Journal articles on the topic 'Muscle'
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1
SHAHIN, KARIMA A., and R. T. BERG. "GROWTH AND DISTRIBUTION OF MUSCLE IN DOUBLE MUSCLED AND NORMAL CATTLE." Canadian Journal of Animal Science 65, no. 2 (June 1, 1985): 307–18. http://dx.doi.org/10.4141/cjas85-037.
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Eighteen Double Muscled (DM), 18 Beef Synthetic (SY) and 18 Hereford (HE) bulls, serially slaughtered from approximately 250 to 800 kg liveweight, were used to determine the influence of maturity type and "double muscling" upon muscle growth patterns and distribution. The left side of each carcass was dissected into major carcass tissues and the weights of individual muscles were obtained and grouped into nine standard anatomical groups. Relative to total side msucle (TSM), breed types tended to have similar growth coefficients for all muscle groups except muscles surrounding the spinal column where HE tended to have a higher growth coefficient than either DM or SY. As TSM increased, the proportion of muscle found in proximal hindlimb, distal hindlimb and distal forelimb decreased (b < 1; P < 0.05), the proportion of muscle in abdominal wall and proximal forelimb remained relatively constant (b = 1; P > 0.05) and the proportion of muscle in thorax to forelimb, neck to forelimb and intrinsic muscles of neck and thorax increased (b > 1; P < 0.05). At the same TSM, compared with the other breed types, DM tended to have more of their muscle in the hip and stifle region but less in the distal parts of both limbs and in neck and thorax. The hyperdevelopment of the large superficial muscles of the proximal part (thigh) and the hypodevelopment of the distal part in the hindlimb give the DM animal the typical 'bottle thigh' appearance. Key words: Bulls (young), muscle growth, muscle distribution, Double Muscled, cattle
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Plenefisch, J. D., X. Zhu, and E. M. Hedgecock. "Fragile skeletal muscle attachments in dystrophic mutants of Caenorhabditis elegans: isolation and characterization of the mua genes." Development 127, no. 6 (March 15, 2000): 1197–207. http://dx.doi.org/10.1242/dev.127.6.1197.
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Over 30 Caenorhabditis elegans mutants were identified with normal muscle differentiation and initial locomotion followed by catastrophic detachment of skeletal muscles from the body wall. Reducing the strength of muscle contraction in these mutants with a myosin gene mutation suppresses muscle detachment. These dystrophic mutants identify a novel class of genes required for growth and maintenance of functional muscle attachments, not exceptional alleles of genes required for muscle differentiation and contractility. Nine new genes, named mua, and two previously published loci, unc-23 and vab-10, cause fragile musscle attachments. The primary sites of muscle detachment, including the plane of tissue separation, are characteristic for each gene. We suggest these genes identify feedback mechanisms whereby local strain regulates the extent of myofibril contraction and the placement of new muscle attachments in functioning muscles. Finally, we draw some comparisons to vertebrate skin fragility diseases and muscular dystrophies.
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Shahin, Karima A., and R. T. Berg. "Growth and distribution of individual muscles in Double Muscled and normal cattle." Journal of Agricultural Science 105, no. 3 (December 1985): 479–90. http://dx.doi.org/10.1017/s0021859600059347.
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SUMMARYEighteen Double Muscled (DM), 18 Beef Synthetic and 18 Hereford bulls, serially slaughtered from approximately 250 to 800 kg live weight, were used to examine the influence of maturity type and Double Muscling on individual muscle growth patterns and distribution.Breed types differed significantly in the relative growth rate of five of the 95 muscles. Individual muscles grew and developed at relatively different rates with muscles associated with locomotion being early developing followed by those associated with structure or posture and finally those which respond to sexual maturation or luxury muscles which were late developing. Individual muscle growth patterns revealed an increasing disto-proximal gradient along the limbs and an increasing caudo-cranial gradient along the whole body. However, within any anatomical region considerable variations with well defined growth gradients were found for individual muscles. In the proximal region of both limbs increasing medio-lateral growth gradients were apparent.At the same total side muscle, breed types differed significantly in adjusted mean weights of 33 of the 95 muscles. When comparison was made at the same total side muscle, DM showed a range of hypertrophy of + 28% to -28% when compared with the more normal breed types.Muscular hypertrophy followed a disto-proximal gradient along the limbs and an inner–outer gradient across the muscle layers with the superficial and bulkiest muscles being the most hypertrophied. At the same total side muscle, DM had heavier expensive or luxury muscles than normal cattle.
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SHAHIN, KARIMA A., R. T. BERG, and M. A. PRICE. "SEX DIFFERENCES IN CARCASS COMPOSITION AND TISSUE DISTRIBUTION IN MATURE DOUBLE MUSCLED CATTLE." Canadian Journal of Animal Science 66, no. 3 (September 1, 1986): 625–36. http://dx.doi.org/10.4141/cjas86-069.
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Nineteen mature Double Muscled (DM) cattle consisting of 11 cows and eight bulls were slaughtered between 470 and 710 kg to determine the influence of sex on carcass composition and muscle, bone and fat in DM cattle. Expressed as a percentage of the total side weight, DM bull carcasses had 15% more muscle and 55% less total fat. When sides were compared DM bulls showed a 17% increase in the muscle:bone ratio compared with DM cows. In bull carcasses, there were shifts in muscle weight distribution towards the forequarter. The ratio of hindquarter muscle:forequarter muscle was greater in cows than in bulls. Expressed as a percentage of the total side muscle, significant differences between sexes were found in 48 of the 95 muscles. The most striking sexual dimorphism was found in the neck region, particularly among the muscles responsible for secondary sexual features and those which act to elevate and extend the head. Sexual dimorphism was less pronounced in the distal parts of the both limbs. The cervical vertebrae and scapula made up a greater proportion of total side bone in DM bulls than in DM cows. There was a consistent but nonsignificant trend for the cows to have more of their bone caudally and less anteriorly compared with the bulls. Key words: Carcass composition, muscle distribution, bone distribution, mature Double Muscled cattle, double muscling
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Nayak, Satheesha B., and Surekha D. Shetty. "Sternocleidohyoid muscle: an unreported variant of cleidohyoid muscle." Surgical and Radiologic Anatomy 43, no. 8 (February 1, 2021): 1327–30. http://dx.doi.org/10.1007/s00276-021-02682-0.
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AbstractSternohyoid, sternothyroid, omohyoid, and thyrohyoid muscles are collectively known as infrahyoid muscles. These muscles frequently show variations in their attachments. Here, an extremely rare variant muscle belonging to this group has been presented. During cadaveric dissection for undergraduate medical students, an additional muscle was found between sternohyoid and superior belly of omohyoid muscles bilaterally in a male cadaver aged approximately 70 years. This muscle took its origin from posterior surface of the manubrium sterni, capsule of the sternoclavicular joint and the posterior surface of the medial part of the clavicle. It was inserted to the hyoid bone between the attachments of sternohyoid and superior belly of omohyoid muscles and was supplied by a branch of ansa cervicalis profunda. There is no report on such a muscle in the literature and it could be named as “sternocleidohyoid muscle”. Knowledge of this muscle could be useful in neck surgeries.
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Sulbarán, Guidenn, Lorenzo Alamo, Antonio Pinto, Gustavo Márquez, Franklin Méndez, Raúl Padrón, and Roger Craig. "An invertebrate smooth muscle with striated muscle myosin filaments." Proceedings of the National Academy of Sciences 112, no. 42 (October 6, 2015): E5660—E5668. http://dx.doi.org/10.1073/pnas.1513439112.
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Muscle tissues are classically divided into two major types, depending on the presence or absence of striations. In striated muscles, the actin filaments are anchored at Z-lines and the myosin and actin filaments are in register, whereas in smooth muscles, the actin filaments are attached to dense bodies and the myosin and actin filaments are out of register. The structure of the filaments in smooth muscles is also different from that in striated muscles. Here we have studied the structure of myosin filaments from the smooth muscles of the human parasite Schistosoma mansoni. We find, surprisingly, that they are indistinguishable from those in an arthropod striated muscle. This structural similarity is supported by sequence comparison between the schistosome myosin II heavy chain and known striated muscle myosins. In contrast, the actin filaments of schistosomes are similar to those of smooth muscles, lacking troponin-dependent regulation. We conclude that schistosome muscles are hybrids, containing striated muscle-like myosin filaments and smooth muscle-like actin filaments in a smooth muscle architecture. This surprising finding has broad significance for understanding how muscles are built and how they evolved, and challenges the paradigm that smooth and striated muscles always have distinctly different components.
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Asp, S., S. Kristiansen, and E. A. Richter. "Eccentric muscle damage transiently decreases rat skeletal muscle GLUT-4 protein." Journal of Applied Physiology 79, no. 4 (October 1, 1995): 1338–45. http://dx.doi.org/10.1152/jappl.1995.79.4.1338.
