What is the Best Time of Day to Work Out? Insights From the Latest Research

by Tom Venuto

What is the best time of day to work out? I wouldn’t blame you if you were confused about this because everyone seems to have an opinion: Conventional wisdom says train in the morning to start your day right and improve compliance. Past research has uncovered evidence that training in the late afternoon gives you the best results. In recent years, a number of training experts have claimed that neither of these times are ideal and that you should actually train at night. A recent analysis published in the Journal of Strength and Conditioning Research has shed some new light on the controversy.

One thing we know for sure is that psychological and physiological functions can indeed change relative to the time of the (solar) day. These variations are known as circadian rhythms. It’s not a question of whether these rhythms exist – they do. The real questions are, how much does this affect your training performance and your results over time?

Several studies found that short-term maximal performance (sprinting, maximal muscle contractions, jumping, etc) peaks in the late afternoon betwen 16:00 and 20:00 hours. The variation in performance has ranged between 3% and 21%.

Why the difference in performance with different training times? One explanation is body temperature.

Exercise physiologists noticed that this rise in athletic performance in the late afternoon paralleled the circadian variation in body temperature (which also peaked in the late afternoon). They hypothesized that the increase in core temperature could have a passive warm up effect, which enhances metabolic reactions, increases extensibility of connective tissue, reduces muscle viscocity and increases the conduction velocity of action potentials.

Studies have also found that tendons are stiffer in the morning. Even the actual muscle architecture itself (arrangement of muscle fibers) is different as the day goes on. Dr. Stuart McGill, a respected professor of spine biomechanics has suggested that certain exercises (involving bending and twisting) should be avoided within an hour of rising from bed. He says the discs are filled with fluid at that time, which magnifies the stresses placed on the spine.

Basically, most people are more likely to have used their muscles during the morning and day, whereas they are cold and tight first thing in the morning.

Hormonal response to training

Some studies say the difference in performance is hormones, because hormone levels can fluctuate based on the time of day. Testosterone and growth hormone are important for muscle growth and there is some evidence that testosterone rises more after a late afternoon training session than it does during a morning workout. The stress hormone, cortisol (which can be catabolic in nature), peaks in the morning and decreases later in the day.

Some experts have started recommending PM workouts for this reason alone – hormones. However, research is very mixed about how much these short-term hormone fluctuations affect performance, and more importantly, whether they affect long term results (strength, hypertrophy, etc) at all.

Of course that hasn’t stopped various fitness gurus and lay-press news sites from swearing that the long-revered advice to train in the morning is incorrect! Journalists, contrarians and other attention mongers love to do that: “The way you’ve been doing it is ALL WRONG!” (doesn’t that drive you crazy?)

Since Burn the Fat Blog readers are much smarter than that and don’t jump to premature conclusions, let’s take a closer look, shall we? First of all, what kind of training are we talking about?

The effect of training time on training type

Although differences have definitely been found in short term exercise performance, most studies have found that when the training is prolonged, the differences disappear or are not significant. There’s little or no evidence that physiological responses fluctuate during the day during middle and long-duration performances which depend on the athlete’s vo2-max, HR max and running/cycling economy.

So now that narrows our focus to something I am particularly interested in: gaining strength and muscle! (This also applies to power training and intense or intermittent types of cardio training).

Ironically, the effect of weight training on strength and hypertrophy is the least studied area. Fortunately, that’s changing. Recent studies have not just stopped with measuring short term performance or acute spikes in hormones, they have begun measuring performance over time and adaptations over time. The findings have been interesting and they were summarized in the recent Strength and Conditioning Research review:

If you are an athlete and you do your regular training at the same time of day that you usually compete (game time or meet time), you are more likely to perform better. In other words, if you compete in the morning, train in the morning. If you compete in the PM, train in the PM

This also suggests that you avoid haphazard or random training times and be aware that if you switch your training time, there might be a decrement in performance at first until you get used to it. If you pick one time – any time – and stick with it, your body may adapt to it – positively.

This subject is still being researched and while best practice guidelines are starting to emerge, the fact is, there are pros and cons to nearly every training time, and in the end, it becomes as much a matter of convenience, personal preference and behavioral/psychological factors as it is anything physiological.

Many people find that training in the morning helps them stay consistent. One positive behavior or accomplishment in the morning can set a postive tone for an entire day and your desire to stay on track (including eating better) remains high all day long. Some people also find that night time workouts are easier to blow off, because they are tired and stressed or work or family issues come up and take precedence (or, like some people I know, happy hour is calling).

Many people also find that if they train too late at night, it disrupts their sleep, and there is some research supporting this. That’s especially important considering that adequate quantity and quality of sleep is one of the factors that affect diurnal variations in sports performance as well as body composition.

Bottom line: Steer clear of rigid ”guru commandments” that you must train at one particular time. Instead, customize your training time just like you customize every other part of your plan. The ideal time for you to work out is the same that a lot of common-sense trainers have been saying all along: Simply train at the time when you can perform the best… when you feel the best physically… when you’re mentally aroused, alert and focused… and when you can stick with it.

Add in what the latest research tells us (once you have “your time” nailed down, do it consistently at that time – as a ritual), and you’ll get the best results possible.

About Fitness Author and Fat Loss Coach, Tom Venuto

Tom Venuto is the author of the #1 best seller, Burn the Fat, Feed the Muscle: Fat Burning Secrets of the World’s Best Bodybuilders and Fitness Models. Tom is a lifetime natural bodybuilder and fat loss expert who achieved an astonishing ripped 3.7% body fat level without drugs or supplements. Discover how to increase your metabolism, burn stubborn body fat and find out which foods burn fat and which foods turn to fat by visiting the home page at: BurnTheFat.com