Fig. 2

Development of the transitory force decrease at an increasing number of pulses with high-frequency stimulation. a, a set of sample recordings of single fast resistant contractions evoked by five trains of pulses including one, two, four, six, and 18 short interpulse intervals of 11.1 ms. Low frequency stimulation: 35 Hz; high frequency stimulation: 90 Hz. b, amplitude of the transitory force decrease as a function of the number of short intervals. All data for one set of recordings (obtained at low-frequency stimulations of 35 Hz and 40 Hz for all 8 examined MUs) are connected. The black line illustrates motor unit presented left. The red line presents mean values; * p < 0.01 in relation to one short interpulse interval