• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.75-83
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• 2006

The purpose of this study was to investigate steady-state force depression following active muscle shortening in human tibialis anterior muscle during voluntary contractions. Subjects (n = 7; age $24{\sim}39$ years; 7 males) performed isometric reference contractions and isometric-shortening-isometric contractions, using maximal voluntary effort. Force depression was assessed by comparing the steady-state isometric torque produced following active muscle shortening with the purely isometric reference torque obtained at the corresponding joint angle. In order to test for effects of the shortening conditions on the steady-state force depression, the speed of shortening were changed systematically in a random order but balanced design. Ankle dorsiflexion torque and joint angle were continuously measured using a dynamometer. During voluntary contractions, muscle activation of the tibialis anterior and the medical gastrocnemius was recorded using surface electromyography. Force depression during voluntary contractions, with a constant level of muscle activation, was 12 %, on average over all subjects. Force depression was independent of the speeds of shortening ($13.8{\pm}2.9%$, $10.3{\pm}2.6%$ for 15 and 45 deg/sec over 15 deg of shortening, respectively). The results of this study suggest that steady-state force depression is a basic property of voluntarily-contracting human skeletal muscle and has functional implication to human movements.

• Journal of Aquaculture
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• v.22 no.1
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• pp.83-91
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• 2009

The Korean doty barbel Hemibarbus mylodon (Cypriniformes; Cyprinidae) is a critically endangered freshwater fish species mainly because of its natural habitat degradation. Three full-length complementary DNA (cDNA) clones representing different muscle actin isoforms were isolated and characterized. The three muscle actin isoforms were 1,294-1,601 bp long with the identical open reading frames of 1,134 bp with the deduced amino acid residues of 377. They showed 83.9-87.2% identities in the coding nucleotide level and 96.8-98.1% identities in the amino acid level. Phylogenetic analysis with the coding nucleotide sequences revealed that three muscle actin isoforms of H. mylodon formed strongly supported monophyletic groups with one of cypriniform skeletal $\alpha$-actin (acta1), cypriniform aortic $\alpha$-actins (acta2), and uncharacterized Danio rerio muscle actin isoform/Salmo trutta slow muscle actin (a novel muscle actin type). Our phylogenetic tree further suggested that cypriniform acta2 only showed the orthologous relationship to tetrapod acta2. Other multiple actin isoforms from diverse teleostean taxa were however clustered to no tetrapod orthologs, i.e., acta1, cardiac $\alpha$-actins (aetc1), acta2, and enteric $\gamma$-actin (actg2). This result strongly suggested that teleostean muscle actins have experienced different and complicated evolutionary history in comparison to mammalian counterparts.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.211-217
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• 2019

This study is designed to reduce worker fatigue, improve efficiency and provide a functional working environment based on previous studies that pain occurs in the shoulder area, especially the upper trapezius muscle, when the keyboard height is not appropriate. In this study, the height of the keyboard is four, the height of the elbow and desk is the same height, the height of the desk is 3cm lower than the elbow, the height of the desk is 6cm high, and the height is 9cm high. When working on the keyboard, the wrist and forerunner were organized into four groups of 10 people so that the height was different for each group. When the height of the keyboard is given in various ways compared to the height of the elbow of the subject, it is verified whether there is a difference in the RMS (Root Mean Square) of the upper trapezius muscle. The results of this study showed that the muscle activity of the upper trapezius muscle cap was significant only in the left and right keyboard height -4cm, 0cm, +4cm, +8cm group, but the difference in muscle activity was not significant in the rest group. The first study will require a study of the control of the factors affecting the tension of the subjects, the measurement of muscle activity against various muscles, and whether the length of the shoulder and fingertips of the subject affect muscle activity according to the keyboard type.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.5
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• pp.640-647
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• 2008

