Affiliations: [a] Department of Biomechanics, Performance Analysis and Strength & Conditioning, Olympic Training and Testing Centre Westphalia, Dortmund, Germany | [b] Institute of Movement and Neuroscience, German Sport University, Cologne, Germany | [c] Research Centre for Elite Sports, MOMENTUM, Cologne, Germany
Correspondence:
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Corresponding author: Tobias Alt, Olympic Training and Testing Centre Westphalia, Strobelallee 60a, 44139 Dortmund, North Rhine-Westphalia, Germany. Tel.: +49 231 477348 23, Fax: +49 231 477348 20, E-mail: tobias.alt@osp-westfalen.de.
Abstract: BACKGROUND: Adequate participant’s fixation affects measurement accuracy and performance of isokinetic exercise. OBJECTIVE: To examine the effects of different fixation methods and contraction modes on the kinetics and 3D kinematics of prone isokinetic knee flexor tests. METHODS: Fourteen healthy male participants performed maximal unilateral concentric and eccentric knee flexion movements with minimal (hand grips), moderate (grips, hip strap) and maximal (grips, thigh and hip strap, hip wedges, shoulder pads) fixation at 30∘/s. RESULTS: Concentric and eccentric peak moments were highest at minimal and maximal fixation, whereas contractional work peaked at minimal fixation. Axis alignment was best at moderate fixation. Initial axis alignment caused an average antero-cranial shift (2.0 and 0.1 cm) as well as mean roll and yaw angle tilts of -0.1∘ and -6.1∘. Hip motion was significantly reduced at maximal fixation. Eccentric movements demonstrated a lower mean angular velocity (26.0∘/s) than concentric tests (29.4∘/s). CONCLUSIONS: Depending on their purpose, prone isokinetic knee flexor tests or training sessions should be conducted with minimal (maximal force production) or moderate (axis alignment) fixation. When interpreting and comparing isokinetic results, the examined kinematic and kinetic effects of different fixation methods should be taken into account.
