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Muscle Fibre Size (muscle + fibre_size)
Selected AbstractsMuscle fibre size and capillarity in Korean diving womenACTA PHYSIOLOGICA, Issue 2 2003K. A. Bae Abstract Aim:, Effects of prolonged habitual cold-water immersion on fibre size and capillarity in vastus lateralis muscle were studied in human beings. The hypothesis tested in the present study was that cold acclimatized human skeletal muscle would have reduced muscle fibre size and higher capillarity, favouring the idea of efficacy of recruitment under cold environment. Methods:, Ten women breath-hold divers (BHDs) and 10 active women (controls CONs) participated in this study. Muscle biopsy was obtained from vastus lateralis and determined fibre type composition and capillary density. Results: A major finding was that all BHDs revealed a markedly smaller cross-sectional area (CSA) in all fibre types than the CONs, or even than any other morphological data reported in previous investigations. Furthermore, mean CSA of type II fibre (range 1205,2766 ,m2) was much smaller than type I fibre (2343,4327 ,m2). The number of capillaries per fibre in different fibre types in the BHDs was higher than in the CONs (P < 0.001), and diffusional area was smaller in type II fibres than in type I fibres (P < 0.001). The BHDs and the CONs have similarity in the percentage of type I fibres, but type II fibre was predominant in both groups. Interestingly the proportion of type IIx fibre in the BHDs was higher (31%) than in the CONs (22%). No significant difference was found in the thigh circumference between the groups. Conclusion:, The present study demonstrates that prolonged habitual cold-water immersion may induce a decrease in fibre size and an increase in capillarity in human skeletal muscle. [source] Chronic Hypoxia Induces Prolonged Angiogenesis in Skeletal Muscles of RatEXPERIMENTAL PHYSIOLOGY, Issue 3 2002D. Deveci Skeletal muscle capillarity and fibre cross-sectional area were investigated within and between diaphragm (Diaph), extensor digitorum longus (EDL), soleus (SOL) and tibialis anterior (TA) muscles of control and chronic hypoxic (12% O2 for 6 weeks) adult male Wistar rats (final body mass ,355 g). Cryostat sections were stained for alkaline phosphatase activity to depict all capillaries, and for succinic dehydrogenase to demonstrate regional differences in oxidative capacity within the muscles. Hypoxia-induced angiogenesis occurred in all muscles (P < 0.01), with capillary-to-fibre ratio (C:F) being higher in the more active and oxidative muscles, Diaph (27%) and SOL (26%), than phasically active and glycolytic muscles, TA (21%) and EDL (15%). Diaph, SOL and EDL maintained fibre size, and hence showed an increased capillary density (CD) and reduced intramuscular diffusion distance (DD), whereas TA showed fibre hypertrophy and maintained CD and DD compared to control muscles. The extent of angiogenesis among different regions of muscle varied so as to suggest that muscle fibre size has an additional influence on capillary growth during chronic systemic hypoxia, which is progressive over an extended period of systemic hypoxia. [source] Fibre type composition of the human psoas major muscle with regard to the level of its originJOURNAL OF ANATOMY, Issue 6 2009Juraj Arbanas Abstract The aim of our study was to explore the fibre type composition of the human psoas major muscle at different levels of its origin, from the first lumbar to the fourth lumbar vertebra, and to compare the muscle fibre size and distribution of different fibre types between levels with respect to its complex postural and dynamic function. Muscle samples were collected from 15 young males (younger than 35 years). Serial transverse sections (5 ,m) of the samples were cut by cryomicrotome. Type I, IIA and IIX muscle fibres were typed using myosin heavy chain identification. The serial sections were analysed using a light microscope with a magnitude of 100×. The differences between measurements were evaluated using a repeated-measures anova and Scheffé test for post-hoc analysis. Our study showed that the human psoas major muscle was composed of type I, IIA and IIX muscle fibres. It had a predominance of type IIA muscle fibres, whereas type I muscle fibres had the largest cross-sectional area. Type IIX muscle fibres were present as a far smaller percentage and had the smallest cross-sectional area. Moreover, the fibre type composition of the psoas major muscle was different between levels of its origin starting from the first lumbar to the fourth lumbar vertebra. We conclude that the fibre type composition of the psoas major muscle indicated its dynamic and postural functions, which supports the fact that it is the main flexor of the hip joint (dynamic function) and stabilizer of the lumbar spine, sacroiliac and hip joints (postural function). The cranial part of the psoas major muscle has a primarily postural role, whereas the caudal part of the muscle has a dynamic role. [source] | ||||||||||