Recent research has shown that exercising at different times across the day benefits the body in unique ways.
Exercising improves health and fitness, and research from the University of Copenhagen has shown that exercise benefits the body in different ways, dependant on the time of the day. But scientists still do not know why exercising at various times produces numerous effects. To gain a better understanding, an international team of scientists recently carried out the most comprehensive study to date of exercise performed at different times of the day.
The researchers found that different health-promoting signalling molecules are produced by the body in an organ-specific manner, following exercise depending on the time of day. These signals have a broad impact on health, influencing sleep, memory, exercise performance and metabolic homeostasis. Their findings were recently published in the journal Cell Metabolism.
“A better understanding of how exercise affects the body at different times of day might help us to maximise the benefits of exercise for people at risk of diseases, such as obesity and type 2 diabetes,” said Professor Juleen R. Zierath from Karolinska Institutet and the Novo Nordisk Foundation Center for Basic Metabolic Research (CBMR) at the University of Copenhagen.
Exercising to promote health benefits
The circadian rhythm is the way cells regulate their biological processes over 24 hours. This means that the sensitivity of different tissues changes to the effects of exercising, depending on the time of day.
Earlier research has confirmed that timing according to our circadian rhythm can optimise the health-promoting effects of exercise.
The study aimed to identify this effect, so the researchers carried out a range of experiments on mice that exercised either in the early morning or the late evening. Blood samples and different tissues, including brain, heart, muscle, liver, and fat, were collected and analysed by mass spectrometry. This allowed the scientists to detect hundreds of different metabolites and hormone signalling molecules in each tissue and to monitor how they were changed by exercising at different times of the day.
The result is an ‘Atlas of Exercise Metabolism’” – a comprehensive map of exercise-induced signalling molecules present in different tissues following exercise at differing times of the day.
“As this is the first comprehensive study that summarises time and exercises dependent metabolism over multiple tissues, it is of great value to generate and refine systemic models for metabolism and organ crosstalk,” added Dominik Lutter, Head of Computational Discovery Research at the Helmholtz Diabetes Center in Munich, Germany.
The new insights included a deeper understanding of how tissues communicate with each other, and how exercising can help ‘realign’ faulty circadian rhythms in specific tissues – faulty circadian clocks have been linked to increased risks of obesity and type 2 diabetes. Furthermore, the study identified new exercise-induced signalling molecules in multiple tissues, which need further investigation to understand how they can individually or collectively influence health.
“Not only do we show how different tissues respond to exercise at different times of the day, but we also propose how these responses are connected to induce an orchestrated adaptation that controls systemic energy homeostasis,” said Associate Professor Jonas Thue Treebak from CBMR at the University of Copenhagen, and co-first author of the publication.
An opportunity for future research
The study has several limitations, and the experiments were carried out in mice. Whilst the mice share many common genetic, physiological, and behavioural characteristics with humans, they also have important differences. For example, mice are nocturnal, and it was limited to treadmill running, which can produce different results when compared with the effects of high-intensity exercise. Finally, the impact of sex, age and disease were not considered in the analysis.
“Despite the limitations, it’s an important study that helps to direct further research that can help us better understand how exercise, if timed correctly, can help to improve health,” said Assistant Professor Shogo Sato from the Department of Biology and the Center for Biological Clocks Research at Texas A&M University, and fellow co-first author.
Fellow co-first author Kenneth Dyar, head of Metabolic Physiology at the Helmholtz Diabetes Center, stressed the utility of the Atlas as a comprehensive resource for exercise biologists.
“While our resource provides important new perspectives about energy metabolites and known signalling molecules, this is just the tip of the iceberg. We show some examples of how our data can be mined to identify new tissue and time-specific signalling molecules,” he said.
