Background: The purpose of the present study is to establish the relationship and degree of contribution between torque and sonomiography variables (pennation angle - muscle thickness), and electromyography variables (EMGAreaUnderCurve - EMGMaximalPeak) of the tibialis anterior muscle during (TA) maximal and relative isometric foot dorsiflexion (IFD). Secondary aim: To determine the measurement's reliability.
Methods: Cross-sectional study. 31 participants (15 men; 16 women) performed IFD at different intensities (100, 75, 50, and 25 %) of the maximal voluntary contraction (MVC) (three times for each intensity).
Outcome variables: To determine the torque, pennation angle, muscle thickness, EMGMaximalPeak, and EMGAreaUnderCurve.
Statistical analysis: In order to test the measurement's reliability, Cronbach's alpha and standard error of the measurement were determined. An inferential analysis was carried out using Pearson correlations(r). For each contraction intensity, a multiple regression analysis was performed, where the dependent variable was torque and the independent variables were EMGAreaUnderCurve, EMGMaximalPeak, muscle thickness and pennation angle.
Results: All outcome variables show excellent reliability. The highest correlation value was 0.955 (thickness 100 % - thickness 25 %). R (2) values ranged from 0.713 (100 % MVC) to 0.588 (25 % MVC).
Conclusion: The outcome variables demonstrated excellent reliability in terms of measuring IFD at different intensities. The correlations between all outcome variables were moderate-to-strong. TA functional and architectural variables have a significant impact on the torque variance during IFD at different intensities.
