Two new studies have found that exercising at different times of the day could bring completely different benefits to your body.
Paolo Sassone-Corsi, a researcher involved in study carried out by the University of California, said the timing of your exercise is crucial.
- Opinion: 'I like it hard' - Our obsession with 'hard' exercise
- How to stay motivated and maintain a good exercise regime in winter
"Exercise done in the wrong time of day could actually bring you little or no much of a help physiologically, while instead, if you do it at the right time of the day, it could be extremely beneficial."
His study put mice on treadmills and looked at the changes in muscle tissue during exercise.
The study found that late-morning exercise appeared to have the greatest effect on metabolism.
"We discovered that exercising at the correct time of day - around mid-morning - results in more oxygen in the cells and a more rejuvenating effect on the body."
However, the test wasn't carried out on humans and so some uncertainty still remains.
"Mice in a lab are all genetically equal and we know they all behave the same, that's not something we can say about humans, we are all different."
Another study carried out by the Weizmann Institute of Science tested mice on treadmills at different times to examine their exercise capacity.
Researchers found overall exercise performance was significantly better towards the end of their 'active time' - what we would call the evening.
They then studied 12 humans and found a similar effect.
Strength and Conditioning Coach Sunesh Singh says there are always benefits to exercising, no matter the time, though it's more important to be consistent.
"No there's no wrong time, I think the wrong time is not doing it at all, so it just comes down to the fact of how consistent you can be at continually doing it," Singh told Newshub.
While more testing of humans is needed to nail down the perfect time to exercise, the message for now is: do what works best for you.