Page 111 - 《运动与健康科学》(英文)2024年第2期

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Journal of Sport and Health Science 13 (2024) 233244

Original article

TaggedAPTARAH1Elevated brain temperature under severe heat exposure impairs cortical

motor activity and executive functionTaggedAPTARAEnd
c
d
TaggedAPTARAPXiang Ren Tan a,b , Mary C. Stephenson , Sharifah Badriyah Alhadad b,d , Kelvin W.Z. Loh ,
d
Tuck Wah Soong , Jason K.W. Lee b,d,e,f,g, *, Ivan C.C. Low b,d, *TaggedAPTARAEnd
a
TaggedAPTARAP Health and Social Sciences, Singapore Institute of Technology, Singapore 138683, Singapore
b
Human Potential Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
c
Centre for Translational Magnetic Resonance Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore
d
Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore
e
Heat Resilience and Performance Centre, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117510, Singapore
f
N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
g
Campus for Research Excellence and Technological Enterprise (CREATE), Singapore 138602, Singapore
TaggedAPTARAEnd Received 1 March 2023; revised 27 May 2023; accepted 20 July 2023
Available online 9 September 2023
2095-2546/Ó 2024 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license.
(http://creativecommons.org/licenses/by-nc-nd/4.0/)
TaggedAPTARAPAbstract
Background: Excessive heat exposure can lead to hyperthermia in humans, which impairs physical performance and disrupts cognitive function.
While heat is a known physiological stressor, it is unclear how severe heat stress affects brain physiology and function.
Methods: Eleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal tempera-
tures (T re ) attained 39.5˚C, inducing exertional or passive hyperthermia, respectively. In a separate trial, blended ice was ingested before and
during exercise as a cooling strategy. Data were compared to a control condition with seated rest (normothermic). Brain temperature (T br ), cere-
bral perfusion, and task-based brain activity were assessed using magnetic resonance imaging techniques.
Results:T br in motor cortex was found to be tightly regulated at rest (37.3˚C § 0.4˚C (mean § SD)) despite fluctuations in T re . With the develop-
ment of hyperthermia, T br increases and dovetails with the rising T re . Bilateral motor cortical activity was suppressed during high-intensity plan-
tarflexion tasks, implying a reduced central motor drive in hyperthermic participants (T re = 38.5˚C § 0.1˚C). Global gray matter perfusion and
regional perfusion in sensorimotor cortex were reduced with passive hyperthermia. Executive function was poorer under a passive hyperthermic
state, and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital cortex. Conversely,
ingestion of blended ice before and during exercise alleviated the rise in both T re and T br and mitigated heat-related neural perturbations.
Conclusion: Severe heat exposure elevates T br , disrupts motor cortical activity and executive function, and this can lead to impairment of physi-
cal and cognitive performance.

TaggedAPTARAPKeywords: Brain functional activity; Cognition; Heat stress; Hyperthermia; Motor functionTaggedAPTARAEnd

sporting events such as the 2015 International Association of
TaggedAPTARAH11. IntroductionTaggedAPTARAEnd
Athletics Federations (IAAF) World Athletics Champion-
TaggedAPTARAPClimate change and rapid urbanization have led to rising 3 4
ships and the 2021 Tokyo Olympics. Extreme heat events
global temperatures. Excessive heat exposure constitutes a major 5
are becoming more common globally and may lead to
issue for subtropical and tropical countries where hard-la-
increased prevalence of heat-related illnesses in competing
bor workers and athletes are susceptible to heat stress as athletes. Thus, it is paramount for us to profile and understand
intense physical exertion exacerbates heat-related deficits. 1,2
the physiological impact of heat stress on the human body to
Moreover, the deleterious impact of heat stress on sports
formulate effective heat management strategies.TaggedAPTARAEnd
performance and health has been underscored in major
TaggedAPTARAPWhen exercising in the heat, endurance performance of
athletes is markedly impaired. 68 Premature fatigue experienced
TaggedAPTARAEndTaggedAPTARAEnd Peer review under responsibility of Shanghai University of Sport. while exercising in the heat is traditionally associated with
TaggedAPTARAEnd* Corresponding authors.
E-mail addresses: phsjlkw@nus.edu.sg (J.K.W. Lee), phsilcc@nus.edu.sg peripheral physiological factors, such as increased thermoregula-
(I.C.C. Low). tory and cardiovascular strain. 911 However, there is increasing
https://doi.org/10.1016/j.jshs.2023.09.001
Cite this article: Tan XR, Stephenson MC, Alhadad SB, et al. Elevated brain temperature under severe heat exposure impairs cortical motor activity and executive
function. J Sport Health Sci 2024;13:23344.