Validity and reliability of combining three methods to determine ventilatory threshold

Purpose: This research was undertaken to validate a combination of methodol ogies to determine ventilatory threshold (VT). Methods: Three methods were used individually and then combined to determine VT as follows: 1) ventilat ory equivalencies, 2) excess CO2 production, and 3) a modified V-slope meth od. Three groups of participants-endurance athletes (N=132), healthy, aerob ically active adults (N=31), and healthy, sedentary/low-active adults (N=22 )-were independently evaluated for VT and compared with the criterion stand ard lactate threshold (LT) defined as the first rise in blood lactate with increasing intensity of exercise. Results: VT and LT were significantly cor related using the combined VT method within each study group (r=0.98, 0.97, and 0.95, respectively; P<0.001). Mean (V)over dotO(2) values at VT and LT were not significantly different between the three groups (P>0.20). The co mbined method improved the determination rate of VT and reduced the standar d deviation of the LT-VT difference by 80-170% over the individual methods. During test-retest procedures (V)over dotO(2)lt and (V)over dotO(2)vt dete rmined by the combined method met criteria demonstrating further reliabilit y. Conclusion: The combined method to determine VT is valid and reliable ac ross a wide fitness range in healthy individuals and improves the determina tion rate and accuracy of VT determination over the use of single methods.