Athletics of To-Day 1929

----- -- -~~ Athletics of To-day the end of the slideway C, and he is in process of converting his forward velocity, due to the approach run, into an upward force by means of his spring. There are then two forces at work simultaneously-one along the line AB, which represents an energy of 937 foot-lb. due to his weight and the velocity of his approach run, and another along the lineAE, which is equal to 6oo foot-lb. due to the energy of his spring upwards. If the two lines referred to are formed into the parallelogram ABDE we get a resultant along the line AD showing a kinetic energy of 1,120 foot-lb. and its direction, which is the force existent at the instant of take-off, along the arc AD. For the sake of convenience I have added to this diagram a section showing the proper method of constructing the sand-pit for the vaulters to land in and have given the usual dimensions. For the benefit of the novice and the young pole vaulter who has followed me through the stages of the approach run and take-off, I will now describe the full action vault as shown in Plate 35. In these six pictures, each of the athletes has made his spring from the left foot. In No. r, Lee Barnes, U.S.A. (Olympic Champion, 1924) is just completing his take-off. Notice that the body is already going well to the pole through the bending of the arms at the elbows, and that the right knee is beginning to pick up to get height into the leg swing. No. 2, of V. Pickard, the Canadian record holder, shows that the bending of the arms at the instant of take-off is only a temporary measure to bring the body close jn to the pole. Note this point, for many a man spoils good vaulting by letting his body fly out from the pole. At this stage of the vault the head is still well back and the body is hanging loosely from the hands as the legs go up in a strong pendulum swing. This swing is gaining speed by the strong bending of the body at the hips. Observe the slight knee flexion and that the legs are beginning to turn over on to their left sides. In o. 3, Lee Barnes shows how the body takes up the turn– ing movement to the left, which the legs have started, and the point at which the arms b gin to raise the body by means of