Fun, Facts & Fitness from Mary Morris MSc.
Travelling back from our recent holiday we travelled east across a timeline, which meant that we had to readjust to losing 8 hours, resulting in the most awful jet lag. You may have suffered too at some point. I have often wondered why it makes you feel so bad. It can completely wipe us out, disturbing sleep for several nights, and when we should be eating breakfast, we are probably eating our dinner!
Then I listened to a most fascinating podcast about circadian rhythms in the body and it all became clear. It is often referred to as the Circadian Clock and is a very clever mechanism in the body that is a natural timer, a 24-hour clock that runs constantly from all parts of the body with the 'central' clock in the brain (the hypothalamus to be precise), and the peripheral clocks that run from all other tissues such as the liver and kidneys and all our muscles.
Let me try to explain it because it is not just linked to jet lag, but also to much of our daily activity and can result in our using the very best time of day to eat and exercise.
This clock runs constantly with a timer attached to all the major organs of the body, including the heart and lungs, liver, kidneys etc. and for us to feel 'on form' all these timers need to be in sync. So, the jet lag scenario is a great example of being 'out of sync'. Our brain may be saying it's 3am, but our digestive system might be at noon and our liver is telling us its 5pm. The result is we feel very washed out and very uncomfortable until they all get back into sync - which can take several days.
Interestingly, these clocks are not linked to night and day. Daylight does not turn the clock on. It is just our regular pattern and schedule of eating and activity that the body adapts to, and makes your personal clock run smoothly. To prove this a group of students went down a dark cave for a period of 40 days, so light was not relevant at all, and they discovered that their sleep and wake cycle remained exactly the same. Fascinating.
Your Muscle Clock
This is where it gets very interesting for those of us who like to exercise regularly. Firstly, it is very important that each day we have a period of 'activity', and for most of us that takes place during the daylight hours. We then follow that with a period of 'rest' where we go to bed to sleep. The interesting thing is that during the active part of the 24-hour clock, scientific research has found that we are at our most 'powerful' in the afternoon. That means that if we want to promote muscle growth (yes please!) then we should take up our hand weights and resistance band during the afternoon.
You are now so familiar with our, often repeated, message about maintaining strong muscles as we get older, and that by using resistance exercise (using a band or light weights) you are going to keep strong enough to lead an independent life. These circadian clocks within our muscles allow us to gain greater strength if we do our resistance exercise later in the day. Apparently, the very best time is around 4pm but there is some flexibility around that.
Surprisingly, we have almost identical 'muscle clocks' to mice and they found that those mice who used the running wheel at the end of the day were by far the healthiest, lived longer and were less likely to become diseased.
I admit this is not good news for those who have always exercised first thing in the morning and for people such as shift workers who may find it hard to be consistent around the timing of their exercise sessions. In that case the message seems to be that we are best exercising before we go to work rather than after.
Timing of Eating
Here again the circadian rhythm clock for eating is best later in the day. This is a shock for those who have always believed (me included) that eating breakfast is vital for starting the day. That still holds true but the point here is the amount you eat at the start of the day and here too, the message is to eat more as the day progresses.
This actually fits in very well for most of us, as generally we like to eat a main meal later in the day. Added to this message is the need to eat protein (meat, fish, eggs, cheese, milk, yogurt, pulses and legumes, etc) at every meal, as the evidence is very striking for ensuring our overall muscle health.
Personally, as I have become older, I find it hard to eat very late in the day, so this idea that we should be eating a main meal late in the afternoon now fits perfectly for me. Many of the people I speak to often say the same. What also seems to be important is the 'window' of time that we eat our meals and there seems to be a consensus that the best mix is to fit them into a 12 hour period with a 12 hour rest from eating. This allows the body to 'repair and restore'.
The Good News
On exploring this concept further than the original podcast I heard, it became clear that the most important thing to be aware of is that our circadian clock works best when we have a regular 'schedule' of eating and exercising every day. If we veer away from that, the clock becomes disrupted. So, if we have always exercised early in the morning and our meals are at the same times every day then we should have a beautifully 'set' clock.
I hope that these little pearls of wisdom I occasionally drop on you are as interesting to you as they are to me. I love continuing to explore how our bodies work with the intention of keeping mine in the very best working order possible. As you are reading this, I can only assume you are of the same mind!
