The Effects of Splanchnic Stimulation on the Contraction of Fatigued Muscle
When skeletal muscle is repeatedly stimulated by a long series of rapidly recurring electric shocks, its strong contractions gradually grow weaker until a fairly constant condition is reached. The record then has an even top—the muscle has reached the “fatigue level.” The effect of splanchnic stimulation was tried when the muscle had been fatigued to this stage. The effect which was often obtained by stimulating the left splanchnic nerves is shown in [Fig. 11]. In this instance the muscle while relaxed supported no weight, and while contracting lifted a weight of 125 grams. The rate of stimulation was 80 per minute.
Figure 11.—Upper record, contraction of the tibialis anticus, 80 times a minute, lifting a weight of 125 grams. Lower record, stimulation of the left splanchnic nerves, two minutes. Time, half minutes.
The muscle record shows a brief initial rise from the fatigue level, followed by a drop, and that in turn by another, prolonged rise. The maximum height of the record is 13.5 millimeters, an increase of 6 millimeters over the height recorded before splanchnic stimulation. Thus the muscle was performing for a short period 80 per cent more work than before splanchnic stimulation, and for a considerably longer period exhibited an intermediate betterment of its efficiency.