Wrist and Shoulder Muscle Activity Changes Across Computer Tasks

2002 ◽  
Vol 46 (13) ◽  
pp. 1129-1132 ◽  
Author(s):  
Jack Dennerlein ◽  
Maria-Helena DiMarino ◽  
Ted Becker ◽  
Peter Johnson
Keyword(s):  
Muscle Activity ◽  
Maximum Voluntary Contraction ◽  
Trapezius Muscle ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Office Work ◽  
Shoulder Muscle ◽  
Physical Risk Factors ◽  
Computer Workstation ◽  
Muscle Groups

The computer workstation is a ubiquitous tool in the office work environment; however, its use varies across many different tasks from surfing the Internet to typing. The question, therefore, is how does exposure to different physical risk factors for musculoskeletal disorders vary across tasks? Fifteen adults (10 females, 5 males) completed tasks simulating work at a computer workstation. The tasks were typing text, completing an html-based form, editing a document, a graphics task, and finally navigating through a series of web pages. During these tasks the muscle activity of the wrist prime movers and three shoulder muscle groups were recorded using surface EMG. For the wrist, the extensors were the most active ranging on average from 8 to 25 percent of Maximum Voluntary Contraction amplitude, with the greatest activity occurring in the typing task. The wrist activity decreased when the work changed from a keyboard-based activity to predominantly mouse-based activity. For the shoulder, the greatest activity was in the Trapezius muscle. The shoulder muscles were most active when both the mouse and the keyboard were required by the task. in summary, wrist and shoulder muscle activities at a computer workstation depend upon the type of task at hand.

Upper extremity muscle activity during household floor vacuuming with upright cleaners

2018 ◽  
Vol 62 (1) ◽  
pp. 1018-1021
Author(s):  
Haerim Bak ◽  
Clive D’Souza ◽  
Gwanseob Shin
Keyword(s):  
Upper Extremity ◽  
Muscle Activity ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Activity Levels ◽  
Physical Demands ◽  
Study Results ◽  
Musculoskeletal Problems ◽  
Muscle Groups ◽  
Intensive Work

Physical demands of household carpet vacuuming and associated risks for musculoskeletal problems have received little attention although the level of muscle exertions is often assumed to be similar to that of occupational vacuuming. The aim of this study was to quantitatively assess the level of muscle activities of the upper extremity during carpeted floor vacuuming with household upright vacuum cleaners. Eighteen participants conducted four different carpet vacuuming tasks with two different cleaner models. Electromyography data from seven upper extremity muscles were collected. Median muscle activity ranged from 4.5% to 47.5% of the maximum voluntary contraction capacity for female participants and from 2.7% to 23.6% for male participants. Normalized muscle activity levels were significantly higher in women compared to men across tasks and muscle groups. Study results suggest that home vacuuming with upright vacuum cleaners is physically intensive work, especially for female users who are less physically capable.

Changes of muscular sound during sustained isometric contraction up to exhaustion

1989 ◽  
Vol 66 (4) ◽  
pp. 1593-1598 ◽  
Author(s):  
C. Orizio ◽  
R. Perini ◽  
A. Veicsteinas
Keyword(s):  
Isometric Contraction ◽  
Exercise Intensity ◽  
Maximum Voluntary Contraction ◽  
Isometric Exercise ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Biceps Muscle ◽  
Output Force ◽  
Contact Transducer ◽  
Four Levels

The sound (SMG) generated by the biceps muscle during isometric exercise at 20, 40, 60, and 80% of maximum voluntary contraction (MVC) up to exhaustion has been recorded by a contact transducer and integrated (iSMG), together with the surface electromyogram (EMG) in eight young untrained men. At the onset of exercise, iSMG and integrated surface EMG (iEMG) amplitude increased linearly with exercise. iSMG remained constant for 253 +/- 73 (SD), 45 +/- 16, 21 +/- 5, and 0 s at the four levels of contraction. Then iSMG increased linearly at 20% MVC, fluctuated at 40% MVC, and decreased exponentially at 60 and 80% MVC. iSMG exhaustion-to-onset ratio was 5.0 at 20%, 1.0 at 40%, and 0.2 at 60 and 80% MVC. On the contrary, independently of exercise intensity, iEMG increased with time, being 1.4 higher at exhaustion than at the onset. The nonunivocal iSMG changes with time and effort of exercise suggest that the sound may be a useful tool to acquire different information to EMG and output force during muscle contraction up to fatigue.

