Description
Physical performance relies on the concerted action of myriad responses, many of which are under circadian clock control. Little is known, however, regarding the time-dependent effect on exercise performance at the molecular level. We found that both mice and humans exhibit day-time variance in exercise capacity between the early and late part of their active phase. The day-time variance in mice was dependent on exercise intensity and relied on the circadian clock proteins PER1/2. High throughput gene expression and metabolic profiling of skeletal muscle revealed metabolic pathways that are differently activated upon exercise in a day-time dependent manner. Remarkably, we discovered that ZMP, an endogenous AMPK activator, is induced by exercise in a time-dependent manner to regulate key steps in glycolytic and fatty acid oxidation pathways and potentially enhance exercise capacity. Overall, we propose that time of the day is a major modifier of exercise capacity and associated metabolic pathways. Overall design: basal, high intensity and moderate intensity runnig protocol at ZT14 and ZT22 in gastrocnemius muscle in C57B6 mice