We all have our own internal circadian rhythm. Your circadian rhythm is a 24 hour body clock following a daily 24 hour cycle, this effects our physical, mental and behavioural changes throughout the day. For example, at times we are full of energy, other times we feel drowsy. This is different from person to person and goes some way to explain why some of us struggle to get up in the morning while others struggle to stay awake past 9pm. You may have been referred to as a ‘night owl’ or an ‘early bird’ but scientists now think there are 4 different categories that we fall into: dolphin, lion, bear and wolf.
Image taken from Elite Daily
If our internal circadian rhythm effects our sleep, can it also affect our behaviour when we are awake: like when we should exercise for instance?
As you can see from the diagram (Image copied from Lux Review) , something is always happening at a hormonal level within the body. This is in order to regulate the body: our temperature, blood pressure, when to eat and sleep. This guide is for the ‘general’ population – those who wake up around 7am. These hormonal balances will change if you’re a shift worker and change with age, illness and whether a dolphin, lion, bear or wolf – we show huge inter individual differences in our behaviour.
Based on this diagram, 17.00 appears to be the time we should be training due to the greatest cardiovascular efficiency and muscle strength. However, is this really best time to train for everyone?
Training in the evening
Research by Bernard et al. (2007) published in the European Journal of Applied Physiology showed there to be an ‘existence of a time-of-day effect in the maximal anaerobic power of cycle and multiple-jump tests’. The graph below also shows a difference in running speed.
Many people worry that training in the evening impacts on their sleep, as you end up energised after a session. You hear many sports players complain that they struggle to get to sleep post game. I don’t think it will impact on your sleep too much though, once you’re in a routine and the session is not right before you sleep. That said, we are all different and you might find you do struggle to sleep after an evening session – that’s fine, you have other options!
It has often been said people who exercise regularly at lunchtime are more productive in the afternoon than those who do not exercise. If you have an important piece of work to do that afternoon, take yourself to a lunchtime class, go for a run or a walk. You will be more alert and productive.
Research published by Husmer (2013) thesis at the University of Connecticut 1200 to be a better time to strength train with regards to the total amount of work when compared to 1800. This is due to the reported potential of stresses from every day tasks.
Morning sessions are less likely to be put off, compared to afternoon/evening workouts. Our motivation to hit the gym can also be dented depending on the day you have had: there always excuses to avoid the gym – energy levels, family engagements, catching up with friends.
Exercising in the morning does not have any impact on growth hormone* release when training. Growth hormone levels increase throughout the day naturally and are released when we train. Research by Kanaley et al. (2001) published in The Journal of Clinical Endocrinology and Metabolism showed there was no significant difference in growth hormone response to exercise by time of day, when subjects trained at 0700, 1900 and 2400. So this is really positive news: no matter what time of day you train, you will still get the same growth hormone response.
The morning workout is also supported by Husmer (2013) who reported participant performed greater work at 0600 when compared to 1200 and 1800
*Growth Hormone: regulates body composition, body fluids, helps with muscle and bone growth, sugar and fat metabolism.
Summarising: morning, afternoon or evening?
The sitting on the fence answer is: it doesn’t matter. Yes, there may be a slight advantage to training early evening due to slightly greater effect on the cardiovascular and strength system, but the research also shows that picking a time of day that suits us is most beneficial. If we look at research by Lastella et al. (2016) published in Journal of Human Kinetics shows that athletes are more likely to pick sports based on there chronotype. Pick a time and activity that suits you: adherence is key as mentioned in a previous blog. And what makes us adhere to things? Enjoyment. What is better for health? Select training times that fit your lifestyle. Doing something is better than doing nothing, just because it is scientifically the ideal time.