• Food Science of Animal Resources
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• v.36 no.6
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• pp.819-828
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• 2016

Muscle fiber characteristics account for meat quality and muscle fibers are mainly classified into three or more types according to their contractile and metabolic properties. However, the majority of previous studies on bovine skeletal muscle are based on myosin ATPase activity. In the present study, the differences in the characteristics of muscle fibers classified by the expression of myosin heavy chain (MHC) among four bovine skeletal muscles such as longissimus thoracis (LT), psoas major (PM), semimembranosus (SM) and semi-tendinosus (ST) and their relationships to beef quality were investigated. MHCs 2x, 2a and slow were identified by LC-MS/MS and IIX, IIA and I fiber types were classified. PM, which had the smallest size and highest density of fibers regardless of type, showed the highest myoglobin content, CIE $L^*$, $a^*$, $b^*$ and sarcomere length (p<0.05), whereas ST with the highest composition of IIX, showed high shear force and low sarcomere length (p<0.05). The correlation coefficients between muscle fiber characteristics and meat quality showed that type IIX is closely related to poor beef quality and that a high density of small-sized fibers is related to redness and tenderness. Therefore, the differences in meat quality between muscles can be explained by the differences in muscle fiber characteristics, and especially, the muscles with good quality are composed of more small-sized fibers regardless of fiber type.

• Asian-Australasian Journal of Animal Sciences
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• v.1 no.4
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• pp.223-232
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• 1988

Fifty-two wether lambs weighing 30 kg were randomly assigned to 5 treatment groups; 1) initial slaughter. 2) control-maintenance (CON-MT), 3) control-ad libitum (CON-AL), 4) cimaterol-maintenance (CIM-MT) and 5) cimaterol-ad libitum (CIM-AL). Ad libitum-fed animals had free access of a high-concentrate diet, whereas maintenance animals were restricted in feed intake to maintain the initial weight of 30 kg for 90 days. Cimaterol was administered in the feed at 10 mg/kg. Regardless of feeding level, the administration of CIM improved carcass weight (p < .05), dressing % (p < .01), longissimus muscle area (p < .01), leg conformation and muscling (p < .01), USDA yield and quality grades (p < .01) and protein concentration (p < .01) in carcass as well as in muscle. Cimaterol feeding decreased organ wt (p < .01), baekfat depth (p < .01), intramuscular fat and overall fatness. Cimaterol was effective for muscle accretion even under restricted feeding condition. The greater accretion of muscle was the result of the hypertrophy of both type I and type II muscle fibers but the hypertrophy of type II fiber (110%) was much greater than that of type I fiber (37%). Cimaterol feeding decreased muscle DNA concentrations but the number of nuclei per muscle fiber was not changed, indicating that the lower DNA concentration was due to the dilution effect caused by the hypertrophy of muscle fiber. As evidenced by lower flank streaking, lower marbling and darker muscle, CIM feeding adversely affected meat quality. Meat tenderness was also adversely affected, resulting in significantly (p H .01) tougher meat in CIM-fed animals.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.7
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• pp.965-971
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• 2010

The purpose of the current study was to examine the influence of different maternal nutrition treatments during pregnancy on body weight, muscle fiber number, carcass traits, and pork quality traits of offspring. A total of 18 crossbred sows (Landrace${\times}$Yorkshire${\times}$Duroc) were randomly assigned to one of three nutritional treatment groups; control, high energy, and high protein. The control group was fed a standard diet, the high energy group was fed a diet that contained 30% increased metabolizable energy, and the high protein group was fed a diet that contained 30% increased limiting amino acids compared to the control. The sows in each group were fed equal quantities of each diet (1.9 kg/d) for the entire gestational period. A total of 36 piglets from each sow were used to evaluate changes in body weight, muscle fiber number in the longissimus dorsi muscle at birth, carcass traits, and pork quality traits. Birth weight of offspring born to sows in the high energy diet group was significantly higher compared to the high protein diet group (p<0.05). However, body weight of offspring after birth was not significantly different between the groups. Muscle fiber number for the longissimus dorsi muscle at birth was not significantly different between the groups. In addition, there were no significant differences in carcass traits or pork quality traits between offspring born to sows in the control group and those born to sows that received high energy or high protein diets during pregnancy. Based on these results, it appears that maternal nutrition treatment during pregnancy, regardless of whether it is with high energy or high protein diets, does not have a significant effect on body weight, muscle fiber number at birth, carcass traits, or pork quality traits.

