Two components of muscle activation: scaling with the speed of arm movement

1992 ◽  
Vol 67 (4) ◽  
pp. 931-943 ◽  
Author(s):  
M. Flanders ◽  
U. Herrmann
Keyword(s):  
Muscle Activation ◽  
Movement Time ◽  
Vertical Plane ◽  
Arm Movement ◽  
Movement Speed ◽  
Weighting Coefficient ◽  
Emg Activity ◽  
Tonic Component ◽  
Force Element ◽  
Weighting Coefficients

1. The temporal waveform of muscle activity was related to the speed of arm movement. Speed was expressed in terms of the duration of a fixed amplitude movement or the "movement time." 2. Human subjects moved their arms to targets in three-dimensional space. The right arm started at a standard initial position and moved directly to the target in a single stroke. The targets were placed in various directions in a vertical plane. The arm movements consisted of shoulder and elbow rotations. 3. Subjects were required to vary the speed of their movements. In most of the experiments, trials with different movement times were randomly ordered. One of the experiments also included randomly interspersed static trials, in which the subject held the arm still at the initial posture, the final posture, or halfway between the two extremes. 4. Electromyographic (EMG) activity was recorded from several superficial elbow and/or shoulder muscles. The time base of rectified EMG records was normalized for movement time such that records from movements with various speeds were compressed to align the ending times of the movements. 5. A principal component (PC) analysis revealed that the compressed EMG waveforms could be described by a summation of PC1 and PC2 waveforms; each individual EMG waveform was approximated by a weighted sum of these two components. 6. The PC1 weighting coefficients scaled down in a monotonic relationship with movement time such that the fastest movement corresponded to a large positive weighting coefficient and the slowest movement corresponded to a small positive weighting coefficient. The PC2 weighting coefficients exhibited a similar monotonic scaling, but the values ranged from positive to negative. Further analysis demonstrated that these two components can be mathematically transformed into a tonic waveform with a constant mathematically transformed into a tonic waveform with a constant weighting coefficient and a phasic waveform with positive weighting coefficients that scale down with movement time. 7. The amplitude scaling of EMG records cannot be described by a single component, but instead requires a summation of two separate components. The tonic component may correspond to the force element needed to counteract gravity, because the magnitude of this element does not scale with movement speed. The phasic component may correspond to the force element that scales quadratically to produce a linear increase in velocity.

Development of an Apparatus for Bilateral Rhythmical Training of Arm Movement Via Linear and Elliptical Trajectories of Various Directions

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Zlatko Matjačić ◽  
Matjaž Zadravec ◽  
Jakob Oblak
Keyword(s):  
Muscle Activation ◽  
Arm Movement ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Arm Cycling ◽  
Arm Reaching ◽  
Direction Of Movement ◽  
Muscle Groups ◽  
Neurologically Intact

Clinical rehabilitation of individuals with various neurological disorders requires a significant number of movement repetitions in order to improve coordination and restoration of appropriate muscle activation patterns. Arm reaching movement is frequently practiced via motorized arm cycling ergometers where the trajectory of movement is circular thus providing means for practicing a single and rather nonfunctional set of muscle activation patterns, which is a significant limitation. We have developed a novel mechanism that in the combination with an existing arm ergometer device enables nine different movement modalities/trajectories ranging from purely circular trajectory to four elliptical and four linear trajectories where the direction of movement may be varied. The main objective of this study was to test a hypothesis stating that different movement modalities facilitate differences in muscle activation patterns as a result of varying shape and direction of movement. Muscle activation patterns in all movement modalities were assessed in a group of neurologically intact individuals in the form of recording the electromyographic (EMG) activity of four selected muscle groups of the shoulder and the elbow. Statistical analysis of the root mean square (RMS) values of resulting EMG signals have shown that muscle activation patterns corresponding to each of the nine movement modalities significantly differ in order to accommodate to variation of the trajectories shape and direction. Further, we assessed muscle activation patterns following the same protocol in a selected clinical case of hemiparesis. These results have shown the ability of the selected case subject to produce different muscle activation patterns as a response to different movement modalities which show some resemblance to those assessed in the group of neurologically intact individuals. The results of the study indicate that the developed device may significantly extend the scope of strength and coordination training in stroke rehabilitation which is in current clinical rehabilitation practice done through arm cycling.