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The effects of concentric and muscle-damaging eccentric contractions on muscle glucose transporter GLUT-4 content were studied in rat muscles. Rats were anesthetized, the calf muscles on one side were stimulated electrically for concentric or eccentric contractions, and bilateral calf muscles were obtained in the postexercise period. Inflammatory and phagocytic cells accumulated in the eccentric white and red gastrocnemius muscles, whereas there were only discrete changes in the eccentric soleus. Glycogen was depleted to the same extent in the white and red gastrocnemius muscles after both types of stimulation, and it remained decreased > 2 days in eccentric muscles. The total GLUT-4 protein content was decreased in the eccentric white and red gastrocnemius muscles 1 and 2 days after the eccentric stimulation, whereas the maximal activity of glycogen synthase was unaffected at these time points. In conclusion, our one-legged stimulation model caused eccentric muscle damage in the white and red gastrocnemius, whereas only minor damage was observed in the soleus muscle. In damaged muscle, muscle glycogen and GLUT-4 protein content were decreased for > 2 days. These findings may suggest (but do not prove) that decreased muscle GLUT-4 protein is involved in the delayed glycogen resynthesis after eccentric exercise.
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Fernandes, J. J., and H. Keshishian. "Nerve-muscle interactions during flight muscle development in Drosophila." Development 125, no. 9 (May 1, 1998): 1769–79. http://dx.doi.org/10.1242/dev.125.9.1769.
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During Drosophila pupal metamorphosis, the motoneurons and muscles differentiate synchronously, providing an opportunity for extensive intercellular regulation during synapse formation. We examined the existence of such interactions by developmentally delaying or permanently eliminating synaptic partners during the formation of indirect flight muscles. When we experimentally delayed muscle development, we found that although adult-specific primary motoneuron branching still occurred, the higher order (synaptic) branching was suspended until the delayed muscle fibers reached a favourable developmental state. In reciprocal experiments we found that denervation caused a decrease in the myoblast pool. Furthermore, the formation of certain muscle fibers (dorsoventral muscles) was specifically blocked. Exceptions were the adult muscles that use larval muscle fibers as myoblast fusion targets (dorsal longitudinal muscles). However, when these muscles were experimentally compelled to develop without their larval precursors, they showed an absolute dependence on the motoneurons for their formation. These data show that the size of the myoblast pool and early events in fiber formation depend on the presence of the nerve, and that, conversely, peripheral arbor development and synaptogenesis is closely synchronized with the developmental state of the muscle.
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Maas, Huub, Can A. Yucesoy, Guus C. Baan, and Peter A. Huijing. "Implications of Muscle Relative Position as a Co-Determinant of Isometric Muscle Force." Journal of Mechanics in Medicine and Biology 03, no. 02 (June 2003): 145–68. http://dx.doi.org/10.1142/s0219519403000703.
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Force is transmitted from muscle fiber to bone via several pathways: (1) via the tendons (i.e. myotendinous force transmission), (2) via intermuscular connective tissue to adjacent muscles (i.e. intermuscular myofascial force transmission), (3) via structures other than muscles (i.e. extramuscular myofascial force transmission). In vivo, the position of a muscle relative to adjacent muscles changes due to differences in moment arm between synergists as well as due to the fact that some muscles span only one joint and other muscles more than one joint. The position of a muscle relative to non-muscular structures within a compartment is altered with each change of the length of the muscle. The aim of this article is to describe recent experimental results, as well as some new experimental data, that have elucidated the role of muscle relative position on force transmission from muscle. Furthermore, relevant literature is discussed, taking into consideration these new insights of muscle functioning. It is concluded that the position of a muscle relative to surrounding tissues is a major co-determinant of isometric muscle force. For muscles operating within their in vivo context of connective tissue, such position effects should be taken into account.
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Houle-Leroy, Philippe, Helga Guderley, John G. Swallow, and Theodore Garland. "Artificial selection for high activity favors mighty mini-muscles in house mice." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 284, no. 2 (February 1, 2003): R433—R443. http://dx.doi.org/10.1152/ajpregu.00179.2002.
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After 14 generations of selection for voluntary wheel running, mice from the four replicate selected lines ran, on average, twice as many revolutions per day as those from the four unselected control lines. To examine whether the selected lines followed distinct strategies in the correlated responses of the size and metabolic capacities of the hindlimb muscles, we examined mice from selected lines, housed for 8 wk in cages with access to running wheels that were either free to rotate (“wheel access” group) or locked (“sedentary”). Thirteen of twenty individuals in one selected line (line 6) and two of twenty in another (line 3) showed a marked reduction (∼50%) in total hindlimb muscle mass, consistent with the previously described expression of a small-muscle phenotype. Individuals with these “mini-muscles” were not significantly smaller in total body mass compared with line-mates with normal-sized muscles. Access to free wheels did not affect the relative mass of the mini-muscles, but did result in typical mammalian training effects for mitochondrial enzyme activities. Individuals with mini-muscles showed a higher mass-specific muscle aerobic capacity as revealed by the maximal in vitro rates of citrate synthase and cytochrome c oxidase. Moreover, these mice showed the highest activities of hexokinase and carnitine palmitoyl transferase. Females with mini-muscles showed the highest levels of phosphofructokinase, and males with mini-muscles the highest levels of pyruvate dehydrogenase. As shown by total muscle enzyme contents, the increase in mass-specific aerobic capacity almost completely compensated for the reduction caused by the “loss” of muscle mass. Moreover, the mini-muscle mice exhibited the lowest contents of lactate dehydrogenase and glycogen phosphorylase. Interestingly, metabolic capacities of mini-muscled mice resemble those of muscles after endurance training. Overall, our results demonstrate that during selection for voluntary wheel running, distinct adaptive paths that differentially exploit the genetic variation in morphological and physiological traits have been followed.
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Herbert, R. D., B. Bolsterlee, and S. C. Gandevia. "Passive changes in muscle length." Journal of Applied Physiology 126, no. 5 (May 1, 2019): 1445–53. http://dx.doi.org/10.1152/japplphysiol.00673.2018.
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This review, the first in a series of minireviews on the passive mechanical properties of skeletal muscles, seeks to summarize what is known about the muscle deformations that allow relaxed muscles to lengthen and shorten. Most obviously, when a muscle lengthens, muscle fascicles elongate, but this is not the only mechanism by which muscles change their length. In pennate muscles, elongation of muscle fascicles is accompanied by changes in pennation and changes in fascicle curvature, both of which may contribute to changes in muscle length. The contributions of these mechanisms to change in muscle length are usually small under passive conditions. In very pennate muscles with long aponeuroses, fascicle shear could contribute substantially to changes in muscle length. Tendons experience moderate axial strains even under passive loads, and, because tendons are often much longer than muscle fibers, even moderate tendon strains may contribute substantially to changes in muscle length. Data obtained with new imaging techniques suggest that muscle fascicle and aponeurosis strains are highly nonuniform, but this is yet to be confirmed. The development, validation, and interpretation of continuum muscle models informed by rigorous measurements of muscle architecture and material properties should provide further insights into the mechanisms that allow relaxed muscles to lengthen and shorten.
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Shahin, Karima A., and R. T. Berg. "Influence of bone growth on muscle growth and bone-muscle relationships in double-muscled and normal cattle." Animal Science 44, no. 2 (April 1987): 219–25. http://dx.doi.org/10.1017/s0003356100018572.
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ABSTRACTEighteen bulls each of double-muscled (DM), Beef Synthetic (SY) and Hereford (HE) breed types, serially slaughtered from about 250 to 800 kg live weight, were used to examine muscle-bone relationships in double-muscled and normal cattle.Relative to total side bone, DM animals differed significantly from the other breed types in relative growth rate of muscles in all regions which exhibited gross muscular hypertrophy. They showed generalized and regionally differentiated muscular hypertrophy. At equal bone weight in the given anatomical region, DM/HE and DM/SY muscle:bone ratios were respectively: proximal hindlimb 1·35 and 1·24; proximal forelimb 1·25 and 117; back and loin 1·20 and 1·10; and the expensive regions 1·30 and 1·20. In the limbs of DM animals, muscular hypertrophy in the proximal region was associated with bone hypotrophy while minimal muscular hypertrophy in the distal parts was associated with relatively heavier bones. Consequently, increased muscle:bone ratios were most pronounced in the proximal region, which suggests that muscles in these animals had increased in weight without proportionate increase of bones, i.e. muscle and bone growth were to some extent independent. Bone response in the distal limbs may have been influenced by a relative increase in weight support function.
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Mu, Liancai, Stanislaw Sobotka, and Hungxi Su. "Nerve-Muscle-Endplate Band Grafting: A New Technique for Muscle Reinnervation." Operative Neurosurgery 69, suppl_2 (July 25, 2011): ons208—ons224. http://dx.doi.org/10.1227/neu.0b013e31822ed596.
