A combined method for estimating ventilatory threshold

Background. The aims of this study were to compare two new methods (D-max a nd CUSUM) for determination of the ventilatory threshold and to examine the consequences of estimation by application of these methods in combination. Methods. Experimental design: a comparative design was used, Setting: the study was performed in the Exercise Physiology Laboratory in t he Faculty of Medicine, Self uh University, Participants: thirty-two untrai ned males (20.6+/-1.2 yrs) performed an incremental exercise test on a cycl e ergometer, Interventions: there is no intervention. Measures: ventilatory and gas exchange variables were measured breath-by-breath. The ventilatory thresholds were detected by conventional linear regression, CUSUM, D-max a nd combined CUSUM-D-max methods. Results. The ventilatory thresholds determined by D-max method gave the hig hest r-values compared to the criterion method. There was no statistical di fference between thresholds determined by all methods or by the same method using different variables, Ventilatory thresholds could not be determined by the conventional linear regression method in three subjects but were det ermined in all subjects by the other three methods. Conclusions. Although all methods presented in this study can be used in th e determination of ventilatory threshold, the D-max method was found to be the most valid one, When using the CUSUM method, combining it with the D-ma x method increases the validity of the measurement.