Strength Assessment of Trunk Rotator Muscles: A Multicenter Reliability Study

Background: Trunk rotator strength plays an important role in sports performance and health. A reliable method to assess these muscles with functional electromechanical dynamometer has not been described. Therefore, the objectives of this paper were (I) to explore the reliability of different strength variables collected in isokinetic and isometric conditions during two trunk rotator exercises, and (II) to determine the relationship of isometric and dynamic strength variables collected in the same exercise. Methods: A repeated measures design was performed to evaluate the reliability of the horizontal cable woodchop (HCW) and low cable woodchop (LCW) exercises. Reliability was assessed using t-tests of paired samples for the effect size, the standard error of measurement, the coefficient of variation (CV) and the intraclass correlation coefficient (ICC). The Pearson ' s (r) correlation coefficient was used to explore the association between isometric and isokinetic tests. Results: HCW exercise is more reliable than LCW exercise in assessing trunk rotator muscles. The strength manifestation that should be used is the average strength, and the most reliable evaluation was the HCW at 0.40 m center dot s (-1) concentric (ICC = 0.89; CV = 10.21%) and eccentric (ICC = 0.85; CV = 9.33%) contraction and the dynamic condition that most correlated with the isometric was LWC at 0.50 m center dot s (-1) (r = 0.83; p < 0.01). Conclusion: HCW is a reliable exercise to measure trunk rotator muscles.

Automated summary

This study aimed to explore the reliability of different strength variables collected in isokinetic and isometric conditions during two trunk rotator exercises and determine the relationship between isometric and dynamic strength variables. The results showed that the horizontal cable woodchop exercise is more reliable than the low cable woodchop exercise, and that average strength should be used as an evaluation measure. The most reliable evaluation was the HCW at 0.40 m/s concentric and eccentric contraction, and the dynamic condition that correlated most with the isometric was LWC at 0.50 m/s.