What time of the day is best to work out?

[LF365]

I would like to start an unbiased, evidence-based conversation about what would be biologically the best time of the day to work out.

There are probably some people, for whatever reason, who can only work out in the morning and some can only work out at night. Please do not let this fact persuade you in your comments to learn and grow. Let's make this a topic of learning, and not a rant back and forth defending a particular convenient position. 

With that being said, let me start this off.

I know that cortisol, the adrenal, stress hormone is secreted in the pre-dawn hours.  This is built into our biology as a mechanism to get us ready for the day ahead.

If we work out during the morning, wouldn't it better to do so and take advantage of this window of opportunity?  In other words to stress the body at a time when it is biologically ready for stress? 

Also wouldn't it be better to also do a morning workout on an empty stomach as not to spike insulin and to maximize fat loss? Do we have to have a pre-workout meal in order to be successful?  If we workout early enough, let's say 5AM and then have our post workout meals, afterward is this enough?

On the other side, If we work out at night, wouldn't we be adding another layer of stress to our day that biologically might not have been there if we didn't work out at night?

I have read that if cortisol levels don't return to baseline during our resting hours, this can be a precursor to many diseases.  So would working out at night elevate cortisol levels and make it harder for the body to return to state of relaxation?

What do you think, based on our biology, and maximum fat loss what is the best time of the day to work out?

[Ró-fhéinní]

I don't have any science behind it, but i prefer to work out first thing in the morning. I feel I get a better workout as I feel fresh and energized whereas at the end of the day I'm a bit worn down.
Lately though, due to work I have been working out at night, with my main meal as my recovery meal which I find very convenient. This is about the only pro I can think of for evening workouts.

Also, with working out in the morning the book says not to have protein for breakfast but breakfast is my recovery meal, so what should I have? Does the body's needs over rule the ideas of the diet?

[Ró-fhéinní]

Disregard my questions, I just reread the book and got my answers

[ishina]

A very interesting topic which is not yet covered by science and there is a good reason behind it.

I am of the opinion, that this question is a very subjective and thus indiviudal one. Lately, I have listened to a podcast covering this question (unfortunately only in German) and they came to the conclusion that the best time to train is whenever you feel like it and am of the opinion that you are able to perform vigorously.

I second their opinion - train when it suits you best. Indeed, the biochemical impact may be different, depending on the time of the day, but biochemical factors are also individual, at least to some degree. But I would not overcomplicate this question. There is an ideal time to train - but it is different for every individual.

Regards,
ishina

[LF365]

I'll continue to post on this topic as I have the time.  It takes a long time for me to write these research articles.

Science has proven the circadian rhythm affects biochemical, physiological and behavioral process of living beings.  This is influenced by light and darkness and other exogenous causes. For example shift workers, or people who work the graveyard shift, greatly upset their natural circadian rhythm and are at a much higher risk for cardiovascular disease, obesity, elevated lipid levels.

In a new study presented at CHEST 2004, the 70th annual international scientific assembly of the American College of Chest Physicians (ACCP), lung function was found to have a natural circadian rhythm, where it is at its peak during the late afternoon hours (4-5PM) and at its lowest around midday.

One study tracked changes in the levels of melatonin, a hormone that helps regulate the body's sleeping and waking cycles which normally peak at night. Nighttime exercise (past 10PM) was associated with 1 to 2 hour delay of both melatonin and thyroid stimulating hormone rhythms whereas early morning exercise had least affect.

Researchers, from the Gladstone Institute of Cardiovascular Disease, the University of California, and Northwestern University, have found that exercise can also alter the expression of clock genes in the muscles themselves. Most scientists thought this process was mediated purely by inputs to the hypothalamus or the central controller which keeps all the peripheral clocks in synch. However the researchers discovered that exercise increased the expression of genes that are normally ‘switched off’ in the morning, and reduced the expression of genes that are normally ‘switched on’ in the morning. In effect, exercise caused a phase shift in the expression of the genes, similar to winding on (resetting) the muscle clock.

When it comes to aging, researchers from Manchester Metropolitan University (MMU), using sophisticated techniques including ultrasound and magnetic resonance measurements, have shown not only that the muscles of older people are made up of fewer cells, but also that these cells are arranged differently. Muscle cells, or fibers, in older people are shorter and thinner than those of younger persons and as we age, tendons stretch more making movements slower.

