A simplified strategy for the estimation of the exercise ventilatory thresholds

Purpose: To analyze the limits of agreement between exercise ventilatory threshold values (VT1 and VT2) estimated from a combination of pulmonary gas exchange and ventilatory variables (cardiopulmonary exercise testing) and those derived from an alternative approach based oil the ventilatory response only (VE. ventilometry). Methods: Forty-two nontrained subjects (24 males, aged 18-48, peak VO2 = 33.1 +/- 8.6 mL(.)min(-1.)kg(-1)) performed a maximum incremental cardiopulmonary exercise testing on all electromagnetically braked cycle ergometer. The participants breathed through a Pilot tube (Cardio(2) System (TM), MGC) and a fixed-resistance ventilometer (Micromed, Brazil), which were connected in series. HR values at the estimated VT (VTHR1 and VTHR2) were obtained by the conventional method (ventilatory equivalents. end-expiratory pressures for O-2 and CO2 and the V-slope procedure) and an experimental approach (VE vs time, VE/time vs time. and breathing frequency vs time). Results: There were no significant between-method differences on VTHR1, VTHR2, VTVE1, VTVE2, and peak VE (P > 0.05). After certification of data normality, a Bland-Altman analysis revealed that the mean bias 95% confidence interval of the between-method differences were lower for VTHR2 than VTHR1 (2 +/- 9 and 0 +/- 17 bpm, respectively). VTHR2 according to ventilometry differed more than 10 bpm from the standard procedure in 3 out of 42 subjects (9%). Between-method differences were independent of the level of fitness, as estimated from peak VO2 (P > 0.05). Conclusions: A simplified approach, based oil the ventilatory response as a function of time, call provide acceptable estimates of the exercise ventilatory thresholds-especially VT2-during ramp-incremental cycle ergometry. This new strategy might prove to be useful for exercise training prescription in nontrained adults.