Why? The Science of Athletics

270 WHY?-THE SCIENCE OF ATHLETICS jump, provided his own centre of gravity continues to follow the true path of the parabola. This brings us to another point which may, I think, be discussed conveniently in this place. It is the problem of preventing the heavy upper parts of the body from coming forward as momentum is lost and, by disposing the weight forward, forcing the heels to ·the sand-pit earlier than they need reach it. FIG. 94 NOTE-The centre of gravity is indicated by a small circle. It must be remembered that at the point H in the curve AD, in Fig. 93, the force of the initial" impulse is facing defeat, and from the point H to the point of landing at E or D the force of gravity is overcoming the athlete's powers of resistance. In this connection it should be remembered that the:Jmrdler cultivates a forward body dip, forcing his trunk down over the thigh of his leading leg, for the sole purpose of driving his foot down to ground on the far side of the hurdle as speedily as possible. Also, the bringing down of the heavy parts of the body to the centre of gravity does not help the long jumper, because he uses no sideways twist and no turn for the sake of raising his hips over a bar, as does the high jumper. What he does want to do is to prevent the forward weight of his body from driving his legs down, and so he uses some combination of arm and leg actions, not to create an additional explosive force to add a purely mythical fresh velocity to his body in flight, but rather to so dispose his