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- Charifi, N., et al.
(författare)
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Enhancement of microvessel tortuosity in the vastus lateralis muscle of old men in response to endurance training
- 2004
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 554:Pt 2, s. 559-569
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Tidskriftsartikel (refereegranskat)abstract
- Muscle microvascularization is usually quantified in transverse sections, in absolute terms (capillaries around fibres, CAF, or capillary-to-fibre ratio, C/F) or as CAF related to fibre area (CAF/area, CAFA). The capillary-to-fibre perimeter exchange ratio (CFPE) has been introduced in order to assess the role of the capillary-to-fibre interface in resistance to O(2) diffusion. The ratio between the length of capillaries in contact with fibres and fibre perimeter (LC/PF) has also been used as an index for capillary tortuosity. The possibility of change in capillary tortuosity with endurance training was not considered in previous studies. Consequently, this study investigated the effect of 14 weeks of endurance training on muscle microvascularization, including microvessel tortuosity, in 11 elderly men (8th decade). Microvessels were analysed using the CD31 antibody. Together with the significant increase in peak oxygen exchange and citrate synthase activity, there was a significant increase in C/F. While CFPE and CAFA remained unchanged, an important finding was the clear increase in LC/PF (56%; P < 0.001) for a same sarcomere length. We also found a strong correlation between oxidative enzyme activity and LC/PF both before and after training. These results indicate that endurance training induces significant remodelling in the microvessel network in elderly men and that an increase in the degree of microvessel tortuosity would be an important mechanism of adaptation to endurance training.
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| 4. |
- Kadi, F, et al.
(författare)
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Concomitant increases in myonuclear and satellite cell content in female trapezius muscle following strength training.
- 2000
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Ingår i: Histochemistry and Cell Biology. - 0948-6143 .- 1432-119X. ; 113:2, s. 99-103
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Tidskriftsartikel (refereegranskat)abstract
- A skeletal muscle fibre maintains its cytoplasmic volume by means of hundreds of myonuclei distributed along its entire length. Therefore it is hypothesised that changes in fibre size would involve modifications in myonuclear number. In this study, we have examined whether 10 weeks of strength training can induce changes in the number of myonuclei and satellite cells in female trapezius muscles. Biopsies were taken pre- and posttraining from the upper part of the descending trapezius muscle of nine subjects. Muscle samples were analysed for fibre area and myonuclear and satellite cell number using immunohistochemistry. There was a 36% increase in the cross-sectional area of muscle fibres. The hypertrophy of muscle fibres was accompanied by an approximately 70% increase in myonuclear number and a 46% increase in the number of satellite cells. Myonuclei number was positively correlated to satellite cell number indicating that a muscle with an increased concentration of myonuclei will contain a correspondingly higher number of satellite cells. The acquisition of additional myonuclei appears to be required to support the enlargement of multinucleated muscle cells following 10 weeks of strength training. Increased satellite cell content suggests that mitotic divisions of satellite cells produced daughter cells that became satellite cells.
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| 5. |
- Kadi, F., et al.
(författare)
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The effects of different training programs on the trapezius muscle of women with work-related neck and shoulder myalgia
- 2000
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Ingår i: Acta Neuropathologica. - Berlin : Springer Berlin/Heidelberg. - 0001-6322 .- 1432-0533. ; 100:3, s. 253-258
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the effects of training on the structural characteristics of the trapezius muscle in women with work-related trapezius myalgia. Muscle biopsies were taken before and after 10 weeks of three different training programs (strength, endurance and coordination). Enzyme-immunohistochemical analysis was performed to assess muscle fibre types, fibre area, capillary supply and cytochrome c oxidase (COX) activity. There was an increase in the proportion of type LIA fibres in strength trained group (P < 0.05). Strength training elicited a preferential increase in the area of type II fibres (P < 0.05); both strength and endurance programs induced an increase in the number of capillaries around type I and IIA muscle fibres. Finally, all training programs induced a decrease in the proportion of COX-negative fibres. In conclusion, the trapezius muscle of women with neck and shoulder myalgia is characterised by a great potential of adaptation to physical exercise over a period of 10 weeks. The significant changes in the number of capillaries and the specific changes induced by training at the level of muscle fibres might well explain the improvement of muscle function.
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