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Abstract BACKGROUND Because currently existing reinnervation methods result in poor functional recovery, there is a great need to develop new treatment strategies. OBJECTIVE To investigate the efficacy of our recently developed nerve-muscle-endplate band grafting (NMEG) technique for muscle reinnervation. METHODS Twenty-five adult rats were used. Sternohyoid (SH) and sternomastoid (SM) muscles served as donor and recipient muscle, respectively. Neural organization of the SH and SM muscles and surgical feasibility of the NMEG technique were determined. An NMEG contained a muscle block, a nerve branch with nerve terminals, and a motor endplate band with numerous neuromuscular junctions. After a 3-month recovery period, the degree of functional recovery was evaluated with a maximal tetanic force measurement. Retrograde horseradish peroxidase tracing was used to track the origin of the motor innervation of the reinnervated muscles. The reinnervated muscles were examined morphohistologically and immunohistochemically to assess the extent of axonal regeneration. RESULTS Nerve supply patterns and locations of the motor endplate bands in the SH and SM muscles were documented. The results demonstrated that the reinnervated SM muscles gained motor control from the SH motoneurons. The NMEG technique yielded extensive axonal regeneration and significant recovery of SM muscle force-generating capacity (67% of control). The mean wet weight of the NMEG-reinnervated muscles (87% of control) was greater than that of the denervated SM muscles (36% of control). CONCLUSION The NMEG technique resulted in successful muscle reinnervation and functional recovery. This technique holds promise in the treatment of muscle paralysis.
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Mersmann, F., S. Bohm, A. Schroll, H. Boeth, G. Duda, and A. Arampatzis. "Muscle shape consistency and muscle volume prediction of thigh muscles." Scandinavian Journal of Medicine & Science in Sports 25, no. 2 (June 27, 2014): e208-e213. http://dx.doi.org/10.1111/sms.12285.
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Gulati, Adarshk. "Pattern of skeletal muscle regeneration after reautotransplantation of regenerated muscle." Development 92, no. 1 (March 1, 1986): 1–10. http://dx.doi.org/10.1242/dev.92.1.1.
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Autotransplantation of rat extensor digitorum longus muscle results in initial myofibre degeneration and subsequent regeneration from precursor myosatellite cells. To determine what effect a reinjury would have on the regenerative response, in the present,study, once transplanted and regenerated muscles were reinjured by reautotransplantion. In rats, four weeks after initial transplantation, when the regeneration was complete, the extensor digitorum longus muscle was transplanted again and the pattern of regeneration in reautotransplanted and once auto transplanted muscles was compared. Muscles were analysed 2, 4, 7, 14 and 30 days after autotransplantation and reautotransplantation. Both autotransplanted and reautotransplanted muscles underwent degeneration and regeneration; however, the pattern of regeneration in these two transplants was quite different. In autotransplants, a thin myogenic zone, marked by activated myoblasts, was first seen at 4 days. By 7 days the width of myogenic zone increased but still many degenerating myofibres were present in the central region of the muscle. By 14 days the muscle was filled with regenerated myotubes and myofibres. The reautotransplanted muscles underwent similar regenerative events; however, the rate of regeneration was considerably faster. The myogenic zone was apparent as early as 2 days and was much larger at 4 days, and by 7 days the entire muscle was filled with regenerated myotubes and myofibres which matured at later time intervals. Furthermore, the decrease in muscle weight in reautotransplanted muscles was not as much as that seen after autotransplantation. These findings reveal that not only is skeletal muscle capable of regeneration after a second injury, but the rate of this regeneration is much faster. This increased rate and recovery may be due to a conditioning effect of the first injury.
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Hansen, J., G. D. Thomas, T. N. Jacobsen, and R. G. Victor. "Muscle metaboreflex triggers parallel sympathetic activation in exercising and resting human skeletal muscle." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 6 (June 1, 1994): H2508—H2514. http://dx.doi.org/10.1152/ajpheart.1994.266.6.h2508.
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Activation of a metabolically generated reflex in exercising skeletal muscle (muscle metaboreflex) in humans is known to trigger increases in sympathetic nerve activity (SNA) to resting skeletal muscles. In seven healthy human subjects, to determine whether this reflex mechanism also increases SNA to the exercising muscles, we recorded muscle SNA with microelectrodes in the right peroneal nerve and in fascicles of the left peroneal nerve selectively innervating the exercising muscles of the left foot. Subjects performed static toe extension at 20% maximal voluntary contraction alone or in combination with foot ischemia. Only static toe extension at 20% MVC during ischemia activated the muscle metaboreflex. This paradigm caused increases in SNA to exercising muscle that paralleled those to the resting muscles: during the first minute of exercise SNA was unchanged, but during the second minute SNA increased from 29 +/- 2 to 38 +/- 2 bursts/min (P < 0.05) to the exercising muscles and from 30 +/- 3 to 40 +/- 2 bursts/min (P < 0.05) to the resting muscles. These bilateral increases in SNA were maintained when metaboreflex activation was sustained by postexercise foot ischemia. In conclusion, these data provide neurophysiological evidence that the muscle metaboreflex evokes parallel sympathetic activation in exercising and resting human skeletal muscle.
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Schneider, Achim G., Karim R. Sultan, and Dirk Pette. "Muscle LIM protein: expressed in slow muscle and induced in fast muscle by enhanced contractile activity." American Journal of Physiology-Cell Physiology 276, no. 4 (April 1, 1999): C900—C906. http://dx.doi.org/10.1152/ajpcell.1999.276.4.c900.
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To identify early changes in gene expression during the fast-to-slow transition induced by chronic low-frequency stimulation, total RNA was extracted from 12-h-stimulated tibialis anterior (TA) muscles of rats and amplified by differential display RT-PCR. Among the signals of differentially expressed mRNAs, a cDNA ∼300 bp in length, which was almost undetectable in control TA muscles but prominent in stimulated TA and normal soleus muscles, was identified. This cDNA was cloned and identified as corresponding to the mRNA of the muscle LIM protein (MLP). Its differential expression in control, stimulated TA, and soleus muscles was verified by Northern blotting. Antibodies against MLP were used to identify by immunoblot analysis a protein of 22 kDa, the predicted molecular mass of MLP. Immunohistochemistry revealed strong reactivity for MLP in all fibers of normal soleus muscle and faint staining of some type IIA and type I fibers in control TA muscle. These fibers increased in number and staining intensity in 4-day-stimulated TA muscle. MLP thus seems to play an essential role during the rearrangement of cytoskeletal and/or myofibrillar structures in transforming adult muscle fibers.
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Turinsky, J., and C. L. Long. "Free amino acids in muscle: effect of muscle fiber population and denervation." American Journal of Physiology-Endocrinology and Metabolism 258, no. 3 (March 1, 1990): E485—E491. http://dx.doi.org/10.1152/ajpendo.1990.258.3.e485.
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One hindlimb of each rat was denervated by sectioning the sciatic nerve. Three days later, soleus, plantaris, and gastrocnemius muscles of the sham hindlimb and the contralateral denervated hindlimb were excised and analyzed for intracellular concentrations of 23 free amino acids and the dipeptides carnosine and anserine. Compared with the sham soleus (slow-twitch) muscle, the sham plantaris and gastrocnemius (fast-twitch) muscles showed 57-81% lower concentrations of histidine, glutamine, glutamate, aspartate, and serine and also 32-78% lower levels of taurine, citrulline, phosphoserine, and ornithine. On the other hand the fast-twitch muscles exhibited 31% higher concentrations of free glycine and alanine and 113-127% higher levels of carnosine and anserine than the soleus muscle. The denervation caused greater changes in soleus muscle than in the other two muscles. The denervation-induced changes in soleus muscle included 38-87% increases in concentrations of free valine, leucine, isoleucine, and glutamate associated with 21-56% decreases in the levels of glutamine, glycine, aspartate, serine, alanine, and citrulline. It is concluded that both muscle fiber population and muscle denervation have an independent effect on the intracellular concentrations of free amino acids in muscles.
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KERA, Takeshi. "Respiratory Muscles and Muscle Strengthening." Rigakuryoho Kagaku 18, no. 1 (2003): 1–6. http://dx.doi.org/10.1589/rika.18.1.
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Bezakova, Gabriela, and Terje Lømo. "Muscle Activity and Muscle Agrin Regulate the Organization of Cytoskeletal Proteins and Attached Acetylcholine Receptor (Achr) Aggregates in Skeletal Muscle Fibers." Journal of Cell Biology 153, no. 7 (June 25, 2001): 1453–64. http://dx.doi.org/10.1083/jcb.153.7.1453.
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In innervated skeletal muscle fibers, dystrophin and β-dystroglycan form rib-like structures (costameres) that appear as predominantly transverse stripes over Z and M lines. Here, we show that the orientation of these stripes becomes longitudinal in denervated muscles and transverse again in denervated electrically stimulated muscles. Skeletal muscle fibers express nonneural (muscle) agrin whose function is not well understood. In this work, a single application of ≥10 nM purified recombinant muscle agrin into denervated muscles preserved the transverse orientation of costameric proteins that is typical for innervated muscles, as did a single application of ≥1 μM neural agrin. At lower concentration, neural agrin induced acetylcholine receptor aggregates, which colocalized with longitudinally oriented β-dystroglycan, dystrophin, utrophin, syntrophin, rapsyn, and β2-laminin in denervated unstimulated fibers and with the same but transversely oriented proteins in innervated or denervated stimulated fibers. The results indicate that costameres are plastic structures whose organization depends on electrical muscle activity and/or muscle agrin.
