Article written by Bill Fantegrossi To most red-blooded Americans, caffeine is a blessed sacrament. In prior generations it fueled our righteous assaults against the Nazi hordes, the Imperial Japanese, and the great red menace. Today it energizes our men and women currently bringing infinite justice to various terrorist death cults in assorted hellholes overseas. Indeed, our children will likely scavenge for caffeine sources among the shattered, smoldering wreckage of their former lives to bolster their resolve as they attempt to rebuild and retake the planet from the self-aware machine swarms on a mission to sterilize all organic life – if, that is, they were unfortunate enough to have survived The Burning Time.
Your children’s future. Thanks, Obama.
For those of us who lift weights, caffeine and related compounds (what those of us with big brains refer to as methylxanthines [see Figure 2]) can improve the work capacity of skeletal muscles by increasing blood flow and contractility, decrease reaction time, increase concentration and alertness, and dilate bronchioles to increase ventilation. All of these effects can be capitalized upon by the intelligent strength athlete in order to crank up the intensity of your training, or your performance on the platform. Note that “intelligent” is the operative work in that previous sentence. Hopefully this article will provide you with some information and “best practices” so you can stop being idiots and start getting the most out of caffeine as a performance enhancer.
Figure 2: Methylxanthine structures of three easily-available, plant derived compounds with performance enhancing effects for strength athletes.
PERFORMANCE-ENHANCING EFFECTS OF CAFFEINE
A surprising number of studies have been conducted on the effects of caffeine in physical performance across a variety of sports. This is really not the place to review them all, but a smattering of relevant data should help seal the deal if you are on the fence about the utility of caffeine for your training. Recently, 3 mg/kg caffeine in the form of an energy drink was shown to significantly increase grip strength and sprint velocity in high level tennis players. A stronger grip and increased speed would obviously be advantageous for just about anything involving a barbell, and may be particularly important for strongman events. This same research group also administered their 3 mg/kg caffeine drink to elite volleyball athletes and found significant increases in squat jump height, maximal countermovement jump height, and a reduced time to complete an agility test. Again, all of these effects would likely be beneficial to weightlifters. More specific to strength sports, 179 mg of caffeine (I really hate it when researchers don’t adjust dose for each subject’s body weight, but whatever) significantly increased the number of repetitions to failure in the bench press, deadlift, prone row, and back squat at 60% of each participant’s 1RM, while decreasing ratings of perceived exertion and increasing perceived readiness to invest mental and physical effort in resistance-trained men. All of these effects were replicated in a subsequent study by the same research group using 5 mg/kg caffeine and including some female participants as well. That same study also extended the previous report to show that caffeine ingestion did not result in differences in peak heart rate or peak blood lactate values as compared to the placebo condition, and also decreased the perception of muscle pain during performance of the lifts. Finally, a study that really warms my pharmacologist heart by actually using multiple caffeine doses shows that the dose required to elicit performance enhancing effects depends on the intensity of the programmed lifts. In the graph below, you can see that bar velocity decreases during performance of the squat as the load increases, which is sort of a “no duh” finding, but it’s important to demonstrate that the incremented loads really were getting more challenging. At lighter loads, every dose of caffeine resulted in greater velocity as compared to the placebo condition, but at 90% of 1RM, the lower caffeine doses failed to improve performance and higher doses were required. This same pattern was also evident for the bench press, where the lowest caffeine dose was ineffective at 75% of 1RM, and where only the highest caffeine dose was effective at 90% of 1RM.
Figure 3: Dose-dependent effects of caffeine on bar velocity during the back squat. Higher doses are necessary as you work closer to your 1RM.
So given all of these amazing effects, why aren’t you busting PRs all over the place every time you slam a can of Coke before training? Spoiler alert – it’s because you’re probably abusing the shit out of caffeine and thereby decreasing your sensitivity to its performance enhancing effects. But in order to really understand that you need to learn a little bit about the pharmacology of caffeine and related drugs.
