Abstract 14706: Novel Mathematical Method of Determining Ventilatory Anaerobic Threshold

Ventilatory anaerobic threshold (VAT) is commonly employed as a submaximal measure of exercise tolerance. However, it must be visually determined. We developed a novel approach to objective mathematical determination. Materials and Methods: Part 1. Retrospective data of normal and cardiac subjects (n = 138, 52 ± 21 yr) undergoing maximal cardiopulmonary exercise testing to develop the method. Part 2. Data of pre- and post-cardiac rehabilitation patients (n = 128, 64 ± 10 yr) undergoing submaximal testing at another institution to apply the method. VAT (V-slope) was determined visually. Results: Part 1. First, (VCO2 - VO2) was calculated for each V-slope data point as an index of excess (or deficit) CO2. This value was plotted against VO2 (Figure), a modification of V-slope. Then, quadratic regression was applied to the plots and the tangent through the nadir was drawn (A). The nadir correlated with VAT (r = 0.886, p <0.001); however, it was significantly lower. Next, horizontal lines of plus 2-20 ml/min (...