Breed differences in adult animals are determined during fetal development. If interventions are to be developed that influence growth of muscle and fat, it is important to know at which time during gestation breed differences appear and are fixed. The objective of this study was to characterize fetal development in cattle of different breeds. Pregnant cows of 4 cattle breeds with different growth impetus and muscularity were slaughtered under normal processing conditions and the fetuses were removed. German Angus, a typical beef cattle; Galloway, a smaller, environmentally resistant beef type; Holstein Friesian, a dairy type; and Belgian Blue, an extreme type for muscle growth were used. Fetuses of each breed were investigated at 3, 6, and 9 mo of gestation. Fetuses were weighed and dissected into carcass, organs, and muscles. Body fat weight was obtained using the Soxhlet extraction method. Fetal weight increased most rapidly in the third trimester of gestation mainly due to the accelerated muscle and fat deposition. The organ weight to body weight (BW) ratios decreased and the muscle and fat weight to BW ratios increased. At 3 mo of gestation, Galloway fetuses had the significantly smallest BW, half-carcass weight, leg weight, organ weight, muscle weight and shortest leg length. In contrast, Holstein fetuses had the significantly greatest BW, liver, kidney, and lung weights and significantly longest leg length among the 4 breeds, but no differences between Holstein Friesian and Belgian Blue were detected in half-carcass and leg weight. Indeed, Belgian Blue fetuses had the significantly greatest half-carcass weight, leg weight, and muscle weight at 9 mo of gestation, and Galloway had a significantly greater body fat to BW ratio than Holstein Friesian and Belgian Blue. These differences were not evident at 3 and 6 mo of gestation. These data show that the profound increase of tissue and organ weights occurred in later gestation in cattle fetuses even though breed differences were evident as early as 3 mo of gestation. Depending on the tissue of interest, impacting fetal growth likely needs to occur early in gestation before the appearance of breed-specific differences.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.691-698
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• 2009

The purpose of this study was to examine the effect of neuromuscular electrical stimulation(LFES) during hindlimb suspension on weight and function of rat hindlimb muscles. Sprague-Dawley rats(body weight 300-350g) were randomly assigned to five groups: a HLS(n=5) that were hindlimb suspended for 14 days, a WB(n=5) that kept as control, a ES14 that were hind limb suspended for 14days with pre-application of LFES for 14 days, ES11 that were hindlimb suspended for 14 days with pre-application of LFES for 11 days, a LFES 7 that were hindlimb suspended for 14 days with pre-application of LFES for 7 days. Gastrocnemius muscle weight, stride length were significantly decreased and toe out angle were significantly increased in HLS and ES7 groups, whereas muscle weight, stride length, toe out angle were maintained in ES14, ES11. this indicated that LFES for 14 days, LFES for 11 days could prevent muscle atrophy and retain function.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.937-942
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• 2009

The aim of this study was to analyze the effects on growth and muscle development during the growing period of the sex-linked dwarf gene in the background of a Taiwan Country chicken strain, L2, selected for egg production. Eight crossbred males, heterozygous for the DW*DW mutation, were each backcrossed to six females of the L2 strain to produce two genotypes of BC females, either normal (DW*N+/-) or dwarf (DW*DW/-). The experiment included 251 normal and 207 dwarf pullets. The effect of the dwarf gene on body weight and shank length was highly significant from 2 weeks of age. The reduction of body weight by the dwarf gene reached 34.8% and 37.4% as compared to normal sibs at 16 and 20 weeks of age, respectively. Parameters of the growth curve were estimated: the age at inflection (TI) was higher in normal pullets (66.9 days) than in dwarf pullets (61.2 days). A significant effect of the dwarf gene on single muscle fiber cross-section area was found from 12 weeks of age onwards, whereas the dwarf gene had no effect on the total number of muscle fibers. Comparing the effect of the dwarf gene on shank length at different ages revealed an earlier effect on skeleton growth, observed from 2 weeks of age, than on muscle development, which was affected from 8 to 12 weeks of age.

• Journal of Oral Medicine and Pain
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• v.42 no.4
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• pp.109-115
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• 2017

Purpose: This study analyzed the effects of digastric muscle injury on mandibular growth in young rats. Methods: Fourteen 4-week-old Wistar rats were divided into 3 groups; experimental group A (n=6) with unilateral (right) shortening of the posterior digastric muscle, experimental group B (n=6) with bilateral shortening of the posterior digastric muscles, and control group C (n=2) who underwent a sham operation. Eight weeks after the operation all animals were sacrificed and the outcomes were compared using body weight evaluation, mensurations on lateral radiograph of hemimandibles and histological evaluation. Results: There was no significant difference between groups A and B in body weight gain. Comparison of the mean values of hemimandible distance on radiograph was performed. The difference in group mean value of mandible-related distances was analyzed using the Wilcoxon test (rank sum test) and a comparison of the homonymous distances of group A and B was performed using the Mann-Whitney test. There were differences between sides in mandibular length in group B and mandibular ramus height and transverse width of the condyle in group A (all, p<0.05). There were differences in condylar height and mandibular length on the left side between groups A and B (p<0.05). Histologic examination of temporomandibular joint showed similar findings in all specimens. Conclusions: Injury of the posterior belly of the digastric muscle during the rat growth period induced shortening of mandibular ramus height and transverse width of the condyle. It can be inferred that trauma to the posterior belly of the digastric muscle affects horizontal and vertical growth of the mandible.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.5
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• pp.313-320
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• 2020

