scholarly journals Exoskeleton for Gait Rehabilitation: Effects of Assistance, Mechanical Structure, and Walking Aids on Muscle Activations

2019 ◽  
Vol 9 (14) ◽  
pp. 2868 ◽  
Author(s):  
Alice De Luca ◽  
Amy Bellitto ◽  
Sergio Mandraccia ◽  
Giorgia Marchesi ◽  
Laura Pellegrino ◽  
...  
Keyword(s):  
Lower Limb ◽  
Statistical Parametric Mapping ◽  
Muscular Activity ◽  
Gait Training ◽  
Motor Deficits ◽  
Gait Rehabilitation ◽  
Mechanical Structure ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Muscle Activations

Several exoskeletons have been developed and increasingly used in clinical settings for training and assisting locomotion. These devices allow people with severe motor deficits to regain mobility and sustain intense and repetitive gait training. However, three factors might affect normal muscle activations during walking: the assistive forces that are provided during walking, the crutches or walker that are always used in combination with the device, and the mechanical structure of the device itself. To investigate these effects, we evaluated eight healthy volunteers walking with the Ekso, which is a battery-powered, wearable exoskeleton. They walked supported by either crutches or a walker under five different assistance modalities: bilateral maximum assistance, no assistance, bilateral adaptive assistance, and unilateral adaptive assistance on each leg. Participants also walked overground without the exoskeleton. Surface electromyography was recorded bilaterally, and the statistical parametric mapping approach and muscle synergies analysis were used to investigate differences in muscular activity across different walking conditions. The lower limb muscle activations while walking with the Ekso were not influenced by the use of crutches or walker aids. Compared to normal walking without robotic assistance, the Ekso reduced the amplitude of activation for the distal lower limb muscles while changing the timing for the others. This depended mainly on the structure of the device, and not on the type or level of assistance. In fact, the presence of assistance did not change the timing of the muscle activations, but instead mainly had the effect of increasing the level of activation of the proximal lower limb muscles. Surprisingly, we found no significant changes in the adaptive control with respect to a maximal fixed assistance that did not account for subjects’ performance. These are important effects to take into careful considerations in clinics where these devices are used for gait rehabilitation in people with neurological diseases.

scholarly journals Muscular activity of lower limb muscles associated with working on inclined surfaces

Ergonomics ◽  
2014 ◽  
Vol 58 (2) ◽  
pp. 278-290 ◽  
Author(s):  
Ming-Lun Lu ◽  
Laurel Kincl ◽  
Brian Lowe ◽  
Paul Succop ◽  
Amit Bhattacharya
Keyword(s):  
Lower Limb ◽  
Muscular Activity ◽  
Lower Limb Muscles ◽  
Inclined Surfaces ◽  
Limb Muscles

Motor control of landing from a countermovement jump in simulated microgravity

2016 ◽  
Vol 120 (10) ◽  
pp. 1230-1240 ◽  
Author(s):  
C. N. Gambelli ◽  
D. Theisen ◽  
P. A. Willems ◽  
B. Schepens
Keyword(s):  
Motor Control ◽  
Lower Limb ◽  
Muscular Activity ◽  
Damping Coefficient ◽  
Gravity Level ◽  
Countermovement Jump ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

Landing from a jump implies proper positioning of the lower limb segments and the generation of an adequate muscular force to cope with the imminent collision with the ground. This study assesses how a hypogravitational environment affects the control of landing after a countermovement jump (CMJ). Eight participants performed submaximal CMJs on Earth (1- g condition) and in a weightlessness environment with simulated gravity conditions generated by a pull-down force (1-, 0.6-, 0.4-, and 0.2- g0 conditions). External forces applied to the body, movements of the lower limb segments, and muscular activity of six lower limb muscles were recorded. 1) All subjects were able to jump and stabilize their landing in all experimental conditions, except one subject in 0.2- g0 condition. 2) The mechanical behavior of lower limb muscles switches during landing from a stiff spring to a compliant spring associated with a damper. This is true whatever the environment, on Earth as well as in environments where sensory inputs are altered. 3) The motor control of landing in simulated 1 g0 reveals an increased “safety margin” strategy, illustrated by increased stiffness and damping coefficient compared with landing on Earth. 4) The motor command is adjusted to the task constraints: muscular activity of lower limb extensors and flexors, stiffness and damping coefficient decrease according to the decreased gravity level. Our results show that even if in daily living gravity can be perceived as a constant factor, subjects can cope with altered sensory signals, taking advantage of the remaining information (visual and/or decreased proprioceptive inputs).

