Reproducibility of the measurements

Day to day (separated by 1–4 days) reproducibility of the measurements was examined on 10 participants for all variables except for soreness. Paired t-tests revealed no significant differences between days in all the variables. The coefficient of variation (CV) and the intraclass correlation coefficient (ICC) for each measurement variable are shown in Table 1. Both the CV and ICC have been widely used to assess reproducibility, and provide a measure of absolute (within-individual) and relative (inter-individual) reliability, respectively⁵⁰. The CV was low for maximal torque (≤5.3%) and T₂ (≤2.0%) but relatively high for the RTD (≥6.3%) especially in the early phase (RTD_{30, 50}: 17.2–21.1%). ICC values were interpreted as excellent: 0.80–1.00, good: 0.60–0.80, and poor: <0.60⁵¹, and all variables ranged from good to excellent (0.70–0.95).

The coefficient of variations (CVs) and intraclass correlation coefficients (ICCs) of the variables in between-days measurements (n = 10).

KE: knee extensors, PF: plantar flexors, RTD_{30, 50, 100, 200}: rate of torque development in the time intervals of 0–30, 0–50, 0–100, and 0–200 ms, respectively, from contraction onset. T₂: transverse-relaxation time. CVs and ICCs for the T₂ are maximum and minimal values, respectively, among the 21 sites.