Gradual versus continuous increase of load in ergometric tests: are the results comparable?

Standard exercise testing (ET) comprises progressive exercise provocation with cardiovascular monitoring. Exercise tolerance is estimated by workload. Cardiopulmonary exercise testing (CPX) is a non-invasive measurement of ventilatory gas exchange which provides more accurate quantifications of cardiorespiratory fitness (CRF). Workload is usually increased stepwise in ET and continuously (ramp) in CPX. Our aim was to examine the comparability of the results. Thirty two healthy volunteers (17 females/15 males, age 26.8±6.1 years, BMI 24.5±3.0) underwent exercise testing on a bicycle ergometer up to maximum physical exhaustion; under ramp protocol (CPX) and 2-7 days later with a stepwise increase of workload (ET). We compared the physical work capacity under both methods at maximum workload, at heart rate of 150 and 170 beats/min (PWC150 and PWC170), and the exercise duration. We found that there were no statistically significant differences in the maximum heart rate (CPX: 177.1±11.7/min vs. ET: 178.5±11.2/min) or maximal workload (CPX: 219.8±50.6 vs. ET: 209.4±42.5). PWC150 and PWC150/kg were higher with CPX than those with ET (156.6±51 vs. 146.4±42.3, p<0.001 and 2.1±0.5 vs. 1.9±0.4, respectively, p<0.001). Exercise duration was almost equal (12.1 vs. 11.3 min). We conclude that overall physical performance was higher with CPX. Since the results are similar, we recommend the CPX: wattage and other parameters in performance assessment are to be determined directly, interpolations are obsolete.