According to the last rules on walkers the schritt must be twice as long as the height.
Does there actually have to be a height?
example:
a snake doesn´t actually lift its body up in order to move, it just removes the weight from parts of its body. the weight is transfered to different parts of the body and the rest just slides along the ground. therefore the height is zero.
(I know its a bad example, a snake isn´t a walker, but it explained what i meant)