Tidal volume and ventilatory frequency during matched stages above the estimated VT2, before and after a Ventilatory Strategies Training programme: a longitudinal case report

Background. In adults born preterm, the literature describes a mechanical ventilatory constraint during exercise, with reduced expiratory flow and a low tidal volume. What becomes of this constraint in a high-level athlete trained on the organisation of his ventilation is poorly documented. Case. An international-level under-23 road cyclist, 22 years old, born preterm, with a ventilatory obstructive disorder diagnosed before the follow-up (FEV1/FEV6 of 0.654 at entry, unchanged maintenance treatment), followed for four and a half months of Ventilatory Strategies Training. Comparisons are within-individual, at matched protocol, with a portable analyser without CO₂ measurement, near-infrared spectroscopy of the vastus lateralis and daily spirometry (154 measurements). Results. In April, at 370 W (103 % of the estimated VT2), tidal volume plateaued and then gave way, from 3.49 L at minute 3 to 2.85 L at minute 8, while ventilatory frequency rose from 35.2 to 48.9 cycles/min and the target power was no longer held. In June, it stayed between 3.98 and 4.15 L at 375 W. At a nominally identical fraction of the estimated VT2 (397 W), it lost only 0.14 L (blood lactate 4.8 mmol/L, against 4.2 in April). In September, it stayed between 3.68 and 3.94 L at the fourth minute of four repetitions of a 430 W block within a single session, at ventilations of 132 to 140 L/min. The nasal pattern, held under instruction up to about 320 W in April, became spontaneous up to about 350 W. In the standardised subset, measured FEV1 values increased by 0.26 L (95 % CI 0.05 to 0.46) and FEV6 values by about 0.4 L over the first month, the FEV1/FEV6 ratio remaining between 0.62 and 0.76. The estimated VT2 rose by 25 W; the best 60 s VO₂ was higher in September, in a different protocol that establishes neither the magnitude nor the direction of a change in VO₂max, with altitude as a possible confounder. Conclusion. The variable targeted by the intervention, the organisation of the ventilatory pattern above the estimated VT2, changed in the intended direction, in an athlete with an obstructive disorder diagnosed before the follow-up. These changes are not attributed to the intervention alone. The case identifies two descriptive variables that made it possible to document this pattern in this athlete.