But these effects of muscle and tendon aging can be reversed. The researches found that just regular, moderate intensity exercise like incline treadmill walking and resistance training two times a week, restored muscle and tendon strength to that of a young adult.

Cortisol is a stress hormone secreted at mainly during pre-dawn hours. Growth Hormone levels are known to be highest during deep and exercise. Exercise of appropriate intensity is a potent stimulus for both GH and cortisol secretion. The Journal of clinical endocrinology and metabolism published a study in 2001 to determine cortisol and growth hormone responses to exercise at different times of day.

It is important to note that normal cortisol levels are necessary for normal skeletal and cardiac muscle function however excess cortisol diminishes protein synthesis and facilitates protein degradation.  Type II muscle fibers are effected the greatest and type I the least.  Excess cortisol also inhibits collagen synthesis leading to fragile blood vessels and thinning of the skin. Normal Cortisol levels are necessary for proper function of the nervous system but excess cortisol can cause insomnia, depression, disturbed memory function, and seizures. Excess cortisol increases appetite, induces adiposity (fat deposits) and stimulates lipogenesis (conversion of glucose to fatty acids).

The body has a natural biological clock to which cortisol levels are secreted and at the highest (pre-dawn hours). Researchers have suggested that self-induced stress such as exercise is best preformed during times when the body is receptive to and ready for such stress. Introducing an abnormal rise in cortisol levels via exogenous means such as exercise could increase the exposure to increased cortisol levels and it's deleterious effects. Since cortisol increase appetite, surpresses insulin and assists in the breakdown of amino acids it would appear that exercise during natural cortisol highs followed by post workout nutrition would be most beneficial. In addition, since cortisol induces the conversion of glucose to fat, it would also appear (if your goal is fat loss) that post workout nutrition should definitely include protein but less glucose or simple carbohydrates.

In that progressive study, 10 moderately trained young men about 24 years old were tested.  After a supervised night of sleep and a standard meal 12 h before exercise (empty stomach) subjects exercised at a constant velocity on a treadmill for 30 min on 3 separate occasions, starting at 7AM, 7PM, and 12 Midnight. Blood samples were obtained at 5-min intervals for 1 h before and 5 h after the start of exercise; subjects were not allowed to sleep during this period. Subjects were also studied on 3 control days under identical conditions without exercise. 

Time of day did had no effect on blood lactate or maximum oxygen values during exercise. Exercise stimulated a significant increase in serum GH concentrations for approximately 105-145 min compared to the control days when there was no exercise. There was no significant difference in the magnitude of this response by time of day.  In other words, GH levels can be maximized through exercise no matter what time of day.

The increase in serum GH concentrations with exercise was followed by a 55-90 min suppression of GH release after exercise at 7AM, 7PM, but not at 12 midnight.  However post-exercise cortisol levels were elevated the longest after exercise at 12 midnight for 130 min compared to 40 min at 7AM. However, both baseline (before exercise) and peak cortisol concentrations during exercise were significantly higher at 7AM than 7PM or 12 Midnight.

This research suggests that GH levels can be maximized through exercise at any time of the day. Early morning (7AM) and early evening (7PM) exercise suppressed GH levels for about an hour after exercise. Exercising late at night (12 Midnight) created the longest lasting rise in cortisol levels after exercise (approx. 2 hours) and caused a 1 to 2 hour delay of both melatonin and thyroid stimulating hormone rhythms. Exercising at 7AM had the highest pre-exercise cortisol levels and highest levels during exercise, but the lowest sustaining cortisol levels after exercise and insignificant effect on melatonin or THS.  This suggests that early morning exercise is positively inline with natural cortisol secretion, and that post workout nutrition is best utilized no more than 40 min after early morning exercise due to increase cortisol-induced appetite and amino acid uptake and utilization.  To reduce lipogenesis, your first morning post workout nutrition should be lower in simple carbohydrates and gluclose, moderate in complex carbohydrates and high in quality amino acids.

[Theo]

okay so i'd have to agree with ishina, within a little boundary.

before bed is a bad idea but any other time of day, go for it.

there's a saying like ' work while it is light, for the night comes when noone can work' i dunno where i's from i remember it fom when i was a kid, probably biblical. i think that it's a good rule though. exercise in the day sleep at night.

now royally fuckin up my circadian rhythm, it's 3 am i've finished work and i'm going to go to asda and get me some food

adios

[ishina]

okay so i'd have to agree with ishina, within a little boundary.

before bed is a bad idea but any other time of day, go for it.

