Fig. 5.

A: a comparison of the iSP in the triceps and biceps measured in the same subjects (n = 8) in all conditions tested. The abscissa shows the conditions tested (Unil, unilateral; Bilat. Agon., bilateral activation of agonist muscles; Bilat. Antag., bilateral activation of antagonist muscles) during the elbow extension (filled bars) and flexion sessions (open bars). The ordinate shows the depth of the iSP. Note the increase in the iSP during bilateral activation of agonist muscles and a decreased during bilateral activation of antagonist muscles compared with a unilateral contraction regardless of the elbow session tested. Error bars indicate SE. *P < 0.05. B: a correlation analysis between flexion and extension sessions of the changes in the iSP depth during bilateral (△, agonist; ○, antagonist) compared with unilateral contractions (a negative number indicates more inhibition and a positive number indicates less inhibition during the unilateral compared with bilateral condition). Each subject is represented by 2 points: one for bilateral agonist and one for bilateral antagonist contractions. Note that subjects who showed more pronounced inhibition in the elbow extension session also showed a similar trend in the elbow flexion session.