6) During single leg support, all the ground reaction forces acting on the stance foot are concentrated at the a) Center of gravity b) Radius of gyration c) Center of pressure d) Sacrum Increasing the angle of lean (leaning forward) body weight about the ankle and causes the COP to move a) Increases / Backward b) Produces no change in / Forward c) Increases / Forward d) Decreases/ Forward the magnitude of the torque produced by under the feet.