Figure 5. Changes in the relation between the amplitude of the motor-evoked potential and the duration of the silent period during isometric and anisometric contractions.

Motor-evoked potential (MEP) amplitude was compared to their corresponding silent period during isometric (circles), shortening (squares) and lengthening (triangles). For the group, relations between the MEP and the silent period are illustrated for the soleus (SOL) muscle (top panel) and for the medial gastrocnemius (MG) (bottom panel). The two parameters are positively correlated regardless of the muscle contraction type (0.82 < r < 0.99; P < 0.01) for both SOL and MG. The slope of this relation was significantly (P < 0.01) greater during lengthening than during isometric and shorteniong contractions for SOL but not for MG.