According to the report of researchers from the University of Copenhagen, depending on the time of the day someone performs it, the effect of exercise may differ. In a mice model, the researchers demonstrate that exercise in the morning results in an increased metabolic response in skeletal muscle, while exercise later in the day increase energy expenditure for an extended period.
As it is generally known how essential a healthy circadian rhythm is, too little sleep can have severe health consequences. However, researchers are still making discoveries to confirm that the body's circadian clock affects human's health.
With the collaboration of researchers from the University of California, Irvine, a team of researchers from the University of Copenhagen have learned that the effect of exercise may differ depending on the time of day it is performed. Studies in mice show that the effect of exercise performed at the beginning of the mouse' dark/active phase, corresponding to our morning, differs from the effect of exercise performed at the beginning of the light/resting phase, corresponding to our evening.
Associate Professor Jonas Thue Treebak from the Novo Nordisk Foundation Center for Basic Metabolic Research, and one of the researchers said that there appear to be rather significant differences between the effect of exercise performed in the morning and evening, and these differences are probably controlled by the body's circadian clock. Morning exercise initiates gene programs in the muscle cells, making them more effective and better capable of metabolizing sugar and fat. On the other hand, evening exercise increases whole-body energy expenditure for an extended period.
However, is morning exercise necessarily better than evening exercise?
The team has measured several effects in the muscle cells, including the transcriptional response and effects on the metabolites. The results reveal that responses are far stronger in both areas following exercise in the morning and that this is likely to be controlled by a central mechanism involving the protein HIF1-alfa, which directly regulates the body's circadian clock.
Thue Treebak stressed that morning exercise appears to increase the ability of muscle cells to metabolize sugar and fat, and this type of effect interests the researchers about people with severe overweight and type 2 diabetes. Also, the results, on the other hand, show that exercise in the evening increases energy expenditure in the hours after exercise. The team, therefore, cannot necessarily conclude that exercise in the morning is better than an exercise in the evening.
He explained further that on this basis, they could not say for certain, which is best, an exercise in the morning or exercise in the evening. They can only conclude that the effects of the two appear to differ, and they certainly have to do more work to determine the potential mechanisms for the beneficial effects of exercise training performed at these two time-points.