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Kernell, Daniel. "Muscle Regionalization." Canadian Journal of Applied Physiology 23, no. 1 (February 1, 1998): 1–22. http://dx.doi.org/10.1139/h98-001.
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In this review, the term muscle fibre regionalization signifies the presence of regional intramuscular differences in fibre type composition. As is well known, highly regionalized muscles commonly have greater concentrations of slow fibres deep than superficially. However, the degree of regionalization varies markedly between muscles and is not confined to deep vs. superficial locations. Fibres of the same myosin type may show regionalized differences in their metabolic enzyme activity, even within single motor units (Larsson, 1992). Regionalization of fibre type composition occurs also within single neuromuscular partitions. The intraspinal position of motoneurones is often coarsely related to the intramuscular sites of their muscle units. Muscles with a marked fibre type regionalization tend to show a corresponding regionalization of activity; in several muscles, however, the activity regionalization may vary depending on the motor task. During early development, fibre type regionalization emerges even under aneural conditions. The mechanisms are still unknown; relevant aspects of early development are briefly reviewed. Key words: skeletal muscle, fiber type, topography, activity, development
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Sandage, Mary J., and Audrey G. Smith. "Muscle Bioenergetic Considerations for Intrinsic Laryngeal Skeletal Muscle Physiology." Journal of Speech, Language, and Hearing Research 60, no. 5 (May 24, 2017): 1254–63. http://dx.doi.org/10.1044/2016_jslhr-s-16-0192.
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PurposeIntrinsic laryngeal skeletal muscle bioenergetics, the means by which muscles produce fuel for muscle metabolism, is an understudied aspect of laryngeal physiology with direct implications for voice habilitation and rehabilitation. The purpose of this review is to describe bioenergetic pathways identified in limb skeletal muscle and introduce bioenergetic physiology as a necessary parameter for theoretical models of laryngeal skeletal muscle function.MethodA comprehensive review of the human intrinsic laryngeal skeletal muscle physiology literature was conducted. Findings regarding intrinsic laryngeal muscle fiber complement and muscle metabolism in human models are summarized and exercise physiology methodology is applied to identify probable bioenergetic pathways used for voice function.ResultsIntrinsic laryngeal skeletal muscle fibers described in human models support the fast, high-intensity physiological requirements of these muscles for biological functions of airway protection. Inclusion of muscle bioenergetic constructs in theoretical modeling of voice training, detraining, fatigue, and voice loading have been limited.ConclusionsMuscle bioenergetics, a key component for muscle training, detraining, and fatigue models in exercise science, is a little-considered aspect of intrinsic laryngeal skeletal muscle physiology. Partnered with knowledge of occupation-specific voice requirements, application of bioenergetics may inform novel considerations for voice habilitation and rehabilitation.
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Arregui, Marina, Emily M. Singleton, Pedro Saavedra, D. Ann Pabst, Michael J. Moore, Eva Sierra, Miguel A. Rivero, et al. "Myoglobin Concentration and Oxygen Stores in Different Functional Muscle Groups from Three Small Cetacean Species." Animals 11, no. 2 (February 9, 2021): 451. http://dx.doi.org/10.3390/ani11020451.
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Compared with terrestrial mammals, marine mammals possess increased muscle myoglobin concentrations (Mb concentration, g Mb · 100g−1 muscle), enhancing their onboard oxygen (O2) stores and their aerobic dive limit. Although myoglobin is not homogeneously distributed, cetacean muscle O2 stores have been often determined by measuring Mb concentration from a single muscle sample (longissimus dorsi) and multiplying that value by the animal’s locomotor muscle or total muscle mass. This study serves to determine the accuracy of previous cetacean muscle O2 stores calculations. For that, body muscles from three delphinid species: Delphinus delphis, Stenella coeruleoalba, and Stenella frontalis, were dissected and weighed. Mb concentration was calculated from six muscles/muscle groups (epaxial, hypaxial and rectus abdominis; mastohumeralis; sternohyoideus; and dorsal scalenus), each representative of different functional groups (locomotion powering swimming, pectoral fin movement, feeding and respiration, respectively). Results demonstrated that the Mb concentration was heterogeneously distributed, being significantly higher in locomotor muscles. Locomotor muscles were the major contributors to total muscle O2 stores (mean 92.8%) due to their high Mb concentration and large muscle masses. Compared to this method, previous studies assuming homogenous Mb concentration distribution likely underestimated total muscle O2 stores by 10% when only considering locomotor muscles and overestimated them by 13% when total muscle mass was considered.
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Dahlqvist, Julia R., Sofie T. Oestergaard, Nanna S. Poulsen, Carsten Thomsen, and John Vissing. "Refining the spinobulbar muscular atrophy phenotype by quantitative MRI and clinical assessments." Neurology 92, no. 6 (January 4, 2019): e548-e559. http://dx.doi.org/10.1212/wnl.0000000000006887.
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ObjectiveTo investigate the phenotypic features, with emphasis on muscle, in 40 patients with spinobulbar muscular atrophy (SBMA) using quantitative MRI, stationary dynamometry, questionnaires, and functional tests.MethodsPatients with genetically confirmed SBMA were included. MRI was used to describe muscle involvement and quantify muscle fat fractions of arm, back, and leg muscles. Muscle strength was assessed with a stationary dynamometer. All patients were evaluated with the SBMA functional rating scale and the 6-minute walk test among others. MRI and muscle strength results were compared with healthy controls.ResultsForty patients with SBMA were included. The muscle fat content was significantly higher in patients with SBMA than in controls: paraspinal fat fraction was 45% vs 33% in controls, thigh fat fraction 36% vs 14%, calf fat fraction 37% vs 15%, upper arm fat fraction 20% vs 8%, and forearm fat fraction was 20% vs 9%. Muscle strength in patients was reduced to approximately half of that in controls in all muscles. Muscle fat content correlated with muscle strength, SBMA functional rating scale score, and 6-minute walk test distance.ConclusionsOur results show that there is a diffuse muscle involvement pattern in SBMA. Leg muscles are more vulnerable than arm muscles, especially the posterior flexor muscles. The muscle fat content correlates with muscle function and disease severity.
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Mitchell, Patrick O., and Grace K. Pavlath. "Skeletal muscle atrophy leads to loss and dysfunction of muscle precursor cells." American Journal of Physiology-Cell Physiology 287, no. 6 (December 2004): C1753—C1762. http://dx.doi.org/10.1152/ajpcell.00292.2004.
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Atrophy of skeletal muscle leads to decreases in myofiber size and nuclear number; however, the effects of atrophic conditions on muscle precursor cells (MPC) are largely unknown. MPC lie outside myofibers and represent the main source of additional myonuclei necessary for muscle growth and repair. In the present study, we examined the properties of MPC after hindlimb suspension (HS)-induced atrophy and subsequent recovery of the mouse hindlimb muscles. We demonstrated that the number of MPC in atrophied muscles was decreased. RT-PCR analysis of cells isolated from atrophied muscles indicated that several mRNA characteristic of the myogenic program in MPC were absent. Cells isolated from atrophied muscles failed to properly proliferate and undergo differentiation into multinucleated myotubes. Thus atrophy led to a decrease in MPC and caused dysfunction in those MPC that remained. Upon regrowth of the atrophied muscles, these deleterious effects were reversed. Our data suggest that preventing loss or dysfunction of MPC may be a new pharmacological target during muscle atrophy.
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Maciejewska-Skrendo, Agnieszka, Katarzyna Leźnicka, Agata Leońska-Duniec, Michal Wilk, Aleksandra Filip, Paweł Cięszczyk, and Marek Sawczuk. "Genetics of Muscle Stiffness, Muscle Elasticity and Explosive Strength." Journal of Human Kinetics 74, no. 1 (August 31, 2020): 143–59. http://dx.doi.org/10.2478/hukin-2020-0027.
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Abstract Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes’ performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.
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Laughlin, M. H., R. E. Klabunde, M. D. Delp, and R. B. Armstrong. "Effects of dipyridamole on muscle blood flow in exercising miniature swine." American Journal of Physiology-Heart and Circulatory Physiology 257, no. 5 (November 1, 1989): H1507—H1515. http://dx.doi.org/10.1152/ajpheart.1989.257.5.h1507.
