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20 Feb

Dear Mark: Should I Consume Caffeine Before My Workout?

In today’s edition of Dear Mark, I cover a topic near and dear to many of your hearts: caffeine. But I don’t just cover caffeine; I explore whether caffeine truly does act as a diuretic, especially during exercise, and whether or not caffeine can actually be helpful to athletic performance. Should we all be downing mugs of joe or cups of tea before we hit the gym or head outdoors?

Let’s find out.

Dear Mark,

I’ve been told that drinking coffee prior to, or during workouts is a big no-no, because it’s a diuretic and will lead to dehydration, which is no good for performance (or health). But I love an iced coffee right before my workouts. I feel like it helps. It could just be placebo, but if it’s not hurting, I’m okay, right?

I wonder if you could give me the lowdown on what the literature says. Thanks!


First, let’s tackle the dehydration question. It has undoubtedly become “common knowledge” that coffee is a potent, perhaps the most potent, diuretic, that drinking it is like drinking negative water, and that if you’re stuck on a desert island you’d be better off drinking your own saliva than that steaming cup of joe from the Starbucks that inexplicably decided to set up shop on a desert island. Yeah, there are a lot of scary stories about coffee, but does it hold up to scrutiny?

No. A quick search on PubMed turns up a couple German-only studies with vociferously and unambiguously worded titles but no abstracts (“Coffee does not cause dehydration!” and “Coffee does not dehydrate. New studies of Germany’s favorite addiction: coffee.”), as well as some English ones with abstracts:

  • One from the University of Connecticut measured fluid, electrolyte, and renal indices of hydration over eleven days of caffeine consumption in human subjects. Doses of up to 6 mg caffeine per kilogram of body weight had no effect on body mass, urine osmolality (urine concentration), urine specific gravity (concentration of excreted materials in urine), urine color, urine volume, sodium excretion, potassium secretion, creatinine content, blood urea nitrogen (forms when protein breaks down), and serum levels of sodium and potassium, causing the researchers to conclude that caffeine does not cause dehydration.
  • Another compared hydration markers in patients who consumed either caffeinated beverages (coffee and cola), non-caffeinated beverages (coffee and other sodas), and/or water. The effect on hydration status was essentially uniform across all beverage categories, regardless of caffeine content.
  • And finally, a review from the American College of Sports Medicine found that not only does caffeine not reduce hydration nor induce electrolyte imbalances, it has no effect on heat tolerance during exercise.

I think that settles that. Caffeine does not dehydrate you or cause you to overheat. It’s “safe.” It’s not bad for the active athlete.

But is it actually good? Does it do anything except fail to dehydrate you?

Oh, yeah. Let’s dig into the literature to find out what it can do for your athletic performance.

Endurance Exercise

Most of exercise/caffeine literature centers on endurance training and performance. I remember back when I was running, the most oft-cited benefit to caffeine before a race or training was that it would increase the oxidation of fat, thus sparing muscle glycogen. That sounds nice and tidy, and it would be awesome if it were true, but the most recent evidence suggests that caffeine has little, if any, effect on fat or glycogen metabolism during endurance exercise. So what are we to make of the older evidence that does show a difference in fat oxidation after caffeine ingestion? Or the 1992 study that found caffeine reduced the tendency of muscle to burn glycogen early on during extended bouts of exercise, thus “sparing” it for later on?

It may be that caffeine simply makes exercise more tolerable, makes muscles work harder and better, and allows those exercising to do so harder. One study found that while pre-workout caffeine did not spare glycogen, it did boost the endorphin response to exercise. If endorphins are high, exercise is more tolerable, even enjoyable. If caffeine can increase the runner’s high, it’s also going to make exercise more effective and more self-perpetuating.

Whatever the case may be, the literature is pretty clear that caffeine improves endurance performance, perhaps by enhancing fuel partitioning or making exercise more tolerable and enjoyable.

Anaerobic Exercise

The extent of research into the effects of caffeine on anaerobic performance – think sprints, weight lifting, and interval training – is limited, but useful literature exists. One review, from 2009, noted that while caffeine appears beneficial to speed endurance training (in the realm of 60 to 180 seconds) and high intensity interval training (HIIT), it has limited use in power sports. It may help lower body muscle endurance, but it appears to have a minimal effect on the upper body. The authors propose a number of mechanisms for caffeine’s action, including enhanced calcium transport and the old fat utilization/glycogen sparing thing, but the most promising idea is that caffeine simply stimulates the central nervous system enough to blunt adenosine receptors, increase pain tolerance, and dampen perceived exertion.

