Abstract

In sports medicine the quantification of motor performance is important for several reasons. Functional deficits can lead to injuries or may be responsible for a lack of progress during sports performance. For measurements of kinematics several motion analysis systems are well established. Isometric, isokinetic and isoinertial testing devices provide information about force or torque production of agonistic and synergistic muscles. There is no ideal testing method for all output-related, scientific questions in sports medicine. A trade-off exists between increasing knowledge about internal forces on one side (e.g. by isometric testing) and increasing realism of the test setting on the other side (e.g. free dynamic tests). The usefulness of strength measurement devices for the estimation of forces that act on a joint is limited. One reason for this is the unknown extent of internal forces that are relevant, especially during dynamic motion. These internal forces may exceed external forces by far. Although numerous studies have been performed with strength testing devices, methodological problems in the use of these machines and questions about criterion-based validity for sports medicine are remaining. Verf.-Referat