This work investigated the passive bending properties of the intact human torso about its three principal exes of flexion: extension, laterla bending, and axil rotation. Additionally, the effects of wearing an abdominal belt and holding the breath (full inhalation) on trunk stiffness was investigated. The torsos of 22 males and 15 females were subjected to bending moments while “floating” in a frictionless jig with isolated torso bending measured with a magnetiv device. Belts and breth holding appear to stiffen the torso about the lateral bending and axial roation axes but not in flexion or extension. Torsos are stiffer in lateral bending and capable of storing greater elastic energy. Regression equations were formulated to define stifiness and energy stored for input to biomechanical models that examine low back function and for bioengineers designing hardware for stabillzation and barcing or investigation of traumatic events such as automobile collsion.
Keywords:
lumbar stiffness; belts; torso; breath hold