The influence of exercise in the healing of the rabbit Achilles tendon.

Effect of exercise on tendon healing was studied in partially tenotomized rabbit achilles tendons by post-operatively applying a plaster splint to the right leg from the knee to the end of the toe, but no external fixation to the left leg. The animals were serially sacrificed, and new tendon tissues generated at the tenotomy site were examined. Collagen type analysis of the new tendon tissue showed a nearly constant ratio of type III to type I collagen of about 10% in the fixed side, but in the non-fixed side it showed an increase to 19% 2 weeks after the operation followed thereafter by a gradual decrease. Ultrastructural examination revealed an earlier increase in the diameter of collagen fibers suggesting their faster maturation in the non-fixed side.