Do you prefer to exercise in the morning? Or the evening? Or *gasp* do you exercise at all??? I’m sure you do. After all, you’re a loyal reader of my articles. Aren’t you? 😉

This week’s question was about the optimal time to exercise.

As I’m sure you know by now (from my articles), the answer is almost never a simple time. There are certain things to take into account when considering the optimal time to exercise.

Your Hormonal Profile and Circadian Rhythm

Ideally, your cortisol levels (that’s the stress hormone) are high in the morning, and lower in the evening. And if that’s you, it would make the ideal time to exercise 2-3 hours after you wake up.

But (and it’s a big “but”) if you have low cortisol in the morning, and high cortisol in the evening, it may be better to exercise later on in the day, like late afternoon. How do you know if you have this kind of cortisol rhythm? The best way is to test for it (you run a test called “salivary cortisol”), but here are some signs:

If you’re not a “morning person”
If you get lightheaded when going from lying to sitting or sitting to standing
If you crave salt

Your Body Temperature

Body temperature fluctuates naturally throughout the day. For most people, it peaks in the late afternoon, between 3PM and 5PM. When your body temperature is at its highest is the best time to exercise, because nerve signals travel faster in a warmer body. If nerve signals travel faster, they force more powerful muscular contractions.

How do you figure out your pattern? After all, just because 3-5PM is the average doesn’t mean it’s your average. That’s a very simple test. For 3 days, measure your body temperature every 2 hours. Notice when you have the highest temperature. If you can, time your workout to happen at this time.

How Exercise Affects Your Sleep

Some people, if they exercise after 4 or 5PM, they can’t fall asleep. In that case, even if most people’s optimal is 3-5 PM, that particular person’s optimal time to exercise is definitely not at that time. This person needs to be exercising earlier in the day.

However, if you’re the type of person who can exercise at 8 or 9 in the evening with no adverse effects on your sleep, and your performance in the gym doesn’t suffer, than that may be your ideal time.

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The Optimal Time to Exercise Changes

Now let’s say that you just can’t exercise at your ideal time. Should you not exercise at all? That’s correct. It’s all or nothing, so don’t bother exercising, because exercise at 7PM will have a drastically worse effect than exercising at 4PM. In fact, it might even cause cancer.

Just kidding.

The truth is that the optimal time to exercise actually changes. Let’s say you’re not an exerciser, and your optimal time is 4PM. That’s when you have the most energy, body temperature is at its highest, and it doesn’t negatively impact your sleep.

But if you start exercising at 7PM, after a period of a few weeks to a couple of months, 7PM becomes your optimal time.

How does that work? Well, children, let me tell you a little story about Pavlov’s dog. Pavlov was a Russian physiologist in the early 1900s. For a period of time, he rang a bell right before he served the dog food. After some time of doing this, eventually, as soon as the dog heard the bell, he would get the same reactions in response to food: increased saliva, increased wagging of the tail, etc.

Eventually, Pavlov stopped ringing the bell, but the dog got the same reaction every time without the bell, because it was the right time to eat.

So even though at first, the dog had no reactions right before meal time, after a certain period of conditioning, he started getting those physiological reactions.

What does this have to do with you? If right now, you don’t feel like going to the gym at 7PM because you’re tired, if you do it for a period of weeks, to a couple of months, your body will get used to that time. What does “getting used to it” involve?

If before you started consistently working out at 7PM, your body temperature would peak around 4PM, after you’ve gotten used to 7PM, your body temperature actually starts to peak at 7PM.

Your hormonal profile leading up to the workout will be such that is most conducive to that workout.

So over time, what may not have been an optimal time for you becomes an optimal time.

You’ll even start drooling and wagging your tail closer to 7PM.

Keep Things in Perspective

I wrote this article because the question was asked. But in the grand scheme of things the time that you exercise is not all that important. There are a lot of other factors that are going to have a FAR bigger impact on your results, like:

Your progression model
The number of repetitions
The amount of weight you use
You choice of exercises
Your tempo
Your intensity

And only waaaaayyyy down the priority list is the time that you actually exercise. So keep things in perspective.