At the Olympic Training Center at Colorado Springs, jump performances of athletes are being tested by using a portable one-dimensional force platform (PFP) (Major, Sands, McNeal, Paine, & Kipp, 1998). The PFP is small and mobile, so that the apparatus can be taken to the athlete. Custom software automatically analyzes and extracts information from the force-time curves that are generated by any type of vertical jump. Figures 1-3 show the types and values of data extracted from typical force-time curves obtained from different types of vertical jumps. There are three basic types of jumps on which athletes are tested (Fig 1-3): static jump (SJ), countermovement jump (CJ), and drop jump (DJ). These jump tasks can be varied to increase the breadth and depth of information obtained by adding weights (e.g., holding dumbbells), using an arm swing or not, dropping from various heights, and/or modifications of the performance instructions (Young, Pryor, & Wilson, 1995). By extracting precise, reliable and valid information from different types of vertical jumps, the sport scientist can diagnose lower extremity strength and power information that can help coaches and athletes determine the current status of the athlete’s lower extremity and indications of where training should go in the future (Marina & Rodriguez, 1999; Schmidtbleicher, 2002). SJ-type jumps reflect concentric only contractile capacity of the lower extremity. CJ-type jumps reflect contractile capacity, recruitment, synchronization, and some elastic character of the lower extremity. DJ-type jumps reflect reactive characteristics of the lower extremity. Moreover, by adding weights to the SJ-type jumps one can obtain a performance curve of the lower extremity’s ability to produce high forces with external loads and thus lower speeds. The CJ-type jumps add an eccentric/stretch-shortening cycle to jump performance at moderate speed. The DJ-type jumps can reflect reactive and ballistic characteristics of strength and power at very high speeds and with varying loads dependent on the height of the drop prior to impact. Lower extremity profiles are constructed from performance comparisons across these different types of jumps and their different performance task demands (M. Marina, personal communication). For example, in bobsleigh tryouts we found that athletes trained in powerlifting were relatively superior in SJ parameters while their CJ and DJ jump parameters were poor relative to other athletes. Powerlifters tend to train with high loads and at slow speeds. Athletes in the tryouts who trained more explosively, typically track and field athletes, were superior at CJ-type and DJ-type jump parameters while they were relatively inferior to the powerlifter in SJ-type jump parameters. The PFP provides a simple, portable, and relatively inexpensive means of measuring lower extremity strength and power. Sport scientists use the force-time information from different types of jumps performed on a PFP to create an athlete-specific profile of lower extremity strength and power that appears to be sensitive to different training modes and methods. Reference List