A skater can at most move his feet at about 7 m/s, and the greatest forward push force will be when he begins skating from rest. At this point the velocity of his foot relative to the ice is 7 m/s. As the skater gains speed this relative velocity changes. For example, if the skater reaches a speed of 5 m/s, the relative velocity of his foot relative to the ice is 2 m/s (assuming he moves his leg backwards, with no sideways component of velocity), and the push force is less as a result. Consequently, there is a maximum speed a skater can reach, which is directly influenced by how fast he can move his feet on the ice. However, the maximum speed the skater can reach is not necessarily 7 m/s. It can be much more than this if the skater, when pushing off the ice, moves his leg backward with a sideways component of velocity. Analyzing the physics to determine the maximum speed involves looking at the biomechanics of the skater.