OPTIMUM PHASE RATIO IN THE TRIPLE JUMP

The purpose of this study was to develop and validate a method to dete rmine the optimum phase ratio that yields the longest actual distance for a given triple jumper. Two hypotheses were tested: (a) for any giv en triple jumper, the greater the gain in the vertical velocity the gr eater the loss in the horizontal velocity; and (b) there is no single optimum phase ratio for all triple jumpers. Kinematic data were collec ted for four elite male triple jumpers. It was found that the loss in the horizontal velocity during a support phase has a significant posit ive linear correlation with the gain in the vertical velocity during t he same support phase. The slope of the regression line was referred t o as the horizontal-to-vertical velocity conversion factor. Based on t his relationship, an optimization model for the longest actual distanc e was developed to determine the optimum phase ratio for each of the f our subjects. The optimization results showed that there was an optimu m phase ratio for the longest actual distance for each triple jumper. The results of a validity test showed that the model predicted the act ual distance with a degree of fair accuracy. The results of sensitivit y analysis showed that the optimum phase ratio for a given athlete was a function of the horizontal-to-vertical velocity conversion factor a nd the horizontal velocity at the touchdown of the hop. These results support the two hypotheses of this study. Copyright (C) 1996 Elsevier Science Ltd.