Work out Time

So I sometimes get the question when is the best time to workout. Most  of my friends would say the morning. I've heard reasons like you are fresh in the morning and more energetic. I've also heard that because you are exercising on an empty stomach you'll burn more fat as your body only has your reserve to get fuel from. I've also heard that if you don't get it done first thing in the morning you are less likely to do it during the day. So being a bioengineer I decided to go to the literature to see if anyone has done any experiments on this subject and what I found surprised me.

First many of the research articles agree that there is a circadian variation in body temperature (ex.

Reilly, T., and G. A. Brooks. "Exercise and the circadian variation in body temperature measures." International journal of sports medicine 7.6 (1986): 358-362.)  A circadian rhythm is one a daily cycle that is based on 24 hours. Most studies find that our maximum body temperature occurs between 4 and 5 pm.

Image from circadian.org

It is also widely believed that exercise effort and max power are affected by a variety of factors including type of exercise, person natural inclination to be a morning or night person, and sleep to name a few. Exercise effort and max power are also affected by the way we fuel our body.

The more "good" stuff we put into our body the more energy we will have and the better our exercise sessions will be.

So now onto what I found that was interesting. One study took subjects and had them bicycle at high intensity. Surprisingly they found that the total work performed was greater in the afternoon than the morning. The greater work was also associated with both a higher anaerobic and aerobic contribution.

(Hill, D. W., et al. "Effect of time of day on aerobic and anaerobic responses to high-intensity exercise." Canadian journal of sport sciences= Journal canadien des sciences du sport 17.4 (1992): 316-319.)

 

Another study looked at exercise affects on mood, appetite sensations, and energy. They also looked at if these varied with time of day the exercise was performed. (Maraki, Maria, et al. "Acute effects of a single exercise class on appetite, energy intake and mood. Is there a time of day effect?." Appetite 45.3 (2005): 272-278.) These subjects did a one hour exercise class that had activities with different intensities and different muscle conditioning exercises.

 

They found that no matter when the exercise was performed appetite increased. They also found that no matter when the exercise was completed the persons' mood became better. They also found that there was no difference in energy intake. They did however find that the  subjects perceived the exercise to take less effort in the afternoon than the morning. They attributed this perception to the fact that we are more limber in the afternoon due to moving around all morning.

The studies go on to say that since the max circadian temperature is from 4-5 the optimal time to exercise is from 4-5pm. One suggestion was to work out while dinner was in the oven.
 

So what does this all mean for us. There is clearly scientific data that says it is actually better for us to exercise in the afternoon. But you may say "I don't have time in the afternoon to workout." I know that working out at any point in the day is better than not working out at all. If you can only fit it in first thing in the morning do it. This is your brain on exercise:

 

 Also by exercising you will get into a better mood. Just remember that by doing any activity at all during any point of the day you are making yourself healthier.

So get out today and exercise. You feel better and your brain will thank you. Have a blessed day everyone.