Inter-rater and test/retest reliabilities of the isokinetic measurements: assessing strength and endurance of the trunk muscles in two different protocols for able-bodied and post-stroke hemiparesis

Background: Stroke represents the largest cause of chronic disability resulting in muscle weakness and instability in the trunk muscles. Despite the reliable measures from isokinetic devices for upper/lower limb muscles, there is a lack of measures for trunk muscles in post-stroke hemiparesis. Objectives: To investigate the reliability of the strength and endurance measures from an isokinetic dynamometer for able-bodied and post-stroke hemiparesis people. Methods: The measures were taken from both groups (control/hemiparesis) performing antagonistic movements (flexion/extension) during different protocols (seated-compressed and semi-standing) to assess strength (60 degrees/s) and endurance (120 degrees/s). The intra-class correlation coefficient (ICC) and limits of agreement (LOA) defined the quality and magnitude of reliability on the measurements plotted with 95% confidence interval (95% CI) by Bland-Altman method. Results: ICC ranged from 0.58 to 0.99, with few ICC values classified as moderate when repeated by raters during test and a single value during retest. The total work was the only variable to present LOA higher than the limits. Conclusion: Results indicate acceptable reliability, in two different protocols, confirming the repeatability of the isokinetic measures for trunk muscles in able-bodied and post-stroke hemiparesis.