Objectives: The aim of this study was to evaluate the relationship between masticatory muscle thickness and mandibular morphology in young Korean adults with normal occlusion and mandibular prognathism. Patients and Methods: Multidetector computed tomography (MDCT) was used to measure the masticatory muscle thickness on the right side in 100 Korean young adults (50 normal occlusion group, 50 mandibular prognathism group). Cephalometric analysis was done to measure mandibular morphology. Pearson correlation analysis was done to investigate the relationship between the masticatory muscle thickness and mandibular morphometry. Results: The four masticatory muscles showed positive correlation with intergonial width in all subjects. All muscles, except temporalis, positively correlated with height of the ramus and mandibular length. Positive correlation was also observed in all muscles, except medial pterygoid, with thickness of the ramus. In the normal occlusion group, all four masticatory muscles showed positive correlation with intergonial width and ramus thickness. Positive correlation was also observed in all muscles (except lateral pterygoid) with mandibular length. Masseter and lateral pterygoid positively correlated with height of the ramus. In the mandibular prognathism group, all masticatory muscles, except lateral pterygoid, showed positive correlation with intergonial width. The masseter muscle showed negative correlation with ANB. Conclusion: The results suggest a positive correlation of the thickness of masticatory muscles with both horizontal and vertical dimensions of the mandible. However, thickness of the masseter was found to decrease in patients with increasing severity of mandibular prognathism.

• Journal of Sport and Applied Science
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• v.7 no.1
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• pp.21-29
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• 2023

Purpose: This study was to investigate the effects of isometric exercise on muscle activity and body balance ability in asymmetrical walkers. Research design, data, and methodology: Twenty gait asymmetry people were divided to unilateral exercise group (UG, n=10) and bilateral exercise group (BG, n=10). UG were performed unilateral exercise for 60 minutes, three times a week, and 16 weeks, and BG were performed one side and then the other side alternately for 60 minutes, three times a week, and 16 weeks. Muscle activity and body balance ability were measured before, after 4 and 16 weeks isometric exercise. Moreover, SI (symmetry index; SI) was calculated from the measured value of SL (step length). Statistical analyses were conducted using one-way ANOVA and two-way ANOVA with repeated measures, a paired t-test, and multiple comparisons according to Scheffe. Results: In the muscle activity, ST decreased significantly in short step length(S-SL) and BG of LS compared to before isometric exercise(p<.05), and GCM decreased significantly in BG of S-SL(p<.05). As for body balance ability, the mSEBT-A difference between L-SL and S-SL was decreased significantly in UG(p<.05). And the respective total scores of L-SL and S-SL, mSEBT-PM and mSEBT-PL were increased significantly in BG(p<.05). Conclusions: As a result, in this study above, it was confirmed that isometric exercise improved muscle activity and body balance ability in asymmetrical walkers.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.4
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• pp.598-604
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• 2009

This work was carried out to study the carcass characteristics, the chemical composition and the fatty acid profile in Longissimus muscle (LM) of bull breeds Nellore, NEL (11), Caracu, CAR (12) and Holstein-Friesian, HFR (12) finished in a feedlot. The bulls were fed twice a day with corn silage, cotton meal, cracked corn, urea, limestone and mineral salt. NEL and CAR bulls had similar (p>0.05) final weight and hot carcass weight. However, NEL and CAR bulls had higher (p<0.05) final weight and hot carcass weight than HFR bulls. Carcass hot dressing, carcass conformation, cushion thickness, Longissimus muscle area and texture were similar (p>0.05) among NEL, CAR and HFR bulls. NEL and HFR bulls had higher (p<0.05) carcass length in comparison to the CAR breed. Nellore breed had higher (p<0.05) leg length in comparison to CAR and HFR breeds. Leg length was similar (p>0.05) between CAR and HFR breeds. Thickness fat, color and marbling score were lower (p<0.05) in NEL breed in comparison to CAR and HFR breeds. LM of NEL bulls had higher (p<0.05) meat moisture content in comparison to CAR and HFR bulls. In contrast, lipid content was lower (p<0.10) in HFR bulls. LM ash and crude protein contents were similar (p>0.05) among breeds. Saturated fatty acids (SFA) were higher (p<0.10) in HFR animals. Monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), n-6, n-3 and PUFA/SFA ratio were similar (p>0.05) among the different breeds. N-6/n-3 ratio was higher (p<0.05) in CAR animals.