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Anaesthesia and Intensive Care Feb 1976Computer control of anaesthesia has been extended to include muscle relaxant drugs. Injection of d-tubocurarine, gallamine, alcuronium or pancuronium was controlled by... (Comparative Study)
Comparative Study
Computer control of anaesthesia has been extended to include muscle relaxant drugs. Injection of d-tubocurarine, gallamine, alcuronium or pancuronium was controlled by computer to reduce the integrated electromyogram to a preset level (40 per cent of control) for one hour. A programmed level of muscle paralysis is therefore possible for use in physiological and pharmacological experiments, and in clinical practice where precise control of the degree of paralysis together with minimal dosage is advantageous.
Topics: Alcuronium; Animals; Computers; Electromyography; Gallamine Triethiodide; Masticatory Muscles; Muscle Contraction; Muscle Relaxants, Central; Muscles; Pancuronium; Rectum; Sheep; Tubocurarine
PubMed: 1251987
DOI: 10.1177/0310057X7600400103 -
Medical Problems of Performing Artists Mar 2019For violinists, the shoulder rest is an ergonomic adaptation to reduce musculoskeletal load. In this study, we aimed to evaluate how the height of the shoulder rest...
AIMS
For violinists, the shoulder rest is an ergonomic adaptation to reduce musculoskeletal load. In this study, we aimed to evaluate how the height of the shoulder rest affects the violin fixation force and electromyographic (EMG) activity of the superficial neck and shoulder muscles.
METHODS
In professional violinists, four different shoulder rest heights during five playing conditions were evaluated. Outcome variables included the jaw-shoulder violin fixation force and bilateral surface EMG of the upper trapezius (mTP), sternocleidomastoid (mSCM), and left anterior part of the left deltoid muscle (mDTA). Playing comfort was subjectively rated on a visual analogue scale (VAS). Linear regression models were estimated to investigate the influence of the shoulder rest height on muscle activity and violin fixation force as well as the muscle activity of the five evaluated muscles on violin fixation force.
RESULTS
20 professional violinists (4 males, 16 females, mean age 29.4 yrs) participated in this study. The shoulder rest condition had a significant effect on playing comfort (p<0.001), with higher shoulder rest conditions associated with decreased subjective playing comfort. The mean violin fixation force for each shoulder rest condition ranged between 2.92 and 3.39 N; higher shoulder rests were related to a higher violin fixation force (p<0.001).
CONCLUSION
In this study, violin fixation force and muscle activity of the left mDTA increased while playing with an increasing height of the shoulder rest. As the shoulder rest influences muscle activity patterns and violin fixation force, adjustment of the shoulder rest and positioning of the violin need to be carefully optimized.
Topics: Adult; Electromyography; Female; Humans; Male; Muscle, Skeletal; Music; Neck Muscles; Rest; Shoulder
PubMed: 30826820
DOI: 10.21091/mppa.2019.1009 -
Journal of the Medical Association of... Jul 2014The present study evaluated the changes in trunk-stabilizer electromyography (EMG) activities during manual lifting with and without a back belt in experienced back belt...
OBJECTIVE
The present study evaluated the changes in trunk-stabilizer electromyography (EMG) activities during manual lifting with and without a back belt in experienced back belt users.
MATERIAL AND METHOD
Eighteen participants from a warehouse and distribution center in Thailand, aged 22 to 44 years, were assessed for trunk stabilizer muscle EMG activity including the rectus abdominis (RA), external abdominal oblique (EO), transversus abdominis (TrA), internal abdominal oblique (IO), erector spinae (ES), and multifidus (MF). The EMG data were recorded during (1) rest and (2) the initial phase of manual lifting in a dynamic semi-squat posture. For both conditions, the data were compared with and without wearing a back belt.
RESULTS
The results showed that wearing a back belt significantly decreased TrA/IO activity during rest (p<0.01) and significantly increased RA activity during the lifting period (p<0.05) as compared with the condition of no back belt.
CONCLUSION
The present study does not recommend healthy workers wear a back belt as a protective device for lower back injury, particularly without any lifting activity. However the back belt can be applied during lifting as it can enhance RA activity, which may help improve abdominal pressure and is less likely cause weakness of the TrA.