Your remark has its reason and therefore I will specify my opinion further.

Whilst not being common sense, it is a rare thing not to be documented, that people do not feel like sleeping the hours after working out.
I strongly advise people to document their experiences with different training times in order to determine which is the best for them and continue doing so, just in case the biorhythm undergoes a grave change (which is unprobable, though). A large number of experience notes can be used to statistically analyze and thereby determine the best training hours for every individual.

I guess there will be no individuals out there which will come to the conclusion (after documenting their experiences for a some weeks) that working out just before going to bed works best for them.

Following the Warrior Diet was the reason I did not mention this type of information - I would always work out prior to your evening meal and never after it - I would go as far as to say that it is practially impossible to do so vigorously.

regards,
cg

[LF365]

One scientific periodical that I frequently read had an article about an early test in 1938 conducted by sleep researchers Nathaniel Kleitman and B. Richardson. Test subject stayed in Kentucky's Mammoth Cave for 32 days with no light or dark alterations and no concept of time of day. They found that their functioning was best when the active parts of the day corresponded to the natural daylight cycle outside of the cave.

It is interesting to note that even though the researches had no exposure to light, their bodies responded to the cycle of the earth (light and dark). The circadian cycle is one biological cycle, mainly endogenous. It is interesting this study points out there appears to be an an innate exogenous rhythm that humans naturally correspond to.

The study of biological rhythms as they relate to physical fitness and nutrition has largely been overlooked and/or dismissed. If our goal is health, fitness and longevity and to maximize every opportunity, this would definitely be one area to explore further. I find it interesting.  I'll try to post more later.

[LF365]

Chronobiology — The science of investigating and objectively quantifying phenomena and mechanisms of the biologic time structure, periodic (cyclic) phenomena in living organisms and their adaptation to solar and lunar related rhythms. It is a new and rapidly developing field of science.

I'm also going to coin the following phrase —

Chronobiomechanics — A branch chronobiology that focuses on the mechanical operations of the human body and how it relates to biological rhythms.

[RoaringMad Mac]

So, would it be safe to say that working out in the morning is optimal. Being that the stress of working out increases cortisol levels.

Cortisol is a stress hormone secreted at mainly during pre-dawn hours. Growth Hormone levels are known to be highest during deep and exercise. Exercise of appropriate intensity is a potent stimulus for both GH and cortisol secretion. The Journal of clinical endocrinology and metabolism published a study in 2001 to determine cortisol and growth hormone responses to exercise at different times of day.

My question would be then. would it be optimal to workout in the morning. such things like Resistance training, and cardio.

But then after the workout would you refuel with moderate protein and simple carbs just a small amount being we are talking about undereating durning the day. Then have your overeating meal at night.

[Theo]

right i normally have some sort of logic to back up my words but this is more of a feeling.

now it's getting to winter i'm taking to training earlier and earlier to get the last of the daylight but it doesn't feel right to eat after.

 i like to feel the need to eat before my meal, which becomes harder to do but i think this is an indication of increased work capacity.

it's so much more satisfying then, it feels more natural. i'm going to start training more because i'd like to become a walking anatomy chart but i'm not gonna eat during the day, i think the cortisol will do me good, i think the hunger will do me good and i think the fasting will do me good.

if you train and take multiple recovery meals you might even end up on the old 6 meals a day routine, which obviously defeats the objective.

i think it is also worth noting that these catabolic hormones don't last forever and exercise throughout the day is very benefical for mental work capacity and stress levels.

[LF365]

Keep in mind that recovery meals on the WD are not the type of meal eaten in the 6 day a meal plan.   If you work out in the morning, a few recovery shakes with whole fruit and fast digesting whey each hour after is good. These take almost no digestion and would still be considered under-eating. There is still almost 10 hours of fasting time before dinner if one chooses to totally fast the rest of the day.

The typical recovery meals on the 6 meals a day plan includes heavy foods like chicken and tuna and eggs and potatoes and oatmeal and foods like that. You don't need heavy foods in order to recover.  In fact, I don't think I could eat that heavy in the morning any more. I actually crave fruit in the morning.

[RoaringMad Mac]

That is what I am starting to do also is crave more fruit in the morning. I have my one banana and that is it.

And I have no problem either with being hungry. Weird.