Effects of CO2 inhalation prior to maximal exercise on physical performance

In the untrained subjects, inhalation of 4.5-6.0% CO2 prior to maximal treadmill exercise does not affect physical performance and maximum oxygen uptake, while blood lactate levels during recovery have a tendency to greater decrease in CO2 breathing than that in the room-air breathing. It was suggested that CO2 inhalation immediately prior to maximal exercise as applied here is not a useful tool in increasing physical performance.