Figure 3: The active force generated by the SM muscle as a function of passive tension, with which the muscle was stretched just before stimulation. The active force was produced by the SM muscle in response to electrical stimulation of the SM nerve. A 200 ms train of 1 mA biphasic pulses at 200 pulses/s was used. Each phase of biphasic pulse lasted 0.2 ms. Data shown in this graph represent average active force, normalized by maximal force (observed at 0.08 N tension). Vertical bars represent standard error. The SM muscle was denervated for 3 months, repaired by end-to-end anastomosis, and left to recover for additional 3 months. The same muscle force-tension characteristic was observed in the noninjured control muscles [18].