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The purpose of this study was to determine whether a vasodilator reserve exists in respiratory muscles and forelimb skeletal muscles in miniature swine during treadmill exercise. Blood flow (BF) was measured with radiolabeled microspheres during preexercise and before and after dipyridamole (DYP; 1 mg/kg iv) at 2 min of treadmill exercise at 11.2 (70% Vo2 max) and 17.6 km/h (Vo2 max). Muscle BFs were increased during exercise, and the relationship between exercise intensity and BF varied among the muscles. The high-oxidative extensor muscles and the flexor muscles attained peak BFs at 11.2 km/h, whereas the more superficial, lower oxidative extensor muscles showed increases in BF up to maximal exercise. During running at 11.2 km/h, DYP produced increases in BF only in cardiac muscle, respiratory muscle and the medial head of the triceps muscle (MHT), which is composed of 91% slow-twitch oxidative (SO) fibers. During maximal exercise (17.6 km/h), DYP produced a 31-mmHg decrease in mean arterial pressure (MAP) and increases in vascular conductance in all muscles studied. BF was only increased in MHT and cardiac muscle. We conclude that vasodilator reserve remains in skeletal muscle and respiratory muscle even during maximal exercise in swine. If it is assumed that DYP-induced vasodilation in a muscle sample is indicative of adenosine production, these results suggest that SO skeletal muscle (MHT) and respiratory muscle are similar to cardiac muscle in that they produce adenosine even when adequately perfused. Furthermore, during maximal exercise, all skeletal muscle appears to produce adenosine, suggesting that muscle BF is restricted under these conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Vagin, Malysheva, and Samofalova. "FEATURES OF THE DISTRIBUTION OF TRICHINELLA LARVAE IN THE MUSCLES OF SPONTANEOUSLY INFECTED RED FOXES (VULPES VULPES)." THEORY AND PRACTICE OF PARASITIC DISEASE CONTROL, no. 23 (April 18, 2022): 107–11. http://dx.doi.org/10.31016/978-5-6046256-9-9.2022.23.107-111.
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The issues related to the distribution of trichinella larvae in various groups of skeletal muscles of animals are quite relevant, as they are of great importance for the diagnosis of trichinosis. There is a lot of contradictory information in scientific papers about the distribution of trichinella larvae in the muscles of spontaneously infected predatory mammals. The purpose of our research was to study the distribution of trichinella larvae in various skeletal muscle groups in spontaneously infected red foxes (Vulpes vulpes). Detection of trichinella larvae was carried out by compressor trichinelloscopy and by the method of digesting muscle tissue in artificial gastric juice. Capsule-forming trichinella (Trichinella spp.) were found in animal muscles. The most intensively affected were the large masticatory muscle (68.1±30.7 larvae in 1 g of muscle tissue), diaphragm (65.3±25.6), intercostal muscles (63.7±23.1) and tongue root muscles (58.9±25.2). A lower intensity of invasion was noted in the splenius (36.6±14.4). In the triceps muscle of the shoulder (2.1±2.2) and the calf muscle (2.9±2.5), a very low intensity of invasion was recorded. Trichinella larvae were not found in the latissimus dorsi muscle, trapezius muscle, biceps femoris muscle, superficial gluteus muscle and middle gluteal muscle. Thus, in the spontaneously infected red foxes studied by us, the highest invasion intensity was noted in the muscles of the trunk and head.
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Suriyut, Janyaruk, Satoru Muro, Phichaya Baramee, Masayo Harada, and Keiichi Akita. "Various significant connections of the male pelvic floor muscles with special reference to the anal and urethral sphincter muscles." Anatomical Science International 95, no. 3 (December 23, 2019): 305–12. http://dx.doi.org/10.1007/s12565-019-00521-2.
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AbstractThe male pelvic floor is a complex structure formed by several muscles. The levator ani muscle and the perineal muscles are important components of the pelvic floor. The perineal muscles comprise the external anal sphincter, bulbospongiosus, superficial transverse perineal muscles, and ischiocavernosus. Although the connections of the muscles of the pelvic floor have been reported recently, the anatomical details of each muscle remain unclear. In this study, we examined the male pelvic floor to clarify the connection between the muscles related to function. Fifteen male pelvises were used for microscopic dissection, and three male pelvises were used for histological examination. On the lateral aspect, the perineal muscles were connected to each other. Bundles of the levator ani muscle extended to connect to the perineal muscles. In addition, the extended muscle bundle from the levator ani muscle and the perineal muscles surround the external urethral sphincter. On the medial aspect, the levator ani muscle and the external anal sphincter form the anterior and posterior muscular slings of the anal canal. The connection between the perineal muscles and levator ani muscle indicates a possible close relationship between the functions of the urethra and anus.
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Brookham, Rebecca L., Linda McLean, and Clark R. Dickerson. "Construct Validity of Muscle Force Tests of the Rotator Cuff Muscles: An Electromyographic Investigation." Physical Therapy 90, no. 4 (April 1, 2010): 572–80. http://dx.doi.org/10.2522/ptj.20090024.
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Background Manual muscle tests (MMTs) are used in clinical settings to evaluate the function and strength (force-generating capacity) of a specific muscle in a position at which the muscle is believed to be most isolated from other synergists and antagonists. Despite frequent use of MMTs, few electromyographic evaluations exist to confirm the ability of MMTs to isolate rotator cuff muscles. Objective This study examined rotator cuff isolation during 29 shoulder muscle force tests (9 clinical and 20 generic tests). Design An experimental design was used in this study. Participants and Measurements Electromyographic data were recorded from 4 rotator cuff muscles and 10 additional shoulder muscles of 12 male participants. Maximal isolation ratios (mean specific rotator cuff muscle activation to mean activation of the other 13 recorded muscles) defined which of these tests most isolated the rotator cuff muscles. Results Three rotator cuff muscles were maximally isolated (obtained highest isolation ratios) within their respective clinical test groups (lateral rotator test group for the infraspinatus and teres minor muscles and abduction test group for the supraspinatus muscle). The subscapularis muscle was maximally isolated equally as effectively within the generic ulnar force and clinical medial rotation groups. Similarly, the supraspinatus and teres minor muscles were isolated equally as effectively in some generic test groups as they were in their respective clinical test groups. Limitations Postural artifact in the wire electrodes caused exclusion of some channels from calculations. The grouping of muscle force tests based on test criteria (clinical or generic tests and muscle action) may have influenced which groups most isolated the muscle of interest. Conclusions The results confirmed the appropriateness of 9 commonly used clinical tests for isolating rotator cuff muscles, but suggested that several other muscle force tests were equally appropriate for isolating these muscles.
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Bonen, A., M. G. Clark, and E. J. Henriksen. "Experimental approaches in muscle metabolism: hindlimb perfusion and isolated muscle incubations." American Journal of Physiology-Endocrinology and Metabolism 266, no. 1 (January 1, 1994): E1—E16. http://dx.doi.org/10.1152/ajpendo.1994.266.1.e1.
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The perfusion of rat hindlimb muscles and the isolated in vitro muscle preparation are usually the preferred methods for investigating muscle metabolism. In light of recent concerns about the incubated muscle preparation, we have examined the problems, the advantages, and the viability of these two experimental techniques, with focus on glucose metabolism. A major advantage of the hindlimb perfusion system is that it maintains its metabolic viability very well, and perfusions in resting muscles can be achieved successfully with cell-free media. However, variations in the perfused rat hindlimb procedures result in considerable differences in perfusate flow among muscles, making quantitative comparisons among perfusion procedures difficult. Metabolic viability has been identified as a problem in some isolated in vitro muscle preparations. We have provided criteria to avoid muscle hypoxia. Minimum levels of insulin seem to be a key requirement to maintaining the muscle's viability, and essential amino acids are required to retard an increase in the basal rate of glucose and amino acid uptake. Under such conditions metabolic viability can be maintained during prolonged incubations (9-30 h). Both the isolated in vitro muscle preparation and the hindlimb perfusion preparation are viable models for the study of muscle metabolism.
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Saga, Norihiko, Kunio Shimada, Douhaku Inamori, Naoki Saito, Toshiyuki Satoh, and Jun-ya Nagase. "Smart Pneumatic Artificial Muscle Using a Bend Sensor like a Human Muscle with a Muscle Spindle." Sensors 22, no. 22 (November 19, 2022): 8975. http://dx.doi.org/10.3390/s22228975.
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Shortage of labor and increased work of young people are causing problems in terms of care and welfare of a growing proportion of elderly people. This is a looming social problem because people of advanced ages are increasing. Necessary in the fields of care and welfare, pneumatic artificial muscles in actuators of robots are being examined. Pneumatic artificial muscles have a high output per unit of weight, and they are soft, similarly to human muscles. However, in previous research of robots using pneumatic artificial muscles, rigid sensors were often installed at joints and other locations due to the robots’ structures. Therefore, we developed a smart actuator that integrates a bending sensor that functions as a human muscle spindle; it can be externally attached to the pneumatic artificial muscle. This paper reports a smart artificial muscle actuator that can sense contraction, which can be applied to developed self-monitoring and robot posture control.
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Amtiran, Chandraone P. Kefi, Filphin A. Amalo, Inggrid T. Maha, and Heny Nitbani. "Muscle Micromorphology and Histomorphometry of Sumba Ongole Cattle (Bos indicus)." JURNAL ILMIAH PETERNAKAN TERPADU 9, no. 3 (December 18, 2021): 265. http://dx.doi.org/10.23960/jipt.v9i3.p265-278.
