FEMORAL VASCULAR OCCLUSION AND VENTILATION DURING RECOVERY FROM HEAVYEXERCISE

Ventilation and cardiac output subside gradually following cessation o f exercise, which is commonly linked to the slow wash-out of materials from the recovering muscles. The effect of hindering the removal of t he metabolic products of heavy cycle exercise on the kinetics of venti lation and gas exchange was studied in 5 subjects by occluding the fem oral circulation with cuffs during the first 2 min of recovery (15 tes ts). Fifteen undisturbed recoveries served as controls. Compared to sp ontaneous recovery, circulatory obstruction induced an immediate (from the first breath) decrease in minute ventilation (V(E)), while end-ti dal CO2 (PET(CO2)) as well as lactate and K+ in venous blood at forear m did not change significantly. A ventilatory deficit of 27 +/- 9 L wa s observed from the 2 min of occlusion. Following cuff deflation, VE r ose 2-3 breaths after PET(CO2) began to increase in every subject. The mechanisms of the normocapnic reduction of VE during occlusion, as we ll as the rise of ventilation following cuff release, are still unclea r. However, these results argue against any significant role for hyper pnea-inducing intramuscular chemoreception, or point to muscular perfu sion as a prerequisite of such a mechanism to operate.