Comparison of force and EMG measures in normal and reinnervated tibialis anterior muscles of the rat

1991 ◽  
Vol 69 (11) ◽  
pp. 1774-1783 ◽  
Author(s):  
Joanne E. Tötösy de Zepetnek ◽  
Tessa Gordon ◽  
Richard B. Stein ◽  
Hor Ven Zung
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Radial Distance ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Square Root ◽  
Sectional Area ◽  
Glycogen Depletion ◽  
Cross Sectional ◽  
Emg Signal

The relationship between motor unit force and the recorded voltage produced by activated muscle unit fibres (electromyogram, EMG) was examined in normal and reinnervated rat tibialis anterior muscles. The number, cross-sectional area, and radial distance from the recording electrode of muscle fibres in a given unit, obtained directly from a sample of glycogen-depleted motor units, were analysed in relation to the magnitude of the EMG signal produced by that unit. EMG peak to peak amplitude and area varied as approximately the square root of twitch force in both normal and reinnervated units. Furthermore, the EMG amplitude increased approximately as the total cross-sectional area of the motor unit (number of muscle fibres × the average cross-sectional area of the fibres) and inversely with approximately the square root of the distance of fibres from the recording electrodes on the surface of the muscle.Key words: motor unit size, electromyogram, reinnervation, glycogen depletion.

Maximal force as a function of anatomical features of motor units in the cat tibialis anterior

1987 ◽  
Vol 57 (6) ◽  
pp. 1730-1745 ◽  
Author(s):  
S. C. Bodine ◽  
R. R. Roy ◽  
E. Eldred ◽  
V. R. Edgerton
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Periodic Acid ◽  
Muscle Fibers ◽  
Motor Units ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Periodic Acid Schiff ◽  
Cross Sectional ◽  
Single Motor Unit

In 11 tibialis anterior muscles of the cat, a single motor unit was characterized physiologically and subsequently depleted of its glycogen through repetitive stimulation of an isolated ventral root filament. Muscle cross sections were stained for glycogen using a periodic acid-Schiff reaction, and single-fiber optical densities were determined to identify those fibers belonging to the stimulated motor unit. Innervation ratios were determined by counting the total number of muscle fibers in a motor unit in sections taken through several levels of the muscle. The average innervation ratios for the fast, fatigueable (FF) and fast, fatigue-resistant (FR) units were similar. However, the slow units (S) contained 61% fewer fibers than the fast units (FF and FR). Muscle fibers belonging to S and FR units were similar in cross-sectional area, whereas fibers belonging to FF units were significantly larger than fibers belonging to either S or FR units. Additionally, muscle fibers innervated by a single motoneuron varied by two- to eightfold in cross-sectional area. Specific tensions, based on total cross-sectional area determined by summing the areas of all muscle fibers of each unit, showed a modest difference between fast and slow units, the means being 23.5 and 17.2 N X cm-2, respectively. Variations in maximum tension among units could be explained principally by innervation ratio, although fiber cross-sectional area and specific tension did contribute to differences between unit types.

Metabolic and fiber size properties of cat tibialis anterior motor units

1988 ◽  
Vol 255 (1) ◽  
pp. C43-C50 ◽  
Author(s):  
T. P. Martin ◽  
S. Bodine-Fowler ◽  
R. R. Roy ◽  
E. Eldred ◽  
V. R. Edgerton
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Single Fiber ◽  
Sample Population ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fiber Size ◽  
The Mean

The variability among single muscle fiber enzymatic activities and fiber size within a motor unit was studied in the cat tibialis anterior (TA) muscle. Fourteen units were isolated for physiological testing using standard ventral root filament stimulation techniques, and the muscle fibers of these units were identified by glycogen depletion. The cross-sectional areas, succinate dehydrogenase (SDH) and alpha-glycerolphosphate dehydrogenase (GPD) activities, and the relative alkaline myofibrillar adenosine triphosphate staining densities of a sample of glycogen-depleted and -nondepleted muscle fibers were determined using quantitative histochemical techniques. Each of the unit types previously identified to be present in the TA, based on physiological criteria, were represented by the sample population. The variability among the fibers of a unit was significantly more than the variability among repeated measures on a single fiber for cross-sectional area and SDH and GPD activities. The mean coefficients of variation for SDH and GPD activity within motor unit fibers were 29 and 56%, respectively, whereas the variability between fibers of different units within a muscle was significantly greater (53 and 69%, respectively). Additionally, the mean coefficient of variation for cross-sectional area among motor unit fibers was less than that among fibers not depleted of glycogen (25 vs. 46%). These data suggest that although there is clear evidence for some level of neural control of the properties of a muscle unit (variation within a unit was less than the variation across units), this control is not complete, since the variability among fibers of a single unit was significantly more than the variability found between repeated measurements on a single fiber.

