Test-retest reproducibility of isokinetic lifting strength measurements

Objectives: To determine the intra-rater reproducibility of normalized lifting strength (NLS) measurements. Methods: 30 healthy male volunteers with a mean age of 28.16 ± 7.59 years participated in this study. Each subject was tested by the same physician twice in a week, with at least 48 hours between the test sessions. For the evaluation of intra-rater reproducibility, intraclass correlation coefficients (ICC), the standard error of measurement (SEM) and the smallest real difference (SRD) and Bland and Altman method were used. Results: Intra-rater ICCs of the NLS were 0.77 and 0.67 at 19.4 and 38.9 cm/s, respectively. The SEM% were 13.2% and 20.1% while the SRD% were 36.6% and 55.8% at these velocities, respectively. Conclusions: The reproducibility of NLS using the Biodex Lift Simulation Attachment was moderate in terms of the ICC and low in terms of the SRD. Thus the test, as described and applied is not sufficiently sensitive to detect clinically relevant changes.