scholarly journals Vibration Attenuation Via Mean of Lower Limb Muscles Occurs During Whole Body Vibrations And Differs Across Frequencies And Postures

2021 ◽  
Author(s):  
Isotta Rigoni ◽  
Tecla Bonci ◽  
Paolo Bifulco ◽  
Antonio Fratini
Keyword(s):  
Muscle Contraction ◽  
Lower Limb ◽  
Soft Tissues ◽  
Muscular Activity ◽  
Whole Body ◽  
Tonic Vibration Reflex ◽  
Leg Muscles ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Whole Body Vibrations

Abstract Lower limb muscles actively contribute to maintain body posture but also act to attenuate soft tissues oscillations that occur during everyday life. This elicited activity can be exploited as a mean of neuromuscular training or rehabilitation. In this study, Whole Body Vibrations (WBV) at different frequencies were delivered to healthy subjects while holding static postures to test the transient muscles mechanical responses. Twenty-five participants underwent WBV at 15, 20, 25 and 30 Hz while holding either a static ‘hack squat’ or ‘fore feet’ posture. Soft tissue accelerations and surface electromyography (sEMG) were recorded from Gastrocnemius Lateralis (GL), Soleus (SOL) and Tibialis Anterior (TA) muscles. Estimated displacement at muscle bellies revealed a resonant pattern, different across frequencies and postures (p<.001). Specifically, a peak in the displacement was measured after the onset of the stimulation, followed by a drop and a further plateau (only after few seconds after the peak) suggesting a delayed neuromuscular activation. Although oscillation dampening was correlated to an increased muscular activity, only specific WBV settings were promoting a significant muscle contraction. For example, SOL and GL induced activation was maximal for subject in forefeet and while exposed to higher frequencies (p<.05). The non-immediate response of leg muscles to a vibratory stimulation confirms the tonic nature of the vibration induced muscle contraction (the tonic vibration reflex) and its strong influence on postural tonic muscles (GL and SOL). This may have significant impact on training or rehabilitation protocols aiming towards postural and balance improvement or recovery.

scholarly journals Systematic review on wearable lower-limb exoskeletons for gait training in neuromuscular impairments

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Antonio Rodríguez-Fernández ◽  
Joan Lobo-Prat ◽  
Josep M. Font-Llagunes
Keyword(s):  
Systematic Review ◽  
Clinical Efficacy ◽  
Lower Limb ◽  
Gait Training ◽  
Health Conditions ◽  
Current Evidence ◽  
Clinical Aspects ◽  
Gait Rehabilitation ◽  
Comprehensive Overview ◽  
Walking Aids

AbstractGait disorders can reduce the quality of life for people with neuromuscular impairments. Therefore, walking recovery is one of the main priorities for counteracting sedentary lifestyle, reducing secondary health conditions and restoring legged mobility. At present, wearable powered lower-limb exoskeletons are emerging as a revolutionary technology for robotic gait rehabilitation. This systematic review provides a comprehensive overview on wearable lower-limb exoskeletons for people with neuromuscular impairments, addressing the following three questions: (1) what is the current technological status of wearable lower-limb exoskeletons for gait rehabilitation?, (2) what is the methodology used in the clinical validations of wearable lower-limb exoskeletons?, and (3) what are the benefits and current evidence on clinical efficacy of wearable lower-limb exoskeletons? We analyzed 87 clinical studies focusing on both device technology (e.g., actuators, sensors, structure) and clinical aspects (e.g., training protocol, outcome measures, patient impairments), and make available the database with all the compiled information. The results of the literature survey reveal that wearable exoskeletons have potential for a number of applications including early rehabilitation, promoting physical exercise, and carrying out daily living activities both at home and the community. Likewise, wearable exoskeletons may improve mobility and independence in non-ambulatory people, and may reduce secondary health conditions related to sedentariness, with all the advantages that this entails. However, the use of this technology is still limited by heavy and bulky devices, which require supervision and the use of walking aids. In addition, evidence supporting their benefits is still limited to short-intervention trials with few participants and diversity among their clinical protocols. Wearable lower-limb exoskeletons for gait rehabilitation are still in their early stages of development and randomized control trials are needed to demonstrate their clinical efficacy.

Measurement and reproducibility of strength and voluntary activation of lower-limb muscles

2004 ◽  
Vol 29 (6) ◽  
pp. 834-842 ◽  
Author(s):  
Gabrielle Todd ◽  
Robert B. Gorman ◽  
Simon C. Gandevia
Keyword(s):  
Lower Limb ◽  
Voluntary Activation ◽  
Lower Limb Muscles ◽  
Limb Muscles
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