Dissociation between exercise intensity thresholds : mechanistic insights from supine exercise
This study tested the hypothesis that the respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme]BP, assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at the same metabolic rate in the upright (U) and supine (S) body positions. Eleven healthy men completed ramp incremental exercise tests in U and S. Gas exchange was measured breath-by-breath and time-resolved-NIRS was used to measure deoxy[heme] in the vastus lateralis (VL) and rectus femoris (RF). RCP (S: 2.56 ± 0.39, U: 2.86 ± 0.40 L·min-1, P = 0.02) differed from deoxy[heme]BP in the VL in U (3.10 ± 0.44 L·min-1, P = 0.002), but was not different in S in the VL (2.70 ± 0.50 L·min-1, P = 0.15). RCP was not different from the deoxy[heme]BP in the RF for either position (S: 2.34 ± 0.48 L·min-1, U: 2.76 ± 0.53 L·min-1, P > 0.05). However, the deoxy[heme]BP differed between muscles in both positions (P < 0.05), and changes in deoxy[heme]BP did not relate to ΔRCP between positions (VL: r = 0.55, P = 0.080, RF: r = 0.26, P = 0.44). The deoxy[heme]BP was consistently preceded by a breakpoint in total[heme], and was, in turn, itself preceded by a breakpoint in muscle surface electromyography (EMG). RCP and the deoxy[heme]BP can be dissociated across muscles and different body positions and, therefore, do not represent the same underlying physiological phenomenon. The deoxy[heme]BP may, however, be mechanistically related to breakpoints in total[heme] and muscle activity.
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2021 |
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| Erschienen: |
2021 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:321 |
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| Enthalten in: |
American journal of physiology. Regulatory, integrative and comparative physiology - 321(2021), 5 vom: 01. Nov., Seite R712-R722 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Goulding, Richie P [VerfasserIn] |
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| Links: |
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| Anmerkungen: |
Date Completed 08.11.2021 Date Revised 08.11.2021 published: Print-Electronic Citation Status MEDLINE |
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| doi: |
10.1152/ajpregu.00096.2021 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM329746189 |
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| 100 | 1 | |a Goulding, Richie P |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Dissociation between exercise intensity thresholds |b mechanistic insights from supine exercise |
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| 500 | |a Date Revised 08.11.2021 | ||
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| 500 | |a Citation Status MEDLINE | ||
| 520 | |a This study tested the hypothesis that the respiratory compensation point (RCP) and breakpoint in deoxygenated [heme] [deoxy[heme]BP, assessed via near-infrared spectroscopy (NIRS)] during ramp incremental exercise would occur at the same metabolic rate in the upright (U) and supine (S) body positions. Eleven healthy men completed ramp incremental exercise tests in U and S. Gas exchange was measured breath-by-breath and time-resolved-NIRS was used to measure deoxy[heme] in the vastus lateralis (VL) and rectus femoris (RF). RCP (S: 2.56 ± 0.39, U: 2.86 ± 0.40 L·min-1, P = 0.02) differed from deoxy[heme]BP in the VL in U (3.10 ± 0.44 L·min-1, P = 0.002), but was not different in S in the VL (2.70 ± 0.50 L·min-1, P = 0.15). RCP was not different from the deoxy[heme]BP in the RF for either position (S: 2.34 ± 0.48 L·min-1, U: 2.76 ± 0.53 L·min-1, P > 0.05). However, the deoxy[heme]BP differed between muscles in both positions (P < 0.05), and changes in deoxy[heme]BP did not relate to ΔRCP between positions (VL: r = 0.55, P = 0.080, RF: r = 0.26, P = 0.44). The deoxy[heme]BP was consistently preceded by a breakpoint in total[heme], and was, in turn, itself preceded by a breakpoint in muscle surface electromyography (EMG). RCP and the deoxy[heme]BP can be dissociated across muscles and different body positions and, therefore, do not represent the same underlying physiological phenomenon. The deoxy[heme]BP may, however, be mechanistically related to breakpoints in total[heme] and muscle activity | ||
| 650 | 4 | |a Comparative Study | |
| 650 | 4 | |a Journal Article | |
| 650 | 4 | |a Research Support, Non-U.S. Gov't | |
| 650 | 4 | |a deoxy- + total (hemoglobin + myoglobin) | |
| 650 | 4 | |a exercise intensity thresholds | |
| 650 | 4 | |a respiratory compensation point | |
| 650 | 4 | |a supine exercise | |
| 650 | 4 | |a time-resolved near-infrared spectroscopy | |
| 650 | 7 | |a Biomarkers |2 NLM | |
| 650 | 7 | |a Hemoglobins |2 NLM | |
| 650 | 7 | |a Myoglobin |2 NLM | |
| 650 | 7 | |a deoxyhemoglobin |2 NLM | |
| 650 | 7 | |a 9008-02-0 |2 NLM | |
| 700 | 1 | |a Marwood, Simon |e verfasserin |4 aut | |
| 700 | 1 | |a Lei, Tze-Huan |e verfasserin |4 aut | |
| 700 | 1 | |a Okushima, Dai |e verfasserin |4 aut | |
| 700 | 1 | |a Poole, David C |e verfasserin |4 aut | |
| 700 | 1 | |a Barstow, Thomas J |e verfasserin |4 aut | |
| 700 | 1 | |a Kondo, Narihiko |e verfasserin |4 aut | |
| 700 | 1 | |a Koga, Shunsaku |e verfasserin |4 aut | |
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