scholarly journals Targeting in Virtual Workspaces: motor learning consolidates spatial memory for performance clusters

2019 ◽  
Author(s):  
Bradly Alicea ◽  
Corey Bohil ◽  
Frank Biocca ◽  
Charles Owen
Keyword(s):  
Repeated Measures ◽  
Target Location ◽  
Movement Time ◽  
Three Dimensional ◽  
Arm Movement ◽  
Hierarchical Cluster ◽  
Movement Speed ◽  
Advantages And Disadvantages ◽  
Training Interval ◽  
Speed And Accuracy

Our objective was to focus on linkages between the process of learning and memory and the placement of objects within an array of targets in a virtual workspace. Participants were instructed to place virtual objects serially within a three-dimensional target array. One phase presented each target sequentially, and required participants to make timed ballistic arm movements. The other phase presented all nine targets simultaneously, which required ballistic arm movement towards the correct target location as recalled from the learning phase. Movement time and accuracy were assessed using repeated-measures ANOVA, a hierarchical cluster analysis, and a multiple linear regression. Collectively, this revealed numerous speed and accuracy advantages and disadvantages for various positional combinations. Upper positions universally yielded longer movement times and larger error measurements. Individual ability for mental rotation combined with task learning over a fixed training interval was found to predict accuracy for specific locations. The prediction that location influences movement speed and accuracy was supported, but with some caveats. These results may be particularly useful in the design of instructor stations and other hybrid physical-virtual workspaces.

Coordinating two degrees of freedom during human arm movement: load and speed invariance of relative joint torques

1996 ◽  
Vol 76 (5) ◽  
pp. 3196-3206 ◽  
Author(s):  
G. L. Gottlieb ◽  
Q. Song ◽  
D. A. Hong ◽  
D. M. Corcos
Keyword(s):  
Degrees Of Freedom ◽  
Arm Movement ◽  
Movement Speed ◽  
Emg Activity ◽  
Joint Torques ◽  
Muscle Torque ◽  
Shoulder Flexion ◽  
Human Arm ◽  
The Individual ◽  
Finger Tip

1. Eight subjects performed three series of pointing tasks with the unconstrained arm. Series one and two required subjects to move between two fixed targets as quickly as possible with different weights attached to the wrist. By specifying initial and final positions of the finger tip, the first series was performed by flexion of both shoulder and elbow and the second by shoulder flexion and elbow extension. The third series required flexion at both joints, and subjects were instructed to vary movement speed. We examined how variations in load or intended speed were associated with changes in the amount and timing of the electromyographic (EMG) activity and the net muscle torque production. 2. EMG and torque patterns at the individual joints varied with load and speed according to most of the same rules we have described for single-joint movements. 1) Movements were produced by biphasic torque pulses and biphasic or triphasic EMG bursts at both joints. 2) The accelerating impulse was proportional to the load when the subject moved “as fast and accurately as possible” or to speed if that was intentionally varied. 3) The area of the EMG bursts of agonist muscles varied with the impulse. 4) The rates of rise of the net muscle torques and of the EMG bursts were proportional to intended speed and insensitive to inertial load. 5) The areas of the antagonist muscle EMG bursts were proportional to intended movement speed but showed less dependence on load, which is unlike what is observed during single-joint movements. 3. Comparisons across joints showed that the impulse produced at the shoulder was proportional to that produced at the elbow as both varied together with load and speed. The torques at the two joints varied in close synchrony, achieving maxima and going through zero almost simultaneously. 4. We hypothesize that “coordination” of the elbow and shoulder is by the planning and generation of synchronized, biphasic muscle torque pulses that remain in near linear proportionality to each other throughout most of the movement. This linear synergy produces movements with the commonly observed kinematic properties and that are preserved over changes in speed and load.

