Validation of continuous determination of respired gases during steady-state exercise

A continuous-flow sampling system (CFS) for convenient and rapid determination of respiratory gas exchange during steady-state exercise was described. CFS was compared to the classical bag collection system (BCS) by utilizing both methods concurrently during exercise for analysis of 32 1-min gas samples. The gas collected by BCS was analyzed by chemical absorption. The error in the gas mixing and sampling technique of CFS contributed to the absolute error of the gas analysis but did not adversely affect the reliability. The linear regression analysis on the data suggests that CFS is a relatively accurate and reliable system for use at light and moderate levels of steady-state work. However, it is hypothesized that unsteady-state conditions and heavy exercise, which elicits high ventilation rates, would compromise the accuracy and reliability of CFS. Therefore, it is recommended that the traditional BCS be utilized for determination of maximal oxygen uptake.