Overview of muscle metabolism, muscle fiber characteristics, and meat quality

최지환 충남대학교 농업과학연구소 2018 Korean Journal of Agricultural Science Vol.45 No.1

Meat comes from the skeletal muscles of farm animals, such as pigs, chickens, and cows. Skeletal muscles are composed of many muscle fibers. Muscle fibers are categorized into three types, fiber type I, IIA, and IIB, based on their contractile speed and metabolic properties. Different muscle fiber types have different biochemical, physiological, and biophysical characteristics. Especially, the characteristics of muscle fiber type I and IIB are opposite to each other. Muscle fiber type I has a relatively strong oxidative metabolic trait and a higher content of lipids. In contrast to fiber type I, muscle fiber type IIB has a strong glycolytic metabolic trait and a relatively lower content of lipids and a higher content of glycogen. Muscle fiber type IIA has intermediate properties between fiber type I and IIB. Thus, muscles with different fiber type compositions exhibit different ante- and post-mortem muscle characteristics. In particular, the different metabolic traits of muscles due to the different compositions of the fiber types strongly affect the biochemical and physiological processes during the conversion of muscle to meat and subsequently influence the quality of the meat. Therefore, understating muscle metabolism and muscle fiber characteristics is very important when discussing the traits of meat quality. This review is an overview on basic muscle metabolism, muscle fiber characteristics, and their influence on meat quality and finally provides a comprehensive understanding about the fundamental traits of muscles and meat quality.

An introduction to skeletal muscle fiber physiology and technology: principles and its applications to exercise science research

( Jeong Hun Bae ),( Jong-hee Kim ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1

Skeletal muscle is a complex structure comprised of not only myocytes, known as muscle cells or muscle fibers, but also connective tissues, blood vessels, and nerves. It plays a major role in voluntary body movements and functions as a direct conveyor of response or adaptation to various conditions such as nutrition, aging, inactivity, disease and exercise. Changes in structure and function of skeletal muscles, moreover, can affect overall health and quality of life. Skeletal muscle fiber physiology reveals contractile and metabolic properties of individual muscle cells, and may show underlying mechanisms that cause structural and functional changes in whole muscle. Skeletal muscle fiber technology is a chemo-mechanically coupled test technique using an instrument called “in-vitro permeabilized fiber test system” for evaluating the mechanical characteristics of muscle fibers such as force-pCa, length-tension, force-velocity-power, and stiffness. In fact, there have been great advances in skeletal muscle fiber-based technology in recent years; however, its application to the field of exercise nutrition and exercise physiology is limited. The purpose of this study is to introduce the basic principles of muscle fiber physiology and technology, including apparatus, fiber preparation, and test procedure. In addition, we will present how this technology has been used in exercise science research. Finally, we will discuss the different physiological and pathological conditions where this technique can be applied.

Estimation of Correlation Coefficients between Histological Parameters and Carcass Traits of Pig Longissimus Dorsi Muscle

Ryu, Y.C.,Rhee, M.S.,Kim, B.C. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.3

The aim of this study was to investigate the histochemical parameters of muscle fibers, and to estimate the correlation between these histological parameters and carcass traits in pigs. A total of 230 crossbred Duroc$\times$(Yorkshire$\times$Landrace) pigs (149 gilts and 81 castrated male pigs) was evaluated. Carcass traits (carcass weight, backfat thickness, and loin eye area), muscle fiber size (crosssectional area, diameter, and perimeter), muscle fiber number (density of fibers/$mm^2$ and total number of fibers), and fiber type composition (percentages of myofibers and relative areas of each fiber type) were evaluated. Mean cross-sectional area (CSA) and type IIB fiber CSA were positively correlated to carcass weight, backfat thickness and loin eye area. Mean fiber CSA was mostly related to type IIB CSA (r=0.98) as a result of the high percentage of type IIB fibers in the longissimus muscle. Correlations between fiber diameters and perimeters were also high, and showed similar results with CSA. Mean fiber density was negatively correlated to carcass weight (r=-0.24), backfat thickness (r=-0.18) and loin eye area (r=-0.27). To the contrary, total fiber number was positively correlated with carcass weight (r=0.27) and loin eye area (r=0.53). Carcass weight and loin eyZe area were not significantly related to muscle fiber composition. For backfat thickness, there was an opposition between type IIA percentage, which was positively related and type IIB percentage, which was negatively related. Fiber type composition of type I and IIA fibers were negatively correlated to that of type IIB fibers (r=-0.67 to -0.74). In the present study, carcass weight and loin eye area were positively correlated to CSA and negatively correlated to fiber density. But, these relationships were generally low. The fiber density was strongly affected by muscle fiber size and the total fiber number was affected either by CSA of muscle fiber and loin eye area. Fiber type composition was much more related to their numerical abundance than their CSA.

