Ovidius University Annals, Series Physical Education and Sport / SCIENCE, MOVEMENT AND HEALTH Vol. XI, ISSUE 2 Supplement, 2011, Romania The JOURNAL is nationally acknowledged by C.N.C.S.I.S., being included in the B+ category publications, 2008-2011. The journal is indexed in: Ebsco, SPORTDiscus, INDEX COPERNICUS JOURNAL MASTER LIST, DOAJ DIRECTORY OF OPEN ACCES JOURNALS, Caby, Gale Cengace Learning TYPOLOGY AND PROFILE OF SPINE MUSCLES. STRUCTURE OF MYOFIBRILS AND ROLE OF PROTEIN COMPONENTS – REVIEW OF CURRENT LITERATURE STRATON ALEXANDRU1, ENE-VOICULESCU CARMEN1, GIDU DIANA1, PETRESCU ANDREI1 Abstract. Muscular profile of spine muscles has a great importance in trunk stability. It seems that muscles which support the spine show a high content of red muscle fiber with a cross section area equal or higher than white muscle fibers. It is possible that lumbar extensor muscles to have different functional capacity between sexes. Most of the myofibril structural proteins except protein actin and protein myosin have a role in maintaining the structural integrity of muscle cell. Key words: muscle, fibres, myofibrils, proteins, spine. thoracic muscle structure lying superficial and deep is Introduction composed of 74% type I fibers, lumbar muscle Proper understanding of muscle fibers profile of structure located superficially is composed of 57% muscles supporting the spine and the role of muscle type I fibers and lumbar muscle structure located deep cell structural proteins leads to better achievements in is composed of 63% type I fibers. Type I muscle fiber performance training and rehabilitation. diameter is significantly larger than that of type II fibers. Another study, conducted on 42 patients Muscle fibers typology divided into two groups - 21 patients with lumbar Skeletal muscle contains two major types of back pain and 21 patients without lumbar back pain muscle fibers: slow twitch red or type I fibers) and almost identical groups as gender, age and body mass fast twitch white or type II fibers). Slow fibers reach index) showed that back muscles of patients with peak tension in about 110ms milliseconds) from the lumbar back pain, has a higher glycolitic profile rich moment of stimulation, and rapid fibers reach peak in white fibers) A. F. Mannion et al., 1997b). tension in about 50ms from the moment of Mannion A. F. et al., 1997a), in a study of 17 male stimulation. So, fast twitch fibers have a rapid subjects and 14 female subjects, using the method of response time to stimulation, more than twice reported muscle biopsies performed in the corresponding spinal to slow twitch fibers. extensor of ten thoracic vertebrae and three lumbar Until now, we have identified only one type of vertebrae, showed that the ratio of cross-sectional area slow twitch fibers and four types of fast twitch fibers: and the smallest diameter of the corresponding muscle IIa oxidative-glycolitic, IIx oxidative glycolitic which fiber is higher in the thoracic region, compared to the has some physiological and biochemical differences, lumbar region. Also, no significant differences were such as time of contraction, motoneuron size, fatigue found between the two regions on the percentage of resistance or oxidative capacity, maximum time of type I fibers, cross-sectional relative area of type I use, power output, mitochondrial density, etc., than IIa fibers and the ratio of cross sectional areas of type I fibers), IIb predominantly glycolitic and IIc A. Nicu fibers and, respectively, type II fibers. Male subjects şi L. Baroga, 1993) which contain transformation have a muscle fiber cross-sectional area bigger than myosin, characterized by the shift from the fast twitch female subjects for all types of muscle fibers and in fibers to slow twitch fibers G. Dumitru, 1994). The both regions - thoracic and lumbar - of the spine. Also, difference between type IIa fibers and type IIb male subjects have a similar average of cross-sectional predominantly glycolitic is characterized mainly by area for all types of muscle fibers, compared to female fatigue and oxidative capacity and frequency of subjects, who have an average cross-sectional area recruitment type IIa fibers, it seems that are increased in type I muscle fibers than type IIa fibers frequently recruited, than type IIb fibers); slow fibers and IIb fibers, the latter showing no significant are mostly recruited and type IIc fibers are poorly differences in average cross-sectional area. Therefore, recruited. fiber characteristics of spine extensor muscles differ On average, the vast majority of muscles are from those of skeletal muscles by, the relative composed of 50% type I fibres, 25% type IIa fibers, predominance in size of type I fibers slow twitch 22-24% type IIb fibers, and 1-3% type IIc fibers. fibers or red fibers), reflecting the complex role of However the exact percentage of these types of those muscles in maintaining posture Mannion A. F. muscle fibers varies considerably in