Ventilatory capacity and its utilisation during exercise

Inadequate ventilation is not usually considered an exercise-limiting factor because it is thought that the respiratory system's maximum ventilatory capacity is never reached during exercise. This so-called reserve can be defined as the difference between the ventilated volume, attained during a maximum voluntary ventilation manoeuvre (MVV) and the maximum ventilation V(Emax) achieved during exercise. This study explores the relationship between ventilatory capacity, the MVV manoeuvre, and respiratory function. Twelve healthy adults completed a maximal cycle test and 12-, 30-, and 60-s MVV manoeuvres while seated or standing. The MVV(12) manoeuvre produced the largest ventilation volume (115 +/- 22 vs. (V(Emax)) 102 +/- 23 L min(-1)), signifying a reserve of 13%. With longer MVV (30 and 60 s) manoeuvres, the ventilated volume and (V(Emax)) were the same, signifying no reserve. MVV increased with the forced expiratory volume at one second, FEV(1). The breath rates were approximately 120 vs. 48 +/- 6 breaths min(-1) and tidal volumes were approximately 1 vs. 2.2 +/- 0.5 L during the MVV and exercise, respectively. The longer MVV manoeuvre provides the best estimate of ventilatory capacity and shows that 100% of the reserve is used during maximal exercise. A nomogram relating MVV to FEV(1) is shown.