Muscle Fiber Typing in Bovine and Porcine Skeletal Muscles Using Immunofluorescence with Monoclonal Antibodies Specific to Myosin Heavy Chain Isoforms

Sumin Song,Chi-Hoon Ahn,Gap-Don Kim 한국축산식품학회 2020 한국축산식품학회지 Vol.40 No.1

The aim of this study was to optimize staining procedures for muscle fiber typing efficiently and rapidly in bovine and porcine skeletal muscles, such as longissimus thoracis, psoas major, semimembranosus, and semitendinosus muscles. The commercially available monoclonal anti-myosin heavy chain (MHC) antibodies and fluorescent dyeconjugated secondary antibodies were applied to immunofluorescence histology. Two different procedures, such as cocktail and serial staining, were adopted to immunofluorescence analysis. In bovine muscles, three pure types (I, IIA, and IIX) and one hybrid type, IIA+IIX, were identified by the cocktail procedure with a combination of BA-F8, SC-71, BF-35, and 6H1 anti-MHC antibodies. Porcine muscle fibers were typed into four pure types (I, IIA, IIX, and IIB) and two hybrid types (IIA+IIX and IIX+IIB) by a serial procedure with a combination of BA-F8, SC-71, BF-35, and BF-F3. Unlike for bovine muscle, the cocktail procedure was not recommended in porcine muscle fiber typing because of the abnormal reactivity of SC-71 antibody under cocktail procedure. Within the four antibodies, combinations of two or more anti-MHC antibodies allowed us to distinguish pure fiber types or all fiber types including hybrid types. Application of other secondary antibodies conjugated with different fluorescent dyes allowed us to get improved image resolution that clearly distinguished hybrid fibers. Muscle fiber characteristics differed depending on species and muscle types.

Distally-extending muscle fibers across involved joints: study of long muscles and tendons of wrist and ankle in late-term fetuses and adult cadavers

Shaohe Wang,Shogo Hayashi,Zhe-Wu Jin,Ji Hyun Kim,Masahito Yamamoto,Gen Murakami,Shin-ichi Abe 대한해부학회 2023 Anatomy & Cell Biology Vol.56 No.1

It is unclear whether forearm and crural muscle fibers extend distally across the wrist and ankle joints, respectively. We hypothesized, in late-term fetuses, an over-production of muscle bellies extending over the joint. Muscle fibers in histological sections from unilateral wrists and ankles of 16 late-term fetuses (30–40 weeks) were examined and compared with 15 adult cadavers. Muscle fibers of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) in fetuses, especially muscle bellies to the third and fourth fingers, were found to extend far distally beyond the radiocarpal joint. The extensor digitorum and extensor pollicis longus on the extensor side of the wrist were found to carry distally-extending muscle fibers, but these fibers did not extend beyond the distal end of the radius. In the ankle, most muscle bundles in the flexor hallucis longus (FHL), fibularis brevis (FB) and extensor digitorum longus extended distally beyond the talocrural joint, with most FB muscle fibers reaching the level of the talocalcaneal joint. In adult cadavers, muscle fibers of the FDP and FHL did not reach the levels of the radiocarpal and talocrural joints, respectively, whereas the FB muscle belly always reached the talocalcaneal joint. Similarly, some of the FDS reached the level of the radiocarpal joint. Generally, infants’ movements at the wrist and ankle could result in friction injury to over-extended muscle. However, the calcaneal and FDP tendons might protect the FB and FDS tendons, respectively, from friction stress.

Comparison of Meat Quality and Muscle Fiber Characteristics between Porcine Skeletal Muscles with Different Architectures

박준영,송수민,Huilin Cheng,임조은,정은영,문성실,최정석,허선진,주선태,김갑돈 한국축산식품학회 2022 한국축산식품학회지 Vol.42 No.5

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. Parallelfibered 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.

Muscle Fiber Characteristics and Their Relationship to Water Holding Capacity of Longissimus dorsi Muscle in Brahman and Charolais Crossbred Bulls

Waritthitham, A.,Lambertz, C.,Langholz, H.-J.,Wicke, M.,Gauly, M. Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.5

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.

