• Asian-Australasian Journal of Animal Sciences
• /
• v.23 no.5
• /
• pp.665-671
• /
• 2010

Muscle fiber characteristics and their relationship to water-holding capacity of longissimus dorsi (ld) muscle were studied in Brahman (BRA) and Charolais (CHA) crossbred bulls fattened under practical farm conditions. Thirty-four BRA and 34 CHA bulls were randomly selected and slaughtered at 500, 550 and 600 kg live weight. Parameters of water-holding capacity such as drip, ageing, thawing, cooking and grilling loss were determined. Muscle fiber characteristics were conducted for muscle fiber type percentage and cross-sectional areas of slow- and fast-twitch fiber types, and correlation coefficients to water-holding capacity parameters were calculated. Results showed that CHA meat had a better water-holding capacity (less ageing, thawing and grilling loss) when compared with BRA, whereas slaughter weights had no significant effects on these parameters. Furthermore, there were no significant differences between genotypes and slaughter weights in muscle fiber type percentage and cross-sectional areas of ld muscle. Slow- and fast-twitch fiber types of all experimental groups averaged 24.4 and 75.6%, respectively. Cross-sectional areas of fast-twitch fibers had almost twice the size of slow-twitch fibers (6,721 and 3,713 ${\mu}m^2$, respectively). The correlation between muscle fiber area and water-holding capacity indicated that muscles with larger fiber areas had a lower drip and ageing loss but a higher cooking and grilling loss.

• Journal of Yeungnam Medical Science
• /
• v.7 no.1
• /
• pp.19-27
• /
• 1990

This investigation was undertaken to clarify the in vitro effect of the various stimulations, such as exercise(E), insulin(I), direct electrical stimulation(EST) and the combinations of the above, on the glucose incorporation into glycogen molecules (glycogen synthesis) of the normal slow(soleus) and fast twitch(plantaris) muscles, and the different responses of slow and fast twitch muscles to persistent overloads causing compensatory muscle hypertrophy. In resting state, slow twitch muscle has greater capacity for glycogen synthesis than fast twitch muscle, and responses of different muscle to various stimuli were differ as follows : In slow twitch muscle, the glycogen synthesis was increased by insulin, and electrical stimulation but not increased by exercise ; exercise increased insulin sensitivity and the effect of electrical stimulation. Whereas the glycogen synthesis in fast twitch muscle was increased only by the stimuli combined with E and EST, and E, I, and EST. As the result of removal of synergistic muscle, both muscles were hypertropied, and the degree of hypertrophy in response to persistent overload was higher in fast twitch muscle(182%) than slow twitch muscle(151%). In hypertrophied muscles, glycogen synthesis of soleus in any groups was lower than that of the control, but similar in plantaris. In conclusions, there were marked heterogeneity in defferent muscle fiber in the effects of exercise and insulin addition and electrical stimulation on muscle glycogen synthesis, and fast twitch muscle may be adapted more easily to that kind of persistent overload than slow twitch muscle.

• Food Science of Animal Resources
• /
• v.30 no.3
• /
• pp.385-391
• /
• 2010

This study was conducted to compare proteins expressed in M. longissimus from Hanwoo and Holstein steers immediately after slaughter. Two-dimensional electrophoresis (2DE)/LC-MS/MS analysis revealed that the total number of detectable protein spots from longissimus muscle tissues was slightly higher in Hanwoo ($575{\pm}65$) than Holstein ($534{\pm}13$) steers, but that these numbers were not statistically significant due to large variation between replicates. A total of twelve protein spots did not match between sample groups, eight of which were expressed in the Hanwoo sample and four that were expressed in the Holstein sample. The protein spots detected in the Hanwoo sample included smooth muscle and non-muscle myosin alkali light chain 6B isomers, ${\alpha}B$ crystallin isomers, hemoglobin ${\beta}$-A chains, slow myosin heavy chains, and slow skeletal muscle troponin T chains. Collectively, these proteins are a class of slow-twitch muscle fiber and mirror that Hanwoo muscle tissue sampled for the current study contained more slow-twitch muscle fibers than Holstein one. Conversely, proteins detected from the Holstein sample included ankyrin repeat domain 2 and creatin kinase isomers. Given that creatin kinase isomers are related to the fast-twitch muscle, these results likely indicate that Holstein muscle tissue sampled for the current study contained more fast-twitch muscle fibers than Hanwoo beef.

• Journal of Korean Institute of Industrial Engineers
• /
• v.5 no.2
• /
• pp.21-36
• /
• 1979

Static muscle contractions when prolonged or frequently repeated result in discomfort, fatigue, and musculosketal injuries. An analytic and quantitative model has been developed in order to expand the working knowledge on muscle fatigue. In this paper, three Markov models of muscle fatigue are developed. These models are based on motor unit fatigue-recovery characteristics obtained from information on motor unit behavior as it relates to fatigue and graded exertions. Three successively more realistic models are developed that involve: (1) homogeneous motor units with intensity-dependent fatigue rates and state-independent recovery rates (the HMSI model); (2) homogeneous motor units, intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model); and (3) non-homogeneous motor units (i.e., Type S and Type F), intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model). The result indicate that a simple stochastic model provide a means to analyze the complex nature of muscle fatigue in sequential static exertions.

