Abstract: Two human motions can be linearly interpolated to produce a new motion, giving the animator control over the length of a jump, the speed of walking, or the height of a kick. Over the past ten years, this simple technique has been shown to produce surprisingly natural looking results. In this paper, we analyze the motions produced by this technique for physical correctness and suggest small modifications to the standard interpolation technique that in some circumstances will produce significantly more natural looking motion.