Organizing principles for single-joint movements. II. A speed-sensitive strategy

1989 ◽  
Vol 62 (2) ◽  
pp. 358-368 ◽  
Author(s):  
D. M. Corcos ◽  
G. L. Gottlieb ◽  
G. C. Agarwal
Keyword(s):  
Muscle Activation ◽  
Human Subjects ◽  
Movement Time ◽  
Initial Position ◽  
Joint Torque ◽  
Movement Speed ◽  
Movement Kinematics ◽  
Antagonist Muscles ◽  
Speed Accuracy ◽  
Organizing Principles

1. Normal human subjects made discrete flexions of the elbow over a fixed distance in the horizontal plane from a stationary initial position to a visually defined target. We measured joint angle, acceleration, and electromyograms (EMGs) from two agonist and two antagonist muscles. 2. Changes in movement speed were elicited either by explicit instruction to the subject or by adjusting the target width. Instructions always required accurately stopping in the target zone. 3. Peak inertial torques and accelerations, movement times, and integrated EMGs were all highly correlated with speed. We show that inertial torque can be used as a linking variable that is almost sufficient to explain all correlations between the task, the EMG, and movement kinematics. 4. When subjects perform tasks that require control of movement speed, they adjust the rate at which torque is developed by the muscles. This rate is modulated by the way in which the muscles are activated. The rate at which joint torque develops is correlated with the rate at which the agonist EMG rises as well as with integrated EMG. 5. The antagonist EMG shows two components. The latency of the first is 30-50 ms and independent of movement dynamics. The latency of the second component is proportional to movement time. The rate of rise and area of both components scale with torque. 6. We propose organizing principles for the control of single-joint movements in which tasks are performed by one of two strategies. These are called speed-insensitive and speed-sensitive strategies. 7. A model is proposed in which movements made under a speed-sensitive strategy are executed by controlling the intensity of an excitation pulse delivered to the motoneuron pool. The effect is to regulate the rate at which joint torque, and consequently acceleration, increases. 8. Movements of variable distance, speed, accuracy, and load are shown to be controlled by one of two consistent sets of rules for muscle activation. These rules apply to the control of both the agonist and antagonist muscles. Rules of activation lead to distinguishable patterns of EMG and torque development. All observable changes in movement kinematics are explained as deterministic consequences of these effects.

Age Differences in Movement Time over Distances Proportional to Size

1979 ◽  
Vol 48 (1) ◽  
pp. 309-310 ◽  
Author(s):  
Kathleen M. Haywood
Keyword(s):  
Young Adults ◽  
Age Differences ◽  
Movement Time ◽  
Early Adulthood ◽  
Arm Movement ◽  
Limb Length ◽  
Movement Speed

Investigations of the differences in movement speed over the age span, childhood to early adulthood, have typically confounded age with size differences which bring about mechanical differences in the task. The present study investigated the effect on arm movement time of confounding age and limb length. Young adults and childen 7 to 9 yr. of age were tested over a distance proportional to their arm length. Despite moving over a proportionally shorter distance, the children were significantly slower than the adults, suggesting that age differences in performance are not solely attributable to size differences among subjects.

Voluntary movement strategies of individuals with unilateral peripheral vestibular hypofunction*

1999 ◽  
Vol 9 (4) ◽  
pp. 265-275
Author(s):  
Diane F. Borello-France ◽  
Jere D. Gallagher ◽  
Mark Redfern ◽  
Joseph M. Furman ◽  
George E. Carvell
Keyword(s):  
Voluntary Movement ◽  
Body Position ◽  
Movement Time ◽  
Motor Planning ◽  
Arm Movement ◽  
Movement Speed ◽  
Directed Movement ◽  
Control Subjects ◽  
Vestibular Hypofunction ◽  
Movement Strategies

