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 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.

Older Age Is Associated with Lower Optimal Vibration Frequency in Lower-Limb Muscles During Whole-Body Vibration

2015 ◽  
Vol 94 (7) ◽  
pp. 522-529 ◽  
Author(s):  
Flaminia Carlucci ◽  
Giorgio Orlando ◽  
Jonida Haxhi ◽  
Luca Laudani ◽  
Arrigo Giombini ◽  
...  
Keyword(s):  
Vibration Frequency ◽  
Lower Limb ◽  
Whole Body Vibration ◽  
Older Age ◽  
Whole Body ◽  
Body Vibration ◽  
Lower Limb Muscles ◽  
Limb Muscles

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).

Long-term activity in upper- and lower-limb muscles of humans

2001 ◽  
Vol 91 (5) ◽  
pp. 2224-2232 ◽  
Author(s):  
Drew S. Kern ◽  
John G. Semmler ◽  
Roger M. Enoka
Keyword(s):  
Lower Limb ◽  
Muscle Activity ◽  
Biceps Brachii ◽  
Type I ◽  
Recording Time ◽  
Men And Women ◽  
Leg Muscles ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Age Range

Despite limited data on humans, previous studies suggest that there is an association between the duration of daily muscle activity and the proportion of type I muscle fibers. We quantified the activity of limb muscles in healthy men and women during normal use and compared these measurements with published reports on fiber-type proportions. Seven men (age range = 21–28 yr) and seven women (age range = 18–26 yr) participated in two 10-h recording sessions. Electromyogram (EMG) activity of four muscles in nondominant upper (first dorsal interosseus and biceps brachii) and lower limbs (vastus medialis and vastus lateralis) was recorded with surface electrodes. Hand and arm muscles were active for 18% of the recording time, whereas leg muscles were active for only 10% of the recording time. On average, upper-limb muscles were activated 67% more often than lower-limb muscles. When lower-limb muscles were activated, however, the mean amplitude of each burst was greater in leg muscles [18 and 17% maximum voluntary contraction (MVC)] compared with hand (8% MVC) and arm (6% MVC) muscles. Temporal association in activity between pairs of muscles was high for the two lower-limb muscles ( r 2 = 0.7) and relatively weak for the two upper-limb muscles ( r 2 = 0.09). Long-term muscle activity was only different between men and women for the biceps brachii muscle. We found no relation between duration of muscle activity in 10-h recordings and the reported values of type I fibers in men and women.

scholarly journals Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

2014 ◽  
Vol 20 (6) ◽  
pp. 675-691 ◽  
Author(s):  
Blair Calancie ◽  
Miriam L. Donohue ◽  
Colin B. Harris ◽  
Gregory W. Canute ◽  
Amit Singla ◽  
...  
Keyword(s):  
Lower Limb ◽  
Spinal Canal ◽  
Pulse Train ◽  
Pedicle Screws ◽  
Leg Muscles ◽  
Lower Limb Muscles ◽  
Thoracic Pedicle Screws ◽  
Limb Muscles ◽  
The Impact ◽  
Train Stimulation

Object Reports of the accuracy of existing neuromonitoring methods for detecting or preventing medial malpositioning of thoracic pedicle screws have varied widely in their claimed effectiveness. The object of this study was to develop, test, and validate a novel neuromonitoring method for preventing medial malpositioning of pedicle screws in the thoracic spine during surgery. Methods This is a prospective, blinded and randomized study using a novel combination of input (4-pulse stimulus trains delivered within the pedicle track) and output (evoked electromyography from leg muscles) to detect pedicle track trajectories that—once implanted with a screw—would cause that screw to breach the pedicle's medial wall and encroach upon the spinal canal. For comparison, the authors also used screw stimulation as an input and evoked electromyogram from intercostal and abdominal muscles as output measures. Intraoperative electrophysiological findings were compared with postoperative CT scans by multiple reviewers blinded to patient identity or intraoperative findings. Results Data were collected from 71 patients, in whom 802 screws were implanted between the T-1 and L-1 vertebral levels. A total of 32 screws ended up with screw threads encroaching on the spinal canal by at least 2 mm. Pulse-train stimulation within the pedicle track using a ball-tipped probe and electromyography from lower limb muscles correctly predicted all 32 (100%) of these medially malpositioned screws. The combination of pedicle track stimulation and electromyogram response from leg muscles proved to be far more effective in predicting these medially malpositioned screws than was direct screw stimulation and any of the target muscles (intercostal, abdominal, or lower limb muscles) we monitored. Based on receiver operating characteristic analysis, the combination of 10-mA (lower alarm) and 15-mA stimulation intensities proved most effective for detection of pedicle tracks that ultimately gave rise to medially malpositioned screws. Additional results pertaining to the impact of feedback of these test results on surgical decision making are provided in the companion report. Conclusions This novel neuromonitoring approach accurately predicts medially malpositioned thoracic screws. The approach could be readily implemented within any surgical program that is already using contemporary neuromonitoring methods that include transcranial stimulation for monitoring motor evoked potentials.

Sign in / Sign up

Export Citation Format

Share Document