Strength Assessment of Trunk Rotator Muscles: A Multicenter Reliability Study

Area of Science:

• Biomechanics and Exercise Physiology
• Musculoskeletal Health and Rehabilitation

Background:

• Trunk rotator strength is vital for athletic performance and overall health.
• Current methods for assessing trunk rotator muscles using functional electromechanical dynamometers lack established reliability.
• This study addresses the need for a dependable assessment tool for these muscles.

Purpose of the Study:

• To evaluate the reliability of various strength variables in trunk rotator exercises under isokinetic and isometric conditions.
• To determine the correlation between isometric and dynamic strength measurements within the same exercises.

Main Methods:

• A repeated measures design was employed to assess the reliability of the horizontal cable woodchop (HCW) and low cable woodchop (LCW) exercises.
• Reliability was determined using paired sample t-tests, standard error of measurement, coefficient of variation (CV), and intraclass correlation coefficient (ICC).
• Pearson's correlation coefficient (r) was used to analyze the association between isometric and isokinetic strength tests.

Main Results:

• The HCW exercise demonstrated higher reliability compared to the LCW exercise for assessing trunk rotator muscles.
• Average strength is the recommended strength manifestation for reliable assessment.
• The most reliable measurements were obtained from the HCW exercise at 0.40 m·s^-1 for both concentric (ICC = 0.89; CV = 10.21%) and eccentric (ICC = 0.85; CV = 9.33%) contractions.
• The low cable woodchop (LCW) at 0.50 m·s^-1 showed the strongest correlation with isometric strength (r = 0.83; p < 0.01).

Conclusions:

• The horizontal cable woodchop (HCW) exercise is a reliable method for measuring trunk rotator muscle strength.
• This finding provides a validated tool for clinicians and researchers assessing trunk rotator function.