Concentric and eccentric isokinetic knee extension: A reproducibility study using the IsoMed 2000-dynamometer

ThepurposeofthisstudywastodeterminerelativeaswellasabsolutereproducibilityfortheIsoMed2000-dynamometer in measuring Peak Torque (PT) during concentric and eccentric maximum knee extension at two angular velocities. Thirty five physically active male subjects (mean age: 23.7 years) with no prior experience of isokinetic exercise were measured on three occasions (T1-T3), separated by 48-72 h. Detection of systematic errors was performed using repeated measures analysis of variance (ANOVA) with Bonferroni post hoc adjustments. Further statistical calculations were done between consecutive pairs of sessions (T1-T2; T2-T3). Intraclass correlation coefficients (ICC 2,1) were calculated to assess relative reproducibility, whereas absolute reproducibility was determined by the standard error of measurement (SEM). A highly significant systematic error was found for theeccentric measurements withvalues on thefirst visit being around 5% lower than corresponding values on thesecond and third visit. ICCvalues of 0.907-0.955 and 0.968-0.984 withcorresponding values of SEMof 7.4-19.1 and 4.5-10.9 Nmwere found for T1-T2 and T2-T3, respectively. In conclusion, high reproducibility was shown for the IsoMed 2000-dynamometer in measuring PT during concentric and eccentric knee extension. However, due to a systematic practice-based improvement found for eccentric measurements, we suggest to do a familiarisation session prior the actual testing sessions in practice.