Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: Mechanistic insights into slow pulmonary oxygen uptake dynamics

Goulding, Richie P and Okushima, Dai and Marwood, Simon and Poole, David and Barstow, Thomas and Tze-Huan, Lei and Narihiko, Kondo and Shunsaku, Koga (2020) Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: Mechanistic insights into slow pulmonary oxygen uptake dynamics. Journal of Applied Physiology, 129 (3). pp. 535-546. ISSN 8750-7587

[thumbnail of J Appl Physiol Resubmission CLEAN (1).docx] Text
J Appl Physiol Resubmission CLEAN (1).docx - Accepted Version

Download (169kB)
[thumbnail of Table 1.docx] Text
Table 1.docx - Accepted Version

Download (14kB)
[thumbnail of Table 2.docx] Text
Table 2.docx - Accepted Version

Download (14kB)
[thumbnail of Table 3.docx] Text
Table 3.docx - Accepted Version

Download (13kB)
[thumbnail of Table 4.docx] Text
Table 4.docx - Accepted Version

Download (15kB)
[thumbnail of Table 5.docx] Text
Table 5.docx - Accepted Version

Download (15kB)
[thumbnail of Figure 1.docx] Text
Figure 1.docx - Accepted Version

Download (88kB)
[thumbnail of Figure 2.docx] Text
Figure 2.docx - Accepted Version

Download (88kB)
[thumbnail of Figure 3.docx] Text
Figure 3.docx - Accepted Version

Download (85kB)
[thumbnail of Figure 4.pptx] Slideshow
Figure 4.pptx - Accepted Version

Download (115kB)
[thumbnail of Figure 5.docx] Text
Figure 5.docx - Accepted Version

Download (39kB)
[thumbnail of Figure 6.docx] Text
Figure 6.docx - Accepted Version

Download (36kB)
[thumbnail of Figure 7.pptx] Slideshow
Figure 7.pptx - Accepted Version

Download (310kB)

Abstract

Oxygen uptake (V ̇O2) kinetics are slowed in the supine (S) position due to impaired muscle O2 delivery (Q ̇O2), however, these conclusions are predicated on single-site measurements in superficial muscle using continuous-wave near-infrared spectroscopy (NIRS). This study aimed to determine the impact of body position (i.e. upright [U] vs. S) on deep and superficial muscle deoxygenation (deoxy[heme]) using time-resolved (TR-) NIRS, and how these relate to slowed pulmonary V ̇O2 kinetics. 17 healthy men completed constant power tests during 1) S heavy intensity exercise; and 2) U exercise at the same absolute work rate, with a subset of 10 completing additional tests at the same relative work rate as S. Pulmonary V ̇O2 was measured breath-by-breath and, deoxy- and total[heme] were resolved via TR-NIRS in the superficial and deep vastus lateralis and superficial rectus femoris. The fundamental phase V ̇O2 time constant was increased during S compared to U (S: 36±10 vs. U: 27±8 s, P<0.001). The deoxy[heme] amplitude (S: 25-28 vs. U: 13-18 µM, P<0.05) and total[heme] amplitude (S: 17-20 vs. U: 9-16µM, P<0.05) were greater in S compared to U and were consistent for the same absolute (above data) and relative work rates (n=10, all P<0.05). The greater deoxy- and total[heme] amplitudes in S vs. U supports that reduced perfusive Q ̇O2 in S, even within deep muscle, necessitated a greater reliance on fractional O2 extraction and diffusive Q ̇O2. The slower V ̇O2 kinetics in S vs. U demonstrates that, ultimately, these adaptations were insufficient to prevent impairments in whole-body oxidative metabolism.

Item Type: Article
Additional Information and Comments: Copyright © 2020 the American Physiological Society. This is the author's version of an article that was accepted for publication in the Journal of Applied Physiology. The published version is available from: https://journals.physiology.org/doi/full/10.1152/japplphysiol.00213.2020
Keywords: Time-resolved near-infrared spectroscopy, oxygen delivery, muscle deoxygenation, oxidative metabolism
Faculty / Department: Faculty of Science > School of Health Sciences
Depositing User: Simon Marwood
Date Deposited: 18 Nov 2020 09:27
Last Modified: 18 Nov 2020 09:27
URI: https://hira.hope.ac.uk/id/eprint/3176

Actions (login required)

View Item View Item