Determining the ventilatory inter-threshold area in individuals with different endurance capacities

Abstract

There is a general consensus in the literature regarding the existence of two ventilation break points during incremental exercise, i.e., Ventilatory Threshold 1 (VT₁) and Ventilatory Threshold 2 (VT₂), which mark the boundaries of the aerobic–anaerobic transition. The Inter-Threshold Area (ITA) has been defined as a parameter that connects the ventilatory thresholds. The main aim of the present study was to examine the ITA i.e., the expressed area between VT₁ and VT₂ for the function: ventilation ÷ oxygen uptake (VE/VO₂ in L² min²) in individuals with various endurance capacities. Six hundred and six men with different levels of endurance completed an incremental exercise test and their ventilatory thresholds were recorded. The ITA is a trapezoid whose area is calculated as the sum of the area of the triangle and rectangle that form it between VT1 and VT2 below the VO₂/V_E function. The mean ITA for the function VO₂–V_E was greater in cyclists, as the main representatives for endurance athletes, than the mean corresponding to physical education students, who averaged a lower endurance level (120 ± 34 vs. 86 ± 40 L²/min²). The results suggest that the determination of the ITA can reflect metabolic status throughout the aerobic–anaerobic transition during maximal incremental exercise tests.