Validity and reliability of combining three methods to determine ventilatory threshold.
OBJECTIVE
This research was undertaken to validate a combination of methodologies to determine ventilatory threshold (VT).


METHODS
Three methods were used individually and then combined to determine VT as follows: 1) ventilatory equivalencies, 2) excess CO2 production, and 3) a modified V-slope method. Three groups of participants-endurance athletes (N = 132), healthy, aerobically active adults (N = 31), and healthy, sedentary/low-active adults (N = 22)-were independently evaluated for VT and compared with the criterion standard lactate threshold (LT) defined as the first rise in blood lactate with increasing intensity of exercise.


RESULTS
VT and LT were significantly correlated using the combined VT method within each study group (r = 0.98, 0.97, and 0.95, respectively; P < 0.001). Mean VO2 values at VT and LT were not significantly different between the three groups (P > 0.20). The combined method improved the determination rate of VT and reduced the standard deviation of the LT - VT difference by 80-170% over the individual methods. During test-retest procedures VO2lt and VO2vt determined by the combined method met criteria demonstrating further reliability.


CONCLUSIONS
The combined method to determine VT is valid and reliable across a wide fitness range in healthy individuals and improves the determination rate and accuracy of VT determination over the use of single methods.
Gaskill
S E
SE
Human Performance Laboratory, Department of Health and Human Performance, University of Montana, Missoula, MT 59812, USA. sgaskill@selway.umt.edu
Ruby
B C
BC
Walker
A J
AJ
Sanchez
O A
OA
Serfass
R C
RC
Leon
A S
AS
D000328:Adult; D015308:Anaerobic Threshold; D000704:Analysis of Variance; D002245:Carbon Dioxide / Q000378:metabolism; D005080:Exercise Test / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008019:Life Style; D008297:Male; D010101:Oxygen Consumption; D010809:Physical Fitness / Q000502:physiology*; D015203:Reproducibility of Results; D012119:Respiration; D013177:Sports / Q000502:physiology
D002245:Carbon Dioxide; D019344:Lactic Acid