Before getting into the pharmacology of these compounds, let’s make sure everybody’s on the same page with regard to what we are actually talking about. Thea sinensis leaves (tea leaves) contain caffeine, theophylline and theobromine, making tea a goddamn trifecta of awesomeness. In contrast, Coffee arabica beans (and the beans of related coffee species) contain caffeine only, and Cola acuminata nuts (used in soft drinks and energy drinks) contain just caffeine too. Finally, seeds of Theobroma cacao (used to make cocoa and chocolate) contain both caffeine and theobromine. All of these drugs function as central nervous system stimulants by binding as antagonists at adenosine receptors within the brain. You can think of adenosine as one of the brain’s primary braking systems – caffeine and related drugs “cut the breaks” and thereby allow you to maintain vigilance, alertness, and other nice things. (For the sticklers out there, all of these compounds certainly have other effects which can be characterized in test tube systems, including mobilization of intracellular calcium, inhibition of phosphodiesterase enzymes, and blockade of GABA-A receptors. But in an intact, living organism, none of these effects are observed until the dose is pushed into the toxic range, so these effects should probably be considered biologically irrelevant.)
As an aside, in case you are one of those knuckleheads who think everything “natural” is necessarily healthy for you, please click on over and read this story about some poor kid in Ohio who killed himself this summer with an overdose of caffeine. I am definitely not suggesting that you all fire up your browsers and start ordering bulk caffeine from some sketchy Chinese internet pharmacy.
Like all drugs, dose is the most important variable to understand if you are looking to maximize some effects (for example, the performance-enhancing effects listed above) while minimizing others (for example, death.) A good rule of thumb here is that a standard 12 oz can of Coca-cola contains just about 30 mg of caffeine (for some reason Diet Coke has just under 40 mg, but diet soda is for communists and pederasts.) This is simple to remember, and should allow you to easily convert any amount of caffeine into “Coke units” (if not, there’s probably a calculator on your phone – and your phone, you dummy, is that glowing thing in your pocket that makes noise and shakes when your buddy drunkenly sends you a photo of his dick.) Most caffeinated soft drinks will have a comparable amount of caffeine as Coke. In comparison, energy drinks vary widely in the amount of caffeine they contain. For example, a Monster 16 oz energy drink contains 160 mg caffeine, or more than 5 Coke units. And Wired X505 drinks pack 505 mg caffeine into 24 oz, or almost 17 Coke units in a single can. Caffeine tablets are also available at most pharmacies, typically containing 200 mg caffeine. Brewed preparations like coffees and teas are harder to gauge in terms of caffeine content, as this will depend on personal factors such as how long you allow the tea to steep (5 min will result in a beverage with about 25% more caffeine than one that was only allowed to steep for 1 min) or the method of coffee preparation (drip preparations will yield more than twice as much caffeine as an equivalent amount of freeze-dried instant coffee.) But the general consensus is that a standard cup of coffee will have about 100 mg of caffeine in it. You’re probably full of caffeine right now, sitting there reading this in your pajamas…
…And that’s why you’re not getting much out of it when you lift.
Drug tolerance is defined as a diminished response to repeated administration of the same dose of the same drug. In some cases, tolerance can be at least partially surmounted by administering a higher dose, while in other cases a person may be able to get around tolerance by switching to a different drug. Neither of these strategies is particularly useful with regards to caffeine. First, it is very important to understand (and I drum this into my students’ thick skulls as often as possible) that tolerance occurs to specific drug effects, and not to drugs themselves. For example, opioids are the best painkillers we have, but tolerance to their analgesic effects occurs much more quickly than does tolerance to their respiratory depressant effects. The result is that, eventually, in order to control a patient’s chronic pain a doctor would have to administer a dose of morphine (for example) large enough to kill the patient by completely shutting down respiration. It seems likely that tolerance to the stimulant effects of caffeine occurs more rapidly than does tolerance to its toxic effects. So escalating your doses until you either die or require a couple pots of coffee to get any effect is certainly an option, but it’s not a particularly wise option.
