INCREASE IN OCCLUSION PRESSURE WITH VENTILATION AND RESPONSE TO MAXIMAL EXERCISE

Fifteen sedentary or mildly active men (low fit group) and 15 trained male athletes (high fit group) performed an incremental exercise bout on a cycle ergometer until exhaustion. At each submaximal load, minute ventilation (V over dot E) and rate of change of mouth pressure (dP/d t) during a brief airway occlusion were computed. The ah-way was occlu ded for 40-200 ms and adjusted according to the level of ventilation. Maximal oxygen uptake (V over dot O-2peak) and minute ventilation (V o ver dot E(peak)) were measured during the last increment. dP/dt was re lated to V over dot E in all subjects as dP/dt = a V over dot E(CURV). The CURV parameter was 0.99-1.95 with a median of 1.49. The subjects were divided into four groups of seven or eight according to their phy sical fitness and their CURV value. Low and high CURV subjects had a C URV below and above the median, respectively. V over dot E/V over dot O-2peak and V over dot E/V over dot CO2peak were significantly higher in the low CURV than in the high CURV group (P < 0.01 and P < 0.05, re spectively). Although factors other than the increase in pulmonary imp edance with ventilation may influence CURV, the present results indica te the possible influence of mechanical constraint of breathing on the ventilatory output.