This study compared voluntary movement strategies of patients with unilateral peripheral vestibular hypofunction with those of age-matched healthy control subjects. All subjects performed three voluntary movement tasks with their dominant upper extremity: a forward flexion arm movement through 90 degrees, a reach to an overhead target, and a reach to a side target. Subjects performed the movement tasks sitting and standing (Body Position), and under precued and choice reaction time (RT) conditions (Task Certainty). Measures of motor planning and movement execution included RT and movement time (MT), respectively. Statistical analysis included separate Group x Task Certainty x Body Position ANOVA calculations for each task. Across tasks, results suggested no between group differences for RT. A Task Certainty main effect for the side and overhead tasks indicated that the choice RT situation resulted in longer RTs as compared to the precued RT condition. Movement time differed between the two groups. Across all three voluntary movement tasks, vestibular impaired subjects moved more slowly than control subjects. Providing vestibular subjects with a precue did not bring MT performance to the level of controls. Body position influenced MT for the side task only. Across both groups of subjects, MT for the side task was longer when performed in the standing position. The results of this study suggest that individuals with unilateral peripheral vestibular hypofunction initiate voluntary movement responses with similar timing as control subjects, but require more time to complete the movement. Vestibular rehabilitation should include goal-directed movement and should address issues of movement speed.

Influence of the globus pallidus on arm movements in monkeys. III. Timing of movement-related information

1985 ◽  
Vol 54 (2) ◽  
pp. 433-448 ◽  
Author(s):  
M. E. Anderson ◽  
F. B. Horak
Keyword(s):  
Reaction Time ◽  
Globus Pallidus ◽  
Muscle Activation ◽  
Movement Time ◽  
Emg Activity ◽  
Movement Velocity ◽  
Critical Stimulus ◽  
Reaching Movement ◽  
Stimulus Period ◽  
Arm Reaching

Monkeys were trained to make a visually triggered arm-reaching movement to a lighted button in a simple reaction-time paradigm, during which the reaction time (RT) and movement time (MT) were measured. Stimulus trains of varying duration were applied at various times before and during the movement at locations in the globus pallidus where application of long stimulus trains caused increased MTs. A critical stimulus period was identified during which stimulus application effectively prolonged MTs. The activity of pallidal neurons was examined during performance of the same behavioral task. More than 60% of the neurons examined showed task-related changes in activity that began before or during the reaching movement. For 45% of these cells, the initial change in firing occurred during the critical stimulus period, 50-150 ms before mechanically detected movement. Comparison of the critical stimulus period, the time of task-related changes in the discharge of pallidal neurons, and the time of EMG activity in muscles acting at the back, shoulder, elbow, and wrist revealed that both the critical stimulus period and changes in neuronal discharge occurred at or after initial muscle activation and during the buildup of EMG activity. These data are consistent with a model in which the globus pallidus plays a role in scaling the magnitude of muscle activity that determines movement velocity without affecting the initiation or sequential organization of the programmed motor output.

Muscle activation patterns for reaching: the representation of distance and time

1994 ◽  
Vol 71 (4) ◽  
pp. 1546-1558 ◽  
Author(s):  
C. A. Buneo ◽  
J. F. Soechting ◽  
M. Flanders
Keyword(s):  
Muscle Activation ◽  
Movement Time ◽  
Target Distance ◽  
Time Base ◽  
Emg Activity ◽  
Correlation Technique ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Shoulder Muscles ◽  
Anterior Deltoid

