Reliability of a novel method assessing muscle power and velocity during seated trunk rotations

Introduction: Isometric and isokinetic dynamometers are mainly used for assessment of strength and endurance of core muscles. However, muscle power represents a more appropriate variable for evaluating of athlete performance that involve dynamic movements of the trunk. This study estimates test-retest reliability of trunk rotational power and velocity over a 1-week interval using the FiTRO Torso Isoinertial Dynamometer. Material and Methods: A group of 32 physically active men performed 5 trunk rotations to each side while seated with a barbell of 1 kg or 20 kg placed on their shoulders. Results: Results showed that assessment of peak and mean velocity in the acceleration phase of trunk rotations with 1 kg provides reliable results (ICC = 0.94 and 0.92 respectively, SEM = 7.0% and 7.3% respectively). However, peak and mean values of velocity and power obtained during trunk rotations with a weight of 20 kg should be interpreted with caution (ICC < 0.80, SEM > 10%). Conclusions: Such an assessment of trunk rotational power and velocity can be used in practice, however with a limitation of performing trunk rotations in a seated position and using lower loads.