Differences among variables of determination of vantilatory thresholds

Abstract

The objective of this study was to investigate the association and sensibility of variables that identify VT1 and VT2, employing the usage of both visual and mathematical methods. Twenty men underwent a progressive test on treadmill with initial velocity between 4 and 6 km.h-1, and increments of 1 km.h-1 per minute. The visual curve analyses of VE, VE/VO2, VE/VCO2, FeO2, FeCO2 and R were applied to VT1 and VT2 identification. The Vslope and multiple linear regressions mathematically determinated VT1 and VT2, respectively. In VT1, VE/VO2 was significantly higher than VE and V-slope methods, whereas in VT2 no significant differences were recognized. In VT1, no significant correlation was identified, despite the higher level of sensibility (75%-95%); In VT2, VE and FeCO2 demonstrated significant correlation coefficient (r= -0.71; p < 0.05) but only FeCO2 and VE/VCO2 demonstrated satisfactory level of sensibility (75% and 80% of individuals, respectively). The V-slope method and multiple linear regressions also demonstrated satisfactory levels of sensibility (75% and 90%, respectively). We concluded that different ventilatory variables may not determine the same points, suggesting dissociation among them and either may not show the same sensibility level.