The savvy reader might think that switching from caffeine to a different compound (theophylline or theobromine, for example) might enable him or her to avoid the problems with drug tolerance. Unfortunately, this strategy will not work due to the phenomenon of cross-tolerance. Without getting too technical, common mechanisms of tolerance include compensatory changes in receptor expression and function within the brain. In the case of the methylxanthines, adenosine receptor upregulation and supersensitivity occurs – there are more receptors “looking” for adenosine, and when it binds, the adenosine transmits a bigger signal. Since all of the methylxanthines have the same mechanism of action (antagonism of adenosine receptors), it doesn’t matter which one you administer. Once you become tolerant to the stimulant effects of caffeine, you’re tolerant to the stimulant effects of theophylline and theobromine too – although no cross-tolerance was observed to the stimulant effects of cocaine, methylphenidate (Ritalin / Concerta) or amphetamine (Adderall) (see Finn and Holtzman, 1987). But switching to one of those drugs and rapidly degenerating into a worthless crackwhore in an attempt to add a quick 10 lbs to your squat is pretty much the definition of failure, so you probably shouldn’t go down that road. Unless you are Bill Kazmaier, in which case, do whatever the hell you want.
Figure 4: Kaz. You should try to be more like him.
Your best bet here is to attenuate your tolerance by slowly weaning off caffeine. Quitting cold-turkey is fine – it’s more than fine actually, it’s pretty goddamn manly – but caffeine withdrawal is a real phenomenon and it sounds like a shitty time. Juliano and Griffiths review signs and symptoms of caffeine withdrawal in humans, and report a syndrome characterized by headache, fatigue, decreased energy and alertness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, and cognitive fog. They also suggest that flu-like symptoms of nausea and vomiting, and muscle pain / stiffness are probably additional symptoms likely to occur. None of that is particularly conducive to strength training, so a gradual weaning off is probably the way to go.
A study involving brain imaging (echo-planar spectroscopy for the nerds out there) presents a really nice data set showing tolerance to metabolic effects of caffeine in the brain, and how these effects are restored after a 1- to 2-month “caffeine holiday”. In the figure below, the y-axis (“the up-and-down part,” you cretin) is the ratio of lactate to N-acetylaspartate, which is an indirect measure of overall brain metabolism. The X-axis (“the left-to-right part,” you mongo) just represents the passage of time. After 3 baseline samples at 10-min intervals, all subjects drank 10 mg/kg caffeine citrate mixed in fruit juice, which is hilariously awesome because that’s 700 mg caffeine for a 70 kg person – a dose that the authors dryly describe as “highly likely to elicit anxiety/panic and physiological arousal in sensitive individuals” and which I would more accurately characterize as “a shitpile.” Anyway, you can see that brain metabolism really didn’t change after caffeine ingestion for the regular caffeine users (the pink dots). That was the expected result. These same subjects then weaned themselves off caffeine over a period of 1- to 2-months, and repeated the study. This time, caffeine administration dramatically increased brain metabolism (the green dots), with a peak around 60 min after ingestion.
Figure 5: Restoration of caffeine’s effects of brain metabolism after tapering off caffeine ingestion to reset tolerance. I Fucking Love Science. As in, sexually.
In all likelihood, you are one of the pink dots right now. As such, knocking back an energy drink, a cup of coffee, or even a commercial “pre-workout supplement” drink is not likely to do much for you. I recognize that many people have an emotional relationship with caffeine: it’s part of their daily wake-up routine, the coffee break at work is a social ritual, etc. But do you want to sit under a blanket sipping a warm cup of ‘jo, or do you want to be a fucking beast? Switch to half-regular / half-decaf for a week or two, then go full decaf. After a month of that, go back to whatever caffeine preparation tickles your fancy about an hour before you go train. It may be advisable to treat caffeine the same way most people treat creatine supplementation – as something to be cycled on when it is useful, and off when you don’t necessarily need it.
The US Food and Drug Administration has been making noise about imposing further regulations and perhaps restrictions on caffeine for some time now, and with this summer’s unfortunate overdose death in Ohio I would expect that to gain traction. Please remember this when you vote for people who believe that more government is the answer to all your problems. For example, those of you in New York who vote for Chuck Schumer should take a good hard look at what you are doing with your lives by supporting a guy who actually believes that commercially-available caffeine aerosols (like those available at http://aerolife.com/) are “nothing more than a club drug designed to give users the ability to drink until they drop”. Ok Chuck, even if that were true, so what? This is America, asshole – we’ll drink until we drop all goddamn day if that’s what we want to do with our freedom.
