Neural drives to breathing during exercise.

This article presents the author's views about the neural drives to breathing during exercise. Two hypotheses are developed, the first being that the rapid changes in ventilation at the start and end of exercise are due to a fast neural drive whose magnitude is related to the frequency of limb movement. Experimental data are presented that this drive persists throughout exercise but declines as exercise continues. Second, the excessive increase in ventilation that occurs above the first ventilatory threshold during an incremental exercise test is due to a heavy exercise neural drive whose magnitude is related to the motor commands to the exercising muscles. Using the electromyographical activity of the working muscles as an index of the strength of the motor commands, experimental evidence is presented showing the coincidence of the first ventilatory threshold and that for the electromyographic activity of the working muscles during incremental exercise tests.