Calculation of additional heart rates using oxygen consumption and carbon dioxide production: A comparative analysis

Research, to date, on the occurrence of additional heart rates during behavioral stressors has employed oxygen consumption as the index of metabolic activity. Although this is the obvious first choice, in certain situations measures of carbon dioxide production may be more readily obtained. The analysis presented in this paper explored the intuitively appealing notion that, since oxygen consumption and carbon dioxide production are themselves intimately related, carbon-dioxide-production measures may also be appropriate in the “additional heart rate” methodology. Data from the most recent additional-heart-rate paper by Turner and colleagues were thus reexamined, and additional heart rates during mental arithmetic and a video game were separately calculated for the 24 subjects by first using oxygen consumption and then by using carbon dioxide production. The values obtained were very highly correlated; the coefficients for the task: periods themselves were 0.99 and 0.96, respectively. Use of carbon-dioxide-production data-in this manner would, therefore, seem to be appropriate.