Effects of mechanical assistance on muscle activity and motor performance during isometric elbow flexion

2020 ◽  
Vol 50 ◽  
pp. 102380 ◽  
Author(s):  
Jeewon Choi ◽  
Wen Liang Yeoh ◽  
Satsuki Matsuura ◽  
Ping Yeap Loh ◽  
Satoshi Muraki
Keyword(s):  
Muscle Activity ◽  
Motor Performance ◽  
Elbow Flexion ◽  
Mechanical Assistance

Changes in Muscle Activity in Response to Assistive Force during Isometric Elbow Flexion

2019 ◽  
Vol 52 (5) ◽  
pp. 634-642 ◽  
Author(s):  
Ping Yeap Loh ◽  
Keisuke Hayashi ◽  
Nursalbiah Nasir ◽  
Satoshi Muraki
Keyword(s):  
Muscle Activity ◽  
Elbow Flexion

scholarly journals Altered visual feedback from an embodied avatar unconsciously influences movement amplitude and muscle activity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pierre Bourdin ◽  
Matteo Martini ◽  
Maria V. Sanchez-Vives
Keyword(s):  
Visual Feedback ◽  
Muscle Activity ◽  
Motor Performance ◽  
Muscular Activity ◽  
Arm Movement ◽  
Body Ownership ◽  
Immersive Virtual Reality ◽  
Body Parts ◽  
Elastic Band ◽  
Visual Inputs

AbstractEvidence suggests that the sense of the position of our body parts can be surreptitiously deceived, for instance through illusory visual inputs. However, whether altered visual feedback during limb movement can induce substantial unconscious motor and muscular adjustments is not known. To address this question, we covertly manipulated virtual body movements in immersive virtual reality. Participants were instructed to flex their elbow to 90° while tensing an elastic band, as their virtual arm reproduced the same, a reduced (75°), or an amplified (105°) movement. We recorded muscle activity using electromyography, and assessed body ownership, agency and proprioception of the arm. Our results not only show that participants compensated for the avatar’s manipulated arm movement while being completely unaware of it, but also that it is possible to induce unconscious motor adaptations requiring significant changes in muscular activity. Altered visual feedback through body ownership illusions can influence motor performance in a process that bypasses awareness.

scholarly journals Upregulation of spinal stretch reflexes during upper-limb posture control task

2019 ◽  
Vol 2 (3) ◽  
pp. 1
Author(s):  
Ryan Raymond Miller ◽  
Tyler Cluff
Keyword(s):  
Upper Limb ◽  
Muscle Activity ◽  
Elbow Flexion ◽  
Repeated Exposure ◽  
Standing Balance ◽  
Lower Limbs ◽  
Control Task ◽  
Baseline Phase ◽  
Stretch Reflexes ◽  
Motor Actions

Background: Sensory feedback from receptors in the eyes, skin, vestibular organs and muscles allows us to build accurate representations of the position and motion of our body within the environment. In unpredictable situations, such as when holding an umbrella in gusting winds, studies have suggested the nervous system upregulates the sensitivity of sensory organs to counter disturbances and increase the probability of success. To date, studies have focused exclusively on the upregulation of feedback mechanisms in the lower-limbs during standing balance. We know comparatively little about whether and how sensory upregulation contributes to the control of upper limb motor actions. Objectives: Examine the upregulation and adaptation of upper limb muscle activity and spinal stretch reflexes when interacting with unpredictable mechanical environments. Methods: Ten healthy, right-handed adults (age range: 20 – 27 years) performed a postural control task where the goal was to maintain their hand within a fixed target. Participants performed the task while seated with their arm supported in an exoskeleton robot that can sense and disturb arm motion. They received real-time feedback of their movements on a virtual reality system. The protocol was delivered in three phases. The baseline phase consisted of 50 trials where subjects maintained their hand in the target in the absence of mechanical disturbances. Subjects then performed a peri-exposure phase that consisted of 100 null trials (no forces applied), 100 step-torque perturbations that produced rapid elbow flexion (+2Nm), and 100 perturbations that caused rapid elbow extension (-2Nm). We then unexpectedly removed the perturbations and subjects performed 75 trials to determine whether muscle activity returned to baseline levels. Kinematics and muscle activity were recorded throughout the experiment. Results: Preliminary results show that background muscle activity and spinal stretch reflexes were the largest when first exposed to unpredictable mechanical perturbations and adapted systematically with repeated exposure. Conclusions: Similar to results observed in the lower-limbs during standing balance experiments, we observed upregulation of background muscle activity and spinal stretch reflexes when interacting with unpredictable mechanical environments with the upper-limb. The amplitude of spinal stretch responses and background muscle activity decayed systematically with repeated exposure to unpredictable mechanical perturbations.

scholarly journals Muscle Activation in Traditional and Experimental Barbell Bench Press Exercise: A Potential New Tool for Fitness Maintenance

Sports ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 224
Author(s):  
Andrea Melani ◽  
Giuliana Gobbi ◽  
Daniela Galli ◽  
Cecilia Carubbi ◽  
Elena Masselli ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Professional Training ◽  
Muscle Activation ◽  
Bench Press ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Upper Body ◽  
Triceps Brachii ◽  
Extended Position ◽  
Lower Load

