Peak Power Assessment of Isokinetic Knee Flexor and Extensor Tests – Pitfalls of a Dynamometer-based Assessment

ABSTRACT

Many sports demand high forces at high movement speeds. Joint power combines these two measures and is frequently analyzed by isokinetic tests. However, various concepts of assessing joint power lead to conflicting results. The aim was to examine different methods to calculate peak power during isokinetic knee tests of sixty-one healthy male participants (20 y, 182 cm, 76 kg). Unilateral movements of the eccentrically working hamstrings and the concentrically working quadriceps at 150°/s were captured by high-speed cameras. Peak power derived from isokinetic data was significantly higher (p < 0.01, d > 1.54) compared to the camera-based kinematic procedures. To achieve best accuracy, peak power should be derived from the camera-based joint angular velocity and the measured moment at time of peak power during the dynamometer’s isokinetic range of motion. A meaningful assessment of isokinetic joint power should incorporate a camera-based kinematic analysis to account for potential measuring inaccuracies owing to anatomical features, axis misalignment, and tissue deformation.

KEYWORDS:

• Quadriceps
• hamstrings
• performance diagnostics
• kinematics
• measuring accuracy

Acknowledgments

The authors would like to thank all subjects who volunteered to participate in this study and demonstrated great motivation and commitment. Dr. Werner Groß-Alt deserves our sincere gratitude because his skills in informatics made these insights possible.

Additional information

Funding

This work was not funded.