No abstract

This study was designed to gain more detailed morphological information on skeletal tendons in the course of adaptation to physical loading. The effect on collagen fibrils was investigated in 6-week-old mice by means of electron microscopy. Physical loading was performed on a treadmill 5 days a week for 1, 3, 5, 7 and 10 weeks. Morphometric analysis of collagen fibrils revealed the mean diameter, the diameter distribution, the number and the cross-sectional area. The principal observations included: 1. After one week of physical loading an increase in mean fibril diameter (30%, p less than or equal to 0.01), in number (15%, p less than or equal to 0.05), and in cross-sectional area (15%, p less than or equal to 0.05), as well as a change in mean fibril diameter distribution. 2. From the third to the seventh week a fall under the level of the controls in mean diameter (26%, p less than or equal to 0.01), in number (26%, p less than or equal to 0.01), and a reduced cross-sectional area (17%, p less than or equal to 0.01), accompanied by signs of splitting of individual collagen fibrils. 3. In the long-term study an increase in fibril number (29%, p less than or equal to 0.01), a fall in mean diameter from 189 nm in the controls to 179 nm (p less than or equal to 0.05) but no statistically significant change in the relative cross-sectional area (32%) per unit in comparison to unloaded tendons. The possible physiological implications of the findings are discussed in the light of several regulatory mechanisms known to appear during the course of physical loading in connective tissues.

We report an experimental study on the effect of exercise on tendon structure in mice. After one week of physical training an increase in mean diameter, in number, and in cross-sectional area, as well as a change in mean fibril diameter distribution, was demonstrated. In the long-term, there was an increase in fibril number, a fall in mean diameter, but no statistically significant changes in the relative cross-sectional area per unit compared with the control tendons.

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The purpose of this study was to examine the effect of anabolic steroid hormones and exercise training on skeletal tendons. Female mice were exercised for 1 and 10 weeks in an endurance running programme on a treadmill. The altered ultrastructure of tendons caused by simultaneously administered anabolic steroid hormone was investigated by electron microscopy. A stereoscopic analysis of collagen fibrils was performed in order to reveal the changes in the architecture of tendons and to quantify the extent of possible injuries to their functional structure. The occurrence of tendon injuries was detected by the appearance of a collagen dysplasia. The morphometric analysis of the degree of the collagen dysplasia in the different experimental groups reveals that it becomes even more conspicuous in the tendons of the mice which were both exercised and given anabolic steroids. The overall picture and the architecture of the tendons provide tentative evidence that anabolic steroid hormones may induce tendon injuries, depending on the duration of treatment. The direct effect of anabolic steroids on tendons has to be taken into account when considering the clinical disorders of tendons and ligaments which occur in high-class athletes.