Thrusting against the ground actively can shorten the braking time and help decrease braking impulse, it is necessary for understanding the running principle to divide carefully the cushioning action of landing, the cushioning action of landing include fore-thrusting and hind-thrusting, we should devote much attention to the leg thrust, it is important t.

By introducing a new dimensional time parameter,the first-order momentum-impulse differential equations were obtained , and the discussion over infinitesimal impulsive interval was transformed into a piece-wise study on the finite region of impulse,so the solution of impulsive dynamics of spatial discrete system with friction was obtained, i.