It's not just our sleep and wake patterns that are governed by natural rhythms. Our heartbeats, hormones, hunger, and digestion, along with other bodily functions move to the rhythm of a daily beat.

Researchers have also discovered that we exercise according to an in-built body clock, and being sedentary can mess up its rhythm and the effect it has on our health.

The pattern is apparent in the way we move more during the day and less at night as we settle ourselves towards sleep.

It also has a more subtle side, with natural fluctuations on a minute-to-minute and hourly basis that appear as patterns over an extended period of time.

One 2009 study found that, as you might expect, young people tend to move a lot more frequently, but with more irregularity in the movement. For instance, one morning they might barely move, while the next they are very active. But, there seemed to be a method to the madness; if they had been still for some time, they would have a burst of activity or vice versa.

The body's ability to respond dynamically to its environment and intuit when it needs to move or be still based on a "memory" of what it has been doing leads to what researchers consider to be a healthy circadian rhythm. They found the patterns in young people similar to those in young animals, indicating there is a biological drive to the way we move.

The pattern changed, though, as people aged and became more sedentary. The "memory" seemed to deteriorate. They moved less in general, but moved more at times when the natural rhythm suggested they should be slowing down – at night, for example.

Was it just a matter of age slowing them down and affecting their "memory"?

The new study, lead by the same researcher from Harvard, sought to understand this change in rhythm better.

Taking young and elderly mice, the research team followed their activity and gave them unlimited access to a running wheel for a month.

In line with the previous research, the young mice ran and rested hard, while the older mice followed a similar, but less intense pattern.

All the mice followed a similar rhythm that changed between day and night.

Then the running wheels were removed.

Quickly, the rhythm of all the mice went out of whack. They became active when they had been still before and vice versa.

The old and young mice moved in a similar way, leading researchers to believe it is the exercise, not the age, that is the distinguishing factor.

"Finally, our data showed that exercise had a stronger influence ... than the effect of age," the authors concluded. "Even in young animals, a lack of exercise leads to strong deterioration."

The good news is that, when they were allowed to exercise again, the animal's body clock "remembered" and regained its rhythm again.

By influencing the biochemistry of the brain, the authors suggested, exercise seems to support an effective body clock; one that instinctively knows what it needs in order for optimum health.