An exploration of the acute response of the asymptomatic Achilles tendon to exercise using diagnostic ultrasound. A systematic review of cohort studies.

OBJECTIVES

To describe the acute effects of exercise on the morphology, mechanical properties and blood flow of the Achilles tendon, as measured with ultrasound.

DESIGN

Systematic review of cohort studies.

METHODS

Seven electronic research databases were systematically searched for exercise intervention-based studies reporting morphology, mechanical properties and blood flow of the Achilles tendon, as measured with ultrasound.

RESULTS

Searches revealed 2460 possible articles and 35 satisfied the inclusion criteria. There is evidence that eccentric heel drops resulted in a reduction in the diameter and cross-sectional area of the tendon whilst running/stretch-shortening cycle activities did not result in a change. The latter did not affect tendon mechanical properties. Tendon blood flow was consistently increased in response to exercise.

CONCLUSIONS

The acute response of the Achilles tendon to exercise showed an increase in blood flow and a reduction in diameter following heel drop exercises. Exercise modes were relevant since eccentric and isometric loading resulted in a greater response in the tendon. Activities like running and hopping placing specific demands on the tendon's spring function resulted in a minimal change in tendon morphology and no change in mechanical properties.