scholarly journals Motor planning perturbation: muscle activation and reaction time

2018 ◽  
Vol 120 (4) ◽  
pp. 2059-2065
Author(s):  
Stefan Delmas ◽  
Agostina Casamento-Moran ◽  
Seoung Hoon Park ◽  
Basma Yacoubi ◽  
Evangelos A. Christou
Keyword(s):  
Reaction Time ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Motor Planning ◽  
Reaction Time Task ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Time Interval ◽  
Voluntary Activity

Reaction time (RT) is the time interval between the appearance of a stimulus and initiation of a motor response. Within RT, two processes occur, selection of motor goals and motor planning. An unresolved question is whether perturbation to the motor planning component of RT slows the response and alters the voluntary activation of muscle. The purpose of this study was to determine how the modulation of muscle activity during an RT response changes with motor plan perturbation. Twenty-four young adults (20.5 ±1.1 yr, 13 women) performed 15 trials of an isometric RT task with ankle dorsiflexion using a sinusoidal anticipatory strategy (10–20% maximum voluntary contraction). We compared the processing part of the RT and modulation of muscle activity from 10 to 60 Hz of the tibialis anterior (primary agonist) when the stimulus appeared at the trough or at the peak of the sinusoidal task. We found that RT ( P = 0.003) was longer when the stimulus occurred at the peak compared with the trough. During the time of the reaction, the electromyography (EMG) power from 10 to 35 Hz was less at the peak than the trough ( P = 0.019), whereas the EMG power from 35 to 60 Hz was similar between the peak and trough ( P = 0.92). These results suggest that perturbation to motor planning lengthens the processing part of RT and alters the voluntary activation of the muscle by decreasing the relative amount of power from 10 to 35 Hz. NEW & NOTEWORTHY We aimed to determine whether perturbation to motor planning would alter the speed and muscle activity of the response. We compared trials when a stimulus appeared at the peak or trough of an oscillatory reaction time task. When the stimulus occurred at the trough, participants responded faster, with greater force, and less EMG power from 10-35 Hz. We provide evidence that motor planning perturbation slows the response and alters the voluntary activity of the muscle.

Spinal Accessory Nerve Neuropathies Followng Neck Dissection

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P45-P45
Author(s):  
Carlos Neutzling Lehn ◽  
Luciana Pereira Lima ◽  
Ali Amar
Keyword(s):  
Neck Dissection ◽  
Cranial Nerve ◽  
Preoperative Evaluation ◽  
Trapezius Muscle ◽  
Electric Activity ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Mean Values ◽  
Shoulder Dysfunction ◽  
Neck Tumors

Objective To evaluate through electromyography (EMG) the injury to the 11th cranial nerve following neck dissection. Methods Prospective study with 60 patients submitted to neck dissection as part of treatment of head and neck tumors. All the cases underwent physiotherapic evaluation of shoulder dysfunction. Nerve integrity was evaluated pre- and postoperatively through surface EMG registering the electric activity of descendent fibers of trapezius muscle during maximal isometric voluntary contraction. The patients were grouped according the type of neck dissection, presence of shoulder pain, impairment during abduction movement, and hypotrophy or atrophy of trapezius muscle. Results The action potential had mean and standard deviation of 61,7±31,6mcV in preoperative evaluation and 15,6±12,4mcV in postoperative evaluation (p<0.001). According to the neck dissection extension, there were mean values of 18,8±14,2mcV after dissection includiog level IIb and 18,8±14,2 mcV after dissection including levels IIb and V (p<0.002). Conclusions Surface EMG is a sensitive and painless for 11th cranial nerve disfunction evaluation. In all cases, the superior fibers of trapezius muscle were affected with presence of pain and impairment abduction movement of the arm. The results suggest the benefit of trapezius muscle EMG to confirm the diagnosis and early physiotherapic intervention in neuropathies of the 11th cranial nerve.

