Each day I drink lots of coffee and energy drinks (redbull 355ml cans). I go to gym 3 times a week (on evenings). Are there any effects on my workouts? I stopped drinking any caffeine (at least from coffee and energy drinks) for 3 weeks and didn't feel any changes. Not during daytime nor before, during or after my workouts. My friends often tell me that my heart will explode from such huge amounts of caffeine (I read about caffeine OD and felt "caffeine induced disorders" symptoms).

My question is what's the effect of caffeine on heart/body when person is working out?

  • 4
    My husband had a big scare last year with his heart doing funny things when consuming too much caffeine, combined with stress. After many tests the cardiologist found nothing wrong, but avoiding caffeine as much as possible certainly seems to keep the symptoms away. Mar 4, 2011 at 13:59
  • I agree that there are negative effects due to caffeine. However, there is a lot of research regarding caffeine and athletic performance. I'll try to make some time and make an argument for it, while also noting the risks. Mar 16, 2011 at 21:52
  • Caffeine is also a diuretic, meaning it inhibits your body from absorbing water. So, if you don't drink enough fluids to counteract this it may cause dehydration (which will make you feel like crap). Mar 20, 2011 at 23:01

2 Answers 2


I suggest you read the wiki article:

In large amounts, and especially over extended periods of time, caffeine can lead to a condition known as caffeinism. Caffeinism usually combines caffeine dependency with a wide range of unpleasant physical and mental conditions including nervousness, irritability, anxiety, tremulousness, muscle twitching (hyperreflexia), insomnia, headaches, respiratory alkalosis, and heart palpitations. Furthermore, because caffeine increases the production of stomach acid, high usage over time can lead to peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease. Caffeine may also increase the toxicity of certain other drugs, such as paracetamol.

There are four caffeine-induced psychiatric disorders recognized by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder not otherwise specified (NOS).

Refer to article for more info and references.


To get into the details of this, there are two things I suggest you read/watch:

Check out this article: Caffeine, Stress and Your Health: Is Caffeine Your Friend or Your Foe?

A snippet from it points to one specific hormone:

Cortisol - Can increase the body’s levels of cortisol, the “stress hormone”, which can lead to other health consequences ranging from weight gain and moodiness to heart disease and diabetes.

Of course this is not the only stress hormone, but caffeine increases stress hormones in the body. To understand some studies on the effects stress can have on your body, watch this National Geographic documentary if you have Netflix (or haven't used your 1 month free trial):

It is quite informative and interesting, and has lead me to re-evaluate my own caffeine consumption as well as the general 'stresses' of my life. Take care and good luck!

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