Scientists think they might have discovered the perfect time of day to exercise

Setting an early alarm to exercise may seem impossible to some.

But Swedish scientists believe squeezing a workout in first thing might be the best way to lose weight.

Although based on a study of mice, experts say the results ‘could prove of value’ to humans.

They studied the biological processes in rodents made to run either in the morning or evening.

Mice that exercised in their early active phase — corresponding to the morning for humans — had the most active metabolism.

Exercise causes the body to release hundreds of signalling molecules that boost health in different ways, such as better sleep, memory, performance and metabolism.

The researchers monitored how these signals are released by different organs in mice, depending on which time of day they did a workout.

One group of mice ran on a treadmill early in the morning, while the others did the same routine later in the evening.

Researchers examined blood samples along with those of the brain, heart, muscle, liver and fat.

Their results were published in the journal Proceedings of the National Academy of Sciences.

Genes involved with breaking down fat and thermogenesis (heat production) were more expressed in the mice which exercised in the morning — suggesting it had a bigger effect on their metabolic rate. 

This bodily process, that turns food into energy for breathing, thinking and moving, dictates how many calories they burn per day.

So those with a higher metabolism use up more calories and are more likely to lose weight.

Professor Juleen Zierath, a biologist at the Karolinska Institutet, said: ‘Our results suggest that late morning exercise could be more effective than late evening exercise in terms of boosting the metabolism and the burning of fat.

‘And, if this is the case, they could prove of value to people who are overweight.

‘The right timing seems to be important to the body’s energy balance and to improving the health benefits of exercise.

‘But more studies are needed to draw any reliable conclusions about the relevance of our findings to humans.’

The team, which also included researchers from the University of Copenhagen in Denmark, hope the results will help contribute to more effective exercise plans, such as to patients with type 2 diabetes and obesity, which are timed to the body clock.

They noted that their study only looked at running and other types of exercise may trigger different results.

And age, sex and underlying health conditions were not considered in the study.

And while mice have are a long-established model for human physiology and metabolism, they are nocturnal, which may influence the findings.

Professor Zierath added: ‘Despite these limitations, we believe that the results are of potential relevance to humans because many aspects of basic physiology are shared between mice and men.’

The researchers now plan to investigate if the same or similar exercise responses occur in humans.

Adults are advised to do two-and-a-half hours per week of moderate activity, such as cycling or brisk walking, or 75 minutes of vigorous activity, such as running or tennis.

On top of this, they should do strength exercises on two or more days every week, health chiefs say.