COMPARISON OF THE RAMP VERSUS STANDARD EXERCISE PROTOCOLS

To compare the hemodynamic and gas exchange responses of ramp treadmill and cycle ergometer tests with standard exercise protocols used clinically, 10 patients with chronic heart failure, 10 with coronary artery disease who were asymptomatic during exercise, 11 with coronary artery disease who were limited by angina during exercise and 10 age-matched normal subjects performed maximal exercise using six different exercise protocols. Gas exchange data were collected continuously during each of the following protocols, performed on separate days in randomized order: Bruce, Balke and an individualized ramp treadmill; 25 W/stage, 50 W/stage and an individualized ramp cycle ergometer test. Maximal oxygen uptake was 16% greater on the treadmill protocols combined (21.4 +/- 8 ml/kg per min) versus the cycle ergometer protocols combined (18.1 +/- 7 ml/kg per min) (p < 0.01), although no differences were observed in maximal heart rate (131 +/- 24 versus 126 +/- 24 beats/min for the treadmill and cycle ergometer protocols, respectively). No major differences were observed in maximal heart rate or maximal oxygen uptake among the various treadmill protocols or among the various cycle ergometer protocols. The ratio of oxygen uptake to work rate, expressed as a slope, was highest for the ramp tests (slope +/- SEE ml/kg per min = 0.80 +/- 2.5 and 0.78 +/- 1.7 for ramp treadmill and ramp cycle ergometer, respectively). The slopes were poorest for the tests with the largest increments in work (0.62 +/- 4.0 and 0.59 +/- 2.8 for the Bruce treadmill and 50 W/stage cycle ergometer, respectively). Normal subjects demonstrated a greater slope (0.71 +/- 4.2) than did patients with chronic heart failure (0.53 +/- 2.8), coronary artery disease (0.51 +/- 2.6) and angina (0.53 +/- 3.1) (p < 0.001). The difference between measured and predicted maximal oxygen uptake was greatest for the tests with the largest increments between stages (> 1 metabolic equivalent (MET) for the Bruce treadmill and 50 W/stage cycle ergometer) and least for the tests with the smallest increments between stages (ramp tests and 25 W/stage cycle ergometer). These findings suggest that the exercise protocol, even when the same mode is used, can result in marked variations in maximal oxygen uptake and the dynamics of gas exchange during exercise testing.