What about resistance training? In one study, caffeine ingestion boosted trained women’s 1RM in the bench press (PDF). In another, caffeine seemed to have no effect. A review from 2010 determined that short-term, acute ingestion of caffeine is beneficial in team-based and power sports, but mostly in individuals who did not routinely ingest caffeine. Six of eleven resistance training studies reviewed in the study showed benefits to caffeine ingestion, so the evidence remains fairly equivocal.

Thus, when you drink coffee before lifting heavy things or sprinting, your performance will not suffer – and it may even improve.

It may even be a simpler, less exciting explanation than anything overtly physiological: that the “benefits” of caffeine to physical performance may actually be a cessation of the negative effects of caffeine withdrawal. As Sweat Science points out in a recent post, before double-blind trials on the effect of caffeine on performance, participants must abstain from caffeine for a day or two. If they’re habitual caffeine fiends (as many people are), by the time they begin the study they’re already suffering withdrawals. Studies on cognitive performance and caffeine have found that when you account for the withdrawal effect, caffeine has little to no benefit to performance. Researchers have yet to examine the withdrawal effect in studies on athletic performance, but it appears a likely candidate for at least some of the reported benefit to caffeine consumption.

It’s also important not to lose sight of the fact that most of us are drinking coffee, not popping pure caffeine pills. Coffee contains tons of polyphenols, bioactive compounds that could have beneficial (or negative) effects on exercise performance. Most of the studies are looking at caffeine, so they have to isolate it. But if you’re drinking coffee, shouldn’t you look for studies that examine coffee? There’s a recent one that found ingesting coffee polyphenols increased fat oxidation (PDF). Of course, the caffeine, polyphenol, and other bioactive compound contents of coffee are not stable. Coffee is a food made up of hundreds of factors. It’s not just a source of caffeine. Based on soil conditions, climate, elevation, roast, and variety of bean, two cups of coffee can display remarkably different characteristics, and it’s likely that the effects of each on exercise performance will also differ.

Bottom line, though: if coffee makes you perform better, keep drinking it before, during, or after you workout. At least we can say for sure that it’s not dehydrating you.

How does coffee affect  your workouts? Better? Worse? No effect? Let me know in the comments!

You want comments? We got comments:

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  1. I take advantage of the perks of caffeine before/during races (Olympic/Half IM Triathlons). I definitely believe that caffeine helps tremendously during endurance races. I usually take gels with a caffeine supplement throughout the race. I feels like it gives me a boost of speed and my pain threshold seems to reduce.

    For everyday training, however, I tend to avoid drinking coffee before intense workouts (TTs on the bike/running intervals). The elevated heart rate becomes more uncomfortable and too stressful due to the caffeine during interval sessions. I can handle the stress on race day but not for everyday training. I also feel a lot better post workout without the caffeine in my system.

    Brandon wrote on February 20th, 2012
  2. Coffee and caffeine are NOT synonymous!

    I’ve found that decaf coffee has the same “moving” effect on my gut as caffeinated and perks me up about the same too. Add to that, I could (but no longer do!) drink a 20oz non-diet Mountain Dew right before bed and have no problems getting to or staying asleep. But coffee, even decaf in larger quantities, much after lunch, and I’ll be up for hours.

    These days my coffee is at most either two cups during the morning at work (one teaspoon of raw sugar and a dollop of whole milk) or else one homemade latte with a smidge of honey and vanilla (I’ve recently found where I can get raw Jersey milk and goat milk). I tried it with almond milk, and maybe it was that particular milk, but I thought it was singularly nasty.

    I haven’t tried drinking coffee or caffeine specifically for workouts, but anything that can help with motivation can’t hurt. As far as hydration, I don’t find coffee makes me pee anymore than an equivalent amount of plain water.

