Abstract
BACKGROUND: Several investigations have reported reproducibility for isokinetic single-joint (SJ) knee strength measurements. However, to date, only a few studies have concentrated on multi-joint (MJ) leg strength measurements.
OBJECTIVE: This study is the first to investigate reproducibility for MJ leg strength measurements using the IsoMed 2000-system, which recently was introduced into the market.
METHODS: Peak Force (PF) of forty-one healthy male subjects (mean age: 24.4 years) performing concentric and eccentric MJ leg extension at standardized mean knee-joint angular velocities 40 and 80°/s (i.e. individual linear foot velocities of 0.12–0.19 and 0.24–0.38 m/s, respectively) was measured in three identical sessions (T1–T3), separated by 10–14 days. Repeated measures analysis of variance (ANOVA) was applied for detection of systematic errors over sessions. Reproducibility was calculated between consecutive pairs of sessions (T1–T2; T2–T3) using intra-class correlation coefficients (ICC 2,1) and standard error of measurement (SEM).
RESULTS: Significant increases in mean measurement values of ≈ 2–4% from T1 to T2/T3 could be seen for concentric measurements at 40°/s and overall eccentric measurements. Reproducibility calculations revealed ICC-values of 0.823–0.956 and 0.911–0.978 with corresponding measures of SEM of 72.1–175.3 and 49.3–125.3 N for T1–T2 and T2–T3, respectively.
CONCLUSIONS: Moderate to high reproducibility was shown for the IsoMed 2000-system in measuring PF during concentric and eccentric isokinetic leg extension. However, as data indicate the presence of an initial practice-based improvement, we recommend the consideration of a familiarisation session in practice.