Application of cineradiography for the metric and kinematic study of in-phase gaits during locomotion of the pika (Ochotona rufescens, Mammalia : Lagomorpha)

In-phase gaits of the pika (Ochotona rufescens) have been studied over a te nfold range of speed. This extensive kinematic study based on cineradiograp hy comprises more than 300 stride cycles. More than 7000 frames have been a nalysed. Gait metrics and kinematics of limb segments and limb joint angles of fore- and hindlimbs including additive lumbar spine movements are descr ibed. A new method of calculating the contribution of angular movements to stance propulsion is presented. Speed depends mainly on step frequency and the distance covered during suspension phase. The pika shows no speed relat ed increase in stance propulsion and swing length. The current paradigm for gait and speed dependent parameters is falsified in part by the present da ta. The limbs have a rigid geometry and speed-independent limb kinematics. Three forelimb and four hindlimb segments are oriented at right angles. Two segments (scapula/forearm, pelvis/shank, and thigh/foot) are not only para llel at foot down and foot up but are displaced in such a way that they alw ays remain relatively parallel. Such a pantograph limb geometry can be comp ared with a parallel linkage system. Advantages of such a system are discus sed.