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Caffeine Before Exercise Could be Risky for Some

Fitness News Flash

-- By Jen Mueller & Nicole Nichols, Fitness Trainers
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A 2006 study suggests that drinking coffee just before a workout might not be the best idea. The Journal of the American College of Cardiology reports that the amount of caffeine in just two cups of coffee limits the body's ability to increase blood flow to the heart during exercise. This is problematic since blood flow to the heart must increase during exercise in order to meet the body's higher demand for oxygen and nutrients.

Study participants were regular coffee drinkers. After abstaining from coffee for 36 hours, their blood flow was measured before and after exercise. Then they ingested caffeine tablets (equal to 2 cups of coffee) and repeated the same test to measure blood floor prior to and after exercise. The caffeine did not affect heart blood flow when the participants were at rest. However, measurements taken immediately after exercise showed a 22% reduction in heart blood flow after they'd taken the caffeine tablets, compared to their previous results. Participants who exercised in a chamber simulating high altitude (15,000 feet) experienced an even greater reduction in blood flow—39% lower.

While caffeine is a stimulant, and previous studies suggest that it may enhance athletic performance, this study suggests the opposite. Caffeine does stimulate the brain, increasing awareness and concentration. Athletes who ingest caffeine before performing may feel that they are enhancing performance, but these researchers suggest that the athletes are simply more alert, awake and focused.

Action Sparked: These study results are especially important for exercisers in high altitudes and cardiac patients who already experience diminished blood flow. When blood flow to the heart is lower than the demands of the body, you won't be able to deliver enough oxygen to the muscles, brain and to the heart itself. This can result in lightheadedness, dizziness or fainting, and these effects can be much worse if a person already has high blood pressure or another heart condition. However, all exercisers should consider abstaining from coffee—and caffeine in general, whether from soda, chocolate, or pills—before working out to decrease their risk.

Instead of hitting the coffee shop on your way to the gym, try filling up your water bottle before you head out the door. Check out the article Drinking Water During Workouts to learn why water is so important before, during and after exercise.
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About The Author

Jen Mueller Jen Mueller
Jen received her master's degree in health promotion and education from the University of Cincinnati. A mom and avid marathon runner, she is a certified personal trainer, certified health coach and advanced health & fitness specialist. See all of Jen's articles.

Member Comments

  • There's merit to this idea, but I have low blood pressure, and I think it's partly due to coffee that I don't have to medicate it - I tried meds for low blood pressure once, it wasn't a good trip (and my only trip, fortunately, never done any recreational drugs).

    I don't drink soda, only tea and coffee, I'm much fitter than I was, and I don't actually drink it right before any fairly high intensity activity. Most of my exercise comes from walking and yoga, so I'll stick to my coffee. - 2/13/2013 10:46:55 PM
  • Ugh. Another study that contradicts other studies. I also saw a different study the other day that said that there's no link between caffeine and high blood pressure. Whatever. - 2/13/2013 8:03:21 AM
  • This is an article that needs dating--the study needs to be cited/dated, and the article itself, too, should be. As a pp has pointed out, it seems the study is several years old.

