Comparison of the vertec and Just Jump Systems for measuring height of vertical jump by young children.

To assess differences between the Vertec and the Just Jump Systems in measuring height of vertical jump, 248 boys and 232 girls between 7 and 11 years were required to perform four maximal countermovement vertical jumps. A maximum of the four trials recorded was the dependent variable. Each vertical jump was simultaneously evaluated by each measuring device and a paired t test indicated the systems were significantly different; however, the experiment wise difference of .93 in has no practical value. The Just Jump System seems a viable alternative. Advantages and potential pitfalls regarding the use of each system are discussed.