Fig. 3.

Overview of the putative inertial forces on the arms, the body acceleration, and the torques during the experiment. A: at target onset, constant acceleration. B: at target onset, forthcoming acceleration. C: at reach onset, constant acceleration. D: at reach onset, forthcoming acceleration. E: end of reach movement, constant acceleration. F: end of reach movement, forthcoming acceleration. Thick black arrows indicate assumed direction of body acceleration, thin black arrows indicate assumed inertial forces on the arms, and gray arrows indicate net torques required to start the reach movement and end the reach movement. In some cases the inertial forces will reduce the required active torques, and in other cases they will increase the required active torque.