In 2012 the ultrasound based method called speckle tracking was first used to describe non-homogenous deformation within the human Achilles tendon and since then a number of research groups internationally have consistently confirmed the results. There is a consensus that during dorsiflexion and plantarflexion motion the deeper portions of the tendon move more than the superficial portions. This has been shown in a variety of activities and different activation modalities of the triceps surae. Recent research now indicates that this non-uniform deformation may be a biomechanically beneficial behaviour indicative of a healthy tendon and that a reduction in non-homogeneity may be negative for tendon function and possibly an etiological mechanism for chronic tendon injury. Running barefoot or in minimalistic shoes has been associated with Achilles tendon injuries and this raises the question whether these conditions affect the internal dynamics of the tendon in a negative manner, i.e. by reducing non-homogenous behaviour. New data now support this hypothesis showing that the differences in displacement between deep and superficial portions of the tendon are decreased when running barefoot or in minimalistic shoes as compared to traditional running shoes. This could be expected to be a mechanism that places the Achilles tendon at risk for injury.
My presentation at iFAB 2020 will take us on the scientific journey from initial indications of non-homogeneity in the human Achilles tendon to the most recent studies exploring the effects that different footwear have on this during running. I will discuss the present state of knowledge concerning possible consequences of non-homogenous tendon deformation during running.