Why? The Science of Athletics

SOME MORE MATHEMATICS FOR ATHLETES 275 end. This proves that the energy released has travelled along the lash as fast as sound travels. Velocity of ProJection Now translate that analogy into terms of any athletic throwing feat and you will see that the hand of the thrower must be moving at the velocity with which the missile is projected at the moment of de– livery, but there is one condition precedent involved here, and that is that the arm should be kept absolutely loose until the jerk intervenes. Even so, the missile must be released at exactly the right instant and in exactly the right position ; that is to say, the "jerk" or "explosion" must ·be concentrated at the right point in the throwing action. These things, however, cannot be done at will, and a perfect throw is the outcome oflong and very careful training. The three pictures which comprise Plate 22 will better illustrate the point. In Fig. 97 Ketil Askildt, the great Norwegian thrower, is beginning to turn in the circle, and it will be seen that his right arm hangs perfectly loosely out from his shoulder, th:e discus being maintained under his hand by the centrifugal force of his turn, while the arm swings out just as do the governors of an engine when it is set in motion. At this stage of the evolution the muscles of the thrower's right arm are completely relaxed. In Fig. g8, Jules Noel, a former French champion, who has touched r6o ft., has gained the throwing position at the end of the turn and has his left foot so placed that his left leg may form the fulcrum, or point of resistance, when he generates the jerk with which the discus will be despatched, but the thrower's right arm is still fully relaxed. In Fig. gg, however, Askildt has put the jerk into operation and the discus is in flight. There is another important matter yet to Range of Arm be examined, and that is the question of Contribution range; Hammer and discus throwers are . able to hurl their missiles to phenomenal distances, because the circumstances of throwing allow