Slowing of carotid-cardiac baroreflex with standing and with isometric and dynamic muscle activity

1996 ◽  
Vol 271 (4) ◽  
pp. H1363-H1369 ◽  
Author(s):  
P. Sundblad ◽  
D. Linnarsson
Keyword(s):  
Muscle Activity ◽  
Sympathetic Activity ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
The Other ◽  
Sitting Position ◽  
Arm Exercise ◽  
Mean Values ◽  
Leg Exercise ◽  
Male Subjects

We hypothesized that the carotid-cardiac baroreflex becomes slowed in conditions with increased sympathetic activity. Changes in heart rate (HR) and blood pressure in response to 10-s trains of 50-mmHg pulses of neck suction (NS) were studied in six male subjects during supine rest, upright rest, isometric arm exercise at 30% of maximum voluntary contraction, and dynamic leg exercise at 100 W in the sitting position. Estimated mean carotid distending pressure increased by approximately 20 mmHg with 50-mmHg, QRS-triggered, pulsatile NS. Repeated NS sequences were performed in each condition. The amplitude of the bradycardic response was highly variable among the subjects and did not differ significantly between conditions, mean values ranging from 0.3 to 0.6 beats.min-1.mmHg-1. In supine rest, the full bradycardic response appeared within < 1 s, i.e., during or immediately after the R-R interval of the first NS pulse. In the other conditions it took significantly longer, 2-3 s or three to seven R-R intervals, for the full HR responses to develop. Our results support the notion that the carotid-cardiac baroreflex in humans becomes slowed under conditions of concurrent sympathetic stimulation.

scholarly journals Pallidotomy Increases Cortical Inhibition in Parkinson's Disease

1997 ◽  
Vol 24 (2) ◽  
pp. 133-136 ◽  
Author(s):  
A. Strafella ◽  
P. Ashby ◽  
A. Lozano ◽  
A.E. Lang
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Magnetic Stimulation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Short Latency ◽  
Cortical Inhibition ◽  
First Dorsal Interosseus ◽  
Before And After ◽  
Posteroventral Pallidotomy

ABSTRACT:Background:Pallidotomy helps parkinsonian symptoms. We tested the hypothesis that this might be due to changes in inhibition in the motor cortex.Methods:We examined 15 patients with parkinsonism before and after posteroventral pallidotomy. Magnetic stimuli were delivered over the motor cortex, while subjects maintained a 30% maximum voluntary contraction of the contralateral first dorsal interosseus (FDI).Results:Weak stimuli inhibited voluntary muscle activity, while slightly stronger stimuli caused short latency facilitation from activation of the corticospinal neurons. After pallidotomy magnetic stimulation, at the threshold for the short latency facilitation, resulted in more inhibition than before.Conclusions:Pallidotomy increases cortical inhibition. This may be associated with improved control of movements.

scholarly journals A self-oblique exercise that activates the coordinated activity of abdominal and hip muscles–A pilot study

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255035
Author(s):  
Yuki Nakai ◽  
Masayuki Kawada ◽  
Takasuke Miyazaki ◽  
Sota Araki ◽  
Yasufumi Takeshita ◽  
...  
Keyword(s):  
Upper Limb ◽  
Muscle Activity ◽  
Gluteus Medius ◽  
Voluntary Contraction ◽  
Significant Activity ◽  
Exercise Load ◽  
Hip Muscle ◽  
Hip Muscles ◽  
Muscle Groups ◽  
Adductor Longus

The importance of an interaction between trunk stability muscles and hip muscle function has been suggested. However, reported exercises rarely act on the trunk and hip muscles simultaneously. Here, we devised an abdominal oblique and hip muscle exercise, the Self-oblique exercise (SOE). We examined whether SOE activated abdominal and hip muscles in the supine and half-kneeling positions, compared with abdominal crunch (AC) and plank exercises; and whether participants could modulate the exercise load. Participants were 20 healthy males with some sports experience such as football and baseball on average 10.5 ± 4.0 years. Participants applied self-pressure to their right thighs using the contralateral upper limb with 40% or 70% of the maximum force in Supine SOE and Half- kneeling SOE. The following abdominal and hip muscles were measured using surface electromyography: bilateral external obliques (EO), bilateral internal obliques (IO), right rectus abdominis, right gluteus medius (GMed), and right adductor longus (ADD). All evaluated muscle groups showed significant differences between exercises (p < 0.001). Supine SOE-70% showed 80.4% maximal voluntary contraction (MVC) for left EO (p < 0.017), 61.4% MVC for right IO (p < 0.027), 24.3% MVC for GMed (p < 0.002), and 42.4% MVC for ADD (p < 0.004); these were significantly greatest among all exercises. Muscle activity during Supine SOE-70% was greater than that during Supine SOE-40%. Similarly, Half-kneeling SOE-40% promoted abdominal and hip muscle exertion, and showed more significant activity in GMed (p < 0.006) and ADD (p < 0.001) than AC and plank. SOE could activate abdominal and hip muscles depends on the pressure applied by upper limb. Also, SOE allows participants to modulate the exercise load in a self-controlled step by step manner. Modulation of the exercise load is difficult in AC or plank compared to SOE, and AC or plank cannot obtain simultaneous oblique and hip muscle activity. SOE could be practiced anywhere, in various positions, without any tools.

