In Vivo Elastic Properties of Human Tendon Structures in Lower Limb

Abstract

The present study was conducted to evaluate the elastic properties of human tendon structures and their influences on human movements, and to investigate the effects of resistance training on tendon properties. During isometric contraction, the elongations of tendon structures in knee extensors and plantar flexors were measured by means of real-time ultrasonography. The resulting tendon force and elongation relationship was non-linear in form, as previously reported on animal and human cadaver tendons in vitro. The estimated Young's modulus, i.e., the slope of the stress - strain curve, tended to be lower than the previously reported values. In human movements, the elastic properties of tendon structures had a favorable effects on stretch-shortening cycle exercises, possibly because of improved storage and release of elastic energy. Furthermore, the adaptation of the tendon structures to physical training varies with the combinations of intensity, contraction time during exercise as previously observed in the animal experiments. Furthermore, the elastic properties of human tendon structures could be new indices of physical resources in vivo.