The effects of work intensity on the transient respiratory responses immediately following exercise¹

Abstract

The changes in minute ventilation (V̇_E), tidal volume (V_T), and breathing frequency (f) were studied in eleven subjects during and immediately after exercise of various intensity. The intensity of exercise affected the offset responses. Peak expiratory flow and f consistently decreased immediately following exercise. However, V_T did not immediately change following light and moderate work loads and increased following work loads of heavy and severe intensity. The changes in endtidal CO₂ approximately parallelled those of V_T. Since f and V_T change reciprocally immediately following high levels of work, it appears that the mechanisms of control of these parameters differ. This mixed offset response results in a small decrease in V_E immediately following exercise and suggests that the neurogenic stimulus to ventilation which is removed by the cessation of motion, plays a relatively minor role, quantitatively, in the exercise hyperpnea under these conditions and primarily by affecting f.