Xiong S, Goonetilleke RS, Witana CP, Rodrigo WDAS. An indentation apparatus for evaluating discomfort and pain thresholds in conjunction with mechanical proper-ties of foot tissue in vivo. J Rehabil Res Dev. 2010; 47(7): 629–42. DOI:10.1682/JRRD.2009.09.0152

Figure 5. Force-deformation curves of heel pad for three trials on 3 different days of one subject.