Sunday, November 22, 2009

Caffeine: The Definitive Blow-Your-Head-Clean-Off Guide.

Without going into the details of "why" (buy me a NorCal Margarita and I might spill the beans), I wrote this and the fish oil guide a few years back, prior to my Crossfit days.   I do have a couple of other "articles" in the works, like I've alluded to, (which includes the good and bad of anti-oxidants, just the plain ol' bad of fructose, and a basic what-the-heck-is vitamin D) but I'm just an amateur geek, so they take me a fair bit of time to compile.

I'll have some more recent thoughts on caffeine, though, at the end of the article.  This one is a big-'un, so strap in, top up your java, and get reading.

Plug "caffeine" into PubMed, and you get over 22,000 studies. Google it, and you get over 21 MILLION pages that reference caffeine in some way. It's clear caffeine is a popular topic. This guide will answer basic questions on caffeine and it's use in athletic endeavors.

Caffeine and exercise.
Paluska SA.
University of Washington, Department of Family Medicine, Roosevelt Medical Center, 4245 Roosevelt Way NE, Box 354775, Seattle, WA 98105, USA.


What Is Caffeine?

1,3,7-trimethylxanthine, or as it's commonly known as caffeine, is a naturally occurring substance found in the beans, leaves and fruit of various plants. It is classified as a methylxanthine alkaloid; theobromine, theophylline and paraxanthine are caffeine derivatives, and can also be naturally occurring in singularity. Guaranine, theine, and mateine, found respectively in guarana, tea and yerba mate, are synonymous with caffeine.

It's most commonly ingested in the form of coffee (beans), tea (leaves), energy drinks (guarana seed, kola nut), and chocolate (cacao beans). It is also readily attainable in OTC forms of pure caffeine tablets and in mixed preparations of analgesics.

"Caffeine is the most widely consumed psychoactive substance in the western world."
-David Tolson

Consumption of caffeine worldwide ranges on average at 70mg/day, and in North America, 200mg/day, and in Norway, Denmark and Sweden, 400mg/day. Needless to say, the world is infatuated by it---and potentially addicted to it. To find out what YOU are drinking, here's a good link: The Really Big Caffeine Database

So the question begs to be asked: What does it do to us?

What Does Caffeine Do?

Despite the numerous studies on caffeine and human physiology, many unproven theories still exist; some have recently been disproven, yet are still perpetuated and taught.

Caffeine directly affects the CNS through multiple mechanisms; the primary effect is antagonism of the adenosine receptors. Adenosine controls the release of numerous neruotransmitters in the brain, including GABA, acetylcholine, dopamine, serotonin, and norepinephrine. Antagonizing, or "blocking" of adenosine increases the release of these neurotransmitters. In layman's terms, it acts as a "disinhibitory" drug---putting the brakes on adenosine causes the wheels to spin faster and the motor to rev higher.

Through the action of increased cAMP, caffeine potentiates the effects of epinephrine; combined with the active metabolites theobromine and theophylline, strong beta-adrengergic stimulation occurs, including smooth muscle relaxation of the bronchioles in the lungs, increased heart rate (chronotropic simulation), and increase force of contractions of cardiac muscle (ionotropic stimulation).

Secondary effects includes potentiation of calcium, and intracelluar driving of sodium and potassium. This in turn, in theory, causes a delay in fatigue and increased force of muscular contraction.

Other effects, related to athletic performance, include analgesia and decreased RPE (Rate of Perceived Exertion); the description is self explanatory---the less pain and discomfort one is feeling while training means one can continue to train at an elevated intensity. No pain, all gain? Works for me.

Caffeine And Weight Loss

While the main point of this guide is to educate on caffeine's use as an ergogenic, it would be erroneous not to point out the potential thermogenic and lipolytic effects.


