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Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males

Kevin John, Sayyam Kathuria, Jenny Peel, Joe Page, Robyn Aitkenhead, Aimee Felstead, Shane Heffernan Orcid Logo, Owen Jeffries, Jamie Tallent, Mark Waldron Orcid Logo

European Journal of Applied Physiology, Volume: 124, Pages: 2489 - 2502

Swansea University Authors: Jenny Peel, Joe Page, Robyn Aitkenhead, Aimee Felstead, Shane Heffernan Orcid Logo, Mark Waldron Orcid Logo

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DOI (Published version): 10.1007/s00421-024-05460-z

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Purpose: Caffeine is a commonly used ergogenic aid for endurance events; however, its efficacy and safety have been questioned in hot environmental conditions. The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in...

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Published in: European Journal of Applied Physiology
ISSN: 1439-6319 1439-6327
Published: Springer Science and Business Media LLC 2024
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URI: https://cronfa.swan.ac.uk/Record/cronfa65826
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The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in the heat. Methods: In a double-blind, randomised, cross-over trial, 12 healthy caffeine-habituated and unacclimatised males cycled to exhaustion in the heat (35 °C, 40% RH) at an intensity associated with the thermoneutral gas exchange threshold, on two separate occasions, 60 min after ingesting caffeine (5 mg/kg) or placebo (5 mg/kg). Results: There was no effect of caffeine supplementation on cycling time to exhaustion (caffeine; 28.5 ± 8.3 min vs. placebo; 29.9 ± 8.8 min, P = 0.251). Caffeine increased pulmonary oxygen uptake by 7.4% (P = 0.003), heat production by 7.9% (P = 0.004), whole-body sweat rate by 21% (P = 0.008), evaporative heat transfer by 16.5% (P = 0.006) and decreased estimated skin blood flow by 14.1% (P &lt; 0.001) compared to placebo. Core temperature was higher by 0.6% (P = 0.013) but thermal comfort decreased by -18.3% (P = 0.040), in the caffeine condition, with no changes in rate of perceived exertion (P &gt; 0.05). Conclusion: The greater heat production and storage, as indicated by a sustained increase in core temperature, corroborate previous research showing a thermogenic effect of caffeine ingestion. When exercising at the pre-determined gas exchange threshold in the heat, 5 mg/kg of caffeine did not provide a performance benefit and increased the thermal strain of participants.</abstract><type>Journal Article</type><journal>European Journal of Applied Physiology</journal><volume>124</volume><journalNumber/><paginationStart>2489</paginationStart><paginationEnd>2502</paginationEnd><publisher>Springer Science and Business Media LLC</publisher><placeOfPublication/><isbnPrint/><isbnElectronic/><issnPrint>1439-6319</issnPrint><issnElectronic>1439-6327</issnElectronic><keywords>Caffeine supplementation; ergogenic; endurance performance; heat; thermoregulation.</keywords><publishedDay>1</publishedDay><publishedMonth>8</publishedMonth><publishedYear>2024</publishedYear><publishedDate>2024-08-01</publishedDate><doi>10.1007/s00421-024-05460-z</doi><url/><notes/><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><apcterm>SU Library paid the OA fee (TA Institutional Deal)</apcterm><funders>Swansea University</funders><projectreference/><lastEdited>2024-10-08T08:56:52.6791790</lastEdited><Created>2024-03-12T14:04:58.6471326</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Sport and Exercise