study, however, 31% of 58 patients with this condition did not participate in vigorous physical activity. 3 In this article, we have concentrated on tendinopathy of the main body of tendo Achillis. We have not dealt with Haglund's condition, insertional tendinopathy, or with lesions of the myotendinous junction. Anatomy. The gastrocnemius muscle merges with the soleus to form tendo Achillis. 4 It has a round upper part and is relatively flat in its distal 4 cm. Its fibres spiral through 90°, increasing the release of stored energy during locomotion. 5 Tendo Achillis is enveloped by a paratenon, originating from the deep fascia of the leg, the fascia cruris. Blood flow in the tendon increases considerably with exercise, probably due to the marked rise in the negative tissue pressure