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This study aims to knowing the micromorphology and histomorphometry of the sumba ongole cattle muscles. The sample used was 6 muscle samples consisted of the longissimus dorsi and bicep femoris muscles taken from three sumba ongole cattle slaughtered at the West Sumba slaughterhouse. Muscle tissue was fixed using 10% formalin and made histological preparations and hematoxylin-eosin (HE) staining. Histological preparations were observed using a light microscope with objective magnifications of 4, 10, 40, and 100 times. The results showed that the muscle micromorphology in the transverse section consisted of many fascicles formed by muscle fibers with cell nuclei at the edges, connective tissue, and intramuscular fat. Muscles in longitudinal sections are formed by muscle fibers with light dark stripes and connective tissue. The muscle fibers diameter, fascicle diameter and thickness of the connective tissue in the bicep femoris muscle is higher than the longissimus dorsi muscle. In contrast, the number of muscle fibers per fascicle is higher in the longissimus dorsi muscle. Muscle histomorphometry are strongly influenced by anatomical location and function of the muscles, as well as the presence of intramuscular fat.
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Taylor, J. A., and S. C. Kandarian. "Advantage of normalizing force production to myofibrillar protein in skeletal muscle cross-sectional area." Journal of Applied Physiology 76, no. 2 (February 1, 1994): 974–78. http://dx.doi.org/10.1152/jappl.1994.76.2.974.
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When maximum isometric force (Po) is normalized to muscle cross-sectional area (CSA), intrinsic differences in force production among muscles may be masked by alterations in myofibrillar protein concentration or extracellular space. We tested the hypothesis that there is a greater deficit in Po when normalized to the average whole muscle CSA than when normalized to the myofibrillar protein CSA under conditions known to alter the concentration of myofibrils or connective tissue protein or interstitial fluid volume. Rats underwent either hindlimb unweighting (HU) to induce atrophy in the soleus muscle, sciatic nerve denervation to induce atrophy in the soleus and extensor digitorum longus (EDL) muscles, or ablation of gastrocnemius and plantaris muscles to induce hypertrophy in the soleus muscle. Po of the soleus muscle normalized to the muscle CSA (specific Po) was 58, 25, and 72% of control muscles with HU, denervation, and hypertrophy, respectively, whereas denervated EDL muscle specific Po was 60% of control muscles (P < 0.05). Soleus muscle Po normalized to the myofibrillar CSA was 80, 53, and 75% of control muscles with HU, denervation, and hypertrophy, respectively, whereas the denervated EDL muscle value was 82% of control muscles (P < 0.05). Both approaches to normalizing Po show force deficits, but normalization to the average myofibrillar protein in the muscle cross section gives values substantially closer to control values for HU and denervated muscles only. Data support the hypothesis because myofibrillar protein concentration is decreased in HU and denervation and interstitial space is increased in HU but neither parameter is altered with hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)
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Roh, Jinsook, Randall F. Beer, Andrew Lai, Monica Rho, Kristopher R. Karvelas, Antoun M. Nader, Mark C. Kendall, and William Z. Rymer. "The Effects of Selective Muscle Weakness on Muscle Coordination in the Human Arm." Applied Bionics and Biomechanics 2018 (September 19, 2018): 1–16. http://dx.doi.org/10.1155/2018/5637568.
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Despite the fundamental importance of muscle coordination in daily life, it is currently unclear how muscle coordination adapts when the musculoskeletal system is perturbed. In this study, we quantified the impact of selective muscle weakness on several metrics of muscle coordination. Seven healthy subjects performed 2D and 3D isometric force target matches, while electromyographic (EMG) signals were recorded from 13 elbow and shoulder muscles. Subsequently, muscle weakness was induced by a motor point block of brachialis muscle. Postblock subjects repeated the force generation tasks. We quantified muscle coordination pre- and postblock using three metrics: tuning curve preferred direction, tuning curve area, and motor modules analysis via nonnegative matrix factorization. For most muscles, the tuning direction for the 2D protocol was not substantially altered postblock, while tuning areas changed more drastically. Typically, five motor modules were identified from the 3D task, and four motor modules were identified in the 2D task; this result held across both pre- and postblock conditions. The composition of one or two motor modules, ones that involved mainly the activation of shoulder muscles, was altered postblock. Our results demonstrate that selective muscle weakness can induce nonintuitive alternations in muscle coordination in the mechanically redundant human arm.
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Butler-Hogg, B. W., and O. P. Whelehan. "Muscle growth and distribution of muscle weight in Clun and Southdown sheep." Animal Science 44, no. 1 (February 1987): 133–42. http://dx.doi.org/10.1017/s0003356100028142.
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ABSTRACTA total of 56 sheep, 28 Clun and 28 Southdown were slaughtered, five of each breed, at birth, 50, 100, 150 and 200 days and three of each breed at 415 days of age. The left half of each carcass was separated anatomically into individual muscles, bones and fat depots. For the purposes of analysis, individual muscles were assigned to one of eight muscle groups, depending upon their anatomical location.The relative growth of some individual muscles was found to change over this age range, as indicated by a significant squared term in the quadratic allometric equation: this was true for proportionately 0·33 of the muscles in Clun and for proportionately 0·44 of those in Southdown, accounting for proportionately 0·33 and 0·47 of total muscle weight in Clun and Southdown respectively.Principal components analysis (PCA) was used to derive the multivariate analogue of the quadratic part of quadratic allometry: the sign of the loading on the second principal component had the same sign as the change observed in bq, the quadratic relative growth coefficient. Thus, PCA offers the potential to identify simultaneously, and independently of shape or conformation, all those muscles whose relative growth coefficients change over the period examined. It could be applied successfully to breed comparisons of conformation.The cumulative effects of changing relative growth rates of muscles were small. Muscle weight distribution appears to be almost fixed within the first few weeks after birth. Despite their differences in conformation and mature size, Clun and Southdown lambs had similar distributions of muscle weight at the same age; the high valued muscles constituted 513·8 g/kg total muscle in Clun and 514·7 g/kg total muscle in Southdown lambs at 200 days of age.
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Arnold, Edith M., and Scott L. Delp. "Fibre operating lengths of human lower limb muscles during walking." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1570 (May 27, 2011): 1530–39. http://dx.doi.org/10.1098/rstb.2010.0345.
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Muscles actuate movement by generating forces. The forces generated by muscles are highly dependent on their fibre lengths, yet it is difficult to measure the lengths over which muscle fibres operate during movement. We combined experimental measurements of joint angles and muscle activation patterns during walking with a musculoskeletal model that captures the relationships between muscle fibre lengths, joint angles and muscle activations for muscles of the lower limb. We used this musculoskeletal model to produce a simulation of muscle–tendon dynamics during walking and calculated fibre operating lengths (i.e. the length of muscle fibres relative to their optimal fibre length) for 17 lower limb muscles. Our results indicate that when musculotendon compliance is low, the muscle fibre operating length is determined predominantly by the joint angles and muscle moment arms. If musculotendon compliance is high, muscle fibre operating length is more dependent on activation level and force–length–velocity effects. We found that muscles operate on multiple limbs of the force–length curve (i.e. ascending, plateau and descending limbs) during the gait cycle, but are active within a smaller portion of their total operating range.
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Josephson, R. K., J. G. Malamud, and D. R. Stokes. "Asynchronous muscle: a primer." Journal of Experimental Biology 203, no. 18 (September 15, 2000): 2713–22. http://dx.doi.org/10.1242/jeb.203.18.2713.
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The asynchronous muscles of insects are characterized by asynchrony between muscle electrical and mechanical activity, a fibrillar organization with poorly developed sarcoplasmic reticulum, a slow time course of isometric contraction, low isometric force, high passive stiffness and delayed stretch activation and shortening deactivation. These properties are illustrated by comparing an asynchronous muscle, the basalar flight muscle of the beetle Cotinus mutabilis, with synchronous wing muscles from the locust, Schistocerca americana. Because of delayed stretch activation and shortening deactivation, a tetanically stimulated beetle muscle can do work when subjected to repetitive lengthening and shortening. The synchronous locust muscle, subjected to similar stimulation and length change, absorbs rather than produces work.
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Lieber, R. L., and J. Friden. "Muscle damage is not a function of muscle force but active muscle strain." Journal of Applied Physiology 74, no. 2 (February 1, 1993): 520–26. http://dx.doi.org/10.1152/jappl.1993.74.2.520.
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Contractile properties of rabbit tibialis anterior muscles were measured after eccentric contraction to investigate the mechanism of muscle injury. In the first experiment, two groups of muscles were strained 25% of the muscle fiber length at identical rates. However, because the timing of the imposed length change relative to muscle activation was different, the groups experienced dramatically different muscle forces. Because muscle maximum tetanic tension and other contractile parameters measured after 30 min of cyclic activity with either strain timing pattern were identical (P > 0.4), we concluded that muscle damage was equivalent despite very different imposed forces. This result was supported by a second experiment in which the same protocol was performed at one-half the strain (12.5% muscle fiber length). Again, there was no difference in maximum tetanic tension after cyclic 12.5% strain with either strain timing. Data from both experiments were analyzed by two-way analysis of variance, which revealed a highly significant effect of strain magnitude (P < 0.001) but no significant effect of stretch timing (P > 0.7). We interpret these data to signify that it is not high force per se that causes muscle damage after eccentric contraction but the magnitude of the active strain (i.e., strain during active lengthening). This conclusion was supported by morphometric analysis showing equivalent area fractions of damaged muscle fibers that were observed throughout the muscle cross section. The active strain hypothesis is described in terms of the interaction between the myofibrillar cytoskeleton, the sarcomere, and the sarcolemma.