scholarly journals A computer simulation study on the influence of motor unit regionalization on the generation of surface myoelectric signals

2019 ◽  
Author(s):  
Ricardo Gonçalves Molinari ◽  
Leonardo Abdala Elias
Keyword(s):  
Motor Unit ◽  
Cross Sectional Area ◽  
Median Frequency ◽  
Sectional Area ◽  
Computer Simulation Study ◽  
Cross Sectional ◽  
Emg Signal ◽  
Muscle Cross Sectional Area ◽  
Best Fit ◽  
Frequency Domain Properties

The present study aims to analyze the influence of motor unit regionalization within the muscle cross-sectional area on time- and frequency-domain properties of surface myoelectric EMG signal. Computer simulations were performed using a phenomenological model of the neuromuscular system. Different contraction intensities were simulated, and the RMS and median frequency of the EMG were calculated for different muscle cross-sectional area morphologies. The level of MU regionalization was adjusted in the model. Results showed that experimental force-EMG relations could be appropriately simulated by the model, irrespective of the muscle cross-sectional area morphology and the level of MU regionalization. However, the best fit between simulation and experimental data is influenced by the level of MU regionalization.

Observations on the number of nuclei within the fibres of some red and white muscles

1977 ◽  
Vol 23 (1) ◽  
pp. 269-284 ◽  
Author(s):  
I.G. Burleigh
Keyword(s):  
Cross Sectional Area ◽  
Growth Potential ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Adult Rats ◽  
Cross Sectional ◽  
Physiological Properties ◽  
Phasic Type ◽  
The One ◽  
Red And White Muscles

Nuclei have been enumerated in muscle fibres of different physiological properties within adult rats and rabbits. Almost invariably, and regardless of muscle type, there is a direct relationship between the cross-sectional area (or fibre breadth) of muscle fibres and the number of nuclei within them. The one exception occurred in muscles of older rats where increased nuclear numbers do not always appear to result in broader muscle fibres. The greater complement of nuclei in broader fibres is accompanied by larger amounts of cell substance per nucleus. Confirming early observations in the literature, red fibres of the slow-phasic type have more nuclei than have white, fast-phasic fibres of similar breadth. These conclusions are not vitiated by differences in the number of nuclei within capillaries or in satellite cells, by differences in nuclear length or by variation in the degree to which fibres are contracted. In respect of their complement of nuclei, and the average amount of cell substance formed per nucleus the small red fibres that occur within muscles of predominantly fast-phasic character appear to be fast-rather than slow-phasic in type. When the number of nuclei observed per fibre is plotted against fibre cross-sectional area, the shapes of the resulting distributions suggest that estimates of muscle nuclei may be valuable not only as an index of growth potential, but of the extent to which that potential is expressed. In one muscle, the above distribution was of a form which indicated that some fibres may have formed abnormally large amounts of protein per nucleus. However, this was not adequately confirmed. Various factors have been investigated that are relevant to the accuracy of enumerating nuclei and measuring fibre breadths.

scholarly journals Variable maternal nutrition and growth hormone treatment in the second quarter of pregnancy in pigs alter semitendinosus muscle in adolescent progeny

2003 ◽  
Vol 90 (2) ◽  
pp. 283-293 ◽  
Author(s):  
Kathryn L. Gatford ◽  
Jason E. Ekert ◽  
Karina Blackmore ◽  
Miles J. De Blasio ◽  
Jodie M. Boyce ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Maternal Nutrition ◽  
Maternal Plasma ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Large White ◽  
Semitendinosus Muscle ◽  
Gh Treatment ◽  
Cross Sectional

