Early morning run-training results in enhanced endurance performance adaptations in mice.

Time-of-day differences in exercise performance are well established in the literature. We observe that after 6 weeks of endurance exercise training there is no longer a time-of-day specific difference in endurance performance.Consistent endurance training performed in morning (ZT13) results in a greater performance increase compared to exercise training during the afternoon (ZT22).Removal of time-of-day differences in performance through exercise training is strongly associated with significant phase shifts (~5 hour advance) of the muscle clock.