The control of body temperature in Spontaneously Hypertensive Rat (SHR) subjected to exercise in warm environment was investigated. Male SHR and Wistar rats were submitted to moderate exercise in temperate (25°C) and warm (32°C) environments while body and tail skin temperatures, as well as oxygen consumption, were registered. Total time of exercise, workload performed, mechanical efficiency and heat storage were determined. SHR had increased heat production and body temperature at the end of exercise, reduced mechanical efficiency and increased heat storage (p < 0.05). Furthermore, these rats also showed a more intense and faster increase in body temperature during moderate exercise in the warm environment (p < 0.05). The lower mechanical efficiency seen in SHR was closely correlated with their higher body temperature at the point of fatigue in warm environment (p < 0.05). Our results indicate that SHR exhibit significant differences in body temperature control during moderate exercise in warm environment characterized by increased heat production and heat storage during moderate exercise in warm environment. The combination of these responses result in aggravated hyperthermia linked with lower mechanical efficiency.

• The practice of physical exercise in warm environment has gained importance in recent decades mainly because of the progressive increases in environmental temperature;

• To the best of our knowledge, these is the first study to analyze body temperature control of SHR during moderate exercise in warm environment;

• SHR showed increased heat production and heat storage that resulted in higher body temperature at the end of exercise;

• SHR showed reduced mechanical efficiency;

• These results demonstrate that when exercising in a warm environment the hypertensive rat exhibit differences in temperature control.