A Astrup, S Toubro, S Cannon, P Hein, L Breum and J Madsen
Research Department of Human Nutrition, Royal Veterinary and Agricultural University, Frederiksberg, Copenhagen, Denmark.
In humans caffeine stimulates thermogenesis by unknown mechanisms and its effect on body weight has not been studies. The effect of placebo and 100, 200, and 400 mg oral caffeine on energy expenditure, plasma concentrations of substrates and hormones, blood pressure, and heart rate was investigated in a double-blind study in healthy subjects who had a moderate habitual caffeine consumption. Caffeine increased energy expenditure dose dependently and the thermogenic response was positively correlated with the response in plasma caffeine (r = 0.52; p less than 0.018), plasma lactate (r = 0.79; p less than 0.000001), and plasma triglyceride (r = 0.53; p less than 0.02). Stepwise regression analysis with the thermogenic response as the dependent variable excluded plasma caffeine and yielded the following equation: thermic effect (kcal/3 h) = -0.00459 X heart rate + 0.30315 X (triglyceride) + 0.53114 X (lactate) + 15.34 (r = 0.86; p = 0.0001). The results suggest that lactate and triglyceride production and increased vascular smooth muscle tone may be responsible for the major part of the thermogenic effect of caffeine.

Through increased secretion of norepinephrine (NE), caffeine ingestion results in increased amounts of circulating free-fatty acids. Initially, this was the mechanism that was thought to induce the ergogenic results. While is has been accepted that adenosine antagonism plays the primary role, NE release does result in lipolysis from adipocytes (fat cells). This is the main reason caffeine is included in most weight-lose preparations, alongside other thermogenic stimulants like ephedrine. The increase in RMR (resting metabolic rate) through increased vasomotor tone and heart rate is probably an insignificant factor.

Ergogenic Effects of Caffeine and Athletes

Aerobic Training

It's well established that caffeine has a positive, ergogenic (enhancing physical performance) effect on endurance training. For the sake of space, I'm not going to post up studies regarding that. A search of PubMed under "caffeine" and "ergogenic" brings up 106 studies, so browse at your leisure. The mechanism of action for sub-maximal training is more than likely due to increase calcium release and analgesia, although this is just pure speculation.

Resistance Training

There is much less positive data on the effects of caffeine and resistance training, as shown in this study. Highlighted, for emphasis: The results indicated that the SUPP had no effect on 1-RM bench press strength or TRE at 85% VO2peak.

Keep in mind this is one study, used as an example of the typical results for caffeine and resistance training, and a reflection of the train of current thought. Without going into the flaws of single studies, one could easily find a flip side, as shown here. Note that while the conclusion states "Acute caffeine intake does not significantly alter muscular strength or endurance during intense bench press or leg press exercise," total weight lifted for the CAF group was 11% and 12% higher.

Anecdotally, there is a plethora of positive results. Just the fact alone that caffeine has the ability to increase muscular contractile force through intracellular Ca+, Na+ and K+ manipulation would be enough to assume a positive ergogenic response. Decreased RPE and enhanced mental clarity are enough to justify it's use to most lifters.

Anaerobic training

The effect of caffeine as an ergogenic aid in anaerobic exercise.
Woolf K, Bidwell WK, Carlson AG.

Department of Nutrition, Arizona State University, Mesa, AZ 85212, USA.


In a study on single and multiple sprints, found here, a positive result was found:
CONCLUSION: Although the effect of recovery duration on caffeine-induced responses to multiple sprint work requires further investigation, the results of the present study show that caffeine has ergogenic properties with the potential to benefit performance in both single and multiple sprint sports.

Caffeine, Exercise, and Hydration

There's a long-standing urban myth in sports performance circles than caffeinated beverages induce diuresis (increase urinary output) and cause dehydration. And as common sense dictates, dehydration is detrimental to optimal athletic performance. So what gives? Will that Red Bull or cup o' Joe kill or enhance my workout?

Larry Armstrong, an avid runner and professor of exercise and environmental physiology, is one of the foremost researchers on caffeine and athletics. In 2002, he completely debunked the idea of caffeine causing enhanced diuresis in this study:

Caffeine, body fluid-electrolyte balance, and exercise performance.
Armstrong LE.