    Nancy wrote on February 20th, 2012
  3. I find that if I drink a cup or two of delicious coffee AND a couple full glasses of water, wait an hour before running and let some of that water make it back out, then my workout doesn’t end up with dry mouth or having to pee. I think you just have to find what amount of water and coffee works for you, and you CAN’T have just drank two cups in a half hour and then go. You have to pee first at least once. Coffee makes my workouts five times easier.

    AdieBeatty wrote on February 20th, 2012
  4. I don’t drink coffee very often because it actually makes me sleepy, with the exception of a frappe like 2 hours before bedtime. Then I’m super hyper. I’m sure it’s got something to do with the high amounts of sugar. Plus, I don’t really like the smell of it, especially the first thing in the morning.

    Alessandra wrote on February 20th, 2012
  5. Hmm…that’s strange. I absolutely love the taste of coffee and drink a cup of black coffee on my rest days, but whenever I consume any sort of caffeine on a workout day I perform horribly.

    Before I went primal, any form of caffeine – soda, energy drinks, coffee – would make me less coordinated when I played sports. That being said, the sports I did (badminton and martial arts) all required lots of precise movements, so maybe that was why caffeine had a negative effect. Too much arousal isn’t good for mentally difficult/complex activities, or at least that’s what my old psychology textbook told me.

    I’m not absolutely sure if my performance worsens while lifting heavy weights since I’ve recently been avoiding caffeine on workout days, but I have a feeling my power cleans won’t be as good because of the complexity of the exercise. I guess I’ll try drinking coffee on a weightlifting day a few times just to see what happens.

    Binh Ho wrote on February 20th, 2012
  6. I love a cup of strong hot coffee in the morning, it does wonders to perk me up.

    I gotta be at work at 7:30am everyday. ‘Gimme my coffee or I will hurt you.’

    Caleigh wrote on February 20th, 2012
  7. Read the latest online edition of life extension magazine…they have a fantastic article of the great benefits of multiple cups of coffee a day….I myself am hardcore…I will put 2 tsps of instant coffee directly in my mouth and chase it with water…too lazy to heat the water and clean the cup….works for me…lol

    Robert wrote on February 20th, 2012
  8. I’m pretty sure that caffeine increases the risk of arrhythmias during long periods of exercising- long runs for example (10+ miles).

    Hanieh Razzaghi wrote on February 20th, 2012
    • Yeppir! PVCs like crazy. No thank you, Mr. Coffee.

      Extra potassium for me and I feel great. Personally, I don’t care for the “my chest is about to explode” during my workouts.

      Algboy wrote on February 20th, 2012
  9. Coffee makes me feel calm in the mornings and like wonder woman during workouts. I would never stop drinking it- even if mark said to.

    Andi wrote on February 20th, 2012
  10. my pre-workout prep involves a tablespoon of almond butter and a small piece of bittersweet chocolate. the caffeine from the chocolate is just enough of a spark to keep things rolling.

    rik wrote on February 20th, 2012
  11. Not a big coffee fan. One cup, black, warm — not scalding — in the morning. Done for the day.

    In the 80s I used to split a pot in the morning and also did several glasses of diet Pepsi {cringe} during the day. I started having PVCs that scared the carp out of me. Cut WAY back on the caffeine.

    I also didn’t like the way my insides started percolating after more than a cup or two. Not a good thing during a hard training run.

    I guess I wouldn’t do well in Seattle. Coffee during the day? YUUUUUCHHH!!!

    Algboy wrote on February 20th, 2012
  12. I still remember my best day of sparring class in my Taekwondo training days was when I had a double mocha right before class. My master instructor even commented on how much ass I kicked that day 😉

    Stephanie wrote on February 20th, 2012
  13. Some interesting comments on the Demon Coffee.
    I have been an exercise enthusiast for many years now, it’s been a big part of my life. I did it because it is a great stress antidote, and I enjoyed it.
    Managed a couple of marathons, and Kayak Ultra marathons, weights, Mountain Biking, all good fun.
    Always ate and drank whatever I wanted, fried food, steaks, lots of fruit and vegies, plenty of whisky, wine, and COFFEE!
    Looking back, as I have just turned 70, I note that almost everything I’ve ever eaten, drank, or done- someone has been either for or against, at different times.
    My advise? If you enjoy it, coffee drinking or not, or any other dietary fad….do it. Probably won’t make much difference longterm anyway.

