Figure 4

FTIR force data obtained during countermovement jumps. Data are shown for the force exerted on the platforms beneath the left (blue) and right (red) feet during a countermovement jump manoeuvre performed barefoot (panel a) and wearing shoes (panel b) both by the same subject. In both cases the force data are obtained by summing the pressures obtained from FTIR contact images (examples shown as insets). The total force exerted on both platforms (green) was obtained by summing the red and blue curves. The legends on the right hand side of the panels give the correspondence between the colour and pressure in the contact pressure map images shown as insets. The inset in panel b also shows a simple photograph of the tread pattern on the underside of the shoe. Examples of movies showing the variation in pressure over the entire duration of each experiment are provided as supplementary material (see SupplementaryMovie2a.avi and SupplementaryMovie2b.avi).