The optimal time of day to train is probably something that you only think about in terms of how it fits in with the rest of your commitments, including work, family and social obligations.

But there is a science to optimising your training times and it can all come down to two words, ‘circadian rhythm’.

What is circadian rhythm?

Your circadian rhythm is your 24-hour internal cycle that’s responsible for regulating various behavioural and physiological systems in your body. The actual term ‘circadian’ comes from the Latin, ‘circa diem’ which means ‘around a day’. Think of your body as having an internal clock that regulates when to activate every system.

One of the best-known circadian rhythms is your sleep-wake cycle. Different people’s systems peak at different times of the day, which means that some people naturally prefer to be awake and active earlier in the day, while others are happier being active (and sleeping) later. Sleep scientists call this your circadian phenotype. But you may be more familiar with people being described as either morning larks or night owls. And, of course, you can always fall somewhere between the two!

Why is any of this important for your strength training or running program (or other physical activity you’re involved in)? Well, science is finding it can really play a part in output and that carefully planning your training schedule depending on your phenotype can have measurable results.

Let’s look at the science more closely

Research published in the journal Current Biology in 2015 found that athletic performance can vary over the course of a day by up to 26% depending on circadian rhythm, and that your phenotype can be important in determining the best time for you to get active.

The study, from the University of Birmingham, selected 20 athletes of similar age and fitness levels to take part in a cardiovascular endurance test at six different times of the day. All 20 were field hockey players with many years of experience and seven had competed at international level.

The participants were chosen to match the different circadian phenotypes of the general population, so larks (28%), intermediate (48%) and owls (24%). So how did they go?

It’s perhaps not surprising (but proves a point) that the early phenotypes or larks performed best in the earlier tests, followed by the intermediates, whereas late types peaked in the evening. The research showed early and intermediate types had a 7% to 10% variation in their physical performance whereas late types (the night owls), varied by up to 26%.

And the biggest factor in predicting performance? The researchers found they could predict how well each group performed at a given time based on the time that had elapsed since their ‘entrained awakening’ — that is, the time they would have naturally woken up in the morning.

Co-author of the paper Roland Brandstaetter, a senior lecturer in biosciences at Birmingham University said the findings leave “no doubt” that the correct determination of an athlete’s personal best performance requires “consideration of circadian phenotype, performance evaluation of different times of day and analysis of performance as a function of time since entrained awakening”.

For sports coaches and trainers, it’s nothing new and many already take this into account when devising training regimes, particularly when there’s travel involved, working to manipulate sleeping, light exposure and activity times to enhance performance and training outcomes.

So how can you make your body’s natural rhythms work for you?

The science of working out

When working out and trying to build strength, your objective is to maximise your physical and mental performance through identifying everything that will provide gains, no matter how marginal.

Circadian rhythm doesn’t just affect your sleep/wake cycle, but also hormone secretions, body temperature, mental alertness and your physical performance capacity.

It’s thought sports performance may be best when you’re at the peak of your circadian rhythm. This is when you’ll experience maximum mental alertness, faster reaction times and the highest core temperature — meaning there’s less viscous blood flow and your muscles are suppler.

In their book The Body Clock Guide to Better Health Michael Smolensky and Lynne Lamberg point to the typical adult cycle being about 24 hours. Okay, makes sense, but here’s where it gets interesting. The authors say that starting in the morning, our lowest body temperature is around 4.30am and peaks around 7pm. We’re highly alert around 10am, our best co-ordination is mid-afternoon at 2.30pm, followed by peak reaction time at 3.30pm and our greatest cardiovascular and muscle strength is around 5pm.

A study out of Charles Sturt University in Bathurst, NSW, looked at the influence of circadian time structure on acute hormonal responses to heavy-resistance exercises in weight-trained men, also suggested that late afternoon training produces a more favourable post-exercise anabolic hormone profile, with higher levels of testosterone and lower levels of cortisol (a steroid hormone associated with muscle tissue breakdown).

That’s of course if your circadian rhythm is fairly typical. If you’re an out and out night owl or a crazy early morning lark, you’re going to have some adjusting to do. You can measure your own circadian rhythm by taking your temperature every two hours or so and plotting the figures to help work out when your peaks occur.

By carefully planning your training schedule to match one of the most powerful rhythms affecting humans, you can maximise your chances to be stronger, faster and more powerful, and also possibly reduce your chance of injuries and sleep better.

At INC we understand the role that your circadian rhythm plays and we understand the link between training and nutrition in helping to achieve your optimal fitness goals. INC Creatine Monohydrate is designed for those want to maximise strength and power and for those seeking increased muscle mass and optimal performance. Micronised for rapid absorption, it comes in an easy-to-mix powder form that can be added to cold water, juice or other drinks.

So whether you’re a lark or an owl or something in between, you can work harder for longer and realise the gains you’ve been looking for. And who doesn’t want that!