• Food Science of Animal Resources
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• v.42 no.5
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• pp.874-888
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• 2022

This study aimed to compare the similarities, physicochemical properties, and muscle fiber characteristics of porcine skeletal muscles. Fourteen types of muscles were collected from nine pig carcasses at 24 h post-mortem and classified by muscle architecture into two main groups, namely parallel and pennate. The muscles were further differentiated into three subtypes per group. These included fan-shaped, fusiform, and strap for the parallel group, and unipennate, bipennate, and multipennate for the pennate group. Parallel-fibered muscles, which were composed of larger I, IIA, IIX, and IIXB fibers and a lower density of IIA fibers, showed higher redness and yellowness values than pennate-fibered muscles (p<0.05). However, the relative fiber area was not significantly different between the parallel and pennate groups (p>0.05). In the subtypes of parallel architecture, the strap group showed lower moisture content and higher redness values than the other subtypes and had considerably higher amounts of oxidative fibers (I and IIA; 72.3%) than the fan-shaped and fusiform groups (p<0.05). In the pennate group, unipennate showed comparatively lower moisture content and higher lightness than other pennate subtypes and was composed of smaller I, IIA, and IIX fibers than the bipennate and multipennate groups (p<0.05). Finally, a different trend of muscle clustering by hierarchical cluster analysis was found between physicochemical properties and muscle fiber characteristics. These results suggest that the physicochemical properties and muscle fiber characteristics of porcine skeletal muscles are not significantly dependent on morphological properties but are rather related to the intrinsic properties of the individual muscles.

• Physical Therapy Korea
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• v.5 no.1
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• pp.63-78
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• 1998

The decrease of muscle power and muscle size between twenties and seventies was about 30% and 40% respectively. The loss of muscle mass by aging resulted in the decrease of muscle power. The loss of muscle mass was due to the decrease of number of Type I fiber and Type II fiber and size of each muscle fiber. The aging skeletal muscle didn't show the loss of glycolysis capacity but showed 20% decrease of the oxidative enzymes and muscle vascularization. The vigorous endurance exercise training with graded intensity played a role in the vascular proliferation, increase of activity of oxidative enzymes and improvement of $VO_2$ max. The graded resistance exercise also played a role in the muscle hypertrophy and increase of muscle power, if it performed with adequate intensity and period. The exercise adaptation of aging skeletal muscle prevented it from sarcopenia, provided the activity of daily living with great effect and provided the aging related disease, that is Type II diabetes mellitus, arteriosclerosis, hypertension, osteoporosis and obesity, with great effect.

• Journal of The Korean Society of Integrative Medicine
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• v.2 no.3
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• pp.57-63
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• 2014

Purpose : The purpose of this study was to identify the muscle activity of leg during stair down in the subjects with flatfoot and normal foot. Methods : The fourteen subjects with the flatfoot group and the fifteen subjects with the normal foot group volunteered for this study. All subjects descended the stairs that the height was 20cm and consisted 25 stairs. The target muscles for recording muscle activity were posterior fiber of gluteus medius, vastus medialis and vastus lateralis oblique, semitendinosus and biceps femoris, tibialis anterior, and medial and lateral fiber of gastrocnemius muscles. The muscle activity was recorded using the wireless EMG system. Results : The flatfoot group had significantly lower the muscle activity of posterior fiber of gluteus medius than the normal foot group in stance phase during stair down(p<.05). The flatfoot group had significantly higher the muscle activity of biceps femoris and tibialis anterior than the normal foot group in swing phase during stair down(p<.05). Conclusions : This study proposed that the subject with flatfoot should train the strengthening exercise for posterior fiber of gluteus medius.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.2
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• pp.405-411
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• 2009