Sciences</level></path><authors><author><firstname>Kevin</firstname><surname>John</surname><order>1</order></author><author><firstname>Sayyam</firstname><surname>Kathuria</surname><order>2</order></author><author><firstname>Jenny</firstname><surname>Peel</surname><order>3</order></author><author><firstname>Joe</firstname><surname>Page</surname><order>4</order></author><author><firstname>Robyn</firstname><surname>Aitkenhead</surname><order>5</order></author><author><firstname>Aimee</firstname><surname>Felstead</surname><order>6</order></author><author><firstname>Shane</firstname><surname>Heffernan</surname><orcid>0000-0002-3297-9335</orcid><order>7</order></author><author><firstname>Owen</firstname><surname>Jeffries</surname><order>8</order></author><author><firstname>Jamie</firstname><surname>Tallent</surname><order>9</order></author><author><firstname>Mark</firstname><surname>Waldron</surname><orcid>0000-0002-2720-4615</orcid><order>10</order></author></authors><documents><document><filename>65826__30123__31b1be92a1c242c186e7141b5959549b.pdf</filename><originalFilename>65826.VoR.pdf</originalFilename><uploaded>2024-04-23T12:27:00.7133198</uploaded><type>Output</type><contentLength>1219705</contentLength><contentType>application/pdf</contentType><version>Version of Record</version><cronfaStatus>true</cronfaStatus><documentNotes>© The Author(s) 2024. 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spelling v2 65826 2024-03-12 Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males 86316fdeb6b4ee7ce0206f789eec781c Jenny Peel Jenny Peel true false dff041586f0621c885755f69eb28eac6 Joe Page Joe Page true false 3e157b6e7d9802d5be3c8dd790c71679 Robyn Aitkenhead Robyn Aitkenhead true false d2a43ac1a6105fc5bc058bd202e630af Aimee Felstead Aimee Felstead true false 72c0b36891dfbec0378c0d0f7916e807 0000-0002-3297-9335 Shane Heffernan Shane Heffernan true false 70db7c6c54d46f5e70b39e5ae0a056fa 0000-0002-2720-4615 Mark Waldron Mark Waldron true false 2024-03-12 Purpose: Caffeine is a commonly used ergogenic aid for endurance events; however, its efficacy and safety have been questioned in hot environmental conditions. The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in the heat. Methods: In a double-blind, randomised, cross-over trial, 12 healthy caffeine-habituated and unacclimatised males cycled to exhaustion in the heat (35 °C, 40% RH) at an intensity associated with the thermoneutral gas exchange threshold, on two separate occasions, 60 min after ingesting caffeine (5 mg/kg) or placebo (5 mg/kg). Results: There was no effect of caffeine supplementation on cycling time to exhaustion (caffeine; 28.5 ± 8.3 min vs. placebo; 29.9 ± 8.8 min, P = 0.251). Caffeine increased pulmonary oxygen uptake by 7.4% (P = 0.003), heat production by 7.9% (P = 0.004), whole-body sweat rate by 21% (P = 0.008), evaporative heat transfer by 16.5% (P = 0.006) and decreased estimated skin blood flow by 14.1% (P < 0.001) compared to placebo. Core temperature was higher by 0.6% (P = 0.013) but thermal comfort decreased by -18.3% (P = 0.040), in the caffeine condition, with no changes in rate of perceived exertion (P > 0.05). Conclusion: The greater heat production and storage, as indicated by a sustained increase in core temperature, corroborate previous research showing a thermogenic effect of caffeine ingestion. When exercising at the pre-determined gas exchange threshold in the heat, 5 mg/kg of caffeine did not provide a performance benefit and increased the thermal strain of participants. Journal Article European Journal of Applied Physiology 124 2489 2502 Springer Science and Business Media LLC 1439-6319 1439-6327 Caffeine supplementation; ergogenic; endurance performance; heat; thermoregulation. 1 8 2024 2024-08-01 10.1007/s00421-024-05460-z COLLEGE NANME COLLEGE CODE Swansea University SU Library paid the OA fee (TA Institutional Deal) Swansea University 2024-10-08T08:56:52.6791790 2024-03-12T14:04:58.6471326 Faculty of Science and Engineering School of Engineering and Applied Sciences - Sport and Exercise Sciences Kevin John 1 Sayyam Kathuria 2 Jenny Peel 3 Joe Page 4 Robyn Aitkenhead 5 Aimee Felstead 6 Shane Heffernan 0000-0002-3297-9335 7 Owen Jeffries 8 Jamie Tallent 9 Mark Waldron 0000-0002-2720-4615 10 65826__30123__31b1be92a1c242c186e7141b5959549b.pdf 65826.VoR.pdf 2024-04-23T12:27:00.7133198 Output 1219705 application/pdf Version of Record true © The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License. true eng http://creativecommons.org/licenses/by/4.0/
title Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
spellingShingle Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
Jenny Peel
Joe Page
Robyn Aitkenhead
Aimee Felstead
Shane Heffernan
Mark Waldron
title_short Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
title_full Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
title_fullStr Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
title_full_unstemmed Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
title_sort Caffeine ingestion compromises thermoregulation and does not improve cycling time to exhaustion in the heat amongst males
author_id_str_mv 86316fdeb6b4ee7ce0206f789eec781c
dff041586f0621c885755f69eb28eac6
3e157b6e7d9802d5be3c8dd790c71679
d2a43ac1a6105fc5bc058bd202e630af
72c0b36891dfbec0378c0d0f7916e807
70db7c6c54d46f5e70b39e5ae0a056fa
author_id_fullname_str_mv 86316fdeb6b4ee7ce0206f789eec781c_***_Jenny Peel
dff041586f0621c885755f69eb28eac6_***_Joe Page
3e157b6e7d9802d5be3c8dd790c71679_***_Robyn Aitkenhead
d2a43ac1a6105fc5bc058bd202e630af_***_Aimee Felstead
72c0b36891dfbec0378c0d0f7916e807_***_Shane Heffernan
70db7c6c54d46f5e70b39e5ae0a056fa_***_Mark Waldron
author Jenny Peel
Joe Page
Robyn Aitkenhead
Aimee Felstead
Shane Heffernan
Mark Waldron
author2 Kevin John
Sayyam Kathuria
Jenny Peel
Joe Page
Robyn Aitkenhead
Aimee Felstead
Shane Heffernan
Owen Jeffries
Jamie Tallent
Mark Waldron
format Journal article
container_title European Journal of Applied Physiology
container_volume 124
container_start_page 2489
publishDate 2024
institution Swansea University
issn 1439-6319
1439-6327
doi_str_mv 10.1007/s00421-024-05460-z
publisher Springer Science and Business Media LLC
college_str Faculty of Science and Engineering
hierarchytype
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 Engineering and Applied Sciences - Sport and Exercise Sciences{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Sport and Exercise Sciences
document_store_str 1
active_str 0
description Purpose: Caffeine is a commonly used ergogenic aid for endurance events; however, its efficacy and safety have been questioned in hot environmental conditions. The aim of this study was to investigate the effects of acute caffeine supplementation on cycling time to exhaustion and thermoregulation in the heat. Methods: In a double-blind, randomised, cross-over trial, 12 healthy caffeine-habituated and unacclimatised males cycled to exhaustion in the heat (35 °C, 40% RH) at an intensity associated with the thermoneutral gas exchange threshold, on two separate occasions, 60 min after ingesting caffeine (5 mg/kg) or placebo (5 mg/kg). Results: There was no effect of caffeine supplementation on cycling time to exhaustion (caffeine; 28.5 ± 8.3 min vs. placebo; 29.9 ± 8.8 min, P = 0.251). Caffeine increased pulmonary oxygen uptake by 7.4% (P = 0.003), heat production by 7.9% (P = 0.004), whole-body sweat rate by 21% (P = 0.008), evaporative heat transfer by 16.5% (P = 0.006) and decreased estimated skin blood flow by 14.1% (P < 0.001) compared to placebo. Core temperature was higher by 0.6% (P = 0.013) but thermal comfort decreased by -18.3% (P = 0.040), in the caffeine condition, with no changes in rate of perceived exertion (P > 0.05). Conclusion: The greater heat production and storage, as indicated by a sustained increase in core temperature, corroborate previous research showing a thermogenic effect of caffeine ingestion. When exercising at the pre-determined gas exchange threshold in the heat, 5 mg/kg of caffeine did not provide a performance benefit and increased the thermal strain of participants.
published_date 2024-08-01T08:56:51Z
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