35 patients with an acute Achilles tendon rupture were randomized to evaluate the benefits of early tensional loading on the mechanical properties of healing Achilles tendons, when compared to conventional cast treatment. Patients were evaluated over 52 weeks, and the evidence presented in this study indicated that elastic modulus was higher in the tensional loading group at 19 and 52 weeks and no significant differences were apparent between groups concerning the Achilles tendon Total Rupture Score (ATRS) or the heel raise index at 52 weeks. A significant correlation between the modulus at 7 weeks and the heel raise index at 52 weeks was observed and no signs of tendon elongation were noted.