Topics: Abdominal Muscles; Adult; Back Muscles; Electromyography; Ergonomics; Humans; Lifting; Posture; Protective Devices; Rest; Torso; Young Adult
PubMed: 25141532
DOI: No ID Found -
Archives of General Psychiatry Oct 1970
Topics: Anxiety; Autonomic Nervous System; Heart Rate; Humans; MMPI; Mental Processes; Muscle Contraction; Muscles; Noise; Personality Inventory; Psychological Tests; Rest; Stress, Psychological
PubMed: 4394151
DOI: 10.1001/archpsyc.1970.01750040071011 -
Journal of Applied Physiology Jun 1971
Topics: Adult; Biopsy; Capillaries; Diffusion; Heart Rate; Humans; Lactates; Male; Muscles; Oxygen Consumption; Physical Exertion; Physical Fitness; Regional Blood Flow; Respiration; Rest; Spirometry; Sports Medicine
PubMed: 5580806
DOI: 10.1152/jappl.1971.30.6.860 -
Neurology May 1964
Topics: Biomedical Research; Humans; Infant; Infant, Newborn; Muscle Tonus; Muscles; Physiology; Posture; Relaxation
PubMed: 14144118
DOI: 10.1212/wnl.14.5.464 -
Journal of Applied Physiology:... Oct 1983The purpose of this study was to determine the effect of running a marathon and subsequent rest or exercise during a 7-day recovery period on muscle glycogen, glycogen... (Clinical Trial)
Clinical Trial Randomized Controlled Trial
The purpose of this study was to determine the effect of running a marathon and subsequent rest or exercise during a 7-day recovery period on muscle glycogen, glycogen synthase, hexokinase, and the activity of hexose monophosphate pathway enzymes. Ten well-trained runners were randomly assigned to either a postmarathon rest or exercise group. The rest group (n = 5) performed no physical activity, whereas the exercise group ran at their highest tolerable volitional intensity for 20-45 min during the recovery period. Muscle biopsies were obtained from the gastrocnemius before and after the marathon and 1, 3, 5, and 7 days after the marathon. Muscle glycogen was supercompensated before the marathon (196 mmol glucosyl units kg wet tissue wt-1, mmol X kg-1) and was reduced to 25 mmol X kg-1 after the marathon. Seven days later it was 141 and 109 mmol X kg-1 in the rest and exercise groups, respectively. Measurement of glycogen synthase activity ratio indicated an active enzyme only immediately postmarathon, whereas measurement of glycogen synthase fractional velocity and relative velocity indicated an active enzyme immediately postmarathon and 1 day postmarathon. Hexokinase activity was significantly elevated immediately after the marathon and remained elevated through 5 days postmarathon. The activities of the hexose monophosphate pathway enzymes declined steadily during the experimental period and were significantly reduced 5 and 7 days postmarathon. Low-intensity exercise during the recovery week did not significantly differentiate the exercise group from the rest group.
Topics: Adult; Glycogen; Glycogen Synthase; Hexokinase; Hexosephosphates; Humans; Male; Muscles; Physical Exertion; Rest; Running
PubMed: 6415016
DOI: 10.1152/jappl.1983.55.4.1219 -
Pflugers Archiv : European Journal of... Oct 2023The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling mechanism (FSM). It is based on preload-dependent activation of sarcomeres-the...
