Measurement for TFS. The experimental set-up for TFS measurement (a), the toe grip dynamometer (b), and a typical example of the force-time curve during maximum TFS measurements (c). Participants performed their maximum TFS in the sitting position, and they placed their test foot within the heel stopper on the dynamometer. Maximum force was recorded on a computer via A/D converter. During the force measurement, the first proximal phalanx was gripped the grip-bar without pulling a leg.