The lumbar multifidus is characterised by larger type I muscle fibres compared to the erector spinae

Anouk Agten,Sjoerd Stevens,Jonas Verbrugghe,Bert O,Eijnde,Annick Timmermans,Frank Vandenabeele 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.2

The metabolic capacity of a muscle is one of the determinants of muscle function. Muscle fiber type characteristics give an indication about this metabolic capacity. Therefore it might be expected that the lumbar multifidus (MF) as a local stabilizer contains higher proportions of slow type I fibers, compared to the erector spinae (ES) as a global mobilizer. The aim of this study is to determine the muscle fiber characteristics of the ES and MF to provide insight into their structural and metabolic characteristics, and thereby the functional capacity of both muscles. Muscle fiber type characteristics in the ES and MF were investigated with an immunofluorescence staining of the myosin heavy chain isoforms. In both the ES and MF, type I muscle fibers are predominantly present. The cross-sectional area (CSA) of type I muscle fibers is significantly larger in the lumbar MF compared to the ES. However, the mean muscle fiber type percentage for type I was not significantly different, which resulted in an insignificant difference in relative cross-sectional area (RCSA) for type I. No significant differences were found for all other muscle fiber types. This may indicate that the MF displays muscle fiber type characteristics that tend to be more appropriate to maintain stability of the spine. However, because we could not demonstrate significant differences in RCSA between ES and MF, we cannot firmly state that there are functional differences between the ES an MF based only on structural characteristics.

점프운동이 내측 비복근 근방추의 형태에 미치는 영향

옥정석,임재형 대한스포츠의학회 1997 대한스포츠의학회지 Vol.15 No.1

The purpose of this study was to evaluate the changes of muscle spindles after jump training. The cross sectional area of muscle spindles was measured by observing light microscopically van Gieson-stained serial sections of muscle of the rat. Intrafusal fibers from the rat medial gestrocnemius were investigated in sedentary animals and animals acutely exercised 50 trials in a day for 10 day for 10 days. Rats were trained in a modified two-way suttle box(7.5W, 0.5mA AC). After a preparatory period of 30 sec from the start of the trial, a light stimulus lasted 5 sec, 5 seconds after the end of the light stimulus, the electric current with 5-duration was applied to the floor grid(foot shock) as the unconditioned stimulus. The electroshock was a series of electro-pulses including both sinusoid and rectangular waves. The rat must jump to the other part of the box in response to the light before the application of the electric shock. The mean cross-sectional area of intrafusal fibers from the exercised animals was significantly less than that of fibers from the sedentary animals(p<0.05). The mean long-radius of intrafusal fibers from the exercised animals was significantly less than that of fibers from the sedentary animals(p<0.01), and so did the mean-circumference of intrafusal fibers. The mean long-radius of nuclear bag fibers from the exercised animals was significantly less than that of fibers from the sedentary animals(p<0.05). The mean cross-sectional area, the mean long-radius, the mean short-radius of nuclear chain fibers from the exercised animals was significantly less than that of fibers from the sedentary animals(p<0.01). On the basis of the results, we have drawn the following conclusions: 1) changes in muscle spindle morphology accompany the jump training, however, The morphology of muscle spindle in the sedentary animals had more levels of the mean cross-sectional area, the mean long-radius, and the mean short-radius than those of fibers in the exercised animals. 2) In contrast to the effect of exercise on the cross-sectional area in extrafusal fibers, there was evidence of less activity in the intrafusal fibers of the exercised animals.

한국 성인 남성의 단일 근섬유 유형별 수축 특성과 하지 근력과의 상관관계

전유나,김희쟁,양소영,이소현,김대영,배준현,이호준,임재영,최승준 한국운동생리학회 2018 운동과학 Vol.27 No.1

PURPOSE: This study investigated the muscle fiber type-related contractile properties and examined the relationship between whole limb muscle strengths and single muscle fiber contractile properties in Korean men. METHODS: Six Korean men (29.8±1.49 yr) were recruited and participated in the study. Samples were obtained from vastus lateralis muscles. CSA, Po, SF, Vo of single fiber segments were measured using an isometric force transducer and a high-speed motor. Silver staining was performed to identify MHC isoform composition of single muscle fiber segments. Multiple regression was tested to identify the relationship between single muscle fiber contractile properties and whole muscle strength. RESULTS: MHC isoforms were distributed in different proportion (Type I: 57.3%, IIa: 34.2%, IIa/IIx: 4.3%, IIx: 4.3%). CSA of type IIx were smaller compared to type I (-50%) and type IIa (-57.5%). Po in type IIa was 12.9% higher compared to type I (p<.05). While SF in type IIa were 7.7% higher than type I, type IIx were higher than type I, IIa, IIa/IIx (31.4%, 25.7%, 30.9%). Vo increased in the order type I<IIa<IIa/IIx<IIx. There was positive correlation between single fiber and properties (Po vs thigh strength: r2=.248, Po vs thigh power: r2=.058, Vo vs thigh power: r2=.095). CONCLUSIONS: These results suggest that single muscle fiber contractile properties were exclusively dependent on fiber type isoforms, ruling out a possibility of race-induced difference in fiber type-matched contractile properties.