Automated systems for measurement of oxygen uptake during exercise testing

We evaluated three automated systems for measurement of O2 uptake and compared them with the conventional Douglas bag method. One system (9000 IV Ergometric system) was only tested with respect to its oxygen kinetics, the other two (MMC-Horizon and EOS-Sprint) were tested during three exercise programs: (1) steady-state exercise at 50-W steps from 0 to 200 W, (2) progressive increasing exercise to maximal load, and (3) single-step exercise from 0 to 250 W. The regression lines of mean O2 uptake and load for six subjects were different for intercept (MMC-Horizon) or slope (EOS-Sprint) compared with the conventional method. The maximal O2 uptake values of six subjects were not significantly different for the two systems when compared with the Douglas bag method. The time constants of the exponential function describing oxygen kinetics during repeated (6 times) step changes in load in two subjects were different for the three systems. MMC-Horizon and 9000 IV Ergometric system had lower (51.8 s and 55.1 s, respectively, vs 62.5 s) and EOS-Sprint higher time constant (94.6 vs 47.7 s) than the conventional method. The automated systems were convenient and efficient for measurement of O2 uptake during steady-state and maximal exercise. When O2 uptake kinetics are essential, one has to take into account the response time of the system.