Tibialis anterior analysis from functional and architectural perspective during isometric foot dorsiflexion: a cross-sectional study of repeated measures.

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.