The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling mechanism (FSM). It is based on preload-dependent activation of sarcomeres-the elementary contractile units in muscle cells. Recent findings show a natural variability in sarcomere length (SL) in resting cardiomyocytes that, moreover, is altered in an actively contracting myocyte. SL variability may contribute to the FSM, but it remains unresolved whether the change in the SL variability is regulated by activation process per se or simply by changes in cell stretch, i.e., average SL. To separate the roles of activation and SL, we characterized SL variability in isolated, fully relaxed rat ventricular cardiomyocytes (n = 12) subjected to a longitudinal stretch with the carbon fiber (CF) technique. Each cell was tested in three states: without CF attachment (control, no preload), with CF attachment without stretch, and with CF attachment and ~ 10% stretch of initial SL. The cells were imaged by transmitted light microscopy to retrieve and analyze individual SL and SL variability off-line by multiple quantitative measures such as coefficient of variation or median absolute deviation. We found that CF attachment without stretch did not affect the extent of SL variability nor average SL. In stretched myocytes, the averaged SL significantly increased, while the SL variability remained unchanged. This result clearly indicates that the non-uniformity of individual SL is not sensitive to the average SL itself in fully relaxed myocytes. We conclude that SL variability per se does not contribute to the FSM in the heart.
Topics: Animals; Rats; Myocytes, Cardiac; Sarcomeres; Myocardium; Rest; Muscle Contraction; Carbon Fiber
PubMed: 37603101
DOI: 10.1007/s00424-023-02848-2 -
Acta Medica Scandinavica 1983A positive relationship was demonstrated between the blood pressure and the fibre composition of the vastus muscle at rest in 17 hypertensive and 17 age- and sex-matched...
A positive relationship was demonstrated between the blood pressure and the fibre composition of the vastus muscle at rest in 17 hypertensive and 17 age- and sex-matched normotensive subjects. The hypertensive group had a higher proportion of fast twitch (FT) fibres (p less than 0.1). The circulatory response was measured during isometric exercise (IE) and cold pressor test (CPT). During IE the blood pressure increase was positively related to the percentage of FT fibres. No such relationship was demonstrated during CPT. It was thus found, particularly in hypertensive subjects, that an individual's muscle fibre profile is of importance for the blood pressure response during IE.
Topics: Adult; Blood Pressure; Cold Temperature; Female; Heart Rate; Humans; Hypertension; Isometric Contraction; Male; Middle Aged; Muscles; Rest
PubMed: 6829315
DOI: 10.1111/j.0954-6820.1983.tb03683.x -
The Journal of Physiology Nov 19771. Pulse synchronous bursts of multi-unit sympathetic activity was recorded from median or peroneal muscle nerve fascicles in fourteen subjects resting in the recumbent...
1. Pulse synchronous bursts of multi-unit sympathetic activity was recorded from median or peroneal muscle nerve fascicles in fourteen subjects resting in the recumbent position. The neural activity was quantitated in terms of burst incidence, i.e. the number of bursts in the mean voltage neurogram/100 heart beats, during successive rest periods of 2-4 min.2. For each individual the burst incidence was fairly constant between different rest periods but the mean burst incidence varied widely between individuals, the range being from less than 10 to more than 90 bursts/100 heart beats.3. Simultaneous double nerve recordings were made on one subject from median and peroneal nerves and on eight subjects from the two peroneal nerves. There was always close similarity between the two records in such experiments regardless of which muscles the nerve fascicles innervated. When analysed separately the difference in burst incidence between the two sides ranged from 0.7 to 5.1 bursts/100 heart beats. The findings suggest that sympathetic neurones destined to skeletal muscles are subjected to a homogenous central drive and that contributions to the activity from ganglionic or segmental sources are of lesser importance.4. On seven subjects repeated recordings at rest were made with intervals of 3 weeks-21 months between recordings. In each subject mean burst incidences were similar in all recordings (range of differences 0.5-11.2 bursts/100 heart beats) suggesting an individually constant level of sympathetic activity in muscle nerves.5. For each individual the variability of burst amplitudes in the mean voltage neurogram was described by burst amplitude spectra. Most subjects had a relatively larger proportion of small than high amplitude bursts, but there was a tendency for more even amplitude distributions in subjects with high burst incidence. The finding may be an indication of interindividual differences in the average number of impulses/burst.6. It is concluded that the multi-unit recording technique can be used for comparisons of the level of muscle nerve ;sympathetic tone' between different subjects.
Topics: Action Potentials; Adult; Humans; Middle Aged; Muscles; Neural Conduction; Peroneal Nerve; Posture; Rest; Sympathetic Nervous System
PubMed: 592196
DOI: 10.1113/jphysiol.1977.sp012050