HARP line tool

Looking at our anatomic wheels in the lab, the spokes (long bones) are whatever they are. That leaves pendulum and velocity properties. We can shorten the overall leg length by hyper-flexing the knee and pointing the foot as speed runners do for faster thigh forward flexion. Our main variable is speed which costs energy equally to go faster or slower than the pendulum properties. Speed in a chosen direction gives us velocity – a vector with magnitude and a relationship to the ground as well as to the person. If we consider the whole leg, then the big contribution is knee motion (flexion/extension) as pivoted on the hip center. Leg = H-K-A which typically is tracked as an angle.