What does this research mean for the field?

The nasal route of breathing significantly amplifies the Tidal/VT ratio by +14.68 AU/L compared to the buccal route in a high-intensity cycling context. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.SUPPORTS_CONSENSUS.

What question did this study set out to answer?

This research aims to evaluate the influence of breathing routes on the tidal volume calibration when using the Tymewear Vital Strap Pro.

March 12, 2026Open Access

Tidal/VT Calibration of the Tymewear Vital Strap Pro Under VST Protocol: Nasal vs. Buccal Route Effects Replicated Across Three Outdoor Studies

Key Points

This research aims to evaluate the influence of breathing routes on the tidal volume calibration when using the Tymewear Vital Strap Pro.
Conducted tests with a World Tour cyclist using the TWP and VO₂ Master Pro across two outdoor sessions.
Utilized nasal and buccal breathing conditions at 285–455W intensity levels.
Performed full Bland-Altman analysis, Hedges g, Mann-Whitney U, and Welch t-tests to assess data accuracy.
The tidal/VT ratio was significantly higher for nasal breathing (100.32 AU/L) compared to buccal (85.64 AU/L), with a Δ of +14.68 AU/L.
Very large effect size (Hedges g=3.21) confirmed the nasal amplification effect.
Buccal route showed stability across sessions, while nasal route had a moderate decrease noted between sessions.

Abstract

Background: The Tymewear Vital Strap Pro (TWP) generates a dimensionless Tidal signal reflecting thoracic strain amplitude per respiratory cycle. Its conversion to tidal volume (VT) requires an individual Tidal/VT ratio sensitive to breathing route. Two prior studies established this: Study 1 (Ricci, 2025; doi:10.5281/zenodo.18667689) documented a +18.8% nasal vs. oral Tidal signal increase at VT1. Study 2 (Ricci, 2026a; doi:10.5281/zenodo.18873288) formalised a four-level hierarchical model (breathing route > position > bicycle type > intensity) with a large nasal vs. oral effect in TT bar position (d=1.06, Δ=+8.7 AU/L). The present study extends this series to an outdoor high-intensity ergometer protocol in a VST-conditioned World Tour cyclist. Methods: One World Tour cyclist (Ath-02; VST ≥2 months) was tested simultaneously with TWP and VO₂ Master Pro across two outdoor sessions (Day J; Day J+1). n=59 total pairs; 1 mixed-route pair excluded → n=58 valid pairs. Conditions: nasal and buccal breathing, 285–455W. Full Bland-Altman analysis; Hedges g; Mann-Whitney U; Welch t (α=0.05). Results: Global RF accuracy (n=58): bias=+0.187 bpm ±0.156, SD=0.607, LoA=−1.003; +1.377, PE=4.1%, ICC=0.9980. Tidal/VT ratio: nasal 100.32±5.72 AU/L vs. buccal 85.64±2.98 AU/L; Δ=+14.68 AU/L; Hedges g=3.21 (very large); p=6.68×10⁻¹¹. Buccal route was inter-session stable (g=−0.55, p=0.14). Nasal route showed a moderate Day J to J+1 decrease (g=0.93, p=0.022), attributed to strap repositioning (~5 AU/L). Conclusion: The nasal amplification effect (Δ=+14.68 AU/L, g=3.21) is convergent across three studies (Δ: +11.5 to +14.7 AU/L; d/g: 1.06 to 3.21) in different contexts, athletes, and intensity ranges. Buccal inter-session stability confirms its role as calibration anchor. All results are individual (n=1 athlete); no population generalisation is claimed

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