Core body temperatures of rats subjected to treadmill exercise to fatigue or exhaustion: The journal Temperature toolbox

Marcelo T Andrade; Karine N O Goulart; Nicolas H S Barbosa; Danusa D Soares; André G P Andrade; Dawit A P Gonçalves; Thiago T Mendes; Cândido C Coimbra; Samuel P Wanner

doi:10.1080/23328940.2022.2115274

Core body temperatures of rats subjected to treadmill exercise to fatigue or exhaustion: The journal Temperature toolbox

Temperature (Austin). 2022 Sep 1;10(3):287-312. doi: 10.1080/23328940.2022.2115274. eCollection 2023.

Authors

Marcelo T Andrade¹, Karine N O Goulart¹, Nicolas H S Barbosa¹, Danusa D Soares¹, André G P Andrade², Dawit A P Gonçalves¹, Thiago T Mendes³, Cândido C Coimbra⁴, Samuel P Wanner¹

Affiliations

¹ Exercise Physiology Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
² Biomechanics Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
³ Department of Physical Education, Faculty of Education, Universidade Federal da Bahia, Salvador, Brazil.
⁴ Laboratory of Endocrinology and Metabolism, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.

Abstract

This study systematically reviewed the literature reporting the changes in rats' core body temperature (T_CORE) induced by either incremental- or constant-speed running to fatigue or exhaustion. In addition, multiple linear regression analyses were used to determine the factors contributing to the T_CORE values attained when exercise was interrupted. Four databases (EMBASE, PubMed, SPORTDiscus, and Web of Science) were searched in October 2021, and this search was updated in August 2022. Seventy-two studies (n = 1,538 rats) were included in the systematic review. These studies described heterogeneous experimental conditions; for example, the ambient temperature ranged from 5 to 40°C. The rats quit exercising with T_CORE values varying more than 8°C among studies, with the lowest and highest values corresponding to 34.9°C and 43.4°C, respectively. Multiple linear regression analyses indicated that the ambient temperature (p < 0.001), initial T_CORE (p < 0.001), distance traveled (p < 0.001; only incremental exercises), and running speed and duration (p < 0.001; only constant exercises) contributed significantly to explaining the variance in the T_CORE at the end of the exercise. In conclusion, rats subjected to treadmill running exhibit heterogeneous T_CORE when fatigued or exhausted. Moreover, it is not possible to determine a narrow range of T_CORE associated with exercise cessation in hyperthermic rats. Ambient temperature, initial T_CORE, and physical performance-related variables are the best predictors of T_CORE at fatigue or exhaustion. From a broader perspective, this systematic review provides relevant information for selecting appropriate methods in future studies designed to investigate exercise thermoregulation in rats.

Keywords: Body mass; environment; heat; hyperthermia; performance; physical exercise; regression analysis; thermoregulation.

Grants and funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. NHSB was the recipient of post-graduate fellowship from CAPES, whereas KNOG received a post-doctoral fellowship from CAPES/Print. SPW receives a fellowship from the Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq) for being a productive researcher (grant number 315199/2021–0). DAPG is currently funded by the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG, grant number APQ-01268-21). DDS, DAPG, TTM, and SPW are researchers of the MEDIANTAR group, which is supported by CNPq/MCTIC/CAPES/FNDCT/PROANTAR (grant number 442645/2018-0).