Adaptation of tendon collagen to exercise.

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.