Diaphragm Function and Diver Endurance

This project will test the following hypotheses: 1. Training of the inspiratory muscles increases underwater endurance and reduces hypercapnia in divers. 2. Inspiratory muscle training while breathing low concentration carbon monoxide (200 ppm) for 30 minutes daily improves diaphragm performance to a greater degree than the same training breathing air. 3. Inspiratory muscle training increases hypercapnia ventilatory response (gain) in those individuals with a low gain. 4. Variability in oxygen (O2) and carbon dioxide (CO2) permeability of erythrocyte membranes is a determining factor in underwater exercise performance.