This study evaluated the effects of Puerariae Radix on the skeletal muscle atrophy, Muscle atrophy was induced by the sciatic nerve transection in Sprague-Dawley rats, then aqueous-extract of Puerariae Radix was administered for 12 days, Muscle wet weight was measured in soleus, plantaris, and medial gastrocnemius. Muscle fiber type was classified by MHCf immunohistochemistry. Muscle fiber type proportion and cross section area of muscle fiber also was observed in medial gastrocnemius. Bax and Bcl-2 expressions in medial gastrocnemius of the damaged hind limb were evaluated with immunohistochemistry. The results are as follows; Puerariae Radix attenuated muscle atrophy in soleus of the sciatic nerve transectioned rats, but there was statistic significance. Puerariae Radix attenuated significantly atrophy in plantaris at 12 days and in medial gastrocnemius at 8 days and 12 days. Puerariae Radix improved histology of the atrophic changes and increased significantly cross section areas of type-I and type-II muscle fibers in medial gastrocnemius of the sciatic nerve transectioned rats. Puerariae Radix did not affect to muscle fiber type proportion in medial gastrocnemius of the sciatic nerve transectioned rats. Puerariae Radix attenuated significantly Bax positive nuclei but did not affect to Bcl-2 positive muscle fibers in medial gastrocnemius of the sciatic nerve transectioned rats.According to above results, Puerariae Radix may have an anti-atrophy effect on the denervated skeletal muscle through anti-apoptotic effects on muscle fibers.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.72.2-72.2
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• 2005

• Food Science and Biotechnology
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• v.17 no.5
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• pp.965-970
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• 2008

The objective of this study was to examine the relationship between instrumental tenderness parameters and histochemical characteristics in the porcine longissimus dorsi muscle, and to investigate a comparison between tenderness parameters such as the Warner-Bratzler shear-force (WBS) and texture profile analysis (TPA). A negative relationship between WBS and fiber area was observed. However, there was no significant relationship between hardness and muscle fiber area. The percentage of fiber type IIb exhibited a positive correlation with hardness. There was a negative relationship between the type IIa composition percentage and hardness. This study showed that some muscle fiber characteristics were related to WBS and TPA parameters, especially hardness.

• Animal Bioscience
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• v.34 no.8
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• pp.1375-1381
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• 2021

Objective: This study was conducted to determine the effect of freeze-thawed cycles (Fresh meat, F-T 1 cycle and F-T 2 cycles) on the quality characteristics of porcine longissimus dorsi muscle. Methods: A total of 20 three-crossbred pigs (Duroc×[Large White×Landrace]) were randomly obtained from a commercial slaughterhouse in Thailand. Muscle samples were immediately taken from 10 to 11th of the longissimus dorsi for histochemical analysis. The muscles were cut into 2.54 cm-thick chops. A minimum of 20 chops were used for each treatment (fresh meat, freeze-thawed 1 and 2 cycles). Individually chops were packaged in polyethylene bags and frozen at -20℃ for 6 months followed by thawing in refrigerator at 4℃ for 24 h (the 1st freeze-thawed cycle). The freeze-thawed procedure was repeated for two cycles (the 2nd freeze-thawed cycle). Thawing loss, shear force value, citrate synthase activity and muscle fiber characteristics were determined on the muscles. Results: Results showed that increasing of freeze-thawed cycle increased the thawing loss (p<0.01) and citrate synthase activity (p<0.001). Shear force value of fresh meat was higher than freeze-thawed 1 and 2 cycles (F-T 1 cycle and F-T 2 cycles). Freeze-thawed cycles affected muscle characteristics. Muscle fiber area and muscle fiber diameter decreased with an increasing number of freeze-thawed cycles (p<0.001), while the thickness of endomysium and perimysium were increased (p<0.001). Conclusion: Repeated freeze-thawed cycles degraded muscle fiber structure and deteriorated pork quality.