Fig. 4.

Motor-evoked potentials during static position, passive shortening and lengthening in soleus, and tibialis anterior with stimuli delivered at different muscle length. a, b Averaged representative traces in response to single-pulse transcranial magnetic stimulation delivered at short, intermediate, and long muscle length during resting position (black line), passive shortening (grey line), and lengthening (dashed line) in soleus (a) and tibialis anterior (b). Each representative trace is an average of 15 waveforms. c, d Amplitude of motor-evoked potential expressed as a percentage of the amplitude of maximal compound action potential (MEP/M_max) during static position (STAT), passive shortening (SHO), and passive lengthening (LEN) in soleus (c) and tibialis anterior (d) at short (left panel), intermediate (centre panel), and long (right panel) muscle length. Open squares and full lines represent the sample mean, whilst open circles and dashed lines denote individual responses (n = 12). *p = 0.023 compared to static position, and p < 0.001 compared to passive lengthening