Reading the exercise ventilatory pattern against static capacity: a graphical field method (reference Rf–Tv envelope and TVUt index)

In the field, the laboratory tools that locate the exercise ventilatory pattern relative to mechanical limits (tidal flow–volume loops within the MEFV envelope, inspiratory capacity for EELV) are rarely available. We propose a graphical reading method that overlays, on the same axes, the athlete’s static ventilatory capacity and what the athlete actually does during exercise. Static capacity is described by the inspired volume–time curve reconstructed from the raw files of a maximal inspiratory manoeuvre on a POWERbreathe K5 and by forced expiratory spirometry (full curve or, failing that, FEV1 and FEV6), measured before and after exercise. The exercise pattern (Rf, Tv per stage or per series) is placed at the time per half-cycle left by its Rf, with an assumed inspiratory-to-expiratory ratio bracketed according to domain and ventilatory route. The figure set shows inspiratory–expiratory balance, before/after changes, the position of each stage relative to the volumes reachable in the available time, and a reference Rf–Tv envelope that reveals where the pattern goes beyond the static reference. Two descriptors summarise this reading stage by stage: TVUt (Tv as a percentage of the reference expirable volume within the available Te) and the required Te. With FEV1 and FEV6 only and Te below 1 s, TVUt reduces to a VE/FEV1 ratio; it carries its own information only with the full expiratory curve or at low frequencies. An illustrative case shows the complete reading. The method is descriptive, demonstrates no mechanical limitation, and proposes a field test of association. A French version is provided as a second file.