Respiration Physiology, 94 (1993) 137-150 137 Elsevier Science Publishers B.V. RESP 02066 Femoral vascular occlusion and ventilation during recovery from heavy exercise P. Haouzi b'*, A. Huszczuk a, J. Porszasz a, B. Chalon b, K. Wasserman a and B.J. Whipp aA aDivision of Respiratory and Critical Care, Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California, USA; b Laboratoire de Physiologic, Facultd de Mddecine de Nancy, France (Accepted 14 June 1993) Abstract. Ventilation and cardiac output subside gradually following cessation of exercise, which is com- monly linked to the slow wash-out of materials from the recovering muscles. The effect of hindering the removal of the metabolic products of heavy cycle exercise on the kinetics of ventilation and gas exchange was studied in 5 subjects by occluding the femoral circulation with cuffs during the first 2 min of recovery (15 tests). Fifteen undisturbed recoveries served as controls. Compared to spontaneous recovery, circula- tory obstruction induced an immediate (from the first breath) decrease in minute ventilation ('¢E), while end-tidal CO 2 (PETco2) as well as lactate and K + in venous blood at forearm did not change significantly. A ventilatory deficit of 27 + 9 L was observed from the 2 min of occlusion. Following cuff deflation, VE rose 2--3 breaths after PETco 2 began to increase in every subject. The mechanisms of the normocapnic reduc- tion of VE during occlusion, as well as the rise of ventilation following cuff release, are still unclear. How- ever, these results argue against any significant role for hyperpnea-inducing intramuscular chemoreception, or point to muscular perfusion as a prerequisite of such a mechanism to operate. Control of breathing, Exercise, recovery, ventilation; Hyperpnea, post-exercise; Mammals, humans; Muscle, metabolites Following the cessation of muscular exercise, ventilation ('~E) declines with an expo- nential profile; that is, VE remains high for several minutes despite no muscular con- traction being performed (see Dejours, 1964; Whipp, 1981 for review). By means of cuff occlusion experiments, it has been shown in humans that "trapping" blood in the exercised limbs, during recovery from light (Dejours et aL, 1955), moderate (Innes et al., 1989) or heavy exercise (Rowell et aL, 1976) actually speeds the ventilatory decline to resting levels. Innes et al. (1989) recently showed that, compared to the control recovery, the re- duction of ~'E in response to the occlusion was immediate (i.e. beginning at the first breath). The response to the release of the occlusion was an immediate increase of VE, Corresponding author: Laboratoire de Physiologie Facult6 de Mtdecine de Nancy, Avenue de la For~t de Haye, B.P. 184 54505 Vandoeuvre-16s-Nancy Cedex, France 1Present address: Dept. of Physiology, St George's Hospital Medical School, Cranmer Terrace, London SW17 ORE, UK.