EFFECT OF EXERCISE TESTING PROTOCOL ON THE RELATIONSHIP BETWEEN MINUTE VENTILATION AND CARBON DIOXIDE PRODUCTION

Background: The effect of exercise protocol on the slope of the relationship between minute ventilation and carbon dioxide production (∆V ˙ E/∆V ˙ CO2) has not fully been studied. Methods: Twenty-five healthy vol-unteers performed two sessions of incremental bicycle exercise, one with a rapidly increasing staged (RIS: 25W every minute) protocol and another with a slowly increasing staged (SIS: 25W every 3 minutes) proto-col to calculate the ∆V ˙ E/∆V ˙ CO2. Six of the subjects also participated in sessions of steady state exercise (SSE) test various work rates. Results: The ∆V ˙ E/∆V ˙ CO2 was significantly lower when the RIS protocol was used than when the SIS protocol was used (23.3±2.3 vs. 24.9±1.8, p<0.001). Data from the subjects who also underwent SSE sessions revealed that the ∆V ˙ E/∆V ˙ CO2 from the SSE protocols was greater than that from the RIS protocol and identical with that from the SIS protocol (25.1±3.7, 20.6±1.7, and 24.0±2.7, re-spectively, p<0.05), while arterial partial pressure of carbon dioxide during exercise was not different be-tween the protocols (43.0±3.3, 39.9±2.1, and 40.8±2.6, respectively, n.s.). Conclusions: Care must be taken in the interpretation of the values of ∆V ˙ E/∆V ˙ CO2, as they are influenced by the difference in exercise proto-col. Key Words: exercise, exercise testing, ventilatory response, reliabilit