Authors:	Heydenreich, Juliane Koehler, Karsten Grosshauser, Mareike Heseker, Helmut Koenig, Daniel Lampen, Alfonso Mosler, Stephanie Niess, Andreas Schenk, Alexandra Carlsohn, Anja
Title:	Effects of internal cooling on physical performance, physiological and perceptional parameters when exercising in the heat: A systematic review with meta-analyses
Online publication date:	26-Jul-2023
Year of first publication:	2023
Language:	english
Abstract:	Background: An elevated core temperature (Tcore) increases the risk of performance impairments and heat-related illness. Internal cooling (IC) has the potential to lower Tcore when exercising in the heat. The aim of the review was to systematically analyze the effects of IC on performance, physiological, and perceptional parameters. Methods: A systematic literature search was performed in the PubMed database on 17 December 2021. Intervention studies were included assessing the effects of IC on performance, physiological, or perceptional outcomes. Data extraction and quality assessment were conducted for the included literature. The standardized mean differences (SMD) and 95% Confidence Intervals (CI) were calculated using the inverse-variance method and a random-effects model. Results: 47 intervention studies involving 486 active subjects (13.7% female; mean age 20–42 years) were included in the meta-analysis. IC resulted in significant positive effects on time to exhaustion [SMD (95% CI) 0.40 (0.13; 0.67), p < 0.01]. IC significantly reduced Tcore [−0.19 (22120.34; −0.05), p < 0.05], sweat rate [−0.20 (−0.34; −0.06), p < 0.01], thermal sensation [−0.17 (−0.33; −0.01), p < 0.05], whereas no effects were found on skin temperature, blood lactate, and thermal comfort (p > 0.05). IC resulted in a borderline significant reduction in time trial performance [0.31 (−0.60; −0.02), p = 0.06], heart rate [−0.13 (−0.27; 0.01), p = 0.06], rate of perceived exertion [−0.16 (−0.31; −0.00), p = 0.05] and borderline increased mean power output [0.22 (0.00; 0.44), p = 0.05]. Discussion: IC has the potential to affect endurance performance and selected physiological and perceptional parameters positively. However, its effectiveness depends on the method used and the time point of administration. Future research should confirm the laboratory-based results in the field setting and involve non-endurance activities and female athletes.
DDC:	333.7 Natürliche Ressourcen 333.7 Natural resources 610 Medizin 610 Medical sciences 796 Sport 796 Athletic and outdoor sports and games 910 Geografie 910 Geography and travel
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 02 Sozialwiss., Medien u. Sport
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-9316
Version:	Published version
Publication type:	Zeitschriftenaufsatz
Document type specification:	Scientific article
License:	CC BY
Information on rights of use:	https://creativecommons.org/licenses/by/4.0/
Journal:	Frontiers in Physiology 14.2023
Pages or article number:	1125969
Publisher:	Frontiers
Publisher place:	Lausanne
Issue date:	2023
ISSN:	1664-042X
Publisher DOI:	10.3389/fphys.2023.1125969
Appears in collections:	DFG-491381577-G