Bounce diagnostics

The analysis of the jumping force capacity is carried out in the biomechanics laboratory of the Institute of Sport and Sport Science at the University of Kassel by means of a standard jumping force diagnosis. In this process, the ground reaction forces are recorded via a three-dimensional measuring pressure plate (Kistler, Winterthur) for three different jump forms (squat jump, countermovement jump, drop jump) and parameterized in a computer program by means of various characteristic values (including an estimation of the body's center of gravity elevation by means of a time-of-flight procedure and an impulse procedure).

The squat jump characterizes a vertical jump performed from a squat body position. The upper body is slightly bent forward before the jump, so that the hip and knee angle is about 90 degrees. The hands are fixed at the hips throughout the jump to minimize the influence of the arms to amplify momentum. The task of the test subjects is to jump maximally still upwards from rest and without an initiating lunging movement.

The Countermovement Jump characterizes a vertical jump with lunge initiated from an upright body position and characterized by a stretch-shortening cycle (DVZ). The lunge should be executed briskly downward to the starting position of the squat jump. The hands are fixed at the hips throughout the jump to minimize the influence of the arms to amplify momentum. The subjects' task is to jump maximally still upward from an upright standing position after an introductory lunging motion. This jump form is used to estimate the reactive force capacity for a self-initiated stretch of the leg extensor muscles.

The drop jump characterizes a low-to-high jump executed from a predetermined low jump height and characterized by a stretch-shortening cycle (DVZ). The low jump should be executed from the base in such a way that the body's center of gravity is lowered as little as possible before the free fall. The hands are fixed at the hips throughout the jump to minimize the influence of the arms to amplify momentum. The task of the test subjects is to jump upwards after the low jump as bouncing as possible and without a heel strike. This jump form is used to estimate the reactive force capability for a foreign-initiated stretch of the leg extensor muscles.