Changes in Muscle and Cerebral Deoxygenation and Perfusion during Repeated Sprints in Hypoxia to Exhaustion

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Serval ID
serval:BIB_5992BC746A54
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Changes in Muscle and Cerebral Deoxygenation and Perfusion during Repeated Sprints in Hypoxia to Exhaustion
Journal
Frontiers in physiology
Author(s)
Willis S.J., Alvarez L., Millet G.P., Borrani F.
ISSN
1664-042X (Print)
ISSN-L
1664-042X
Publication state
Published
Issued date
2017
Peer-reviewed
Oui
Volume
8
Pages
846
Language
english
Notes
Publication types: Journal Article
Publication Status: epublish
Abstract
During supramaximal exercise, exacerbated at exhaustion and in hypoxia, the circulatory system is challenged to facilitate oxygen delivery to working tissues through cerebral autoregulation which influences fatigue development and muscle performance. The aim of the study was to evaluate the effects of different levels of normobaric hypoxia on the changes in peripheral and cerebral oxygenation and performance during repeated sprints to exhaustion. Eleven recreationally active participants (six men and five women; 26.7 ± 4.2 years, 68.0 ± 14.0 kg, 172 ± 12 cm, 14.1 ± 4.7% body fat) completed three randomized testing visits in conditions of simulated altitude near sea-level (~380 m, FIO2 20.9%), ~2000 m (FIO2 16.5 ± 0.4%), and ~3800 m (FIO2 13.3 ± 0.4%). Each session began with a 12-min warm-up followed by two 10-s sprints and the repeated cycling sprint (10-s sprint: 20-s recovery) test to exhaustion. Measurements included power output, vastus lateralis, and prefrontal deoxygenation [near-infrared spectroscopy, delta (Δ) corresponds to the difference between maximal and minimal values], oxygen uptake, femoral artery blood flow (Doppler ultrasound), hemodynamic variables (transthoracic impedance), blood lactate concentration, and rating of perceived exertion. Performance (total work, kJ; -27.1 ± 25.8% at 2000 m, p < 0.01 and -49.4 ± 19.3% at 3800 m, p < 0.001) and pulse oxygen saturation (-7.5 ± 6.0%, p < 0.05 and -18.4 ± 5.3%, p < 0.001, respectively) decreased with hypoxia, when compared to 400 m. Muscle Δ hemoglobin difference ([Hbdiff]) and Δ tissue saturation index (TSI) were lower (p < 0.01) at 3800 m than at 2000 and 400 m, and lower Δ deoxyhemoglobin resulted at 3800 m compared with 2000 m. There were reduced changes in peripheral [Δ[Hbdiff], ΔTSI, Δ total hemoglobin ([tHb])] and greater changes in cerebral (Δ[Hbdiff], Δ[tHb]) oxygenation throughout the test to exhaustion (p < 0.05). Changes in cerebral deoxygenation were greater at 3800 m than at 2000 and 400 m (p < 0.01). This study confirms that performance in hypoxia is limited by continually decreasing oxygen saturation, even though exercise can be sustained despite maximal peripheral deoxygenation. There may be a cerebral autoregulation of increased perfusion accounting for the decreased arterial oxygen content and allowing for task continuation, as shown by the continued cerebral deoxygenation.

Keywords
NIRS, altitude, blood flow, convection, diffusion, maximal exercise, oxygenation, repeated sprint ability
Pubmed
Web of science
Open Access
Yes
Create date
10/10/2017 14:46
Last modification date
20/08/2019 14:13
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