Maximal Oxygen Uptake and Oxygen Kinetics in Cardiac Patients

Résumé du livre

The purpose of this study was to investigate the maximal oxygen uptake capacity of cardiac patients and several transient submaximal exercise characteristics. The specific problem was to identify the speed at which oxygen uptake (VO(,2)) and heart rate (HR) reached steady state and the relationship of that speed with maximal oxygen uptake (VO(,2)max). All subjects (N = 19) were currently taking beta receptor blocking agents or calcium channel blocking agents for treatment of coronary artery disease, hypertension, myocardial infraction, or dysrhythmias. Subjects exercised on a calibrated bicycle ergometer at a work load of 300 kpm (50 watts) for 6 min. VO(,2) and HR were recorded every 20 sec and plotted against time to establish response characteristics of the change of VO(,2) and HR from testing values to steady state values for each subject. The time constant (TC) was used to define the speed at which VO(,2) (TCVO(,2)) and HR (TCHR) rose from rest to steady state. TC was calculated using a semi-log plot and regression analysis. The steady state respiratory exchange ratio (R), mechanical efficiency (ME), TCVO(,2), and TCHR were statistically analyzed to establish the correlation coefficients with VO(,2)max. VO(,2)max (x = 1.82 (+OR- ) 0.33 l/min) had correlations between TCVO(,2), TCHR, and R of -0.496, -0.542, and -0.500, respectively. Correlation coefficients reported above were statistically significant with p