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Updated: May 20, 2026
Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography
Published on: March 12, 2021
Reliability of shoulder rotators isokinetic strength imbalance measured using the Biodex dynamometer
Pascal Edouard1, Philippe Codine, Pierre Samozino
1Department of Physical Medicine and Rehabilitation, University Hospital of Saint-Etienne, Faculty of Medicine, Jean Monnet University, Saint-Etienne, France. Pascal.Edouard42@gmail.com
Background:
Isokinetic assessment of shoulder internal and external rotators is commonly used by clinicians to assess muscle performance and to guide rehabilitation. The reliability of isokinetic assessment is fundamental to track small but clinically relevant changes.
Objectives:
We aimed to analyze the absolute and relative reliability of strength imbalance indices such as peak torque ratios (ERconc/IRconc, ERecc/IRecc, ERecc/IRcon, IRecc/ERcon), bilateral concentric and eccentric strength ratios, and to examine the reliability of external rotator and internal rotator peak torque measured using a Biodex(®) dynamometer in the seated position.
Design:
Cross-sectional laboratory study.
Methods:
Forty-six healthy participants were tested twice with seven days between sessions, at 60°/s and 120°/s concentrically, and 30°/s eccentrically.
Results:
Low to moderate relative reliability (intraclass correlation coefficient: 0.25-0.81) was found for unilateral and bilateral strength imbalance ratios. High intraclass correlation coefficient values (0.87-0.97) were found for peak torque. Concerning absolute reliability, the standard error of measurement ranged from 9.1 to 25.6% for strength imbalance ratios and from 7.7 to 14.5% for peak torque measurements, and minimal detectable change ranged from 25.2 to 71% for strength imbalance ratios and from 21.3 to 40.2% for peak torque measurements.
Conclusions:
The standard error of measurement and minimal detectable change reported in the present study should be taken into account when evaluating the individual longitudinal changes in clinical practice.
