Fig. 2

Obstacle delivery apparatus. A steel block (1) rests on an acrylic track (2) via flanged bearing stacks (3). The block is held in place by an electromagnet (4), whose position is determined by the height of the metal rod (5). The track is mounted to an aluminum frame (6) with adjustable, vibration-damping feet (7). Foam (8) is adhered to the front and bottom of the block to protect the subject’s toes and reduce the impulsive loading on the treadmill, respectively