Note that this question is related to Excessive caffeine consumption effect on heart/body. The question and answers however only cover long term usage effects, I want to know about the short term effects.

Which effects does consumption of caffeine during workout have?
I usually drink one or two 0.7l bottles of water before, during and after workout. I drink about one or two cans of tea daily, and was wondering if it has a detrimental effect when I keep drinking tea instead of water while working out.
I also noticed that some pulverized energy drinks contain some amount of caffeine and was wondering what the effects of caffeine consumption are on both strength and cardio exercises.

As I regularly drink coffee, tea or mate I am somewhat used to caffeine. Would there be different effects if I'd increase the dose or if someone who isn't used to caffeine would start consuming during exercise?

  • 2
    Caffeine has been proven to have some positive effects on endurance exercise, but in higher amounts than you are drinking, and when the person doesn't regularly consume caffeine. For your case, there wouldn't be much effect unless you cut out caffeine and then dosed before an event. I'm not aware of any positive effects on short burst strength based activities.
    – JohnP
    Jan 6, 2013 at 15:25
  • @JohnP If there are negative effects it would be interesting to know, too. Eg caffeine increases the heartbeat, so I wonder if this might just be 'too much' when doing something like HIIT.
    – Baarn
    Jan 6, 2013 at 15:30
  • Hi Informaficker. Your question is off-topic here, but may be more appropriate at this site: area51.stackexchange.com/proposals/44550/nutrition
    – Kenshin
    Jan 6, 2013 at 17:11
  • 5
    @Chris it is not off topic as it relates to exercise.
    – Baarn
    Jan 6, 2013 at 18:13
  • @Informaficker, you misunderstand. The question does relate to exercise, but I was under the impression that questions requiring "List" answers were off topic on this site. Answering the question "What are the short term effects of caffeine" comprehensively requires a list of effects.
    – Kenshin
    Jan 7, 2013 at 2:23

1 Answer 1


Your caffeine consumption, practically speaking, probably does not affect your workouts positively or negatively. As @JohnP pointed out, caffeine studies are on greater amounts than a couple of cans of tea per day. According to the Sports Med. 2001;31(11):785-807, "ingestion of caffeine as coffee appears to be ineffective compared to doping with pure caffeine."

  • Caffeine Dosage before exercise for performance:

    According to the American College of Sports Medicine:

    The optimal dose for maximizing the chance that exercise performance will be enhanced is ~3 – 6 mg/kg, where side effects are minimized and urine levels are legal.

    Caffeine ingestion (3-9 mg/kg bw) prior to exercise increases performance during prolonged endurance exercise and short-term intense exercise lasting approx. 5 minutes in the laboratory.

    (Note: That is 3-9 mg per kg of body weight.)

  • Positive Effects

    "ingestion of 3-9 mg of caffeine per kilogram (kg) of body weight one hour prior to exercise increased endurance running and cycling performance in the laboratory.

    Short Term-

    Research suggests that caffeine ingestion improves performance during short-term exercise lasting approximately 5 minutes at 90 to 100 percent of maximal oxygen uptake in the laboratory."

    According to this Sports Medicine article

  • Caffeine has been "shown to increase speed and/or power output in simulated race conditions. These effects have been found in activities that last as little as 60 seconds or as long as 2 hours. "

  • on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue

  • Ingesting caffeine reduces muscular pain during exercise in hot but not cold temperatures, This study found that, although caffeine improves exercise capacity, its effect on leg muscle pain is dependent on ambient temperature. Although exercise in the heat increases muscle pain compared to a cooler environment, caffeine reduces this pain.

  • Negative Effects: According to the American College of Sports Medicine:

  • The side effects of caffeine ingestion include anxiety, jitters, inability to focus, gastrointestinal unrest, insomnia, irritability, and, with higher doses, the risk of heart arrhythmias and mild hallucinations. While the side effects associated with doses of up to 9 mg/kg do not appear to be dangerous, they can be disconcerting if present prior to a competition and may impair performance.

    According to this Sports Med. 2001;31(11):785-807 article

  • There is no evidence that caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other adverse effects.

As for whether or not the effects vary depending on if someone consumes caffeine regularly, while this would seem to be the case, and is often said to be the case, I don't have a reference to confirm this.

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