When your body clock becomes misaligned, it’s not just your sleep cycle that is thrown off course, but your immune system and hunger regulation as well. This misalignment can happen if you work at night instead of during the day and when you travel. Inside your body, it is also possible for tissues to become misaligned with your central “clock.”
A new study published on Monday in The Journal of Physiology suggests that exercise may be able to help the body fine-tune an internal clock that has been knocked out of sync, but this excursive must happen at the exact right time of day.
How does exercise change the body clock?
Your “body clock” is your circadian rhythm, which is a cycle of hormone release that responds to cycles of light and dark in your environment. This cycle not only helps your body regulate when you wake up or go to sleep but also helps determine when you feel hungry or burn calories.
The master clock of your body clock is located in the brain, but there are other thousands on other clocks that play a hand, too. In muscle cells, certain genes are expressed at specific times in sync with your body clock.
New research suggests that exercise can help either advance or delay the circadian rhythms of the other clocks in your body, called peripheral clocks, that are located in the body. Researchers emphasized that timing is key in this process.
The study, which was conducted on mice, found that when mice exercised five hours into their resting phase, which would be the middle of your night’s sleep, they “advanced” the phase of those muscular clocks by an average of 100 minutes.
When the mice exercised one hour before the resting phase ended, which would be one hour before you woke up, the phase of those muscular clocks was delayed by 62 minutes.
According to the authors of the study, exercise may serve as “a time cue for the muscle clock,” meaning use of our muscles could be one way to help the body keep time and reset the clocks if their typical rhythms become altered. Rhythms can become altered if we live out of sync with natural rhythms, as is the case for people who work at night instead of during the day.
How does exercise change your muscle’s clock?
The research team had 30 mice run at moderate intensity for an hour at three different time periods. First, they had them run in the middle of their resting phase, and then at the end of their resting phase, and finally, in the middle of their active phase.
While the active phase is comparable to the middle of the day for people, mice are nocturnal, so their active phase was a “dark period” in the study and the lights were on during the resting phase.
The researchers found that exercising in the middle of the resting phase caused a significant 100-minute phase advancement while exercising towards the end of the resting period caused a phase delay. On the other hand, exercising in the middle of the active period was not linked to any significant changes.
The research team conducted a followup exercise to test if it was truly the muscle contractions that caused the phase shifts. This experiment analyzed the mice’s cells, which were electrically stimulated to mimic a real workout. The researchers stimulated the cells when one Bmal1, a transcription factor that is the core driver of the mammalian clock, was at its highest and lowest levels.
They found that the muscle contractions that were applied when Bmal1 was at the peak caused a delay of 27.2 minutes, meanwhile, the ones applied when it was at its lowest caused a delay of 64.6 minutes.
Looking at both studies, the research suggests that muscle contractions can directly simulate changes in these muscular clocks, which allows for the possibility of extremely specific fine-tuning. This research is important because it shows that the muscle movements themselves are what make these changes happen.
Who can benefit from body clock realignment?
“If this is replicated in humans it means that night-shift workers can use exercise to help shift their body clocks,” said Christopher Wolff, co-lead author of the study and a post-doctoral researcher at the University of Florida. “We may also be able to use exercise as a treatment for a ‘body clock disorders’ that can occur in many chronic diseases such as heart disease.”
Jennifer Fabiano is an SEO reporter at Ladders.