Author(s): CIORCIARI, A., IRIZARRY, E., GALASSO, L., CASTELLI, L., ROVEDA, E., CARRARO, A., MONTARULI, A., LAMIA, K., Institution: FREE UNIVERSITY OF BOZEN-BOLZANO, Country: ITALY, Abstract-ID: 1011

INTRODUCTION:
Core body temperature (CBT) is a key marker of circadian synchronization, reflecting behavioral, metabolic, and environmental adaptations. Disruptions in CBT rhythms, as seen in shift workers or jetlag, indicate circadian misalignment and can have significant health consequences. Exercise is a potent non-photic zeitgeber that may facilitate circadian realignment, but its role in re-entrainment after abrupt phase shifts remains unclear. This study examined whether voluntary exercise accelerates the re-entrainment of CBT and metabolic rhythms in mice subjected to a 12-hour light-dark cycle inversion (LDI).
METHODS:
Fifteen C57BL/6J mice underwent LDI and were divided into sedentary controls (CTRL) and running wheel (RW) groups. CBT was continuously recorded using implanted temperature-monitoring capsules, and metabolic parameters were assessed via metabolic cages.
RESULTS:
RW mice exhibited a faster re-entrainment of CBT compared to CTRL mice, with higher Percentage of Rhythm (PR) and Amplitude (AMP) values during early recovery (T2). Interestingly, RW mice initially displayed a greater disruption post-LDI (lower PR at T1), suggesting that unstructured physical activity may act as a conflicting signal, temporarily exacerbating misalignment. Nevertheless, exercise accelerated recovery, as RW mice achieved a CBT phase peak closer to the new light-dark cycle target. VO₂ rhythms in RW mice also trended toward faster realignment.
CONCLUSION:
These findings highlight the dual role of exercise as a zeitgeber, capable of both disrupting and accelerating circadian realignment depending on timing and context. Voluntary exercise may thus serve as an effective intervention to restore circadian synchrony and metabolic homeostasis in individuals experiencing circadian disruption.