Maternal nutrition and growth hormone (GH) treatment during early- to mid-pregnancy can each alter the subsequent growth and differentiation of muscle in progeny. We have investigated the effects of varying maternal nutrition and maternal treatment with porcine (p) GH during the second quarter of pregnancy in gilts on semitendinosus muscle cross-sectional area and fibre composition of progeny, and relationships between maternal and progeny measures and progeny muscularity. Fifty-three Large White×Landrace gilts, pregnant to Large White×Duroc boars, were fed either 2·2 kg (about 35 % ad libitum intake) or 3·0 kg commercial ration (13·5 MJ digestible energy, 150 g crude protein (N×6·25)/kg DM)/d and injected with 0, 4 or 8 mg pGH/d from day 25 to 50 of pregnancy, then all were fed 2·2 kg/d for the remainder of pregnancy. The higher maternal feed allowance from day 25 to 50 of pregnancy increased the densities of total and secondary fibres and the secondary:primary fibre ratio in semitendinosus muscles of their female progeny at 61 d of age postnatally. The densities of secondary and total muscle fibres in semitendinosus muscles of progeny were predicted by maternal weight before treatment and maternal plasma insulin-like growth factor-II during treatment. Maternal pGH treatment from day 25 to day 50 of pregnancy did not alter fibre densities, but increased the cross-sectional area of the semitendinosus muscle; this may be partially explained by increased maternal plasma glucose. Thus, maternal nutrition and pGH treatment during the second quarter of pregnancy in pigs independently alter muscle characteristics in progeny.

scholarly journals Heart size and mean muscle fibre cross-sectional area related to birth weight in pigs

2008 ◽  
Vol 16 (3) ◽  
pp. 259 ◽  
Author(s):  
M. RUUSUNEN ◽  
E. PUOLANNE ◽  
K. PARTANEN
Keyword(s):  
Birth Weight ◽  
Growth Performance ◽  
Muscle Mass ◽  
Carcass Composition ◽  
Cross Sectional Area ◽  
Heart Weight ◽  
Longissimus Dorsi ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Cross Sectional

One of the aims in domestic pig breeding has been to increase the size of litters resulting in variation in birth weight of piglets. Pig breeding has also resulted in increased body muscle mass. Muscles with the same size can consist either of large number of thin muscle fibres or small number of thick muscle fibres. Larger body muscle content means that in living animal the heart must pump blood to larger muscle mass than earlier. Our interest in this study was to investigate the relationship between the pig’s birth weight and (i) growth performance and carcass composition, (ii) the size of organs, and (iii) the mean muscle fibre cross-sectional area at slaughter. The study consisted of twenty pigs slaughtered at the age of 165±2 days. The day after the slaughter, the carcass composition was determined by dissecting the chilled carcass into lean, fat, bones, and skin and organs were weighed. The average cross sectional area of muscle fibres was determined from three fast-twitch muscles longissimus dorsi, semimembranosus, gluteus superficialis, and two slow-twitch muscles infraspinatus and masseter. The birth weight of pigs ranged from 0.9 to 2.2 kg. We found no clear relationships between the birth weight and the pig’s growth performance from birth to slaughter. When the birth weight increased the heart weight at slaughter increased as well (P < 0.01). The heart weight was higher in those pigs with high carcass weight (P < 0.05) and with the high weight of total muscle mass in the carcass (P < 0.001). The cross sectional area of muscle fibres in M. longissimus dorsi (P < 0.05), M. semimembranosus (P < 0.10), and M. gluteus superficialis (P < 0.05) was larger in those pigs with low birth weight compared to those found in pigs with high birth weight.;

Variability in skeletal muscle fibre characteristics during repeated muscle biopsy sampling in human vastus lateralis

2020 ◽  
Vol 45 (4) ◽  
pp. 368-375 ◽  
Author(s):  
Joshua P. Nederveen ◽  
George Ibrahim ◽  
Stephen A. Fortino ◽  
Tim Snijders ◽  
Dinesh Kumbhare ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Biopsy ◽  
Fibre Type ◽  
Vastus Lateralis ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Cross Sectional ◽  
Type Distribution ◽  
Fibre Type Distribution

