Determination of Optimum Heel Inclination For Maximum Height Vertical Jumps

Abstract

In order to provide better shock absorption, athletic shoe companies have increased the heel thickness creating a positive heel Inclination. The heel inclination for most athletics shoes is about 4 degrees. It i s hypothesized that the protection gained from increasing the heel thickness may cause a decrease In performance. The purpose of this study was to find the optimum heel inclination that w l l l maximize jump height. More specifically, this study attempted to determine the effect of negative and posltlve.hee1 Inclination on the height an individual can Jump. Eight female and five male Division I track and field athletes volunteered to perform standing vertical Jumps from a platform designed to allow for the possibility of a continuous range of negative and positive degrees of heel inclinations. The subjects performed three vertical jumps using the Sargent Vertical Jump Test protocol under five conditions: 4, 0. -2. -3. -4 degrees of inclination. Before testing, the subjects performed their usual warm up and during testing were given as many practice jumps as desired. At the apex of their Jumps, the subjects marked an over hanging chalked board with their finger. Any obviously poor test result was discarded and the test was repeated. The differential over their maximum standing reach was then recorded. The testing was conducted during one session; however, two series of Jumps were used to collect the data. The objective of the f l r s t series of Jumps was to find the angle of Inclination at which maximum height can be attained. After the optimum angle of inclination was determined, a second series of Jumps were performed In order to further compare the optimum angle with the +4 degree inclination (If a difference existed). The results show a statistically significant difference In jump height at the different angles F(4.36) = 15.89, p < .OO I). The data also show an upward trend In Jump height as the heels were lowered from 4 to -4 degree of inclination. On average, the subjects increased their Jump height by 6% when using a -4 degree heel inclination over the 4 degree inclination. In conclusion, we have found convincing evidence that negative heel inclination will Increase standing vertical Jump height with the optimum angle being about -4 degrees. A followup study will involve running vertical jumps.