Departments of Kinesiology, Nutritional Sciences, and Physiology & Neurobiology, University of Connecticut, Storrs, CT 06269-1110, USA.



He followed this up with another study in 2005:


University of Connecticut, Human Performance Laboratory, Storrs, CT 06269, USA.

PMID: 16131696 [PubMed - indexed for MEDLINE]

Final points:
  • When caffeine or a caffeinated beverage is consumed, the body retains some of the fluid;
  • Caffeine consumption causes a mild diuresis very similar to that of water (water, when consumed in large volume, increases urine output);
  • There is no evidence that consumption of caffeinated beverages causes a fluid-electrolyte imbalance that is detrimental to health or exercise performance;
  • A person who regularly consumes caffeine has a higher tolerance to the diuretic effect;
  •  The determination of safety or risk of consuming caffeine and caffeinated beverages depends on several factors, including the amount consumed and tolerance to caffeine.

      Pharmacokinetcis and Optimal Dosing Some important numbers:
      • The LD50 (the dose that'll kill 50% of the population) is 192mg/kg in rats; it's speculated that in humans, the toxic dose is 150-200mg/kg. For a 180pound guy, that's over 12 GRAMS on the low end.
      • The half-life, or how long it take for the body to metabolize half of the dose, is 3-4 hours in a healthy adult. This can vary greatly from person to person, based on weight, RMR, and age.
      • The onset of action can vary from 10 to 45minutes after oral ingestion. This is important for timing. Considerations include intake form (liquid or tablet), ingestion with a solid meal, and individual variances. Ingestion with fat will speed the onset of action due to the fact caffeine is lipophilic, which causes it to bypass heaptic metabolism and enter the bloodstream via the lymphatic system.
      So how much should one take? Based on the Really Big Caffeine Database, an average cup of coffee is around 145mg. Tablets are supplied in 200mg doses. Based on your own dietary intake habits, size, and age, YOU have to decide this through trial and error. If you've never had a cup of coffee in your whole life, never taken pure caffeine tablets, and never been blasted into orbit by a Redline Power Rush, then I'd suggest dosing SMALL. As stated earlier, tolerance builds rapidly, so what's good for me is NOT good for you. Common sense rules here, so use some.       But What About Building Up Tolerance?      It is a clear fact that tolerance to caffeine builds rapidly in users; the adenosine antagonistic activity of caffeine on the CNS is clearly evident in first time users, but is rapidly blunted in subsequent use. It is unknown if this is due to increased secretion of adenosine, or a compensatory up regulation of other neurotransmitters. High doses of 900-1200mg/daily for multiple days have shown a decrease in the effects of caffeine both centrally and peripherally. Incomplete tolerance has also been demonstrated in daily average doses. Complete tolerance, though, is highly unlikely at average consumption dosages (200-400mg/daily), as shown in this study. While the CNS and PNS effects are decreased, Some degree of stimulation is still noted. Longer abstinence times (20+hrs) decrease tolerance; theoretically, 48-72 hours would completely abolish tolerance.    

    This quote, taken from here, also demonstrates how perceivable effects are diminished through regular use, but CNS and cardiovascular benefits still exist:

    "Regular caffeine users who are physically active respond to an acute caffeine challenge by increasing plasma epinephrine and fat oxidation. Even on increasing caffeine consumption by 500 mg/day for 6 weeks caffeine challenge still increased fat oxidation, though epinephrine response was less. This might suggest that even if tolerance develops, it might not be complete tolerance to all the effects."

    Tolerance brings about some positive effects, though, as can be seen in the elimination of the minor diuresis from theobromine, and insomnia due to hypersensitivity.