The percutaneous muscle biopsy procedure is an invaluable tool for characterizing skeletal muscle and capillarization. Little is known about methodological or biological variation stemming from the technique in heterogeneous muscle. Five muscle biopsies were taken from the vastus lateralis of a group of young men (n = 29, 22 ± 1 years) over a 96-h period. We investigated the repeatability of fibre distribution, indices of muscle capillarization and perfusion, and myofibre characteristics. No differences between the biopsies were reported in myofibre type distribution, cross-sectional area (CSA), and perimeter. Capillary-to-fibre perimeter exchange index and individual capillary-fibre contacts were unchanged with respect to the location of the muscle biopsy and index of capillarization. The variability in the sampling distribution of fibre type specific muscle CSA increased when fewer than 150 muscle fibres were quantified. Variability in fibre type distribution increased when fewer than 150 muscle fibres were quantified. Myofibre characteristics and indices of capillarization are largely consistent throughout the vastus lateralis when assessed via the skeletal muscle biopsy technique. Novelty Markers of muscle capillarization and perfusion were unchanged across multiple sites of the human vastus lateralis. Myofibre characteristics such as muscle cross-sectional area, perimeter, and fibre type distribution were also unchanged. Variation of muscle CSA was higher when fewer than 150 muscle fibres were quantified.

Muscle growth and development in Atlantic cod larvae (Gadus morhua L.), related to different somatic growth rates

1999 ◽  
Vol 202 (15) ◽  
pp. 2111-2120 ◽  
Author(s):  
T.F. Galloway ◽  
E. Kjorsvik ◽  
H. Kryvi
Keyword(s):  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Muscle Growth ◽  
Somatic Growth ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Cross Sectional ◽  
First Feeding

The present study describes the development of the axial musculature in first-feeding larvae of Atlantic cod (Gadus morhua L.) with different somatic growth rates achieved by using different nutritional conditions. Muscle growth was assessed by determining the number of muscle fibres (hyperplasia) and the growth of existing fibres (hypertrophy). Larvae were fed rotifers containing a high (1. 4; treatment 1) or low (0.2; treatment 2) ratio of docosahexaenoic acid to eicosapentaenoic acid from day 5 after hatching. From day 17, the larvae were fed Artemia nauplii with the same enrichment in both treatments. Treatment 1 gave the highest somatic growth rate and hence the highest dry mass at the end of the experiment, but no difference in larval standard length was found between treatments. In slow-growing larvae, higher priority was thus put into reaching a certain length than into increasing muscle mass. The largest fibres, which were present from hatching, increased in cross-sectional area during larval development, but no differences were found between treatments in the cross-sectional area of individual fibres or the total cross-sectional area of these fibres at the end of the experiment. The first white recruitment fibres were observed at the dorsal and ventral apices of the myotome at approximately the onset of first feeding (larval length 4.5 mm). In larvae 8.5 mm long, the total cross-sectional area of white muscle fibres in the treatment 2 group was 75 % of that in the treatment 1 group. The highest somatic growth rate was associated with an increased contribution of hyperplasia to axial white muscle growth. In the faster-growing larval group, the relative contribution of hyperplasia to the total white muscle cross-sectional area was 50 %, whereas it was 41 % in the slower-growing larval group. The subsequent growth potential may thus be negatively affected by inadequate larval feeding.

The effect of selection for altered body weight on the ultrastructural components of skeletal muscle fibres

1983 ◽  
Vol 36 (2) ◽  
pp. 223-227
Author(s):  
A. C. B. Hooper ◽  
M. P. Hurley
Keyword(s):  
Body Weight ◽  
Biceps Brachii ◽  
Muscle Growth ◽  
Cross Sectional Area ◽  
Muscle Fibres ◽  
Sectional Area ◽  
Weight Changes ◽  
Cross Sectional ◽  
Microscopic Studies ◽  
Selection For

ABSTRACTUltrastructural parameters of muscle growth were measured in lines of mice which had undergone 15 generations of selection for high and low body weight. Previous light microscopic studies of these lines had shown that selection for altered body weight evokes correlated responses in the weight of skeletal muscles as a result of changes in both the number and the longitudinal and transverse dimensions of the fibres.The length of the myosin filaments and of the actin filaments (including the Z disc) did not differ significantly from the controls in the mm. sternomastoideus, biceps brachii and tibialis anterior of mature male mice from the two selection lines. The mean cross-sectional area of the myofibrils of the mm. sternomastoideus and biceps brachii were also unaltered by selection for high and low body weight. Changes in the area of the fibres were brought about by increases and decreases in the number of their constituent myofibrils and corresponding changes in the non-contractile elements.Selection for high and low body weight did not affect the dimensions of the contractile elements of the muscle fibres. The genetically determined alterations in the length and cross-sectional area of the fibres were due to changes in the number of their constituent sarcomeres and myofibrils. These changes are similar to those which occur during growth.

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