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Xiao, Ming, and Jill Higginson. "Sensitivity of Estimated Muscle Force in Forward Simulation of Normal Walking." Journal of Applied Biomechanics 26, no. 2 (May 2010): 142–49. http://dx.doi.org/10.1123/jab.26.2.142.
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Generic muscle parameters are often used in muscle-driven simulations of human movement to estimate individual muscle forces and function. The results may not be valid since muscle properties vary from subject to subject. This study investigated the effect of using generic muscle parameters in a muscle-driven forward simulation on muscle force estimation. We generated a normal walking simulation in OpenSim and examined the sensitivity of individual muscle forces to perturbations in muscle parameters, including the number of muscles, maximum isometric force, optimal fiber length, and tendon slack length. We found that when changing the number of muscles included in the model, only magnitude of the estimated muscle forces was affected. Our results also suggest it is especially important to use accurate values of tendon slack length and optimal fiber length for ankle plantar flexors and knee extensors. Changes in force production by one muscle were typically compensated for by changes in force production by muscles in the same functional muscle group, or the antagonistic muscle group. Conclusions regarding muscle function based on simulations with generic musculoskeletal parameters should be interpreted with caution.
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Ahn, A. N., and R. J. Full. "A motor and a brake: two leg extensor muscles acting at the same joint manage energy differently in a running insect." Journal of Experimental Biology 205, no. 3 (February 1, 2002): 379–89. http://dx.doi.org/10.1242/jeb.205.3.379.
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SUMMARYThe individual muscles of a multiple muscle group at a given joint are often assumed to function synergistically to share the load during locomotion. We examined two leg extensors of a running cockroach to test the hypothesis that leg muscles within an anatomical muscle group necessarily manage (i.e. produce, store, transmit or absorb) energy similarly during running. Using electromyographic and video motion-analysis techniques, we determined that muscles 177c and 179 are both active during the first half of the stance period during muscle shortening. Using the in vivo strain and stimulation patterns determined during running, we measured muscle power output. Although both muscles were stimulated during the first half of shortening, muscle 177c generated mechanical energy (28 W kg–1) like a motor, while muscle 179 absorbed energy (–19 W kg–1) like a brake. Both muscles exhibited nearly identical intrinsic characteristics including similar twitch kinetics and force–velocity relationships. Differences in the extrinsic factors of activation and relative shortening velocity caused the muscles to operate very differently during running. Presumed redundancy in a multiple muscle group may, therefore, represent diversity in muscle function. Discovering how muscles manage energy during behavior requires the measurement of a large number of dynamically interacting variables.
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Pistilli, Emidio E., Parco M. Siu, and Stephen E. Alway. "Interleukin-15 responses to aging and unloading-induced skeletal muscle atrophy." American Journal of Physiology-Cell Physiology 292, no. 4 (April 2007): C1298—C1304. http://dx.doi.org/10.1152/ajpcell.00496.2006.
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Interleukin-15 (IL-15) mRNA is constitutively expressed in skeletal muscle. Although IL-15 has proposed hypertrophic and anti-apoptotic roles in vitro, its role in skeletal muscle cells in vivo is less clear. The purpose of this study was to determine if skeletal muscle aging and unloading, two conditions known to promote muscle atrophy, would alter basal IL-15 expression in skeletal muscle. We hypothesized that IL-15 mRNA expression would increase as a result of both aging and muscle unloading and that muscle would express the mRNA for a functional trimeric IL-15 receptor (IL-15R). Two models of unloading were used in this study: hindlimb suspension (HS) in rats and wing unloading in quail. The absolute muscle wet weight of plantaris and soleus muscles from aged rats was significantly less when compared with muscles from young adult rats. Although 14 days of HS resulted in reduced muscle mass of plantaris and soleus muscles from young adult animals, this effect was not observed in muscles from aged animals. A significant aging times unloading interaction was observed for IL-15 mRNA in both rat soleus and plantaris muscles. Patagialis (PAT) muscles from aged quail retained a significant 12 and 6% of stretch-induced hypertrophy after 7 and 14 days of unloading, respectively. PAT muscles from young quail retained 15% hypertrophy at 7 days of unloading but regressed to control levels following 14 days of unloading. A main effect of age was observed on IL-15 mRNA expression in PAT muscles at 14 days of overload, 7 days of unloading, and 14 days of unloading. Skeletal muscle also expressed the mRNAs for a functional IL-15R composed of IL-15Rα, IL-2/15R-β, and -γc. Based on these data, we speculate that increases in IL-15 mRNA in response to atrophic stimuli may be an attempt to counteract muscle mass loss in skeletal muscles of old animals. Additional research is warranted to determine the importance of the IL-15/IL-15R system to counter muscle wasting.
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Gedrange, T., R. Mai, G. Richter, P. Wolf, A. Lupp, and W. Harzer. "X-ray Microanalysis of Elements in the Masticatory Muscle after Paresis of the Right Masseter." Journal of Dental Research 84, no. 11 (November 2005): 1026–30. http://dx.doi.org/10.1177/154405910508401111.
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Muscle activity and function appear to be related to ionic concentrations in the muscle. We investigated whether muscle paresis induced by injection of Botulinum toxin A (Botox) in 16-week-old pigs over a 56-day period is associated with ionic changes in the affected muscles. Tissue samples were taken from the masseter, temporalis, medial pterygoid, and geniohyoid muscles by a standardized method and used for energy-dispersive x-ray microanalysis in an environmental scanning electron microscope. The largest increase in Na+ was measured in the right and left sides of the masseter muscle in treated animals. Additionally, a significant elevation of Na+ was measured in the anterior part of the temporalis muscle and in the pterygoid muscle (P < 0.05). In temporalis and pterygoid muscles, an increase in sulfur in both sides of treated pigs’ heads was observed. Botox® has an indirect impact on ion concentrations, resulting in changes in muscle functional capacity and adaptive compensation of paretic muscle function by other muscles.
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Vachhani, Rooju, and Himanshi Sharma. "Effectiveness of Suboccipital Muscle Inhibition Technique versus Muscle Energy Technique on Hamstring Muscle Flexibility in College Going Students." International Journal of Research and Review 8, no. 6 (June 29, 2021): 160–74. http://dx.doi.org/10.52403/ijrr.20210620.
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Background: Hamstring is one of the commonest muscle which often gets tight. Suboccipital muscle inhibition technique is a method of relaxing tension in four muscles located between occiput and axis which regulates the upper cervical vertebra. When the tone of suboccipital muscles falls, it has been reported that the tone of knee flexors such as hamstrings also decreases due to relaxation of myofascia. This is because hamstrings and suboccipital muscles are connected by one neural system, which passes through the duramater called the superficial back line. Muscle energy technique is a procedure that involves voluntary contraction of a patient’s muscle in a precisely controlled direction, at varying levels of intensity and has been utilized in lengthening of tight muscles. Method: The study was done after obtaining approval from ethical committee. Subjects having hamstring tightness who fulfilled inclusion criteria were selected from the population. 52 subjects were included and divided into two groups. The study was carried out for 5 days. Subjects in the experimental group were treated with SMIT and Subjects in control group were treated with MET. Outcome measures used were Active Knee extension test and Back Saver Sit and Reach Test. Data was analysed post treatment (Immediate effects) and at the end of 5th session using non- parametric tests at 5% level of significance. Result: Within group analysis at post treatment and at the end of 5th session showed significant improvement in both the outcome measures in experimental and control group. Between group analysis showed no significant effect post treatment whereas after 5 days significant difference was found where more improvement was found in the control group i.e. Muscle energy technique group. Conclusion: Suboccipital Muscle Inhibition Technique and Muscle Energy Technique both were effective in improving hamstring flexibility but Muscle energy technique was found to be more effective. Keywords: Suboccipital Muscle Inhibition Technique, Muscle Energy Technique (MET), Flexibility, Active Knee Extension (AKE), Back Saver Sit and Reach Test (BSRT).
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Kholodnyi, R. D. "MODELING THE SKELETAL MUSCLE INJURY IN RATS." International Journal of Veterinary Medicine, no. 3 (October 18, 2022): 253–57. http://dx.doi.org/10.52419/issn2072-2419.2022.3.253.
Full textAbstract:
Muscles are the most important executive organs - effectors. Both according to morphological and functional characteristics, muscles are divided into two types - striated and smooth. Striated muscles, in turn, are usually divided into skeletal and cardiac. Striated muscles form the motor apparatus of the skeleton, oculomotor, chewing and other motor systems in animals. The striated muscles, with the exception of the heart muscle, are completely controlled by the central nervous system, they are devoid of automatism.The problem of damage to skeletal muscles is very relevant and widespread. These injuries disrupt the musculoskeletal function of animals, up to its complete loss. To search for methods for restoring the structure and function of muscles, experiments are being carried out on laboratory animals. This article is devoted to the selection of the optimal model of skeletal muscle injury, performed on laboratory rats. The study was conducted on Wistar rats. The choice of the muscle on which the models will be worked out, as well as the surgical access to it, is substantiated. Three options for inflicting damage to muscle tissue (cut wounds directed parallel to muscle fibers; cut wounds directed across muscle fibers; crushed wounds of muscle tissue) and the timing of healing of these injuries are proposed. The result of the study showed that the gastrocnemius muscle is the most suitable for modeling damage to muscle tissue in rats, and a crushed wound has the longest healing time.
