A lot has been said about the importance of the body’s day-to-day rhythm affects health – and for good reason. The impact of a routine cannot be overlooked. And a recent study from the University of Copenhagen found that the effect of exercise may differ depending on the time of day it is performed.
The study was conducted in collaboration with researchers from University of California in Irvine on mice and showed that impact of exercise performed in the beginning of the mouse' dark/active phase - corresponding to human beings’ morning - differs from the effect of exercise performed in the beginning of the light/resting phase, corresponding to human beings’ evening.
“There appears 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,” said Associate Professor Jonas Thue Treebak from the Novo Nordisk Foundation Center for Basic Metabolic Research .He is one of the researchers behind the study. “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,” he continued.
The research measured number of effects in the muscle cells including the transcriptional response and effects on the metabolites. Findings showed far stronger responses in both areas following exercise in the morning – courtesy a central mechanism involving the protein HIF1-alfa which regulates the body's circadian clock.
Exercising in the morning showed the increased ability to metabolise sugar and fat. The study also showed that evening exercise increased energy expenditure in the hours after exercise. But Jonas Thue Treebak stressed that the study could not conclude that exercise in the morning is better than exercise in the evening.
“On this basis we cannot say for certain which is best, exercise in the morning or exercise in the evening. At this point, we can only conclude that the effects of the two appear to differ, and we certainly have to do more work to determine the potential mechanisms for the beneficial effects of exercise training performed at these two time-points,” he explained. “We are eager to extend these studies to humans to identify if timed exercise can be used as a treatment strategy for people with metabolic diseases.”