Fig. 7. Energy storage capacity of the tendon and aponeurosis as function of the tendon force between the runners of group 1 (high running economy) and the runners of groups 2 and 3 (moderate and low running economies), and percentage differences relative to group 1 in the quadriceps femoris muscle-tendon unit (as statistically significant differences in the force-strain relationship were found only between group 1 and both other groups, groups 2 and 3 have been considered together).