Reward and over-commitment increase trapezius muscle activity in a real office work environment

2013 ◽  
Author(s):  
Jennifer L. Bruno Garza ◽  
Belinda H. W. Eijckelhof ◽  
Maaike A. Huysmans ◽  
Peter W. Johnson ◽  
Jaap H. van Dieen ◽  
...  
Keyword(s):  
Work Environment ◽  
Muscle Activity ◽  
Trapezius Muscle ◽  
Office Work

scholarly journals An Evaluation of Hand-Force Prediction Using Artificial Neural-Network Regression Models of Surface EMG Signals for Handwear Devices

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Masayuki Yokoyama ◽  
Ryohei Koyama ◽  
Masao Yanagisawa
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Regression Models ◽  
Maximum Voluntary Contraction ◽  
Surface Emg ◽  
Voluntary Contraction ◽  
Force Prediction ◽  
Hand Force ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

Hand-force prediction is an important technology for hand-oriented user interface systems. Specifically, surface electromyography (sEMG) is a promising technique for hand-force prediction, which requires a sensor with a small design space and low hardware costs. In this study, we applied several artificial neural-network (ANN) regression models with different numbers of neurons and hidden layers and evaluated handgrip forces by using a dynamometer. A handwear with dry electrodes on the dorsal interosseous muscles was used for our evaluation. Eleven healthy subjects participated in our experiments. sEMG signals with six different levels of forces from 0 N to 200 N and maximum voluntary contraction (MVC) are measured to train and test our ANN regression models. We evaluated three different methods (intrasession, intrasubject, and intersubject evaluation), and our experimental results show a high correlation (0.840, 0.770, and 0.789 each) between the predicted forces and observed forces, which are normalized by the MVC for each subject. Our results also reveal that ANNs with deeper layers of up to four hidden layers show fewer errors in intrasession and intrasubject evaluations.

scholarly journals The Electrical Activity of the Temporal and Masseter Muscles in Patients with TMD and Unilateral Posterior Crossbite

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Krzysztof Woźniak ◽  
Liliana Szyszka-Sommerfeld ◽  
Damian Lichota
Keyword(s):  
Electrical Activity ◽  
Muscle Activity ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Asymmetry Index ◽  
Subjective Symptoms ◽  
Posterior Crossbite ◽  
Rest Position ◽  
Torque Coefficient ◽  
Masseter Muscles

The aim of this study was to assess the influence of unilateral posterior crossbite on the electrical activity of the temporal and masseter muscles in patients with subjective symptoms of temporomandibular dysfunctions (TMD). The sample consisted of 50 patients (22 female and 28 male) aged 18.4 to 26.3 years (mean 20.84, SD 1.14) with subjective symptoms of TMD and unilateral posterior crossbite malocclusion and 100 patients without subjective symptoms of TMD and malocclusion (54 female and 46 male) aged between 18.4 and 28.7 years (mean 21.42, SD 1.06). The anamnestic interviews were conducted according to a three-point anamnestic index of temporomandibular dysfunction (Ai). Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Recordings were carried out in the mandibular rest position and during maximum voluntary contraction (MVC). Analysis of the results of the EMG recordings confirmed the influence of unilateral posterior crossbite on variations in spontaneous muscle activity in the mandibular rest position and maximum voluntary contraction. In addition, there was a significant increase in the Asymmetry Index (As) and Torque Coefficient (Tc), responsible for a laterodeviating effect on the mandible caused by unbalanced right and left masseter and temporal muscles.

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