The relationship between speed and amplitude of the fastest voluntary contractions of human arm muscles

1978 ◽  
Vol 31 (1) ◽  
Author(s):  
H.-J. Freund ◽  
H.J. B�dingen
Keyword(s):  
Human Arm ◽  
Arm Muscles ◽  
Voluntary Contractions ◽  
The Relationship

scholarly journals The Movement- and Load-Dependent Differences in the EMG Patterns of the Human Arm Muscles during Two-Joint Movements (A Preliminary Study)

2016 ◽  
Vol 7 ◽  
Author(s):  
Tomasz Tomiak ◽  
Tetiana I. Abramovych ◽  
Andriy V. Gorkovenko ◽  
Inna V. Vereshchaka ◽  
Viktor S. Mishchenko ◽  
...  
Keyword(s):  
Human Arm ◽  
Arm Muscles ◽  
Preliminary Study ◽  
Emg Patterns

Regulation of 3D Human Arm Impedance Through Muscle Co-Contraction

2013 ◽  
Author(s):  
Harshil Patel ◽  
Gerald O’Neill ◽  
Panagiotis Artemiadis
Keyword(s):  
Dimensional Space ◽  
Human Subjects ◽  
Three Dimensional ◽  
Mechanical Impedance ◽  
Dominant Factor ◽  
Robot Arm ◽  
End Point ◽  
Human Arm ◽  
Arm Muscles ◽  
Experimental Trials

Humans have the inherent ability of performing highly dexterous and skillful tasks with their arms, involving maintenance of posture, movement, and interaction with the environment. The latter requires the human to control the dynamic characteristics of the upper limb musculoskeletal system. These characteristics are quantitatively represented by inertia, damping, and stiffness, which are measures of mechanical impedance. Many previous studies have shown that arm posture is a dominant factor in determining the end point impedance on a horizontal (transverse) plane. This paper presents the characterization of the end point impedance of the human arm in three-dimensional space. Moreover, it models the regulation of the arm impedance with respect to various levels of muscle co-contraction. The characterization is made by route of experimental trials where human subjects maintained arm posture while their arms were perturbed by a robot arm. Furthermore, the subjects were asked to control the level of their arm muscles’ co-contraction, using visual feedback of their muscles’ activation, in order to investigate the effect of this muscle co-contraction on the arm impedance. The results of this study show a very interesting, anisotropic increase of arm stiffness due to muscle co-contraction. These results could lead to very useful conclusions about the human’s arm biomechanics, as well as many implications for human motor control-specifically the control of arm impedance through muscle co-contraction.

EMG Controlled Soft Robotic Bicep Augmentation

2019 ◽  
Author(s):  
Jiayue Zhang ◽  
Daniel Vanderbilt ◽  
Ethan Fitz ◽  
Janet Dong
Keyword(s):  
Hybrid Control ◽  
Biceps Brachii ◽  
Pressure Sensors ◽  
Industrial Workers ◽  
Pneumatic Muscle ◽  
Repetitive Lifting ◽  
Human Arm ◽  
Lifting Capacity ◽  
Arm Muscles ◽  
Repetitive Loading

Abstract Repeated lifting tasks are often required of industrial workers. Such repetitive loading of workers’ arms throughout the workday can lead to injury and fatigue. This paper details the development and prototyping of a wearable soft robotic device to augment a worker’s arms by sensing and mimicking the contractions of their arm muscles. The device shares lifting loads with the user’s muscles to increase their lifting capacity, thereby preventing injury and reducing fatigue. The human arm contains many muscles that coordinate to produce movement. However, as a simplified proof of concept, this project developed a prototype to augment just the biceps brachii muscle since it is the primary pulling muscle used in lifting movements. Key components of the prototype include a soft robotic actuator analogous to the biceps, a control system for the actuator, and a method of attaching the actuator to the user’s arm. The McKibben-inspired pneumatic muscle was chosen as the soft actuator of the prototype. The Electromyography (EMG) and pressure sensors are used to inform a hybrid control algorithm combining PID and model-based control methods. The method and results of the design and preliminary feasibility testing of the pneumatic muscle, the controlling algorithm, and the overall prototype are discussed in this paper. Based on these results, a wearable EMG controlled soft robotic arm augmentation could feasibly increase the endurance of industrial workers performing repetitive lifting tasks.

Relationship Between Simulated Common Synaptic Input and Discharge Synchrony in Cat Spinal Motoneurons

2001 ◽  
Vol 86 (5) ◽  
pp. 2266-2275 ◽  
Author(s):  
Marc D. Binder ◽  
Randall K. Powers
Keyword(s):  
Synaptic Input ◽  
Human Subjects ◽  
Motor Units ◽  
Human Hand ◽  
Spinal Motoneurons ◽  
Common Input ◽  
Voluntary Contractions ◽  
High Degree ◽  
The Relationship ◽  
Repetitive Discharge

Synchronized discharge of individual motor units is commonly observed in the muscles of human subjects performing voluntary contractions. The amount of this synchronization is thought to reflect the extent to which motoneurons in the same and related pools share common synaptic input. However, the relationship between the proportion of shared synaptic input and the strength of synchronization has never been measured directly. In this study, we simulated common shared synaptic input to cat spinal motoneurons by driving their discharge with noisy, injected current waveforms. Each motoneuron was stimulated with a number of different injected current waveforms, and a given pair of waveforms were either completely different or else shared a variable percentage of common elements. Cross-correlation histograms were then compiled between the discharge of motoneurons stimulated with noise waveforms with variable degrees of similarity. The strength of synchronization increased with the amount of simulated “common” input in a nonlinear fashion. Moreover, even when motoneurons had >90% of their simulated synaptic inputs in common, only ∼25–45% of their spikes were synchronized. We used a simple neuron model to explore how variations in neuron properties during repetitive discharge may lead to the low levels of synchronization we observed experimentally. We found that small variations in spike threshold and firing rate during repetitive discharge lead to large decreases in synchrony, particularly when neurons have a high degree of common input. Our results may aid in the interpretation of studies of motor unit synchrony in human hand muscles during voluntary contractions.

