How Time of Day May Impact Exercise Results
Physical activity at the right time of day appears to increase fat metabolism, at least in mice. Mice exercising during the early active phase (the human equivalent of morning exercise) promote metabolic rest more than mice exercising during their usual exercise times, according to a new study from the Karolinska Institutet in Sweden and the University of Copenhagen in Denmark.The results are published in the journal Proceedings of the National Academy of Sciences (Member of the National Academy of Sciences).
Physical activity at different times of the day affects the body in different ways because biological processes depend on the circadian rhythm of cells. To determine how the time of day for exercising affects fat burning, researchers at the Karolinska Institutet and the University of Copenhagen studied adipose tissue in mice following high-intensity exercise at two points in the day cycle, the early active phase and Early rest phases (corresponding to late morning and early evening hours in humans, respectively). The researchers looked at various markers of fat metabolism and analyzed which genes were active in fat tissue after exercise.
independent of food intake
The researchers found that physical activity during the early active phase increased fat tissue breakdown, thermogenesis (heat production), and the expression of mitochondria-related genes in fat tissue, indicating a higher metabolic rate. These effects were only observed in mice that exercised during the early active phase and were not related to food intake.
“Our findings suggest that exercising later in the morning may be more effective than evening exercise in terms of boosting metabolism and fat burning, and if so, they may be of value to overweight individuals,” said Prof. Juleen R. Zierath from Department of Molecular Medicine and Surgery and Department of Physiology and Pharmacology, Karolinska Institutet.
Improve the health benefits of exercise
Mice and humans share many basic physiological functions, and mice are well-established models of human physiology and metabolism. However, there are some important differences, such as that mice are nocturnal.
“The right timing appears to be important for the body's energy balance and improving the health benefits of exercise, but more research is needed to draw any firm conclusions about the relevance of our findings to humans,” Professor Zierath said.
Reference: “Time of day determines motility in mouse adipose tissue” by Logan A. Pendergrast, Leonidas S. Lundell, Amy M. Ehrlich, Stephen P. Ashcroft, Milena Schönke, Astrid L. Basse, Anna Krook, Jonas T. Treebak Post-Metabolism,” Lucile Dollet and Juleen R. Zierath, February 13, 2023, Proceedings of the National Academy of Sciences.
The study was carried out in close cooperation with the Novo Nordisk Foundation Center for Basic Metabolic Research (CBMR) at the University of Copenhagen and was supported by the Novo Nordisk Foundation, Novo Nordisk, the Swedish Diabetes Foundation, the Swedish Research Council and Card Funding from Rollinska Institutet.