This Might Be Why Your Morning Workouts Feel Like Torture, Research Reveals
So you desperately want to be one of those people who does yoga before work, but you just can’t seem to muster the energy in those early morning hours? It probably doesn’t have anything to do with your fitness level or motivation. We humans may actually be biologically primed to move more efficiently in the evening. Research published in Cell Metabolism suggests that working out later in the day may improve exercise performance, as it naturally complements our body’s circadian rhythm.
For one of their experiments, study researchers put mice on treadmills at different times of day and examined their exercise capacity with different regimens. They found that overall exercise performance was substantially better—about 50 percent better on average—in the "mouse evening" compared to morning hours. (Because the research was on mice, which are nocturnal, researchers translated this data into human timing. So “mouse evening” = our evening.)
But why exactly was exercise efficiency so much better? Researchers noted higher levels of a metabolite called ZMP when mice were exercising in the evening. ZMP activates pathways related to glycolysis (the conversion of sugar into usable energy) and fatty acid oxidation (the conversion of fat into energy)—essentially freeing up more “fuel” for our bodies to use.
Of course, this mouse data can’t be directly applied to us. But when researchers then examined the exercise performance of 12 people, they found that evening exercise resulted in lower oxygen consumption—which meant they were exercising more efficiently. Their rate of perceived exertion (how hard they felt like their body was working) was lower, too.
Previous research also backs up the benefits of late-night sweat sessions—or at least the fact that they may feel easier than a morning workout. One 2012 study found that strength and flexibility are greatest in the late afternoon, while perceived exertion is the lowest.
But, there’s absolutely nothing wrong with working out first thing if that’s what you’re into. In fact, this same 2012 study found that by regularly working out in the morning, you could—over time—improve your exercise performance to be on par with what you’d normally experience in the afternoon. You just need to be consistent about it.
Bottom line: The best time to work out is whenever it works best for you. So if you’re constantly fighting your way through your morning HIIT session or barre class, flipping your workout schedule might be just what you need.
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