The effect of load on Achilles tendon structure in novice runners

Objectives: To observe the changes in Achilles tendon structure in novice runners, with loading prescriptions of 100% body weight compared to 20% body weight. Design: Randomised crossover. Methods: Twenty novice runners participated in two separate running bouts spaced 14 days apart, one of high load at 100% body weight, and one of low load at 20% body weight. Tendon structure was measured by ultrasonographic tissue characterisation on 6 occasions; immediately prior to each run, 2 and 7 days after each run. Results: The interaction effect of time and condition was not found to be significant for echotypes I-IV [Wald chi-square = 2.8, d.f. = 2, P=0.247; Wald chi-square=2.888, d.f. = 2, P=0.236; Wald chi-square=1.385, d.f. = 2, P=0.5; Wald chi-square=4.19, d.f. = 2, P=0.123], respectively. A significant effect of time was found for echotypes Ill [Wald chi-square=6.785, d.f. = 2, P=0.0.034] and IV [Wald chi-square=7.491, d.f. = 2, P=0.0.024]. Conclusions: The decrease in echotypes III and IV suggest that moderate loads can be applied to the Achilles tendon without compromising tendon structure. Low to moderate loads may be beneficial in the management of Achilles tendinopathy. Further studies should focus on protocols with higher loading and/or repetitive loading in athletic populations with and without Achilles tendinopathy to assess any differences in tendon structure. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved