From ventilation to muscle: reading performance as a system — The HNS ventilatory index ecosystem

A power meter measures an output, never its cause. This white paper sets out the HNS ventilatory index ecosystem as an integrated reading framework for the complete oxygen chain — from ventilation through muscular extraction (NIRS-based VEC and ICP SmO₂) to cardio-peripheral coupling (Efficiency Factor, O₂ Pulse). Its thesis: an elite cyclist's limiter cannot be read from any single number; each index is a reading layer, read in cascade and cross-checked against its neighbours, so as to measure every link, identify the limiter and rank the training priority. The paper develops three contributions distinct from the proprietary-indices article it complements (Ricci 2026, doi:10.5281/zenodo.20132550): (i) the reading extended across the whole chain rather than the inspiratory/expiratory mechanics alone; (ii) cross-system convergence, with the triple lock at VO₂max as its archetype; and (iii) the field-level disambiguation of a respiratory-muscle metaboreflex from CO₂ intolerance through the temporal coupling of transcutaneous CO₂, ICP SmO₂ kinetics and the Rf/Tv pattern. Mechanistic hypotheses are graded by level of evidence; reference values rest on an in-house cohort (n = 80), unpublished, publication in preparation 2026. Functional reading, no medical diagnosis. Companion to the VST monograph (doi:10.5281/zenodo.19691514).