Figure 1.

An illustration of the experimental setup. It shows a top view of the setup. As indicated by the two thin arrows in the left panel, the concentric contraction involved the index finger moved away from the middle finger (muscle shortening), in which the FDI muscle force was greater than the external resisting force, and the eccentric contraction involved the index finger moved toward the middle finger (muscle lengthening), which was a result of a greater external force than the force produced by the FDI muscle.