AimsIn the present study, we sought to investigate the relationship between photoperiodic daily fluctuations of internal body temperature (Tcore) with physical capacity (Workload) and neuronal activation induced by progressive treadmill exercise test.MethodsAnimals were subjected to protocols of progressive exercise test (n=11), resting on treadmill (n=12) or without prior manipulation (n=12) during dark and light phases. At the end of the last experimental session, the animals were perfused and the brains removed for immunohistchemical analysis of neuronal activation in the locus coeruleus (LC), paraventricular nucleus (PVN), supra‐optic nucleus (SO) and suprachiasmatic nucleus (SQN).ResultsWorkload was 23% higher in the light phase when compared to dark phase exercise (p<0.001). PVN, SO and LC were strongly activated by exercise until fatigue independent of circadian phase (p<0.001). The SQN was not activated neither by exercise nor time of the day. A strong correlation between the activation of PVN, SO and LC was found only during the dark phase of the photoperiod.ConclusionThereafter, the time of the day, possibly through its centrally mediated mechanisms favors physical performance during light phase independent of basal spontaneous locomotor activity levels. Besides, the SQN seemed to be resistant to exercise related disturbances.Research sponsored by CAPES, CNPq and FAPEMIG.