How exercise affects the body at different times of day

A new study led by the University of Copenhagen has investigated how different health-promoting signaling molecules produced by various organs of our bodies following physical exercise are influenced by the time of the day when exercise is performed. Understanding the relationship between circadian rhythms and exercise can have broad impacts on our health, helping us improve our sleep, memory, and metabolic homeostasis.

Most of our cells regulate their biological processes over a 24-hour period, operating in so-called “circadian rhythms.” Thus, the sensitivity of different bodily tissues to the effects of exercise depends on the time of day when exercise is performed. In order to better understand this complex connection, the researchers carried out experiments on mice that exercised either in the early morning or late evening. 

Using mass spectrometry to analyze blood samples and tissues from the specimen’s heart, liver, brain, muscle, or fat, the scientists detected hundreds of metabolites and signaling molecules in each type of tissue, and monitored how they were changed by exercising at different times of the day. This resulted in an “Atlas of Exercise Metabolism,” a complex and comprehensive map of exercise-induced molecules found in different tissues following exercise at different times of day.

“A better understanding of how exercise affects the body at different times of day might help us to maximize the benefits of exercise for people at risk of disease, such as obesity and type 2 diabetes,” said study co-author Juleen R. Zierath, an expert in Circadian Biology at the University of Copenhagen.

“Not only do we show how different tissues respond to exercise at different times of the day, we also propose how these responses are connected to induce an orchestrated adaptation that controls systemic energy homeostasis,” added study co-author Jonas Thue Treebak, an associate professor specializing in molecular metabolism at the same university.

This research sheds new light on how tissues communicate with one another, and how exercise can help “realign” in particular tissues faulty circadian rhythms that have previously been linked to increased risks of metabolic diseases, such as obesity or type 2 diabetes. Further research is needed to understand how newly identified exercise-induced signaling molecules in multiple bodily tissues individually or collectively affect health.

The study is published in the journal Cell Metabolism. 

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By Andrei Ionescu, Earth.com Staff Writer