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Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise

Kiran Chopra, Owen Jeffries, Jamie Tallent, Shane Heffernan Orcid Logo, Liam Kilduff Orcid Logo, Adrian Gray, Mark Waldron Orcid Logo

Aerospace Medicine and Human Performance, Volume: 93, Issue: 1, Pages: 13 - 21

Swansea University Authors: Shane Heffernan Orcid Logo, Liam Kilduff Orcid Logo, Mark Waldron Orcid Logo

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DOI (Published version): 10.3357/amhp.5919.2022

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Introduction Repeated ischemic preconditioning (IPC) can improve muscle and pulmonary oxygen on-kinetics, blood flow and exercise efficiency but these effects have not been investigated severe hypoxia. The aim of the current study was to evaluate the effects of 7 d of IPC on resting and exercising m...

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Published in: Aerospace Medicine and Human Performance
ISSN: 2375-6314
Published: Aerospace Medical Association 2022
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URI: https://cronfa.swan.ac.uk/Record/cronfa58541
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spelling 2022-02-16T12:10:02.1515794 v2 58541 2021-11-03 Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise 72c0b36891dfbec0378c0d0f7916e807 0000-0002-3297-9335 Shane Heffernan Shane Heffernan true false 972ed9a1dda7a0de20581a0f8350be98 0000-0001-9449-2293 Liam Kilduff Liam Kilduff true false 70db7c6c54d46f5e70b39e5ae0a056fa 0000-0002-2720-4615 Mark Waldron Mark Waldron true false 2021-11-03 STSC Introduction Repeated ischemic preconditioning (IPC) can improve muscle and pulmonary oxygen on-kinetics, blood flow and exercise efficiency but these effects have not been investigated severe hypoxia. The aim of the current study was to evaluate the effects of 7 d of IPC on resting and exercising muscle and cardio-pulmonary responses to severe hypoxia. Methods Fourteen subjects received either: 1) 7 d of repeated lower-limb occlusion (4 x 5 min, 217±30 mm Hg) at limb occlusive pressure (IPC) or SHAM (4 x 5 min, 20 mm Hg). Subjects were tested for resting limb blood flow (72), relative microvascular deoxyhemoglobin concentration ([HHB]) and pulmonary oxygen (V ̇O2p) responses to steady state and incremental exercise to exhaustion in hypoxia (fractional inspired O2 = 0.103), which was followed by 7 d of IPC or SHAM, and retesting 72 h post intervention. Results There were no effects of IPC on maximal oxygen consumption, time to exhaustion during the incremental test or minute ventilation and arterial oxygen saturation. However, the IPC group had higher delta efficiency based on pooled results and lower steady state delta[HHB] (IPC ~24% vs. SHAM ~6% pre-to-post), as well as slowing the [HHB] time constant (IPC ~26% vs. SHAM ~3% pre-to-post) and reducing the overshoot in [HHB]:V ̇O2 ratio during exercise onset. Conclusions Collectively, these results demonstrate that muscle O2 efficiency and microvascular O2 distribution can be improved by repeated IPC but there are no effects on maximal exercise capacity in a severe hypoxia. Journal Article Aerospace Medicine and Human Performance 93 1 13 21 Aerospace Medical Association 2375-6314 conditioning; oxygen kinetics; near-infrared spectroscopy; hypoxic 1 1 2022 2022-01-01 10.3357/amhp.5919.2022 COLLEGE NANME Sport and Exercise Sciences COLLEGE CODE STSC Swansea University 2022-02-16T12:10:02.1515794 2021-11-03T13:25:22.9042865 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Sport and Exercise Sciences Kiran Chopra 1 Owen Jeffries 2 Jamie Tallent 3 Shane Heffernan 0000-0002-3297-9335 4 Liam Kilduff 0000-0001-9449-2293 5 Adrian Gray 6 Mark Waldron 0000-0002-2720-4615 7 58541__21421__16e8c4a6606648a7bd1388ca5cac8319.pdf 58541.pdf 2021-11-03T13:27:59.6433430 Output 701204 application/pdf Accepted Manuscript true false
title Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
spellingShingle Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
Shane Heffernan
Liam Kilduff
Mark Waldron
title_short Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
title_full Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
title_fullStr Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
title_full_unstemmed Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
title_sort Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise
author_id_str_mv 72c0b36891dfbec0378c0d0f7916e807
972ed9a1dda7a0de20581a0f8350be98
70db7c6c54d46f5e70b39e5ae0a056fa
author_id_fullname_str_mv 72c0b36891dfbec0378c0d0f7916e807_***_Shane Heffernan
972ed9a1dda7a0de20581a0f8350be98_***_Liam Kilduff
70db7c6c54d46f5e70b39e5ae0a056fa_***_Mark Waldron
author Shane Heffernan
Liam Kilduff
Mark Waldron
author2 Kiran Chopra
Owen Jeffries
Jamie Tallent
Shane Heffernan
Liam Kilduff
Adrian Gray
Mark Waldron
format Journal article
container_title Aerospace Medicine and Human Performance
container_volume 93
container_issue 1
container_start_page 13
publishDate 2022
institution Swansea University
issn 2375-6314
doi_str_mv 10.3357/amhp.5919.2022
publisher Aerospace Medical Association
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Sport and Exercise Sciences{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Sport and Exercise Sciences
document_store_str 1
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description Introduction Repeated ischemic preconditioning (IPC) can improve muscle and pulmonary oxygen on-kinetics, blood flow and exercise efficiency but these effects have not been investigated severe hypoxia. The aim of the current study was to evaluate the effects of 7 d of IPC on resting and exercising muscle and cardio-pulmonary responses to severe hypoxia. Methods Fourteen subjects received either: 1) 7 d of repeated lower-limb occlusion (4 x 5 min, 217±30 mm Hg) at limb occlusive pressure (IPC) or SHAM (4 x 5 min, 20 mm Hg). Subjects were tested for resting limb blood flow (72), relative microvascular deoxyhemoglobin concentration ([HHB]) and pulmonary oxygen (V ̇O2p) responses to steady state and incremental exercise to exhaustion in hypoxia (fractional inspired O2 = 0.103), which was followed by 7 d of IPC or SHAM, and retesting 72 h post intervention. Results There were no effects of IPC on maximal oxygen consumption, time to exhaustion during the incremental test or minute ventilation and arterial oxygen saturation. However, the IPC group had higher delta efficiency based on pooled results and lower steady state delta[HHB] (IPC ~24% vs. SHAM ~6% pre-to-post), as well as slowing the [HHB] time constant (IPC ~26% vs. SHAM ~3% pre-to-post) and reducing the overshoot in [HHB]:V ̇O2 ratio during exercise onset. Conclusions Collectively, these results demonstrate that muscle O2 efficiency and microvascular O2 distribution can be improved by repeated IPC but there are no effects on maximal exercise capacity in a severe hypoxia.
published_date 2022-01-01T04:15:09Z
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