The influence of time-of-day variation and loading on the aponeurosis plantaris pedis: An ultrasonographic study

Aim. The aim of this paper was to investigate the effect of time-of-day on the thickness of the the aponeurosis plantaris pedis, and to examine the acute effects of high-load strength training and long distance running on the thickness of the aponeurosis plantaris pedis. Methods. Proximal aponeurosis plantaris pedis thickness was assessed with a 13-MHz linear-array transducer. In substudy 1, ten participants (ten aponeurosis') were measured five times during 24 hours. In sub-study 2, ten participants (ten aponeurosis') were measured just before, immediately after and again three hours after 3x12 unilateral heel-rises. In sub-study 3, 11 healthy experienced runners (11 aponeurosis') were measured just before, immediately after and two hours after a 15km run. The average thickness of three scans of each foot was used in the analysis. The data was analysed using repeated measures one-way ANOVA. Results. The mean thickness of the aponeurosis plantaris pedis' fluctuated significantly during the 24 hours (p=0,02), but it did not change in relation to the high-load strength training (p=0,86) or 15km of running (p = 0,70). Conclusion. High-load strength training and long distance running do not induce changes in the thickness of the aponeurosis plantaris pedis. Time-of-day influences the thickness of the aponeurosis plantaris pedis, but the changes are not larger than measurement uncertainty.