What is the best time of day to exercise?

Posted by & filed under Exercise and Training.

Beautiful sunset.  It says to the brain, 'Bedtime.'

Beautiful sunset. It says to the brain, ‘Bedtime.’

What is the best time of day to exercise is, for many, a hypothetical question.  Exercise usually has to fit around work and other commitments.  The brief answer to the question is about 11am.  And not many people can achieve this.  But an understanding of what happens in the body when we exercise can sometimes make us change our routine.

The thing to think about when deciding when and how to exercise is cortisol.  Cortisol is a stress hormone that should be high in the morning, sinking during the day and low at night when we want to go to sleep.  During the night it slowly rises, waking us in the morning.  Exercise can raise cortisol – and sometimes should – so if we exercise vigorously in the evening, our cortisol will rise, making it hard for us to get a good night’s sleep.  One of the symptoms that everything is not alright is exercising fit to burst in the evening and fall into a deep sleep a couple of hours later.  I have been there!  It is a sure sign that we are on the fast track to exhaustion.

What sort of exercise raises cortisol?

  • Weight training lasting longer than one hour.  In order to get stronger/bigger, it is critical that weight training lasts under the hour, shorter even better.  For the first 20 mins, testosterone rises and we are at our maximum ability to grow our muscles.  Beyond that, cortisol starts rising and after 60 mins is higher than testosterone.  Cortisol breaks muscle tissue down.  So short, hard session shoving weights about are going to give much better results than marathon sessions in the gym.
  • Cardio.  Particularly effective cardio.  A 2 -3 hour hard bike ride will have sky-high cortisol at the end.  To come home, have a shower and a bowl of cereal will mean that, long term, these long hard training sessions will get slower and slower.  And recovery longer and longer.  The most effective cardio session is 30 – 40 mins long and is interval in nature.  It is best done in the morning when cortisol is naturally high.  Long slow distance stuff is also better done during the day rather than late afternoon/evening.
  • Cardio and weights do not go together in the same workout.  They can both be done on the same day, but at least 4 – 6 hours apart.  Various reasons, cortisol being only one.

Circadian rhythms will also dictate exercise timing and type.  The rise and fall of cortisol should be universal, but if an evening person, then the most vigorous exercise will probably feel better later in the afternoon and vice versa if a morning person.

All this is fine in theory, but what to do if the only time we have to exercise is in the evening?  Post exercise, take calming amino acids, such as taurine; instead of showering, take a bath and, ideally, eat fish or pale meats post exercise.  Practise calming, deep breathing and anything else that is calming.   Listening to thrash metal in the car on the way home is not a particularly good idea, no matter how jacked up we feel.


And then there is the very early in the morning run.  I think the photo to the right was taken on a jog at about 4am in July.  Personally, I think this is utterly bonkers.  But if you are a morning person,  go to bed very early and do not feel at all tired during the day, then this can work.  What on earth these people do when they go out in the evening to have fun is beyond me.  10.30pm will feel like 1am!  BUT to exercise early in the morning at the expense of sleep is entirely counterproductive and can only lead to long term exhaustion, decreased mental performance, lowered immunity and sugar cravings.

In conclusion, if we can’t exercise at 11am – and who can? – then provided we don’t just treat out body like a car and take care of ourselves afterwards, calming down, feeding properly, not neglecting our need for sleep, not over doing it and so on then exercise can be as exhilarating and as good for us we we like.

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