Relationship Between Fatigue and Changes in Swim Technique During an Exhaustive Swim Exercise

2016 ◽  
Vol 11 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Natália M. Bassan ◽  
Tadeu E.A.S. César ◽  
Benedito S. Denadai ◽  
Camila C. Greco
Keyword(s):  
Peak Torque ◽  
Stroke Rate ◽  
Elbow Flexors ◽  
Front Crawl ◽  
Stroke Length ◽  
Swim Test ◽  
Strength Tests ◽  
Before And After ◽  
Arm Muscles ◽  
The Relationship

Purpose:To analyze the relationship between the responses of isometric peak torque (IPT) and maximal rate of force development (RFDmax) with the changes in stroking parameters in an exhaustive exercise performed in front crawl.Methods:Fifteen male swimmers performed, on different days, the following protocols: maximal 400-m trial, strength tests before and after an exhaustive test at 100% of the mean speed obtained during the 400-m test, and the same procedures on day 2.Results:The IPT of elbow flexors (79.9 ± 19.4 and 66.7 ± 20.0 N·m) and elbow extensors (95.1 ± 28.0 N·m and 85.8 ± 30.5 N·m) was decreased after the swim test, as was RFDmax (521.8 ± 198.6 and 426.0 ± 229.9 N·m/s; 420.6 ± 168.2 and 384.0 ± 143.5 N·m/s, respectively). Stroke length decreased during the swim test (1.96 ± 0.22 and 1.68 ± 0.29 m/stroke), while stroke rate increased (37.2 ± 3.14 and 41.3 ± 4.32 strokes/min). The propulsive phases increased while the nonpropulsive phases decreased during the test. Significant correlation was found between the changes in IPT and stroke length, stroke rate and recovery (elbow flexors), and entry and catch phase (elbow extensors). In addition, significant correlation was found between the changes in RFDmax of elbow flexors with the changes in pull and recovery phases.Conclusion:Changes in swim technique during an exhaustive test can be, at least in part, associated with fatigue of the arm muscles.

Voluntary activation of human quadriceps during and after isokinetic exercise

1991 ◽  
Vol 71 (6) ◽  
pp. 2122-2126 ◽  
Author(s):  
D. J. Newham ◽  
T. McCarthy ◽  
J. Turner
Keyword(s):  
Human Subjects ◽  
Knee Extension ◽  
Voluntary Activation ◽  
Isometric Contractions ◽  
Knee Angle ◽  
Lower Velocity ◽  
Isokinetic Contractions ◽  
Normal Human ◽  
Voluntary Contractions ◽  
The Relationship

The extent of voluntary activation in fresh and fatigued quadriceps muscles was investigated during isometric and isokinetic voluntary contractions at 20 and 150 degrees/s in 23 normal human subjects. The muscles were fatigued by a total of 4 min of maximal knee extension at an angular velocity of 85 degrees/s. Voluntary activation was determined by the superimposition of tetanic electrical stimulation at 100 Hz for 250 ms, initiated at a constant knee angle. The relationship between voluntary and stimulated force was similar to that found with the established twitch superimposition technique used on isometric contractions. In fresh muscle all the subjects showed full voluntary activation during isometric contractions. Some activation failure was seen in five subjects at 20 degrees/s [2.0 +/- 0.9 degrees (SE)] and in two subjects at 150 degrees/s (0.7 +/- 0.5). After fatigue all subjects showed some activation failure at 0 and 20 degrees/s (36.4 +/- 3.1 and 28.8 +/- 4.1 degrees, respectively), but only two showed any at 150 degrees/s (1.4 +/- 5.7). We conclude that brief high-intensity dynamic exercise can cause a considerable failure of voluntary activation. This failure was most marked during isometric and the lower-velocity isokinetic contractions. Thus a failure of voluntary activation may have greater functional significance than previous studies of isometric contractions have indicated.

scholarly journals Explanation of Fitts’ law in Reaching Movement based on Human Arm Dynamics

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Misaki Takeda ◽  
Takanori Sato ◽  
Hisashi Saito ◽  
Hiroshi Iwasaki ◽  
Isao Nambu ◽  
...  
Keyword(s):  
Inverse Dynamics ◽  
Reaching Movements ◽  
Temporal Constraints ◽  
Reaching Movement ◽  
Fitts Law ◽  
Human Arm ◽  
Behavioural Experiment ◽  
Error Distributions ◽  
Dynamics Models ◽  
The Relationship

AbstractWhy does Fitts’ law fit various human behavioural data well even though it is not a model based on human physical dynamics? To clarify this, we derived the relationships among the factors applied in Fitts’ law—movement duration and spatial endpoint error—based on a multi-joint forward- and inverse-dynamics models in the presence of signal-dependent noise. As a result, the relationship between them was modelled as an inverse proportion. To validate whether the endpoint error calculated by the model can represent the endpoint error of actual movements, we conducted a behavioural experiment in which centre-out reaching movements were performed under temporal constraints in four directions using the shoulder and elbow joints. The result showed that the distributions of model endpoint error closely expressed the observed endpoint error distributions. Furthermore, the model was found to be nearly consistent with Fitts’ law. Further analysis revealed that the coefficients of Fitts’ law could be expressed by arm dynamics and signal-dependent noise parameters. Consequently, our answer to the question above is: Fitts’ law for reaching movements can be expressed based on human arm dynamics; thus, Fitts’ law closely fits human’s behavioural data under various conditions.

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