Fig. 1.

Methodology. A: experimental setup. Stretches of elbow flexors [biceps brachii (BB), brachioradialis (BR)] or extensors [triceps lateralis (TL), triceps medialis (TM)] were produced with a torque motor of the manipulandum. B: 20° and 70° stretches and velocity profiles. C: procedures: 4 blocks (40 trials in each) were done starting from stretching flexors (blocks 1 and 2) and then extensors (blocks 3 and 4). D: in different subjects chosen randomly, the experiments started from stretching extensors (blocks 1 and 2) and then flexors (blocks 3 and 4). E: example of a trial excluded from analysis: in 1 or 2 trials per subject, the muscle activity was reduced prematurely, before the stretch onset. F: identification of an inhibitory period (IP) in the integrated EMG (curve iEMG) and raw EMG. To minimize prediction of the stretch onset time, the latter was randomized within the range of 0.5–1 s after the initial position was stabilized, but in this and other figures only a segment of kinematic and EMG data just preceding the stretch onset is shown.