• Journal of Nutrition and Health
• /
• v.35 no.10
• /
• pp.1031-1037
• /
• 2002

The purpose of present study was to evaluate the effect of endurance exercise training on skeletal muscle free amino acid concentrations, and differences in free amino acid concentration between soleus muscle which consists of mostly slow twitch oxidative fiber and extensor digitorum longus muscle which consists of fast twitch oxidative glycolytic fiber. Sixteen male SD rats (4 weeks old) were randomly devided into two groups, and fed a purified AIN-93M diet with or without aerobic exercise training according to the protocol (running on the treadmill at 25 m/min for 60 min, 5 days a week) for 6 weeks. Exercise-training for 6 weeks significanly reduced the commulative body weight gain (p＜0.05) and food efficiency ratio (p＜0.01) of rats. The result showing mitochondrial citrate synthase activity of soleus muscle was significantly higher in exercise-trained rats compared to the value for control animals (p＜0.01) indicates aerobic exercise-training was successfully accomplished in the trained group. No difference was found in the muscle aminogram pattern between soleus muscle and extensor digitorum longus muscle of control animals. However, free amino acid concentrations of soleus muscle were from 1.2 to 3.9 times of those found in extensor digitorum longus muscle of control rats, depending on an individual amino acid. Intermediate level of endurance exercise training for 6 weeks did not influence concentrations of most of free amino acid in soleus muscle of rats collected at an overnight fasted and rested state. In contrast, isolucine and leucine concentrations in extensor digitorum longus muscle of exercise-trained rats were significantly lower than those for control animals. These results indicate that aerobic energy metabolism had not been efficiently conducted, and thereby the utilization of BCAA for energy substrate was enhanced in fast twitch oxidative glycolytic fibers of extensor digitorum longus muscle of rats followed exercise-training protocol for 6 weeks.

• The Korean Journal of Physiology
• /
• v.22 no.1
• /
• pp.63-77
• /
• 1988

This study was carried out to investigate relationships between maximal running time (MRT) and glycogen supercompensation in fast twitch white fibers (white vastus, WV), fast twitch red fibers (red vastus, RV) and slow twitch red fibers (soleus muscle, SM) of endurance-trained rats. Male rats of a Sprague-Dawley strain were divided into the trained groups and untrained groups. Untrained groups were acquired to run on the treadmill 10 minutes for 3 days and remained rest and maintained with mixed diet for 4 weeks. For last 10 days of resting period, the untrained rats were divided into 3 groups i.e. mixed diet (untrained control), high and low carbohydrate (CHO) diet groups. And each group was subdivided into 2 groups, one group was tested for the MRT and the other was sacrificed to measure the blood glucose, blood lactate, glycogen contents of liver and muscles. The experimental groups were trained on treadmill by a modified method of Constable et al. (1984) maintained with mixed diet for 4 weeks. After measurement of MRT of this group, they were also divided into high and low CHO groups and fed with these diet for 2 days and MRT of each group was measured again to see the effect of high or low CHO feeding on the MRT. Each group was maintained with the same diet for next 2 days during which some of the rats were sacrificed at given time intervals for the measurements of blood glucose and lactate, liver and the muscles glycogen. The results were summarized as follows; 1) In the untrained group, there were no significant differences between subgroups in MRT, glycogen conent of SM, RV and WV. But blood glucose concentration and glycogen content of liver of low CHO group were significantly lower than those of mixed diet group. 2) The MRT and glycogen content of SM, RV and WV of trained mixed diet group were significantly increased compared to those of untrained mixed diet group, but there was no significant difference in glycogen content of liver. 3) MRT of trained mixed, high CHO and low CHO groups were $137{\pm}9.8,\;176{\pm}9.8\;and\;129{\pm}7.3\;min$ respectively with the significant difference between them. 4) There were no differences in blood lactate concentrations between the trained high and low CHO groups immediately after maximal running and during recovery period. 5) Glycogen contents in RV and SM of trained high CHO group were significantly increased, and glycogen contents in RV, WV and liver of trained low CHO group were significantly decreased compared to those of trained mixed diet group. 6) Immediately after maximal running, the blood glucose concentrations of trained high CHO and low CHO groups were $73{\pm}4.0\;and\;67{\pm}6.9mg%$ respecitively. The blood glucose of the trained high CHO group was fully recovered within one hour by feeding. But blood glucose concentration of low CHO group was slowly recovered up to $114{\pm}4.1mg%$ after two hours of feeding and maintained. Those values were still significantly lower than that of trained mixed diet group. The synthetic rates of glycogen in liver and muscles during the recovery period followed the similar time course of the blood glucose recoveries in each group. These results suggest that an increase in MRT of trained high CHO group was attributed to the glycogen supercompensation in slow twitch muscle fibers. And a decrease in MRT of trained low CHO may be due to decreased glycogen contents of liver and muscles. The results also suggest that glycogen supercompensation was more evident in slow twitch red fibers of endurance-trained rats and blood glucose is one of the limiting factors of glycogen synthesis.