Background: The bench press exercise (BP) is commonly practiced in both recreational and professional training. The weight is lowered from a position where the elbows are at a 90° angle at the start and <90° at the end of eccentric phase, and then returned to the elbows extended position. In order to focus the exercise more on the triceps brachii (TB) rather than the pectoralis major (PM), the inter-handle distance (IHD) is decreased diminishing the involvement of the PM in favor of the TB. Purpose: To improve performance of the exercise by reducing force dissociation and transmitting 100% of the external load to the muscle tissue we propose a prototype of the barbell with a bar on which two sleeves are capable of sliding. The dynamic modifications of the IHD keep the elbow flexion angle constant at 90°. Results: Analysis of the inter-handle distance (IHD) signals of the upper body muscles showed a marked increase in muscle activity using the experimental barbell for the PM (19.5%) and for the biceps brachii (173%). Conclusions: The experimental barbell increased the muscle activity typical of the bench press exercise, obtaining the same training induction with a lower load and consequently preventing articular stress.

scholarly journals The Effects of Botulinum Toxin Injections on Spasticity and Motor Performance in Chronic Stroke with Spastic Hemiplegia

Toxins ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 492
Author(s):  
Yen-Ting Chen ◽  
Chuan Zhang ◽  
Yang Liu ◽  
Elaine Magat ◽  
Monica Verduzco-Gutierrez ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Motor Performance ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Force Variability ◽  
Stroke Survivors ◽  
Modified Ashworth Scale ◽  
Before And After ◽  
Spastic Hemiplegia ◽  
Botulinum Toxin Injections

Spastic muscles are weak muscles. It is known that muscle weakness is linked to poor motor performance. Botulinum neurotoxin (BoNT) injections are considered as the first-line treatment for focal spasticity. The purpose of this study was to quantitatively investigate the effects of BoNT injections on force control of spastic biceps brachii muscles in stroke survivors. Ten stroke survivors with spastic hemiplegia (51.7 ± 11.5 yrs; 5 men) who received 100 units of incobotulinumtoxinA or onabotulinumtoxinA to the biceps brachii muscles participated in this study. Spasticity assessment (Modified Ashworth Scale (MAS) and reflex torque) and muscle strength of elbow flexors, as well as motor performance assessment (force variability of submaximal elbow flexion) were performed within one week before (pre-injection) and 3~4 weeks (3-wk) after BoNT injections. As expected, BoNT injections reduced the MAS score and reflex torque, and elbow flexor strength on the spastic paretic side. However, motor performance remained within similar level before and after injections. There was no change in muscle strength or motor performance on the contralateral arm after BoNT injections. The results of this study provide evidence that BoNT injections can reduce spasticity and muscle strength, while motor performance of the weakened spastic muscle remains unchanged.

Coactivation to Reduce Variability in the Elderly

Motor Control ◽  
1998 ◽  
Vol 2 (4) ◽  
pp. 314-330 ◽  
Author(s):  
Rachael D. Seidler-Dobrin ◽  
jiping He ◽  
George E. Stelmach
Keyword(s):  
Muscle Activity ◽  
Visual Target ◽  
Model Simulation ◽  
Elbow Flexion ◽  
The Elderly ◽  
Elderly Subjects ◽  
Elderly Persons ◽  
Movement Variability ◽  
Burst Amplitude ◽  
Young Subjects

The aim of this experiment was to determine whether elderly persons exhibit reciprocal phasing of muscle activity and scale EMG burst amplitude in the same manner as young people. Seven young and 7 elderly adults performed 30° elbow flexion movements at 800 ms duration to a visual target against varying inertial loads. The elderly were not able to achieve the required movement duration as frequently and spent a greater portion of the movement accelerating than the young. The young and the elderly subjects scaled EMG burst amplitude to the increasing loads in the same fashion, although the elderly subjects coactivated the agonisthtagonist muscles more than did the young subjects and thus did not accelerate the limb as rapidly. We hypothesized that the elderly used coactivation to reduce movement variability, and we developed a single-joint model with two muscles to examine this hypothesis. The model simulation correctly predicted the variability reduction due to coactivation. It appears, however, that this reduces the capability to accelerate rapidly.

Lift speed moderates the effects of muscle activity on perceived heaviness

2018 ◽  
Vol 71 (10) ◽  
pp. 2174-2185 ◽  
Author(s):  
Morgan L Waddell ◽  
Eric L Amazeen
Keyword(s):  
Muscle Activity ◽  
Angular Acceleration ◽  
Elbow Flexion

Research has shown that perceived heaviness is a function of the ratio of muscle activity (measured by electromyogram [EMG]) to the resulting acceleration of the object. However, objects will commonly be lifted at different speeds, implying variation in both EMG and acceleration. This study examined the effects of lifting speed by having participants report perceived heaviness for objects lifted by elbow flexion at three different speeds: slow, preferred, and fast. EMG and angular acceleration were recorded during these lifts. Both EMG and angular acceleration changed across lift speed. Nevertheless, despite these variations, perceived heaviness consistently scaled to the ratio of EMG to angular acceleration. The exponents on these parameters suggested that the saliency of muscle activity and movement changed across the three lift speeds.

scholarly journals 2H1-4　Upper arm muscle activity characteristics when performing isometric elbow flexion with assistance

2018 ◽  
Vol 54 (Supplement) ◽  
pp. 2H1-4-2H1-4
Author(s):  
Yuanyuan WANG ◽  
Jeewon CHOI ◽  
PingYeap LOH ◽  
Satoshi MURAKI
Keyword(s):  
Muscle Activity ◽  
Elbow Flexion ◽  
Upper Arm
Sign in / Sign up

Export Citation Format

Share Document