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Shield, M. A., H. S. Haugen, C. H. Clegg, and S. D. Hauschka. "E-box sites and a proximal regulatory region of the muscle creatine kinase gene differentially regulate expression in diverse skeletal muscles and cardiac muscle of transgenic mice." Molecular and Cellular Biology 16, no. 9 (September 1996): 5058–68. http://dx.doi.org/10.1128/mcb.16.9.5058.
Full textAbstract:
Previous analysis of the muscle creatine kinase (MCK) gene indicated that control elements required for transcription in adult mouse muscle differed from those required in cell culture, suggesting that distinct modes of muscle gene regulation occur in vivo. To examine this further, we measured the activity of MCK transgenes containing E-box and promoter deletions in a variety of striated muscles. Simultaneous mutation of three E boxes in the 1,256-bp MCK 5' region, which abolished transcription in muscle cultures, had strikingly different effects in mice. The mutations abolished transgene expression in cardiac and tongue muscle and caused a reduction in expression in the soleus muscle (a muscle with many slow fibers) but did not affect expression in predominantly fast muscles: quadriceps, abdominals, and extensor digitorum longus. Other regulatory sequences with muscle-type-specific activities were found within the 358-bp 5'-flanking region. This proximal region conferred relatively strong expression in limb and abdominal skeletal muscles but was inactive in cardiac and tongue muscles. However, when the 206-bp 5' enhancer was ligated to the 358-bp region, high levels of tissue-specific expression were restored in all muscle types. These results indicate that E boxes and a proximal regulatory region are differentially required for maximal MCK transgene expression in different striated muscles. The overall results also imply that within skeletal muscles, the steady-state expression of the MCK gene and possibly other muscle genes depends on transcriptional mechanisms that differ between fast and slow fibers as well as between the anatomical and physiological attributes of each specific muscle.
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Hwang, Willy, Jason C. Carvalho, Isaac Tarlovsky, and Aladin M. Boriek. "Passive mechanics of canine internal abdominal muscles." Journal of Applied Physiology 98, no. 5 (May 2005): 1829–35. http://dx.doi.org/10.1152/japplphysiol.00910.2003.
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The internal abdominal muscles are biaxially loaded in vivo, and therefore length-tension relations along and transverse to the directions of the muscle fibers are important in understanding their mechanical properties. We hypothesized that 1) internal oblique and transversus abdominis form an internal abdominal composite muscle with altered compliance than that of either muscle individually, and 2) anisotropy, different compliances in orthogonal directions, of internal abdominal composite muscle is less pronounced than that of its individual muscles. To test these hypotheses, in vitro mechanical testing was performed on 5 × 5 cm squares of transversus abdominis, internal oblique, and the two muscles together as a composite. These tissues were harvested from the left lateral side of abdominal muscles of eleven mongrel dogs (15–23 kg) and placed in a bath of oxygenated Krebs solution. Each tissue strip was attached to a biaxial mechanical testing device. Each muscle was passively lengthened and shortened along muscle fibers, transverse to fibers, or simultaneously along and transverse to muscle fibers. Both transversus abdominis and internal oblique muscles demonstrated less extensibility in the direction transverse to muscle fibers than along fibers. Biaxial loading caused a stiffening effect that was greater in the direction along the fibers than transverse to the fibers. Furthermore, the abdominal muscle composite was less compliant than either muscle alone in the direction of the muscle fibers. Taken together, our data suggested that the internal abdominal composite tissue has complex mechanical properties that are dependent on the mechanical properties of internal oblique and transversus abdominis muscles.
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Blake, Ollie M., and James M. Wakeling. "Muscle coordination limits efficiency and power output of human limb movement under a wide range of mechanical demands." Journal of Neurophysiology 114, no. 6 (December 1, 2015): 3283–95. http://dx.doi.org/10.1152/jn.00765.2015.
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This study investigated the influence of cycle frequency and workload on muscle coordination and the ensuing relationship with mechanical efficiency and power output of human limb movement. Eleven trained cyclists completed an array of cycle frequency (cadence)-power output conditions while excitation from 10 leg muscles and power output were recorded. Mechanical efficiency was maximized at increasing cadences for increasing power outputs and corresponded to muscle coordination and muscle fiber type recruitment that minimized both the total muscle excitation across all muscles and the ineffective pedal forces. Also, maximum efficiency was characterized by muscle coordination at the top and bottom of the pedal cycle and progressive excitation through the uniarticulate knee, hip, and ankle muscles. Inefficiencies were characterized by excessive excitation of biarticulate muscles and larger duty cycles. Power output and efficiency were limited by the duration of muscle excitation beyond a critical cadence (120–140 rpm), with larger duty cycles and disproportionate increases in muscle excitation suggesting deteriorating muscle coordination and limitations of the activation-deactivation capabilities. Most muscles displayed systematic phase shifts of the muscle excitation relative to the pedal cycle that were dependent on cadence and, to a lesser extent, power output. Phase shifts were different for each muscle, thereby altering their mechanical contribution to the pedaling action. This study shows that muscle coordination is a key determinant of mechanical efficiency and power output of limb movement across a wide range of mechanical demands and that the excitation and coordination of the muscles is limited at very high cycle frequencies.
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van Eijden, T. M. G. J., and S. J. J. Turkawski. "Morphology and Physiology of Masticatory Muscle Motor Units." Critical Reviews in Oral Biology & Medicine 12, no. 1 (January 2001): 76–91. http://dx.doi.org/10.1177/10454411010120010601.
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Motor unit territories in masticatory muscles appear to be smaller than territories in limb muscles, and this would suggest a more localized organization of motor control in masticatory muscles. Motor unit cross-sectional areas show a wide range of values, which explains the large variability of motor unit force output. The proportion of motor unit muscle fibers containing more than one myosin heavy-chain (MHC) isoform is considerably larger in masticatory muscles than in limb and trunk muscles. This explains the continuous range of contraction speeds found in masticatory muscle motor units. Hence, in masticatory muscles, a finer gradation of force and contraction speeds is possible than in limb and in trunk muscles. The proportion of slow-type motor units is relatively large in deep and anterior masticatory muscle regions, whereas more fast-type units are more common in the superficial and posterior muscle regions. Muscle portions with a high proportion of slow-type motor units are better equipped for a finer control of muscle force and a larger resistance to fatigue during chewing and biting than muscle portions with a high proportion of fast units. For the force modulation, masticatory muscles rely mostly on recruitment gradation at low force levels and on rate gradation at high force levels. Henneman's principle of an orderly recruitment of motor units has also been reported for various masticatory muscles. The presence of localized motor unit territories and task-specific motor unit activity facilitates differential control of separate muscle portions. This gives the masticatory muscles the capacity of producing a large diversity of mechanical actions. In this review, the properties of masticatory muscle motor units are discussed.
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Sun, Yunfeng, Caterina Fede, Xiaoxiao Zhao, Alessandra Del Felice, Carmelo Pirri, and Carla Stecco. "Quantity and Distribution of Muscle Spindles in Animal and Human Muscles." International Journal of Molecular Sciences 25, no. 13 (July 3, 2024): 7320. http://dx.doi.org/10.3390/ijms25137320.
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Muscle spindles have unique anatomical characteristics that can be directly affected by the surrounding tissues under physiological and pathological conditions. Understanding their spatial distribution and density in different muscles is imperative to unravel the complexity of motor function. In the present study, the distribution and number/density of muscle spindles in human and animal muscles were reviewed. We identified 56 articles focusing on muscle spindle distribution; 13 articles focused on human muscles and 43 focused on animal muscles. The results demonstrate that spindles are located at the nerve entry points and along distributed vessels and they relate to the intramuscular connective tissue. Muscles’ deep layers and middle segments are the main topographic distribution areas. Eleven articles on humans and thirty-three articles on animals (totaling forty-four articles) focusing on muscle spindle quantity and density were identified. Hand and head muscles, such as the pronator teres/medial pterygoid muscle/masseter/flexor digitorum, were most commonly studied in the human studies. For animals, whole-body musculature was studied. The present study summarized the spindle quantity in 77 human and 189 animal muscles. We identified well-studied muscles and any as-yet unfound data. The current data fail to clarify the relationship between quantity/density and muscle characteristics. The intricate distribution of the muscle spindles and their density and quantity throughout the body present some unique patterns or correlations, according to the current data. However, it remains unclear whether muscles with fine motor control have more muscle spindles since the study standards are inconsistent and data on numerous muscles are missing. This study provides a comprehensive and exhaustive approach for clinicians and researchers to determine muscle spindle status.