Figure 1 shows examples of electromyographic (EMG) activity of “experimental cramps” elicited with this method in four muscles of a representative healthy subject. From these recordings, it is worth noting that an involuntary EMG activity is present in the cramping muscle, whereas only fasciculation potentials are observed in synergistic muscles. Conversely, these four muscles (the two gastrocnemii and two intrinsic foot muscles) work in synergy during a voluntary contraction