Caffeine metabolism and half life

I keep debating whether i should use an energy drink with 200mg before my 5pm workout as it would likely still affect my sleep.

Will a hard workout speed up my metabolism and in return reduce the half life of caffeine significally?

There are a lot of papers on the effects of caffeine on exercise, but not many the other way round… Normally it takes only takes about 45 minutes for most of the caffeine to be absorbed. But the half-life is typically 4 to 6 hours (on average)

One paper (European Journal of Clinical Pharmacology, March 1991, Volume 40, pp 279-282 ) using 12 subjects, half of whom were heavy coffee drinkers and half, light coffee drinkers, measuring serum caffeine levels. For both groups, exercise appeared to reduce the half-life (from an average of 3.99 hours to 2.29 hours.


My $0.02: I recently read “Why we sleep,” actually based on the recommendation of the TR podcast crew. It’s an eye-opening read (so to speak) and I recommend it.

The scholarship cited in that book makes it pretty clear how key sleep of good quality and duration is for pretty much everything, including athletic performance, recovery, making good dietary choices and more. I would suggest that the possibility that caffeine intake could compromise sleep quality would outweigh any training benefit from taking it before a workout.


I’d wager you will get the needed affect on a much lower dose (especially if you are not a heavy caffeine user). Even 100mg tablets will affect sleep though. I tend to use them when I just need to perk up a bit as opposed to thinking I need them for the RPE lowering (of which it certainly does).

My advice start with the lowest dose, so quarter of a tablet, how did you go? Did you sleep? What was the quality like (if you can tell) If that’s enough then you’re golden, if not then just experiment until you find a level that works.

Save the big doses for race day.

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I say no but your mileage may vary. The time it takes caffeine to clear your system varies quite a bit depending on genetics. For me (and I suspect most), is it a good idea to take 200mg of caffeine 5 hours before bedtime? OMG, NO! Ha! On the other hand I’ve known ppl who could drink a cup of coffee at 9:30p and be sound asleep by 10p…but I would say that type of person is the exception, no the rule.

From a bigger picture perspective…I don’t think it’s a good idea to go Tom Simpson on your workouts on a regular basis. Special occasions for big workouts, ok. On a weekly basis? I don’t know. Don’t put yourself in the position where you HAVE to take down 200mg of caffeine before the start just to feel normal.

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I always try to have my last coffee ± 7 hours before bed. This used to be 5 hours (which was 30 min before my workout) and the 2 hour shift actually made quite a difference on my sleep. You can still benefit from the intake even if it’s, lets say, 2 hours before your workout.

Research I’ve read indicates a dose of about 3mg of caffeine per kg of body weight is needed to get a measurable effect on exercise performance.

So at 70kg, that’s 210mg, so right about what the OP was suggesting.

I’d argue however that using caffeine to get through a workout is not something you need to do very often. Maybe for only the hardest workouts with highest IFs.

Caffeine for a race totally makes sense.

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I love coffee. I usually drink somewhere between 5 and 7 large cups per day. Additionally to that I have two large cups mixed with almond milk before/during my workouts. Even late in the evening.

I really like the taste and have the impression that it makes workouts a bit easier. That being said it doesn’t seem to affect my sleeping at all. Guess it’s because I am used to it. So basically all benefits.
Though I wouldn’t consume energy drinks on a regular basis. It’s basically poison if you ask me. Being the hypocrite that I am, I do have them every now and then. Like once a month or so. :slight_smile:

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I also take a pre-workout before exercise sometimes, but ONLY in the morning. I may take a little Amino Energy that late in the day but that is 50-100mg, but I am usually pretty strict about no caffeine past 1-2 PM with a usual 9-10pm bedtime.

You may be able to fall asleep ok with that dose, but internally your sleep quality is going to suffer. Same goes for Melatonin, sleep aids, etc. They may help you fall asleep, but they will not keep you asleep or help you achieve that DEEP REM sleep that your body needs for true recovery.

I would try and ditch the caffeine that late in the day and save those workouts for your easy/Zone 1/2 workouts.

My .02

I seem to remember @Nate mentioning a supplement that helps mitigate caffeine. Can anyone recall that episode? It seemed to be in the context that Nate was going to a race, loaded up on caffeine, and then DNS’d for some reason and took something to reduce the caffeine effect. I might be making this up, who knows.

I got the audible version but stopped listening part way through, largely because the book made me realize that I’ve lost the better years of my life forcing myself not to sleep (work, school, partying, etc). Now that I’m middle-aged and have trouble sleeping, it looks like I’m doomed.

Any idea how much of an impact this is? I’ve been curious about this ever since seeing it show up on my 23&me report as more likely to drink a lot of caffeine (and if I’m understanding the report correctly, metabolize it).

My own experience w/ caffeine supplementation is if I take it (240 mg) and then don’t train for whatever reason I feel lousy (manic / anxious, mostly). But post / during workout I feel fine.

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I don’t recall the episode.

However, some caffeine supplements have L-Theanine to reduce the jitters. I think mostly for folks who aren’t engaging in athletic activity, e.g. students. Was he talking about that stuff?

I do seem to recall it being an amino acid so this very likely might be it! I’ll search the archives tonight and see if I can confirm. Thanks!

I’ll toss in my n=1 which is that I learned a long time ago to not drink coffee after my noon-1pm lunch. I do my workouts after work, somewhere between 4-7pm. Believe Nate suggested 1pm cutoff on a recent podcast. On the other hand my wife works in an office that makes espresso everyday at 3pm and she doesn’t have a problem.

On the other hand my wife works in an office that makes espresso everyday at 3pm and she doesn’t have a problem.

My wife has that gene that nullifies any effect caffeine has on her body, she can drink an espresso right before bed and fall asleep before her head hits the pillow.

On the other hand, I’m min my 3rd week of not drinking any coffee after 7AM. I used to drink a 3-shot mocha around 9/10AM, but decided to call it quits and just drink a 4oz regular coffee to help with the morning constitutional.

So far, I’ve been able to fall asleep faster at night though I’m still struggling with waking up in the early morning (3AM-5AM) and having trouble falling back asleep.

EDIT: I’ve also noticed that I can go without naps during the day easier, now that I don’t have a ton of coffee in the morning.

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Nate was discussing Theanine, a compound in black tea which is supposed to counter act the effects of caffeine. I bought a Whoop with the sole purpose of doing a 12 week experiment tracking sleep with coffee in the morning and caffeine free. Just embarked on the coffee part of the study. I’ll report my N=1 when I’m finished. As far as “Why We Sleep”, he is pretty insistent on a minimum of 8 hrs of sleep. Other studies have shown overall mortality is less for about 7 hrs of sleep and climbs with sleep intervals longer and shorter.

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half-life can vary by as much as 100%. So if you took 200mg of caffeine at time 0 & waited until less than 25mg was still circulating in the blood it might take 10 hours or it might take 20 hours…depending on the individual. Half-life can vary from 2.5hrs to 5hrs.

Interesting, thank you. The shorter half life seems to fit with my past experience (and somewhat vague 23&me report).

I think serum half life is only part of the picture. Caffeine is a phosphodiesterase inhibitor, and accentuates signaling pathways. In my case, gene testing shows a fast metabolizer, but I’m very sensitive to caffeine. I never used it in the form of tea or coffee until my mid 50’s. Went all the way through college, medical school and more than 10 years of post graduate training without caffeine.

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