different subjects et al., 1997a). and different muscles J. H. Wilmore and D. L. Also at the level of the spine extensor muscles, in a Costill, 1994). study of 16 subjects 9 male and 7 female, aged between 20 and 30 years) using the muscle biopsies Muscular profile at the level of thoraco-lumbar method performed in the lumbar region of the human spine erector spinae on multifidus and the longissimus Sirca A. and Kostevc V., 1985) showed that muscles, showed no significant differences between 1 Faculty of Physical Education and Sport, Ovidius University of Constanta, ROMANIA Email: [email protected] 627 Received 23.04.2011 / Accepted 19.06.2011 Ovidius University Annals, Series Physical Education and Sport / SCIENCE, MOVEMENT AND HEALTH Vol. XI, ISSUE 2 Supplement, 2011, Romania The JOURNAL is nationally acknowledged by C.N.C.S.I.S., being included in the B+ category publications, 2008-2011. The journal is indexed in: Ebsco, SPORTDiscus, INDEX COPERNICUS JOURNAL MASTER LIST, DOAJ DIRECTORY OF OPEN ACCES JOURNALS, Caby, Gale Cengace Learning the two muscles on the relative occurrence of type I form a helix structure F-actin), which at seven G- fibers 62% versus 57%), type IIa fibers 20% vs. actin monomers is twisted by about half arc circle. 22%), type IIb fibers 18% vs. 22%) and, on the Each chain of F-actin is a polymer composed of about absolute size of muscle fibers average between 58 200 G-actin molecules R. M. Enoka, 1994). Each G- and 66 microns). In female subjects, type I fibers actin monomer has an active site in which myosin occupied a larger relative area than male subjects 70- molecules can couple during muscle contraction. The 75% vs. 54-58%), even though the relative number of groove formed along the helix structure is a series of type I fibers was similar for both sexes. This can be fibrous elongated protein molecules called explained by a cross-sectional area of type II fibers tropomyosin. Each tropomyosin molecule spans on a smaller than the cross sectional area of type I fibers, in distance of seven G-actin monomers along F-actin women. These data suggest a different functional groove R. R. Seeley et al., 2004). At one of the ends capacity of the lumbar extensor muscles between of the tropomyosin molecule there is a protein sexes A. Thorstensson and H. Carlson, 1987). complex called troponin consisting of three adjacent Another study realised on 13 subjects 9 females subunits: troponin-C capable to reversibly bind and 4 males, aged between 24 and 55), using the calcium ions, troponin-T which attaches the this muscle biopsy from the abdominal muscles right complex troponin) on tropomyosin and troponin-I abdominal muscle, oblique external abdominal that has an inhibitory function inhibits four to seven muscle, oblique internal abdominal muscle and G-actin molecules to bind on the myosin, when transversal abdominal muscle) showed that there are tropomyosin is present). Troponin-C has four binding significant differences between subjects, in muscle sites, two for Ca2+ ions and two for Ca2+ ions or Mg2+ fiber type variation. Mean distribution of muscle ions R. M. Enoka, 1994). There are also, differences fibers was 55-58% type I fibers, 15-23% of type IIa in troponin-C protein, corresponding to fast fibers fibers, 21-28% of type IIb fibers and 0-1% type IIc compared to slow fibers S. V. Perry, 1985). fiber. Muscle fibers diameter was similar for most Troponin-tropomyosin complex regulates skeletal muscle groups studied average 50-54 microns), muscle contraction, through the influence of actin except transversal abdominal muscles which had a activity R. M. Enoka, 1994). smaller diameter for the type II fibers average 45 Fundamental unit of thick filaments is myosin, a microns). Also, muscle fiber composition, complex molecule with several distinct regions. Most histochemically studied at different abdominal of the length of this molecule forms a region often muscles, appear to exert similar functional capacity T. called the "tail" composed of light meromyosin Häqqmark and A. Thorstensson, 1979). LMM). The rest of the molecule, heavy meromyosin HMM), is composed of a protein chain that ends with Structure of myofibrils and role of protein a section called globular head. Globular portion, components called the S1 region subfragment 1) is responsible for Muscle-tendon structure is a complex biological chemical and enzymatic activity, which produces organ capable of generating considerable force in muscle contraction. It also contains the actin binding order to stabilize and/or move the body segments and site, which can interact with the thin filament, and the in energy absorption, which acts on the human body. place of ATP binding site, which is involved in energy This muscle-tendon structure is controlled by neural supply to achieve muscle contraction process. The impulses, generating power by converting chemical chain protein, called S2 region subfragment 2) serves energy into mechanical energy.