Exercise Capacity of Mice: Effect of Resting Rectal Temperature and Verification by Peptide Uptake

Introduction – Core body temperature is closely related to exercise capacity, and most studies focused on the impact of core body temperature during exercise on exercise capacity. Here we show that preexercise core body temperature may also affect the exercise capacity in animal models by using resting rectal temperature as a representation of core body temperature in the studies. Methods – The resting rectal temperature of mice before exercise was measured. Ovalbumin peptide was used as functional food to intervene in the exercise capacity and related physiological indicators (including resting rectal temperature) of mice at different doses. Exercise capacity was quantified by exhaustive swimming time and exercise-related physiological indicators to find the effect of preexercise resting rectal temperature on the exercise capacity. Results – We found that there exists an optimal resting rectal body temperature baseline range (36.5°C–38°C) for exercise capacity (exhaustive swimming time 162.87 ± 53.89 s) in mice. When the rectal temperature was below 36.5°C (90.50 ± 12.05 s) or above 38°C (92.25 ± 16.57 s), the exhaustive swimming time of the mice was significantly shortened (P < 0.001). Further studies revealed that when the resting rectal temperature was within the range of 36.5°C–37.5°C, the mice showed significantly higher levels of lactate dehydrogenase activity (P < 0.01), blood glucose (P < 0.05), and liver glycogen (P < 0.001) compared with other temperature groups, whereas blood lactic acid (P < 0.01) and blood urea nitrogen levels (P < 0.0001) were significantly lower. Ovalbumin peptide (0.4 g·kg⁻¹⋅d⁻¹) enhances the exercise capacity of mice by improving exercise-related physiological indicators. Conclusions – The results of this study demonstrate that the preexercise resting rectal temperature of mice can affect the exercise capacity.