Leg strength diagnostics

A leg force measuring device (BKM) developed at the University of Kassel is used to determine the maximum and rapid force capacity for the leg extensor muscles. The device is equipped with two separate force plates (each with three one-dimensional piezo force sensors), so that both unilateral and bilateral force measurements can be made. The leg extension forces exerted on the measuring plates are tapped by a charge amplifier(KISTLER company, Winterthur) via charge displacements on the piezo force sensors and forwarded to a special computer evaluation program via an A/D converter. 

For the standardization of the leg force measurement, the test subjects adopt a predefined posture with specified hip, knee and ankle angles.

Test instruction: The subjects' task is to realize the highest possible force value from a relaxed leg position through an explosive use of force in response to a signal from the trainer. The largest force amplitude (maximum force) and the largest slope (explosive force) of the force-time curve are recorded as characteristic values of the maximum and rapid force behavior for a maximum isometric force development. In addition, force measurements under maximum eccentric working conditions are performed to estimate the maximum activating capacity. With an electronic feedback method developed at the University of Kassel, eccentricity can be triggered individually by features in the force curve.  Both different strain amplitudes and different strain rates can be selected.