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.10
• /
• pp.1496-1502
• /
• 2006

Skeletal muscle contains slow and fast twitch fibers. These skeletal muscle fibers express type I and type II myosin, respectively, and these myosin isoenzymes have different ATPase activity. The aim of this study was to investigate protein profiles of bovine skeletal muscles by proteomic analysis. Fifty seven spots of distinct proteins were excised and characterized. The expression of sixteen spots was differed in longissimus dorsi muscle with a minimal 2-fold change compared to biceps femoris muscle. The majority of differentially expressed proteins belonged to metabolic regulation-related proteins such as glyceraldehyde 3-phosphate dehydrogenase, triosephosphate isomerase and carbonic anhydrase 3. The real time-PCR assay confirmed an increase or induction of specific genes: RGS12TS isoform, GAPDH, triosephosphate isomerase and carbonic anhydrase. These results suggest that the expression of metabolic proteins is under a specific control system in different bovine skeletal muscle. These observations could have significant implications for understanding the physiological regulation of bovine skeletal muscles.

• Journal of the Korean Society of Physical Medicine
• /
• v.1 no.1
• /
• pp.117-123
• /
• 2006

Objectives : The purpose of this study was conducted to find correct facilitation and clinical facilitation with proprioceptive neuromuscular facilitation (PNF). Methods : This is a literature study with books, articles, seminar note and books for PNF international course. Results : Treatment approach was changed from managements of reflex to facilitation. The facilitation will make passive or active motion. But it can not match with normal functional activities, lack of the active movement, and facilitation of musculoskeletal can interaction with environment. Conclusions : Facilitation of the Functional activities in the main therapy goal. Any necessary information, such as visual and acoustical information must be integrated. Spatial summation and temporal summation integrated also. Integrated information for the facilitation will be increased activity of alpha-motorneurons, activity of interneurons, and muscle fiber structural changes from slow twitch fibers to fast twitch fibers. Suggested facilitate goal-oriented of movements at a functional level and reduce stiffness at structural level.

• Physical Therapy Korea
• /
• v.10 no.1
• /
• pp.109-128
• /
• 2003

This study tested whether repeated measurement of median frequency (MDF)-related variables could express the muscle power changes during a 12-week DeLome strengthening program, by using consecutive overlapping FFT (Fast Fourier transformation) and integrated EMG (IEMG) from surface EMG data for isometric and isotonic exercise. To evaluate the effect of training, the following were recorded every 3 weeks for the elbow flexors and knee extensors of 5 healthy male volunteers: MVC, lRM, limb circumference, and surface EMG during isometric MVC or isotonic contraction at 10RM load. From the EMG data, IEMG and variables from a regression analysis between MDF and time were obtained. MVC, lRM, IEMG, and initial MDF increased linearly over the training period. The fatigue index and slope of the regression line increased temporarily until the 6th week and decreased thereafter. From these results, there appeared to be enhanced neural recruitment of fast twitch fibers in the first 6 weeks and continued enhancement in the recruitment and hypertrophy of fast twitch fibers, which led to increased fatigue resistance, over the last 6 weeks. Accordingly, the MDF and IEMG analysis technique could demonstrate the effect of the program detected significant changes in both isometric and isotonic contractions. EMG analysis methods can be used to estimate the electrophysiological and histological changes in skeletal muscles during a strengthening program.

• Physical Therapy Korea
• /
• v.10 no.3
• /
• pp.141-149
• /
• 2003

Median frequency can be regarded as a valid indicator of local muscle fatigue. As local muscle fatigue develops, the muscle fiber conduction velocity decreases, the fast twitch fibers are recruited less, and consequently the median frequency shifts toward the lower frequency area. The aim of this study was to test the characteristics of the median frequency according to exercise load (30% and 60% of MVC on the biceps brachii, 40% and 80% of MVC on the vastus lateralis) during the fatiguing isometric exercise. Thirteen healthy male volunteer students of Yonsei University were recruited. After the testing maximal voluntary isometric contraction, three variables (initial median frequency, regression slope, fatigue index) from the regression line of MDF data were measured in each exercise load. The results showed that the regression slope and fatigue index were significantly different for the biceps brachii, but not for the vastus lateralis initial MDF was not significant difference according to the exercise load on both muscles. The regression slope and fatigue index could monitor physiologic muscle change during fatiguing isometric exercise. The results showed that two MDF variables reflect the local muscle fatigue according to the exercise load.