Many runners twist in their upper body while they run. You can see this by watching the logo on their tee-shirt move sideways. You can also see it when their arms cross in front of their body instead of moving straight forward and back. We have found that runners do this because of tightness in their shoulders. When they bring their right arm back, for instance, tightness in their right shoulder will twist their shoulders to their right, throwing their left arm across their body. Less well known is that they also swing their right leg to their left to counter the twisting to their right in their upper body. In some cases, they may even cross over the midline. We would like to be able to compute the amount of extra work, or extra energy expended, to twisting and counter-twist like this while running. We are able to quantify the amount of lateral movement of the arms and legs with a biomechanical analysis of a runner, but we don't know how to quantify the amount of work or energy expended. Any help very much appreciated.