    Not only that, but caffeine tablets aren't the same as drinking coffee--the mechanism for internal absorption, rate of absorption, and accompanying ingredients are all different. As a coffee drinker who has, on occasion, used more direct caffeine supplementation, I know there is a significant difference, not accounted for here. - 12/6/2012 8:49:34 PM
  • I always drink my coffee AFTER my morning runs. This has nothing to do with my ability to breathe or bloodflow, however...The one time I did drink a cup of coffee before running (at least an hour before my run), my stomach was NOT happy. (I had also eaten breakfast with it.) So from now on, I run first, and coffee is my reward!!!! - 12/6/2012 6:28:47 PM
  • I checked the link to the other study, and it does appear to be the same one. Thing is, that study was from January of 2006. It may not seem like that long ago, but a lot changes in 6 years when it comes to nutrition and fitness research. I would like to see more recent studies, with more controlled variables, a wider range of subjects (maybe non-caffeine drinkers as well), and more subjects. While this info is intriguing, there should be follow-up studies done, imo. - 12/6/2012 2:57:33 PM
  • I have heart arrhythmia when I drink caffeine. This article totally makes sense to me. If the caffeine is decreasing blood flow, the heart beats would get erratic. It's a hard sell in this day and age, though. Seems everyone is addicted to caffeine and PROUD of it. - 12/6/2012 2:36:59 PM
  • Whoa, this is scary--I've been holding on to a bag of guarana seed powder to add to my pre-workout smoothies once I hit a fat-burning plateau. Glad I came across this first. o_O - 12/6/2012 2:07:38 PM
  • This makes total sense. I'm a 35-year old who regularly drank Coca-Cola, coffee, etc. Recent heart palpitations and tests that revealed high blood pressure among other things caused me to rethink my caffeine addiction. I still drink black tea on occasion, but gave up the other stuff. I do notice a difference in blood flow...I have difficulty in the uptake of blood in one of my arteries. This has been a wakeup call to treat my body better, and I love not having the tension and headaches all the time. I still eat chocolate on occasion, usually dark chocolate, but so far black tea and chocolate seem to be OK. Thanks for the informative article. - 12/6/2012 12:40:30 PM
  • This is a very good article. My husband who had a quadruple bypass last year walks on a daily basis - lately he consumes two (16) oz cups of coffee prior to his walks. Although one of his bypassed vein failed in the right bottom of the heart , his heart muscle is strong. My point is that he has noticed the difference if he consumes coffee prior to a workout, he tends to be out of breathe. On the days that we juice prior to his walks his ability is swifter. Hmmmm - 12/6/2012 10:00:23 AM
  • Just waiting for the next study that says people who drink coffee after live longer! It seems things go back and forth.

    I drink my coffee. I will continue to drink my coffee. One of my last races I had a few sips of coffee with my breakfast. The 5k race was at 8 am. I would have had a nasty headache if I just abstained but I didn't want to be running for the bathroom either so just a few sips did me right.

    So I read this and thought "How interesting." and am moving on with my day. - 12/6/2012 8:34:55 AM
  • Totally picky comment - chocolate does NOT contain caffeine - it contains theobromine which is one molecule different from chocolate and doesn't necessarily create/produce the same effects. - 12/6/2012 8:32:19 AM
  • I have to comment again, after reading the comments...
    You people have no idea how happy you have made my morning. I see an article based on a study, and everyone is reading the article and thinking critically of it. They aren't just blindly following advice; they are wanting to read the study, see the methods utilized in the study, who the participants were, people are wanting to know how different variables could have changed the outcome of the study.
    I love you people. I LOVE YOU PEOPLE! - 12/6/2012 8:18:19 AM
  • VERY interesting! Did I miss the citation for the study, though? I don't see it...
    I enjoy drinking coffee on weekend mornings, about 30 minutes before my workout. I don't do it to increase performance; I just love my coffee!
    I have experimented with energy gels (which usually contain quite a bit of caffeine), but only when I am planning on running in excess of an hour.
    This is very interesting. I would love to see this study replicated, so that the results can be verified. If so, then maybe I will have to change my weekend coffee habits. - 12/6/2012 8:14:44 AM
  • Interesting results. I can't wait for more detailed research, like everyone else is suggesting (with more realistic caffeine intake and coffee instead of tablets). I did however drink a lot of coffee yesterday and my workout felt pretty bad. So I guess considering to quit the caffeine on workout days doesn't seem such a bad idea! - 12/6/2012 4:38:08 AM
  • Abstaining from caffeine for 36 hours - more than a DAY- and then drinking not one but TWO cups of coffee doesn't simulate my pre-workout caffeine consumption at all! Sorry, but I'll wait for more substantial research with more controlled conditions before condemning myself to miserable caffeine-free workouts. - 12/6/2012 2:20:53 AM
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