May 24, 2022

Is it better to exercise in the morning or in the evening?

That physical activity is good for your health – like almost everything, in moderation – is no longer in doubt today. We even know that its effects are not the same depending on the time of day when we are active. By doing sports in the morning, we will rather tend to play on the immediate metabolism of sugars and fats, thanks to genes expressed in the muscle cells. Conversely, getting active in the evening will rather result in an increase in energy expenditure throughout the body and over time.

But if they start to master the comment, scientists still stumble over the Why different effects of the same physical activity occur at different times of the day. This is why an international team has just conducted the most exhaustive study on the subject to date.

Constituting a real atlas of the metabolism of physical activity, the results of this work, published on January 13 in the journal Cell Metabolism, show how, after sport, the body produces different signaling molecules beneficial to health depending on the time of day, in a specific way for each organ. These signals constitute a wide and diverse range and influence sleep, memory, exercise performance or the regulation (homeostasis) of the metabolism.

Maximizing the benefits of sport

Led initially by Paolo Sassone-Corsi, specialist in epigenetics and circadian rhythms affiliated in particular with Inserm then, after his death in 2020, by Juleen R. Zierath, diabetes biologist teaching at the University of Copenhagen, the scientists carried out their experiments on mice which they activated, as a human equivalent, at 6 a.m. or 10 p.m.

Then they took blood and samples from them in different organs and tissues – brain, heart, muscle, liver and fat. From their analysis, the researchers were able to detect hundreds of metabolites and hormone signaling molecules in each tissue, and track how they changed depending on the moment of physical activity.

In particular, the study provides a better understanding of how tissues communicate with each other, and how playing sports is able to “reparameterize” defective circadian rhythms in certain organs – a derangement that is known to increase the risk of obesity. and type 2 diabetes.

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In addition, the team was able to identify new signaling molecules induced by exercise in numerous tissues. So many avenues to explore in order to understand how, individually or collectively, they affect health. And to ensure that the benefits of sport are maximized in individuals most at risk of suffering from metabolic disorders.