Reliability of ventilatory threshold using the computerized V- slope method

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Authors
Bulow, Joseph A.
Advisor
Dwyer, Gregory Byron, 1959-
Issue Date
1994
Keyword
Degree
Thesis (M.S.)
Department
School of Physical Education
Other Identifiers
Abstract

The ventilatory threshold (VT) is measured frequently during graded exercise tests (GXT) for exercise prescription purposes. The computerized V-slope method for VT determination has been reported to be valid yet little data exists concerning the reliability of the measure. The purpose of this study was to determine the reliability of the VT using the computerized V-slope method. Sixteen healthy volunteers, (eight men and eight women) ages 21-27 (23.6 ± 1.7yrs), performed three maximal GXT on an electronically-braked cycle using an individualized ramp protocol. A minimum of 48 hours separated each test; all three tests were completed within two weeks. Breath-by-breath analysis of gas exchange was performed using a SensorMedics 2900 cart. The VT, expressed as L • min1, was selected by a computerized V-slope method. There were no differences in V02 max between the 3 trials, (overall mean 3.18 ± 0.87 L - min-1). No significant differences were observed for V02 at VT (L - min-1) for tests 1, 2, and 3 (1.62 ± 0.44, 1.58 ± 0.49, and 1.49 ± 0.48) respectively. The VT was determined to be 49.7 ± 7.9% of V02 max. Correlations between the VT in trials 1-2, 1-3, and 2-3 were 0.829, 0.791, and 0.925, respectively. The overall coefficient of variation (C.V.) of the VT measures was 10.61 ± 5.1%. The overall (male and female) variability in VT was 1.28 ± 0.63 METS. Due to high variability and a wide range in correlations, the results failed to support the reliability in the computerized V-slope method.

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