Heterogeneous Loading of the Human Achilles Tendon In Vivo.

The free Achilles tendon is considered a homogeneous structure that transmits muscular force in a linear manner. However, the tendon undergoes longitudinal rotation and is separated in mechanically independent segments with distinct mechanical and material tissue properties. The present article examines the hypothesis that the human Achilles tendon is loaded asymmetrically and undergoes heterogeneous deformation during movement.