Figure 6: Senator Chuck Schumer (D, NY): A clueless bloke who doesn’t even lift.
With regards to caffeine being a prohibited substance, the World Anti-Doping Agency (WADA) has taken a pretty goofy position on this. In 1972 they actually stripped a Mongolian judoka of his medal for what they considered excessive levels of caffeine. WADA removed caffeine from the prohibited substances list in 2004, but prior to that they limited athletes to a level below 12 mg per ml of urine (a concentration probably achievable after an intake of 600-800 mg.) WADA is currently monitoring caffeine levels in athletes, and there is some suggestion that its use has increased since its removal from the banned substances list. Whether or not WADA will reinstate a limit or invoke an outright ban remains to be seen. So if you are competing at a reasonably high level and your federation follows WADA guidelines, you might want to watch it. But if you follow my advice and work your tolerance back down, you’re not likely to be pushing 600 to 800 mg of caffeine before a competition anyway.
ABOUT THE AUTHOR
Bill received his Ph.D. from the University of Michigan in 2002 and is currently a tenured Associate Professor in the Department of Pharmacology and Toxicology at the University of Arkansas for Medical Sciences College of Medicine in Little Rock. His own research focuses on the behavioral pharmacology of emerging drugs of abuse, and his peer-reviewed research is available at http://www.ncbi.nlm.nih.gov/pubmed/?term=fantegrossi. For the most part, he lifts in his basement and his back yard. He’s decently strong for a scientist in his 40s, and enjoys eating meatballs as often as possible.
Bunker ML and McWilliams M (1979) Caffeine content of common beverages. J Am Diet Assoc 74(1):28-32.
Dager SR, Layton ME, Strauss W, Richards TL, Heide A, Friedman SD, Artru AA, Hayes CE and Posse S (1999) Human brain metabolic response to caffeine and the effects of tolerance. Am J Psychiatry 156(2):229-37.
Del Coso J, Pérez-López A, Abian-Vicen J, Salinero JJ, Lara B and Valadés D (2014) Enhancing physical performance in male volleyball players with a caffeine-containing energy drink. Int J Sports Physiol Perform 9(6):1013-8.
Duncan MJ, Smith M, Cook K and James RS (2012) The acute effect of a caffeine-containing energy drink on mood state, readiness to invest effort, and resistance exercise to failure. J Strength Cond Res 26(10):2858-65.
Duncan MJ, Stanley M, Parkhouse N, Cook K and Smith M (2013) Acute caffeine ingestion enhances strength performance and reduces perceived exertion and muscle pain perception during resistance exercise. Eur J Sport Sci 13(4):392-9.
Finn IB and Holtzman SG (1987) Pharmacologic specificity of tolerance to caffeine-induced stimulation of locomotor activity. Psychopharmacology 93(4):428-34.
Gallo-Salazar C, Areces F, Abián-Vicén J, Lara B, Salinero JJ, Gonzalez-Millán C, Portillo J, Muñoz V, Juarez D and Del Coso J (2014) Caffeinated Energy Drinks Enhance Physical Performance in Elite Junior Tennis Players. Int J Sports Physiol Perform, in press.
Juliano LM and Griffiths RR (2004) A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology 176(1):1-29.
McCusker RR, Goldberger BA and Cone EJ (2006) Caffeine content of energy drinks, carbonated sodas, and other beverages. J Anal Toxicol 30(2):112-4.
Pallarés JG, Fernández-Elías VE, Ortega JF, Muñoz G, Muñoz-Guerra J and Mora-Rodríguez R (2013) Neuromuscular responses to incremental caffeine doses: performance and side effects. Med Sci Sports Exerc 45(11):2184-92.
Reissig CJ, Strain EC and Griffiths RR (2009) Caffeinated energy drinks – a growing problem. Drug Alcohol Depend 99(1-3):1-10.