Achilles tendon loading during weight bearing exercises

Objective: Compare the estimated Achilles tendon (AT) loading using a musculoskeletal model during commonly performed weight bearing therapeutic exercises. Design: Controlled laboratory study. Setting: University biomechanics laboratory. Participants: Eighteen healthy males (Age: 22.1 +/- 1.8 years, height:177.7 +/- 8.4cm, weight = 74.29 +/- 11.3 kg). Main outcome measure(s): AT loading was estimated during eleven exercises: tandem, Romberg, and unilateral standing, unilateral and bilateral heel raising, unilateral and bilateral jump landing, squat, lunge, walking, and running. Kinematic and kinetic data were recorded at 180 Hz and 1800 Hz respectively. These data were then used in a musculoskeletal model to estimate force in the triceps surae. AT cross-sectional images were measured by ultrasound to determine AT stress. A repeated measure multivariate analysis of variance (alpha = 0.05) was used on AT loading variables. Results: Squat and unilateral jump landing were the most different in AT stress. Peak AT stress variables were generally greater during more dynamic, unilateral exercises compared to more static, bilateral exercises. Conclusions: Bilateral, more static exercises resulted in less AT loading and may serve as a progression during the rehabilitation compared to more dynamic, unilateral exercises. (C) 2018 Published by Elsevier Ltd.