Cardiopulmonary Measurements
While exercising, the subjects breathed through a mouthpiece connected to a two-way valve. measured respiratory gases at the mouthpiece using a mass spectrometer (Perkin Elmer, MGA 1100). Ventilation was measured with a pneumotachometer. An online computer (Medical Graphics Corp 2001) performed breath-by-breath calculation of O, consumption, CO, production, minute ventilation, and other measurements. Wfe monitored heart rhythm on an oscilloscope (Anthrometrics Electrocardiograph System) and measured heart rate from a rhythm strip obtained during the last 5 s of each minute. The anaerobic threshold is reported as the Vo, (L/min) for the interval during which Ve/Vo, increased without a corresponding increase in Ve/Vco,. flovent inhaler
Gas Exchange Measurements
One hour before exercise, a 20 gauge catheter was inserted into a radial artery of the nondominant arm. A 25 cm connecting tube with a three-way stopcock was attached to the catheter to permit anaerobic sampling while the subject exercised. Patency of the catheter and connecting tube was maintained with a heparin solution (10 USP unit/ml). Blood samples were drawn anaerobically into 3 ml preheparinized glass syringes. The first was obtained 10 minutes prior to exercise while the subject sat quietly, off die mouthpiece.