Fig. 3

Anterolateral view of each finger for individual flexor digitorum superficialis (FDS) activity. a All fingers are kept straight, thus not contracting the FDS. b The index finger is flexed at a fixed angle of 90° at the proximal interphalangeal joint and maintained straight and free from any muscle contraction at the distal interphalangeal joint; this is done to only activate the FDS and to eliminate the effect of flexor digitorum profundus contraction of the specific finger. The participants maintain the activation by keeping the finger bent. c The FDS activation of the middle finger. d The FDS activation of the ring finger