Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males

Rafael D.A. Azevedo; J. E. Béjar Saona; Erin Calaine Inglis; Danilo Iannetta; Juan M. Murias

doi:10.14814/phy2.14478

Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males

Rafael D.A. Azevedo, J. E. Béjar Saona, Erin Calaine Inglis, Danilo Iannetta, Juan M. Murias^*

^*Corresponding author for this work

University of Calgary

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

This study investigated the effect of reduced inspired fraction of O₂ (FiO₂) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near-infrared spectroscopy-derived deoxygenated hemoglobin signal ([HHb]_bp) during a ramp-incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO₂ = 20.9%) or hypoxia (HYPO, FiO₂ = 16%). Oxygen uptake ((Formula presented.) O₂), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak (Formula presented.) O₂ (2.98 ± 0.36 vs. 3.39 ± 0.26 L min⁻¹) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The (Formula presented.) O₂ and PO associated with RCP and [HHb]_bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min⁻¹; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min⁻¹; 244 ± 29 and 241 ± 28 W, respectively) (p <.05). Within the same condition, the (Formula presented.) O₂ and PO associated with RCP and [HHb]_bp were not different (p >.05). Bland–Altman plots mean average errors between RCP and [HHb]_bp were not different from zero in HYPO (0.01 L min⁻¹ and 1.1 W) and NORM (0.00 L min⁻¹ and 3.6 W) conditions. The intra-individual changes between thresholds associated with (Formula presented.) O₂ and PO in HYPO from NORM were strongly correlated (r =.626 and 0.752, p <.05). Therefore, breathing a lower FiO₂ during a RI test resulted in proportional reduction in the RCP and the [HHb]_bp in terms of (Formula presented.) O₂ and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.

Original language	English
Article number	e14478
Journal	Physiological Reports
Volume	8
Issue number	12
DOIs	https://doi.org/10.14814/phy2.14478
Publication status	Published - 1 Jun 2020
Externally published	Yes

Keywords

RCP
cycling
deoxygenation breakpoint
exercise intensity
thresholds

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10.14814/phy2.14478

Cite this

@article{097f8e367dc34c61adf3e0cbeaba94f2,

title = "Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males",

abstract = "This study investigated the effect of reduced inspired fraction of O2 (FiO2) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near-infrared spectroscopy-derived deoxygenated hemoglobin signal ([HHb]bp) during a ramp-incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO2 = 20.9\%) or hypoxia (HYPO, FiO2 = 16\%). Oxygen uptake ((Formula presented.) O2), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak (Formula presented.) O2 (2.98 ± 0.36 vs. 3.39 ± 0.26 L min−1) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The (Formula presented.) O2 and PO associated with RCP and [HHb]bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min−1; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min−1; 244 ± 29 and 241 ± 28 W, respectively) (p <.05). Within the same condition, the (Formula presented.) O2 and PO associated with RCP and [HHb]bp were not different (p >.05). Bland–Altman plots mean average errors between RCP and [HHb]bp were not different from zero in HYPO (0.01 L min−1 and 1.1 W) and NORM (0.00 L min−1 and 3.6 W) conditions. The intra-individual changes between thresholds associated with (Formula presented.) O2 and PO in HYPO from NORM were strongly correlated (r =.626 and 0.752, p <.05). Therefore, breathing a lower FiO2 during a RI test resulted in proportional reduction in the RCP and the [HHb]bp in terms of (Formula presented.) O2 and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.",

keywords = "RCP, cycling, deoxygenation breakpoint, exercise intensity, thresholds",

author = "Azevedo, \{Rafael D.A.\} and \{B{\'e}jar Saona\}, \{J. E.\} and Inglis, \{Erin Calaine\} and Danilo Iannetta and Murias, \{Juan M.\}",

note = "Publisher Copyright: {\textcopyright} 2020 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.",

year = "2020",

month = jun,

day = "1",

doi = "10.14814/phy2.14478",

language = "English",

volume = "8",

journal = "Physiological Reports",

issn = "2051-817X",

publisher = "John Wiley \& Sons Inc.",

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TY - JOUR

T1 - Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males

AU - Azevedo, Rafael D.A.

AU - Béjar Saona, J. E.

AU - Inglis, Erin Calaine

AU - Iannetta, Danilo

AU - Murias, Juan M.

PY - 2020/6/1

Y1 - 2020/6/1

N2 - This study investigated the effect of reduced inspired fraction of O2 (FiO2) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near-infrared spectroscopy-derived deoxygenated hemoglobin signal ([HHb]bp) during a ramp-incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO2 = 20.9%) or hypoxia (HYPO, FiO2 = 16%). Oxygen uptake ((Formula presented.) O2), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak (Formula presented.) O2 (2.98 ± 0.36 vs. 3.39 ± 0.26 L min−1) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The (Formula presented.) O2 and PO associated with RCP and [HHb]bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min−1; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min−1; 244 ± 29 and 241 ± 28 W, respectively) (p <.05). Within the same condition, the (Formula presented.) O2 and PO associated with RCP and [HHb]bp were not different (p >.05). Bland–Altman plots mean average errors between RCP and [HHb]bp were not different from zero in HYPO (0.01 L min−1 and 1.1 W) and NORM (0.00 L min−1 and 3.6 W) conditions. The intra-individual changes between thresholds associated with (Formula presented.) O2 and PO in HYPO from NORM were strongly correlated (r =.626 and 0.752, p <.05). Therefore, breathing a lower FiO2 during a RI test resulted in proportional reduction in the RCP and the [HHb]bp in terms of (Formula presented.) O2 and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.

AB - This study investigated the effect of reduced inspired fraction of O2 (FiO2) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near-infrared spectroscopy-derived deoxygenated hemoglobin signal ([HHb]bp) during a ramp-incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO2 = 20.9%) or hypoxia (HYPO, FiO2 = 16%). Oxygen uptake ((Formula presented.) O2), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak (Formula presented.) O2 (2.98 ± 0.36 vs. 3.39 ± 0.26 L min−1) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The (Formula presented.) O2 and PO associated with RCP and [HHb]bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min−1; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min−1; 244 ± 29 and 241 ± 28 W, respectively) (p <.05). Within the same condition, the (Formula presented.) O2 and PO associated with RCP and [HHb]bp were not different (p >.05). Bland–Altman plots mean average errors between RCP and [HHb]bp were not different from zero in HYPO (0.01 L min−1 and 1.1 W) and NORM (0.00 L min−1 and 3.6 W) conditions. The intra-individual changes between thresholds associated with (Formula presented.) O2 and PO in HYPO from NORM were strongly correlated (r =.626 and 0.752, p <.05). Therefore, breathing a lower FiO2 during a RI test resulted in proportional reduction in the RCP and the [HHb]bp in terms of (Formula presented.) O2 and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.

KW - RCP

KW - cycling

KW - deoxygenation breakpoint

KW - exercise intensity

KW - thresholds

UR - https://www.scopus.com/pages/publications/85087029554

U2 - 10.14814/phy2.14478

DO - 10.14814/phy2.14478

M3 - Article

C2 - 32592338

AN - SCOPUS:85087029554

SN - 2051-817X

VL - 8

JO - Physiological Reports

JF - Physiological Reports

IS - 12

M1 - e14478

ER -

Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males

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Keywords

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