1. The timing and intensity of phasic muscle activation were related to the distance of reaching movements of the human arm. We dissociated phasic components of muscle activation from complete muscle activation waveforms by subtracting waveforms obtained during very slow movements. 2. We recorded electromyographic (EMG) activity from elbow and/or shoulder muscles as standing subjects reached forward and upward to targets at four distances. Accuracy was deemphasized and no terminal corrections were allowed. In the first part of the experiment subjects were asked to move at their preferred speed. In the second part of the experiment they were asked to move using a range of speeds. 3. In the first part of the experiment subjects moved faster to more distant targets but they also increased movement time as a nearly linear function of target distance. The slope of this function was very similar across subjects. The phasic EMG waveforms for different distances appeared to be similar in shape but of variable duration. EMG time base was quantified using a correlation technique that identified the time base scale factor that best superimposed a given trace with a template. This technique revealed that the slope of the relation between EMG time base and target distance was not the same for all muscles. 4. In the second part of the experiment, where subjects moved to each target at a range of specified speeds, time base scaling was again significantly different for different muscles. The scaling differed most dramatically between anterior deltoid and medial head of triceps. 5. EMG intensity was more strongly related to movement time than to distance. We quantified the correspondence of distance and movement time to phasic EMG intensity using a multiple regression analysis of all distances and speeds, assuming a power relation. Distance exponents were positive and movement time exponents were larger and negative. This implies that movement time is more important than distance in its relation to EMG intensity.

Influence of globus pallidus on arm movements in monkeys. I. Effects of kainic acid-induced lesions

1984 ◽  
Vol 52 (2) ◽  
pp. 290-304 ◽  
Author(s):  
F. B. Horak ◽  
M. E. Anderson
Keyword(s):  
Kainic Acid ◽  
Globus Pallidus ◽  
Movement Time ◽  
Reaction Times ◽  
Arm Movement ◽  
Reaction Time Task ◽  
Emg Activity ◽  
Arm Reaching ◽  
Sequential Organization ◽  
Sequential Activation

The role of basal ganglia output via the globus pallidus (GP) was examined in monkeys trained to make rapid arm-reaching movements to a visual target in a reaction-time task. When neurons in the globus pallidus were destroyed by injection of kainic acid (KA) during task execution, contralateral arm movement times (MT) were increased significantly, with little or no change in reaction times (RT). The slowed movements were associated with a generalized depression in the amplitude and rate of rise of electromyographic (EMG) activity in all the contralateral muscles studied at the wrist, elbow, shoulder, and back, but there was no change in the sequential activation of these muscles. The most profound and persistent increases in movement time occurred when neurons were destroyed in the ventrolateral and caudal aspects of the internal as well as external pallidal segment. These results suggest a role for globus pallidus output in scaling the magnitude and/or buildup of EMG activity without affecting the initiation or the sequential organization of the programmed motor output.

Normalized Jerk: A Measure to Capture Developmental Characteristics of Young Girls' Overarm Throwing

2000 ◽  
Vol 16 (2) ◽  
pp. 196-203 ◽  
Author(s):  
Jin H. Yan ◽  
Richard N. Hinrichs ◽  
V. Gregory Payne ◽  
Jerry R. Thomas
Keyword(s):  
Movement Time ◽  
Hand Movement ◽  
Arm Movement ◽  
Developmental Differences ◽  
Movement Speed ◽  
Alternative Approach ◽  
Overarm Throwing ◽  
Older Subjects ◽  
Developmental Characteristics ◽  
Tennis Balls

This study was designed to examine Ihe developmental differences in the speed and smoothness of arm movement during overarm throwing. The second purpose of this investigation was to evaluate whether jerk is a useful measure in understanding children's overarm throwing. Fifty-one girls, aged 3 to 6 years, voluntarily participated in the study. Each subject threw tennis balls as hard as she could toward a large target on the wall. A 2-camera video system was used to obtain 3-D coordinates of the hand and ball using the DLT algorithm. The variables of velocity and jerk (for the hand and ball) served as the movement outcome measures. The age-associated differences in velocity and normalized jerk (absolute jerk standardized relative to movement time and distance) were examined by ANOVAs. The results supported the hypothesis that the older subjects demonstrated faster and smoother hand movements than their younger counterparts during the forward acceleration phase (from the beginning of forward motion to ball release). In addition, the correlation results indicated thai increased hand movement speed was associated with decreased movement jerk in older subjects, whereas increased hand speed was associated with increased jerk in younger subjects. The findings suggest that examining the jerk parameter (normalized or absolute jerk) is a useful and alternative approach to capture the variance of hand movement execution for children's overarm throwing.

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