Is it worth getting up early to exercise? Or is an evening run just as good for you? Researchers at the University of Copenhagen were determined to find out, using mice instead of people. Their study, conducted with researchers at the University of California, Irvine, measured a number of effects in the muscle cells, including the transcriptional response and effects on the metabolites. It revealed that responses are far stronger in both areas following exercise in the morning, possibly because the phenomenon is controlled by a mechanism involving the protein HIF1-alfa, which directly regulates the body’s circadian clock.
In slightly less scientific terms, morning exercise appears to increase the ability of muscle cells to metabolize sugar and fat, so if losing weight is the main goal, it might be worth setting the alarm an hour earlier. Evening exercise, on the other hand, was shown to increase energy expenditure in the hours after exercise. The bottom line? The researchers won’t commit to one or the other.
“We cannot say which is best,” says Jonas Treebak, an associate professor at the Novo Nordisk Foundation Center for Basic Metabolic Research. “At this point, we can only conclude that the effects of the two appear to differ, and we have to do more work to determine the potential mechanisms for the beneficial effects of exercise training performed at these two time-points.”