Einfluss unterschiedlicher Probandensitzpositionen im Isokinetic-Dynamometer auf das Drehmoment, die EMG-Aktivität und die mechanischen Eigenschaften des Muskelsehnen-Komplexes der unteren Extremitäten bei Frauen

Florian Hornbachner
2018 unpublished
Due to the variety of structures involved, including muscles, tendons, ligaments, and partial joints, human ankle exams pose a major challenge. Isokinetic dynamometers are a widely used and easy-to-use tool for determining joint loads and effective torques. For Plantarflexion on the Ankle joint, not least because of the immense forces acting, several sources of error exist, which cause a deviation between the measured torque and the resulting torque on the joint and can subsequently lead to
more » ... missible statements about the muscle-tendon complex. Herzog (1988) calls the influence of gravity on the joint, inertial effects (can be neglected in isometric experimental design), as well as the relative movements of the dynamometer parts and body segments to each other as possible causes. The aim of the current study was to minimize this relative movement during a plantarflexion by means of a modified examination and positioning procedure, by gradually reducing the horizontal distance of the subjects to the dynamometer and thus enabling more reliable statements. Nine athletic and healthy subjects (age: 25.5 ± 3.44 years, mass: 63.8 ± 6.54 kg, body size: 170.3 ± 4.38 cm) were examined on an Isokinetic dynamometer of the HUMAC® NORM ™ Model 770 type. The subjects had to perform maximal voluntary isometric plantar flexions in four different sitting positions (0, 3, 6, 9 cm). Kinematic data were recorded using a motion- tracking system based on reflective motion markers (© Vicon MX), a pressure-distribution (pedar © -X) to determine the force application point, and EMG activation of the involved muscles via surface electrodes (Delsys Trigno™). The collected data show a statistically significant influence of the subject seat position on the achieved torque. The reduced horizontal distance resulted in a higher preload of the foot and ankle, which reduced joint rotation by ~55% and increased torque values (~18% increase) compared to the usual subject position. In addition, it could be shown that by reducing the horizontal dist [...]
doi:10.25365/thesis.53173 fatcat:oxmopiyewjag7bus2gmyazk5zi