I know caffeine increases your endurance/cardio abilities, but does anyone know of any negative effects that could arise during exercise because of caffeine?

For example, does the heart rate change when exercising at the same intensity with/without caffeine? Or any other consequence...

  • Just to narrow the scope a bit, you mean besides overdose or caffeine side effects (as a drug itself)?
    – C. Lange
    Commented Nov 2, 2020 at 2:09
  • I mean the negative effects of a combination of caffeine and exercise, not the potential general health issues (I have found a lot of research on those already).
    – user34310
    Commented Nov 3, 2020 at 2:54

1 Answer 1


Studies have shown that caffeine causes a dose-independent improvement in endurance performance1,2,3, which means that you get the same effect from taking a very large dose as you would with taking a small dose, presumably above some minimum threshold dose. (And the maximum dose given in these studies, with no negative effect on performance demonstrated, was a massive 13mg/kg, which would be around 11 cups of coffee for an 80kg athlete!) This demonstrates that even very high doses of caffeine do not adversely affect endurance performance.

If considering longer term effects, one potential deleterious effect on performance would be that large doses of caffeine, or even small or moderate doses taken later in the day, could adversely affect sleep, which would impact recovery, reducing performance in the long term.

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