Ramp Incremental Cycling Protocol Underpredicts V[Combining Dot Above]O2max in Sedentary Normal-Weight and Overweight/Obese Adults

The maximum rate of oxygen consumption (V[Combining Dot Above]O2max) is the gold-standard index for assessing cardiorespiratory fitness. The presence of a VO2/work-rate plateau at the highest work rates during incremental testing represents the primary way to confirm that a “true V[Combining Dot Above]O2max” was attained; however, such a plateau is often lacking. Instead, V[Combining Dot Above]O2max is often confirmed using “secondary criteria” based on arbitrarily-determined values for heart rate, RPE, RER and/or blood-lactate concentration. A constant-work-rate “verification bout” can also confirm V[Combining Dot Above]O2max; however, support for this practice comes predominantly from studies performed on recreationally-active/athletic populations. PURPOSE: To compare the peak V[Combining Dot Above]O2 responses from an incremental and verification bout in sedentary normal and overweight/obese adults. METHODS: Twenty-eight sedentary, but otherwise healthy normal-weight (n=15; BMI, 22.6±1.4 kg/m2) or overweight/obese (n=13; BMI, 31.3±2.9 kg/m2) subjects (male/female, n=15/13; age, 28.1±4.9 years) performed a “ramp” incremental cycling test (15-20 W[BULLET OPERATOR]min-1) to limit of tolerance on a lower-body ergometer followed (10 minutes) by constant-work-rate cycling to limit of tolerance at the highest work rate attained. RESULTS: Intraclass correlation coefficient (.980) and coefficient of variation (4.64±3.69%) indicate good reliability for peak V[Combining Dot Above]O2 measurement across protocols; however, the value was significantly higher during the verification bout (2.19±0.57 vs. 2.10±0.56 L/min; p=0.001) with 18 of 28 subjects demonstrating a value ≥ 2% above that derived from incremental testing. This implies that incremental testing does not reveal a true V[Combining Dot Above]O2max for a substantial proportion of these subjects. However, the peak incremental response would have been accepted as V[Combining Dot Above]O2max in all but eight subjects if the method often used (i.e., attainment of two of three criteria based on heart rate, RPE and RER) was employed. Indeed, despite the lower peak V[Combining Dot Above]O2 response, peak heart rate and RPE were not lower for the incremental bout while peak RER was higher (1.23±0.09 vs. 1.18±0.09; p=0.003). CONCLUSION: The ramp incremental protocol revealed an underprediction of V[Combining Dot Above]O2max in normal and overweight/obese sedentary adults. Use of secondary criteria resulted in false V[Combining Dot Above]O2max acceptance in 32% of subjects.