Could a Short Incremental Test Be a Valid Cardiorespiratory Efficiency Assessment Tool in Obese Adults? A Comparison between Two Exercise Testing Protocols

Background: To assess cardiorespiratory efficiency in obese adults, two exercise test treadmill protocols with 2- or 3-min stages were compared. Methods: Thirty-six obese adult subjects were involved in this study. Sixteen men (age 51.5±10.5 years; BMI 36.7±4.8 kg/m2) and 20 women (age 42.4±12.4 years; BMI 36.5±4.7 kg/m2) performed submaximal incremental graded tests on treadmills with 2- or 3-minute stages on different days. During each testing session, heart rate (HR), oxygen uptake (VO2 mL/min/kg), rate of perceived exertion (RPE), fat oxidation (FO) at maximal fat oxidation (MFO) and maximal fat oxidation zone (Fatmax zone) were measured. Results: No differences were found for HR, VO2, and RPE at MFO between the two protocols. Significant differences (2-minute vs. 3-minute) were found for FO (576.3±162.9 mg/min vs. 506.0±148.1 mg/min respectively; P<0.05) at MFO between the two protocols. No differences were found for VO2 and HR in high and low Fatmax zone borders. Moreover, a difference was found for FO at the low and high borders. Conclusion: Exercise intensity at which the MFO and Fatmax zone occur is not influenced by the duration of stage-to-stage increments. The two exercise testing protocols could be considered interchangeable to assess HR, VO2, and RPE at MFO.