Reliability of Maximal Voluntary Isometric Contraction of Ankle Dorsiflexion in Male Subjects

Maximum voluntary isometric contraction (MVIC) of the ankle dorsiflexion is a common strength measurement used in clinical and research environment. It can be a clinical tool to assess several pathologies, such as amyotrophic lateral sclerosis and diabetic neuropathies. Its practical use depends on many factors, but an important one is the reliability of the technique. Therefore, the purpose of this study was to investigate the reliability of MVIC through a test-retest analysis and with a two-stage nested design. Ten male subjects (age 25.5 ± 1.43 years, mean ± SD) were investigated in three consecutive days, in each day, the subjects performed the MVIC twice. This procedure allows to investigate test-retest reliability and also to build a two-stage nested design with random factors to estimate the global variances components among the three sources of variation: subjects, days, and trials. The Bland-Altman plots and the paired t-test indicated no systematic bias in the data and no significant difference in the within-day analysis for the three days. The intraclass correlation coefficient (ICC) obtained through the two-stage nested design was 86.6%, the variability attributed to days was 8.6% and the variability attributed to trials was 4.6%, therefore presenting excellent reliability according to the typical standard, which consider an ICC higher than 80% to be excellent. This work suggests that the MVIC of the ankle dorsiflexion is a highly reliable measure to study in a young population and consequently may be useful for investigators in training and clinical applications.