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Background. The aims of this study were to compare two new methods (D",ax and 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 the Faculty of Medicine, Selquk University. Participants: thirty-two untrained males (20.61.2 yrs) performed an incremental exercise test on a cycle 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, Dmax and combined CUSUM-Dm methods.
Results. The ventilatory thresholds determined by Dmax method gave the highest r-values compared to the criterion method. There was no statistical difference 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 determined in all subjects by the other three methods.
Conclusions. Although all methods presented in this study can be used in the determination of ventilatory threshold, the D,nax method was found to be the most valid one. When using the CUSUM method, combining it with the Dn,ax method increases the validity of the measurement.
KEY WORDS: Ventilatory threshold - Ventilation - Anaerobic threshold - Exercise test.
The anaerobic threshold (AT) has been used to evaluate the physical performance of athletes and patients, and can be invasively detected from a rapid rise of blood lactate concentration during exercise. 12 However, determinations through the gas exchange technique have the advantage of being noninvasive and convenient.=* The most commonly used non-invasive method is the detection of ventilatory threshold (VT). Carbon dioxide output (VCOZ) increases more than oxygen uptake (V02) due to the bicarbonate buffering of accumulated blood lactate after AT. Ventilation (VE) also rises to remove the increased CO2. The break points where a rapid increase occurs in VE and VCOZ values are termed VT and have a close correlation with AT.4-7 Although VT has commonly...