The Science Behind The Time You Work Out

An Article by Amy Boyington

It would be very surprising if you haven’t heard the phrase “timing is key” at least once in your life. The importance of timing in helping you reach your goals efficiently has always been emphasized.

But, it has been given more attention recently in the exercise and nutrition field. Nutrient timing and pre-workout supplements have all surged in popularity. Now, this attention is being paid to workout timing.

Some studies have started showing that not only how, but also at what time, you train can have a significant impact on your results.

But, why?

The Circadian Rhythm
Many people may be unfamiliar with the term “circadian rhythm” but may be very familiar with the term “biological clock”. Despite the different terms, the two are one and the same.

Your body experiences natural changes in hormone levels due to a mix of stimuli. These can include exposure to light, physical activity, and even the time you eat. These hormonal changes form a pattern or rhythm. Depending on the time over which these patterns exist, they can be classed as:

• Circadian rhythms, which last just over 24 hours. These can include fluctuations in hormones like cortisol and testosterone.
• Diurnal rhythms, which are the parts of the circadian rhythm that sync with day and night. An example includes a variation in immune cell count at night versus the day.
• Ultradian rhythms, which are short and high-frequency patterns within the circadian rhythm. These can include things like heart rate and blinking.
• Infradian rhythms, which are patterns that last longer than the circadian rhythm. A perfect example is the menstrual cycle, which can also impact training and results.

The above rhythms all influence elements of behavior. For example, it’s hard to stay relaxed if your heart rate is 180 bpm. It’s also hard not to blink more if someone’s flashing a light in your face.

More long-term examples include when you get tired, which is partly caused by the timed release of the chemical GABA (Gamma-Aminobutyric-Acid for the chemistry geeks!) throughout the day.

Hunger is also influenced through the release of hormones like Neuropeptide Y and Corticotropin-releasing hormone (CRH). This can be why some people feel like snacking every hour, while some can go the entire day before feeling hungry.

Interestingly though, these hormones may be used to your advantage. Case and point, testosterone is a hormone associated with increased muscle growth and recovery. So, it would stand to reason that training at a time when this is elevated could help improve results over time.

It might seem like unlikely, but studies have started emerging showing this might actually be the case. Another factor would be how you’re normal behavior around the time of exercise could indirectly impact your results, such as fasted workouts or inadvertent nutrient timing.

So, is there a “best” time to train? How does training at different times impact progress for different goals? How can certain training times be used to optimize training results?

Below, we look at how all of these can be used to help you get the best results from your workouts, no matter the goal.

Morning Workouts

Time period: 05:30 – 12:00 approx.

Contrary to what many might believe, the early bird doesn’t get the worm, at least not with training.

Multiple studies have all shown that training later in the day will lead to better results in almost every aspect than morning workouts.

But, there are a few areas where morning training can help improve your goals. Firstly, fasted cardio is easier to do if you’re carrying out morning training. Research has shown fat oxidation to be slightly higher during fasted aerobic training, so this is a plus.

Also, if you’re carrying out multiple training sessions in a day, you’re going to have little other choice than to do one of them in the morning. The result can be a greater amount of calories burned over the day and a slightly higher burning of fat for fuel.

So, for the hardcore athletes training for performance or those looking to maximize fat loss, early morning training may help.

Best type of training for this period: HIIT training or exercise devoted to fat loss

Most suitable goal: Fat loss

Afternoon Workouts

Time period: 12:00 – 18:00 approx.

The majority of studies favor performing workouts in the afternoon for maximum results. One caveat here is that a lot of studies can define “afternoon” as anywhere from 2pm to 8pm. So, much of what’s written here can be carried over to the below section as well.

But, certain studies that have focused on the earlier afternoon have found significantly better results for things like aerobic and anaerobic capacity, strength, and muscle growth.

This is likely due to factors like an ideal body temperature, testosterone-to-cortisol ratio, and Growth Hormone release. All of these can help maximize workout performance and recovery.

For a more specific timezone, 3-6pm has generally been shown to be the optimal time of day for people to train.

Best type of training for this period: Strength (and muscle growth) training, aerobic and anaerobic endurance training

Most suitable goal: Strength and power, muscle gain, or peak athletic performance

Evening Workouts

Time period: 18:00 – 21:00 approx.

As stated, many of the above recommendations for afternoon training can be made for evening training. But, strength and power training have a few studies showing the later timezone to be the optimal time to train.

It also helps that eating high protein, and larger, meals in the evening can help boost muscle mass more than if eaten in the morning.

So, if you’re going to prioritize a certain goal for your evening training, make it strength and power development.

Best type of training for this period: Strength and power training

Most suitable goal: Strength, muscle mass and power development

A Few Considerations
See, there’s an ever-so-slight issue with your circadian rhythm. It can change.Pretty significantly too. This is actually the basis for jet lag. Your body is basically operating in a different time zone than it is used to. The result, as many know, include sleep and mood disturbance.

But, as many also know, your body adapts to this. The same is true of exercise and food intake. Diet has actually been shown to impact your circadian rhythm, to the point where there is now an effective anti-jet lag diet.

But, these changes have to be consistent for a change on the circadian rhythm to be made.

People also have different genetic rhythm types (like the annoying “morning people”). These individuals may actually be better suited to training earlier than their late-rising counterparts.

Caffeine can also help in offsetting your circadian rhythm when exercising (for the record: so can cocaine, but I’d recommend coffee). This means that early-risers may be able to compensate and obtain similar results from a morning workout as a later one.

Diet efficacy can also be influenced by circadian rhythm.

Wrap Up And Take Home Points

• Your body goes through a lot of hormonal changes throughout the day.
• These changes can be used to help you get the best results out of your training program.
• For the majority of goals, training in the afternoon or evening will help you get the best results.
• But, some individuals may be better suited to training later or earlier in the day, depending on their genetics.
• Some secondary factors, like performing faster cardio in the mornings or synching your evening workouts with a high protein intake can also help in maximizing results.
• Changing your exposure to light, training times, or food intake could also help you change your circadian rhythm.
• Caffeine may also help offset circadian rhythm-based lags in performance in morning workouts.

Amy Boyington

I’m Amy, a content writer from Ohio. As a work at home business woman, I enjoy helping other women learn how to create their dream careers with the perfect balance between their professional and personal lives. You can find some of my work on Reader’s Digest and other online lifestyle publications.

Freelance Writer and Editor of The Work at Home Mom Blog

Richie started Hurricane Fitness in 2011. Starting out as a Boxer at the age of 11 and winning County, Provincial, National and International medals in Boxing, he began running fitness classes and personal training.
Since then he has gone on to work alongside Olympic, World and European Champions and has trained many clients, both at home and abroad, with a wide range of goals and needs.
You can find him on his website; hurricanefitnessireland.com, or on his Facebook or Instagram page.
Richie Hedderman