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Impact of steady-state and exercise modality on estimating oxygen consumption in men with and without coronary artery
J Milani1, B Fernhall, P Gorman
1Employee Health Promotion Program, University of New Mexico, Albuquerque 87131-1251, USA.
Purpose:
This study examined the effect of steady-state on the ability of 15 men with coronary artery disease (CAD) and 13 men without CAD disease (non-CAD) to reach a rate of oxygen consumption (VO2) relative to population norms during treadmill and cycle ergometry exercise testing.
Methods:
Subjects completed a maximal graded exercise test on the treadmill and cycle ergometry involving 3-minute stages and a submaximal exercise test involving 6-minute stages to 80% of maximal effort. Estimates of VO2 were derived from commonly cited clinical estimation equations.
Results:
Only the Foster equation accurately estimated maximal VO2 during a treadmill graded exercise test in patients with CAD. However, each of cited clinical equations accurately estimated maximal VO2 during a treadmill graded exercise test in the non-CAD group. No equation accurately estimated VO2 at submaximal efforts during treadmill exercise for either group. Cycle ergometry estimation equations accurately estimated VO2 in both groups at maximal effort, but were inconsistent at submaximal efforts. Both the CAD and the non-CAD group reached steady-state VO2 within 3 minutes, at submaximal workloads.
Conclusions:
The inability to attain an expected VO2 during exercise did not seem related to steady-state VO2 because both CAD and non-CAD groups readily reached steady-state VO2, though the estimation of VO2 remained inaccurate for most treadmill estimation equations. Because VO2 was accurately estimated for cycle ergometry exercise, estimation accuracy seems to be influenced by exercise modality.