The biomechanical and metabolic effects of a running regime on the Achilles tendon in the rat.

The Achilles tendons of 192 albino rats were subjected to biomechemical and metabolic testing after a defined running period and compared with a control group. After 2, 4, 8, 12 and 16 weeks, the cross-sectional area, ultimate tensile strength and oxygen uptake of the Achilles tendons were determined. Different reactions were demonstrated particularly after intensive training. These tendons showed an increase in cross-sectional area and a decrease of ultimate tensile strength when compared to the control group after 12 and 16 weeks of training. In contrast to these results the oxygen uptake was higher than in the control groups after 4 and 8 weeks of training. Alterations in the biomechanical and metabolic properties of tendon tissue occur at different times after the running regime.