    It must be noted that because a tolerance is built, dependency can result, and therefore, withdrawal symptoms can occur in abstinence. This generally isn't an issue, as caffeine has become a daily part of most people's lives and is readily available. Common withdrawal symptoms after 24hr of discontinued intake can include headache, malaise, and mood irritability. These generally dissipate within 48 hours.

    So, how can one avoid tolerance as much as possible, yet continue to utilize the positive stimulatory effects of caffeine in workouts? Much like nutrition, exercise, and nutrient timing, caffeine must be timed appropriately. These tips can help you maximize the effectiveness without losing your mind to withdrawal:
    • Only utilize supplemental caffeine preWO
    • Keep your dietary caffeine intake low to moderate
    • Do not take caffeine PWO
    • Cycle your caffeine, based on your workouts.
      Related Reading & Links

      Caffeine Roundtable With JB & Co. - A brainiac discussion on caffeine and athletics with John Berardi and friends.

      Caffeine Supplement Profile - An excellent article by David Tolson.

      Coffee Science Information Center - A website about the effects of coffee on health.

      Coffee Science - Another pro-coffee site with articles on coffee and health.

      Coffee, Diabetes and Weight Control - A review of various studies by Lyle McDonald on the connection of caffeine/coffee and diabetes and fat loss.

      The Effects of Caffeine on Physical Activity and Athletic Performance - An excellent review of various studies on athletes and caffeine by kinesiology student Ryan Gage

      Did you get through all that?  Impressive. 

      ***Ok, so what about Crossfit and NOW?  Personally, despite ALL the great shit caffiene does, it can be a double-edged sword; too much of a good thing is a bad thing.  I've felt great on some WODs, and SHITTY on others.  In the past, all of my martial arts training was roughly, give or take, the same pace, regardless of activity, opponent, or movement.

      Crossfit, on the other hand, is NOT like that, as anyone who has done more than half a dozen different WODs knows.  I haven't found the reason why supplementing with caffiene is hit-and-miss with metcons, but the max-effort metcon just doesn't leave much room for error in the rocket fuel category.  Heavy thrusters have an ability to fire you over the lactate threshold moon REALLY quickly; I have a sneaky suspicion that the reasoning lies behind this somewhere, but it'd just be pure speculation on my part.

      There's also the fact that caffeine is reputed to be PRO-arrythmic; that is, disrupts the electrical conduction of your heart.  This article states otherwise, but bear in mind, hundreds of young, perceivably healthy athletes drop from cardiac disrthymias of unknown etiology every year.  Caffeine?  Perhaps.  It DOES cause palpitaions and PVCs (premature ventricular contractions).  The potential IS there, so you are forewarned.  I have yet to see an automated defibrillator show up at CFLA, and when I'm there, I'm a trainer, not a paramedic, so I'd just scream like a 9 year old girl if someone collapsed.  No, not really.  But it would suck.

      What I do NOW:  I drink coffee, and I rarely, if every, supplement with caffeine.  The upside?  Coffee offers a decent amount of caffiene, aprox 150mg in a large cup of drip, and a plethora of health benefits.  It's has soooooo many health benefits that it's beyond the scope of this already too-long blog post.  Drink it.  Don't be stupid.  I kinda view it like fish oil:  You're and idiot if your not taking it.

      Downside?  No controlled dosing.  With a 200mg tab, I know I'm getting 200mg, every time.  Not so with a beverage, be it coffee or some of that canned shit.  Even if the labeling on a can of Blast-Off or whatever your choice is, it ain't gonna be controlled dosing like a tab.

      Alright, enough.  I talk too much.

      Nov18th, CFLA

      Front Squat

      185#x3  Felt
      245#x3  10# PR from Nov2.

      5 Rounds for Time:

      5 FS@50% 3RM (125#)
      250m Sprint row
      10 GHD Situps

      11:48. Time lost in transition was fairly evident, but the last couple of rounds were slooooooooow, especially the row and GHDs. Thurs/Fri I was MIA in my house in an ibuprofen-induced haze as I think the combo of heavy FS and FS in the metcon trashed my upper back.