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

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 (<i>n</i> = 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 (<i>p</i> &lt; 0.001), initial T_CORE (<i>p</i> &lt; 0.001), distance traveled (<i>p</i> &lt; 0.001; only incremental exercises), and running speed and duration (<i>p</i> &lt; 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.本研究对相关文献进行了系统综述，这些文献报道了递增速度或恒定速度跑步至疲劳或力竭时，大鼠核心体温（T_CORE）的变化情况。此外，本研究采用多元线性回归分析，旨在确定运动中断时达到的核心体温的影响因素。2021年10月，我们检索了EMBASE、PubMed、SPORTDiscus以及Web of Science四个数据库，并于2022年8月更新了本次检索。最终共有72项研究（总样本量n=1538只大鼠）被纳入本次系统综述。这些研究的实验条件存在异质性，例如环境温度范围为5℃至40℃。不同研究中，大鼠停止运动时的核心体温差异超过8℃，最低值与最高值分别为34.9℃和43.4℃。多元线性回归分析结果显示，环境温度（p<0.001）、初始核心体温（p<0.001）、运动距离（p<0.001，仅针对递增速度运动）以及跑步速度与运动时长（p<0.001，仅针对恒定速度运动）均能显著解释运动结束时核心体温的变异。综上，进行跑台运动的大鼠在疲劳或力竭状态下的核心体温存在异质性。此外，无法为高热状态下的运动终止大鼠确定一个狭窄的核心体温区间。环境温度、初始核心体温以及与运动表现相关的变量，是预测疲劳或力竭时核心体温的最佳指标。从更广泛的视角来看，本系统综述为未来开展大鼠运动体温调节相关研究的方法选择提供了有价值的参考信息。