Reliability of isokinetic ankle dorsiflexor strength in young healthy men and women

ABSTRACT. The purposes of this study were: (i) to determine the test–retest reliability of isokinetic ankle dorsiflexor strength measurements in young healthy adults using the Biodex dynamometer, and (ii) to examine several statistical measures for the interpretation of reliability. Thirty men and women (mean age 23 3 years) performed three maximal concentric contractions at 30 ° /s, 60 ° /s, 90 ° /s, 120 ° /s and 150 ° /s. Reliability of peak torque, work and torque at a specific time were assessed by calculating the intraclass correlation coefficient (ICC 2,1), Pear-son product moment correlation coefficient (r), standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV), and by plotting the differences between observations against their means. Isokinetic tests of ankle dorsiflexor strength in healthy young adults using the Biodex dynamometer were highly reliable (ICC 0.61–0.93). It is recommended that test–retest reliability analyses include the ICC and assessments of measurement errors (SEM, ME or CV), as well as graphs to indicate any systematic variations in the data. Key words: ankle joint; biomechanics; movement; muscle contraction; skeletal muscle; physical medicine; reference values; reproducibility of results; research design; statistics