    JB wrote on February 20th, 2012
  14. anything wrong with taking a caffeine pill 200-400mg prior to working out? I don’t like the taste of coffee.

    Eric wrote on February 20th, 2012
  15. coffee tastes terrible I have no problem with caffeine but what else is in coffee? If it is a super health beverage why does it make peoples breath smell like ass? and sweat smell worse?

    Its a product that you are meant to buy and become addicted to, and its an extremely thirsty crop , not very enviro friendly.

    Bob wrote on February 20th, 2012
    • Well since beauty is in the eye of the beholder, taste (good or bad) must be on the buds of the imbiber =)

      As for the smelly breath: I think most of us agree that garlic is a very healthy food (the russian penicillin, right?). I assure you that smell and health in this sense don’t have anything in common.

      What else is in coffee? Here’s a few:

      As a home roaster I can tell you that the amounts of the different compounds vary greatly depending on the origin/soil of the bean (well actually it’s a seed),your roast profile since they develop/diminish at different temperatures.
      Bonus fact: Coffees chemical composition is around 2,5 times more complex than red wine. -always a great kicker when battling hobbies with a wine connessieur 😉

      If you worry about the environment (as we all should) go for organic fair trade coffee -or even better direct trade. There are hundreds of great coffee farms to choose from in this category.

      Andreas wrote on February 21st, 2012
      • Almost forgot:

        Most studies done on coffee and health point toward coffee consumed in moderation (generally 6 or less cups a day) have a beneficial effect on preventing Alzheimers, Parkinson disease (one study up to 75% reduced risk!) and diabetes.
        In addition, skin cancer risk may be reduced by caffeine and/or caffeine sodium benzoate (Study in progress).
        Lastly let’s not forget the antioxidants. Green tea may be the winner here, but coffee is on board as well.

        Andreas wrote on February 21st, 2012
  16. I’m not a coffee drinker, but I do have green tea. I notice that even that small hit of caffeine definitely improves my workouts! On the days I don’t have it pre-workout I notice I may be slightly more sluggish. And there is health benefits to green tea too so I’m just gonna keep on drinking it

    Sarah @ The Healthy Diva wrote on February 20th, 2012
  17. I prefer green tea. Especially the Japanese Sancha, or the Chinese Bancha.

    Combined with some dark choclate, it feels like heaven.

    Steven wrote on February 20th, 2012
  18. What do you all think about caffeine tablets ? I bought some on spec because I can’t stand the taste of coffee (like the smell though). They’re 100mg per tab, I’ve been having one before the gym. Not sure if it is a placebo but I seem to be able to do more.

    davecoconutty wrote on February 21st, 2012
  19. Are you kidding me? Coffee doesn’t dehydrate? ya ok.. Everytime I drink it I urinate way more and feel dehydrated afterwords. I’m gonna have to disagree with pubmed. I’m sure I can find several sources on pubmed that supports that coffee dehydrates.

    lulz wrote on February 21st, 2012
  20. Mark,
    Thanks for your great article. No surprise caffeine boosts mood and performance. But I wonder:
    1. How does caffeine affect long term health? Particularly cardiac health.
    2. How does caffeine affect our ability to maintain lean muscle mass and bone density, especially as we age?
    I’d love to hear your thoughts on this. Thanks again.

    Kaden wrote on February 21st, 2012
  21. Sometimes, when I drink a lot of coffee, my pee smells like coffee. That is when I know I have gone too far.

    Nick wrote on February 21st, 2012
  22. Now my only concern is the side effects that pre work out drinks with nitric oxide have in comparison to coffee. If grok had NO ExPlode, white flood, jack3d, etc would he take it and then go maul a wildebeest?

    Tucker wrote on February 21st, 2012
  23. I love coffee- it truly helps with my workouts and gives me a fresh start to my morning.
    I will caveat however, that I gave it up several weeks again because it was severely aggravating my eczema, and interfering with my sleep. I will admit however, that my dosage was quite high. Moderating my coffee however, may yield different results. In the meantime, I’ve gone “cold turkey” so to speak, to eliminate my habitual need of 5-6 cups per day!

