Leg strength diagnostics

A leg strength measuring device (BKM) developed at the University of Kassel is used to determine the maximum and rapid strength of 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 carried out. The leg extension forces exerted on the measuring plates are picked up by a charge amplifier(KISTLER, Winterthur) via charge displacements on the piezo force sensors and forwarded to a special computer evaluation program via an A/D converter.

To standardize the leg force measurement, the test subjects adopt a predefined posture with fixed hip, knee and ankle angles.

Test instruction: The task of the test subjects is to realize the highest possible force value from a relaxed leg position by an explosive application of force in response to a signal from the test supervisor. The greatest force amplitude (maximum force) and the greatest gradient (explosive force) of the force-time curve are recorded as characteristic values of maximum and rapid force behavior for maximum isometric force development. In addition, force measurements are carried out under maximum eccentric working conditions to estimate the maximum activation capability. Using an electronic feedback method developed at the University of Kassel, the eccentricity can be triggered individually by characteristics in the force curve. Different strain amplitudes as well as different strain rates can be selected.