As part of the research, in mice, they demonstrate that exercise in the morning results in an increased metabolic response in skeletal muscle, while exercise later in the day increases energy expenditure for an extended period of time.
Studies in mice reveal 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.
According to the researchers, 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.
The findings were published in the Journal of Cell Metabolism.
Morning exercise initiates gene programs in the muscle cells, making them more effective and better capable of metabolising sugar and fat. Evening exercise, on the other hand, increases whole-body energy expenditure for an extended period of time.
The researchers have measured a number of effects in the muscle cells, including the transcriptional response and effects on the metabolites. The results show 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.
Morning exercise appears to increase the ability of muscle cells to metabolise sugar and fat, and this type of effect interests the researchers in relation to people with severe overweight and type 2 diabetes.
On the other hand, the results also show that exercise in the evening increases energy expenditure in the hours after exercise. Therefore, the researchers cannot necessarily conclude that exercise in the morning is better than an exercise in the evening, Jonas Thue Treebak stresses.