One could probably argue that I have something of a caffeine addiction. Two double-shot espressos in a day is a light day, and a higher use day would be more like 4 double shot espressos and a 200 mg caffeine pill before training. This begs the question – how much coffee is too much coffee? Instead of littering this blog post with links to boring research papers, I’m just going to leave a link here to the examine.com page on caffeine, which has a great summary of the effects of caffeine and links to most of the relevant research.
By the way, this post is totally not just an attempt to justify my addiction. I swear.
How much Caffeine?
So that we’re all on the same page – how much caffeine is actually in coffee? That’s a trickier question than it first appears because there are a lot of variables which come into play. Different beans have different caffeine contents, which affect the final coffee, brewing time, water pressure, temperature, and so on all affect caffeine content too. Having said that, the rule of thumb I go by is that an espresso shot is about 80 mg, and a cup of plunger coffee is about the same.
In research, caffeine dosing is usually quoted in terms of “mg of caffeine per kilogram of body weight” (mg/kg), usually something like 4 to 6 mg/kg. If you happen to read the research, be careful! A lot of the research is done in rodent models, but because of metabolic differences, rodents can handle much higher relative doses! You would have a pretty bad time if you were giving yourself 10 mg/kg more than occasionally.
Effects of Caffeine
Caffeine is a stimulant and has all the effects you’d expect from any stimulant – elevated heart rate, elevated blood pressure, increased power output, increased time-to-exhaustion in aerobic exercise, increased serum concentrations of adrenaline and noradrenaline, increases in fat oxidisation and acute cortisol, improved reaction time, increased training volume, decreases in perceived exertion… Unfortunately, there are some negative effects too. Obviously, if you’re hypertensive or pre-hypertensive, increasing your blood pressure isn’t a good thing. If you’ve got high intra-ocular pressure, caffeine will increase your intra-ocular pressure even more. One of the main effects of caffeine is increased wakefulness which is great if you’re about to go into an exam or boring meeting, but much less great if you’re about to go to sleep.
Dosing for Effects
Most of the beneficial effects of caffeine start at relatively low doses. If you’re caffine naive (i.e. don’t use it a lot) then as little as 100 mg will give you the energy boost that you’re probably looking for. For peak athletic performance, you’re looking at more like 5 mg/kg body weight (which means for someone like me, I’d be looking to have about 450 mg before the competition, and maybe top that up with another 200 mg after a couple of hours.) The biological half-life of caffeine is something like 5 hours (depending on individual differences) so if you’re competing in a long event you do need to top up.
The bad negative effects don’t start until much higher doses. I’m guessing a little (because it’s unethical to do this on humans!) but I suspect something like 12 mg/kg or more would start being pretty uncomfortable, and about the point where the shakes, high blood pressure, and anxiety that results from caffeine consumptions start to outweigh the improved power outputs. It’s pretty hard to overdose on caffeine – the LD50 is about 195 mg/kg, which for most people would require you to just sit down and eat a jar of caffeine pills.
Until recently, the conventional wisdom regarding caffeine was that it needed to be cycled, as it would lose effectiveness with repeated exposure. A recent study (which I can’t seem to find, please let me know if you can find a link to it!) showed that this doesn’t seem to be the case, so there really isn’t any need to cycle off caffeine. I plan to continue to cycle my use, but non-performance reasons.
The examine.com page on caffeine hasn’t yet updated with reference to the new study and still suggests cycling caffeine (which isn’t harmful!)
Stimulants as a Skill
Bear with me here. I have a working hypothesis that using stimulants is (in part) a skill. When you haven’t done it before, it’s just weird and scary. If you drink coffee, try to imagine you had never tasted it before. You drink this weird black liquid that smells amazing but it kind of bitter, and 20 minutes later your heart rate is elevated, you’re kind of anxious, and you’ve started sweating non-stop. That’s fucking weird, and it’s probably going to stop you from being able to fully take advantage of the improvements in power output that you might otherwise get.
Think of it like wearing knee wraps, or a sling-shot for the first time. It doesn’t add anything to your lift, you might just fall on your face, and it’s mostly just a lot of new stimuli all at once. By the time you’ve used it a hanful of times, you’re much better at using it effectively.
So what am I saying with this? Basically, I’m suggesting that you don’t start using caffeine the first time on competition day – use it in training at least a few times before you get on the platform caffeinated to your eyeballs!
So… How much can I take?
As far as I can tell, excessive caffeine will make you uncomfortable a long time before it becomes dangerous, so unless you’re taking caffeine sufficiently close to going to sleep that it is going to keep you awake, take as much as you feel like you want. If you’re taking it for performance reasons, starting with a dose of around 5 mg/kg on competition day seems to be a good bet. Your milage may vary.
That’s my thoughts on caffeine. Have I missed anything important? Do you use caffeine, and if so when and how much?