    Saleen wrote on February 21st, 2012
  24. I have a question that I haven’t seen addressed here yet : MY KIDS LOVE COFFEE! My 2 preteens (very athletic & eat mostly primal) both love coffee in the morning. I have always let them have a cup as long as they are eating healthy otherwise. I hear the old “It’ll stunt their growth” BS from people, but I don’t believe that caffeine or coffee can have a highly negative effect on really healthy athletic kids. Especially given what most kids eat these days, my kids having this one “questionable” indulgence doesn’t seem bad to me. They do not eat any processed food or drink soda, and eat primal at home & do pretty good selecting good foods when at a resatuant, school, or a friends house too. I am interested to see what you all think about this.

    Lora wrote on February 21st, 2012
  25. Caffeine really helps give me more energy during my workouts. Howevr, every time I drink or eat something that has caffeine in it, I cannot eat for several hours after because it gives me acid reflux. Why does caffeine cause acid reflux in some people, but not in other people?

    Jason wrote on February 21st, 2012
  26. I used to drink a lot of coffee, especially before P90X or Crossfit style workouts (nearly 2 years). Things went downhill; I found out I had low testosterone. Factors included little sleep, overtraining, and insufficient nutrition. Looking for a natural fix, eating primal came first, then, more sleep. I started training less, but my cortisol still felt like it was through the roof(1 year). After quitting coffee and cutting training way down, I FINALLY noticed improvement in a couple months time.

    Jesse wrote on February 22nd, 2012
  27. Mark,

    This is a good post. Interesting pint about the instability of coffee depending on soil, place of origin, etc. I am type 1 diabetic, so I generally have to keep a very close beat on my endocrine system. I find that when I drink most mass produced, commercial coffee (especially Folgers), my Insulin sensitivity plummets and I require a lot more. Obviously, this is undesirable. I figure there must be some compound present in the coffee that I responsible. I switched to organic coffee, and everything returned to normal.

    Eli wrote on February 22nd, 2012
  28. I definitely consume my fair share of caffeine as I drink a cup of coffee in the (very early) morning then try to get 2 cups of tea later on the day. But before exercise I try to avoid it. Tends to make me jittery.

    “Studies on cognitive performance and caffeine have found that when you account for the withdrawal effect, caffeine has little to no benefit to performance.” That’s an interesting point and would love to see more as it relates to athletic performance.

    Chad Anderson wrote on February 23rd, 2012
  29. Still mention of thermogenesis?

    “Caffeine increased energy expenditure dose dependently and the thermogenic response was positively correlated with the response in plasma caffeine…”

    Dave Sill wrote on February 23rd, 2012
  30. Someone once suggested that my unstoppable coffee habit is actually self-medication for my blood pressure. Last time I had it taken, the corpsman asked me if I have ever been diagnosed with low blood pressure: I had no caffeine and had fasted for a blood sugar test, and my blood pressure was a dead-on 90/60.

    Maybe that explains why it takes A LOT to make me jittery. One cup in the morning starts my day off right, and one cup early in the afternoon just makes me cheerful. Literally just plain happy.

    No sleep problems for me, nor any real workout benefits.

    Deanna wrote on February 25th, 2012
    • If I had read your comment years ago, I would have totally related. I tend toward low blood pressure myself. I’m starting to wonder, though, about the relationship between caffeine and blood pressure.

      Until my first pregnancy in my mid 20’s, a reading of 90/60 would not be at all unusual. I finally had my first “normal” blood pressure readings – around 110/70 – during the second trimester.

      Now, at age 59, I still have good blood pressure – 115/75 (pre-primal) – despite being over weight and having other markers for metabolic syndrome. I also tend to have a low resting heart rate, even after a cup of coffee.

      That said, I have also developed sensitivity to caffeine. It disrupts my sleep, even one cup early in the AM. One time I drank several cups throughout the day just to see what would happen. I got hyper and edgy – plus the expected insomnia. Not much of an effect on blood pressure, though.

      Now, after several weeks eating 100% primal and only drinking decaf, my blood pressure is looking more like it did in my 20’s. Average 105/65. And, I am still sensitive to caffeine in terms of insomnia.

      rarebird wrote on February 25th, 2012
  31. Relatedly, I had always heard that coffee and tea leach vitamins & nutrients out of your system, so you shouldn’t drink them near the time you eat (or take supplements).

    Has anyone heard/read anything to support or contradict this?

    Mia wrote on February 28th, 2012

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