lack of supraspinal control in the model. In addition, the optimal control simulations showed that damping has a large effect on the overall lower-body muscle activity, with the muscle effort cost function used to optimize the biomechanics increasing 203% between 5 Ns/m and 2000 Ns/m at a stiffness of 10 kN/m. Overall, these findings point to new insights and considerations for advancing our understanding of human neuromotor control of locomotion and enhancing robot-aided gait rehabilitation.

neuroscience↗