Human running over visible and camouflaged drops

Ten volunteers run with a constant speed of 5.0 ± 0.5 m/s along a 17m track with two consecutive force plates in its center. The force plate of the first contact was fixed at ground-level concerning the running track. The force plate at the second contact was adjustable in height. First, the subjects had to run over two visible settings: for one the track was even (visible 0 cm), for the other the force plate on the second contact was lowered by 10 cm (visible drop of 10 cm). Thereafter, for the camouflaged setting, the basic set-up was the same as for the visible 10 cm condition. Additionally, on the force plate of the second contact a wooden block with a height of 10 cm was randomly either present or absent. The wooden block was camouflaged with a thin, opaque sheet of paper, so that the subjects did not know whether they were stepping down 10 cm (camouflaged drop of 10 cm) or not (camouflaged 0 cm). For each condition kinetic and kinematic data were collected.