Here's a simple improvement you might want to make to your exercise regime: commit to doing whatever activity you do at the same time each day. A new study in mice suggests several benefits come with a regular exercise rhythm.
While we have a central body clock in the brain (in the suprachiasmatic nucleus, or SCN), we also have other, more localized body clocks. Exercise can reset the local body clocks in the joints and spine, according to the research led by the University of Manchester in the UK.
If that reset happens at the same time each day, these local clocks can better stay in sync with the SCN clock, the team discovered. Previous research has shown that out-of-sync clocks in peripheral tissues can increase the risk of problems such as diabetes and cardiovascular disease. "Our results showed that physical activities in the morning, associated with daily patterns of sleep/wake cycle, convey timing information from the light-sensitive central clock in the brain to the weight bearing skeletal tissues," says Qing-Jun Meng, a chronobiologist at the University of Manchester.
"In effect it's telling your skeletal system it's time to wake up." The researchers used a genetic reporting technique to monitor the clocks in the cartilage (joints), intervertebral discs (spine), and brains of transgenic mice, while they exercised on treadmills at different times. Samples of cartilage tissue taken from the mice were also studied for their osmotic responses.
We know these areas - the joints and spine - are particularly involved in exercise, and we also know that water is pressed out of them through the day (making us slightly shorter). This partly resets the localized body clocks on a daily basis. What the team found was that activity added to this process of osmolarity (water reduction), further resetting these clocks and - if done on a consistent schedule - improving the timing links between the clocks in the body. These results still need to be shown in humans, but it's likely similar effects are at play.
The health of bones and joints has an impact on everything from how well we can perform in sports to how likely we are to get injured or develop conditions such as arthritis - that risk of injury may be increased in athletes traveling through time zones for example, the researchers suggest. They also observed the same clock syncing in older animals too - so even for those of us in later life who might only do some brisk walking each day, doing it at the same, consistent time is still likely to be helpful.
"Not only have we identified that misalignment between cartilage and intervertebral disc clocks and our central clock in the brain can occur through exercising at an inappropriate time," says Meng, "we have found the mechanism by which this happens and that skeletal clocks can resynchronize to daily patterns of physical activity."