(a) Mean ± SE SICI obtained during maximal power grip, at 25%, 50% and 75% into the relaxation period during the grip-and-relax trials (Experiment 1) as well as at sustained contractions at the matching background EMG levels (Experiment 2), and at rest in Study 2. SICI was 32% greater for relaxation than sustained contraction (p < 0.05). (b) Mean ± SE nonconditioned and conditioned MEPs obtained during maximal power grip, during 25%, 50% and 75% into the muscle relaxation period (Experiment 1), during sustained contraction at the matching background EMG levels (Experiment 2), and at rest in Study 2.