Aug 2010 23
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(Almost) Everything You Need To Know About Caffeine and Sports Performance

Caffeine is one of humankind’s oldest drugs – and the most widely used. While coffee consumption is not believed to have begun in earnest until the 15th century, researchers believe caffeine itself may have been consumed as early as 700,000 years ago. Prehistoric humans got their caffeine fix, not by firing up their Mr Coffee® espresso machines, but by chewing on the seeds, leaves and bark of caffeine-containing plants.

Some 90% of adults in the United States consume caffeine daily, in the form of coffee, tea, soda, and energy drinks. US adults ingest an average of 3 mg/kg (225 mg for a 75 kg person) of caffeine daily.

One of the reasons caffeine-containing beverages and foods have enjoyed such enduring popularity is because of caffeine’s stimulant effects. These properties have not gone unnoticed by the athletic community, and caffeine has enjoyed a long history of use as an ergogenic aid.

Despite this long history, confusion reigns when it comes to caffeine and sports performance. How much caffeine is necessary to produce performance-enhancing effects? Exactly when should you take caffeine to enjoy a performance boost? Do the ergogenic effects of caffeine diminish with regular use? Will caffeine boost your maximum strength, or only your endurance?

I recently sat down and poured through some interesting studies and reviews on the topic of caffeine and athletic performance and figured I’d share the key findings with my readers. Before I do that though, there’s something we need to clear up.

Coffee versus Caffeine

While coffee and caffeine have become nearly synonymous in common parlance, it goes without saying the two are not the same thing. Caffeine (1,3,7-trimethylxanthine) is just one of many compounds found in coffee. Most of the research examining the effects of caffeine on sports performance has employed isolated caffeine in the form of anhydrous caffeine capsules; caffeine gums, gels, and caffeine-containing energy drinks have also been studied. Despite its universal consumption, few studies have examined the ergogenic effect of actual coffee.

Whether coffee offers the same ergogenic benefits as caffeine is a point of contention. I was in Borders the other day browsing through a popular US bodybuilding magazine when I came across an article flatly inisting coffee offered none of the ergogenic benefit imparted by caffeine. The author’s evidence for this claim appeared to be a single Canadian study published in 1998. Let’s take a look at this study, then the other studies involving coffee and athletic performance.

Is Coffee an Ergogenic Dud?

Graham et al from University of Guelph in Ontario, Canada, compared the effects of coffee versus caffeine in a double-blind fashion in nine young adults who were active endurance runners[1]. On five separate occasions, the subjects consume either a placebo capsule with water, a caffeine capsule with water, decaffeinated coffee, decaffeinated with added caffeine, or regular coffee.

In all three caffeine trials, the caffeine dose was 4.45 mg/kg body weight (i.e., 334 mg for a 75 kg person) and the volume of liquid was identical. One hour after consuming the caffeine/coffee/placebo, the subjects jumped on a treadmill and ran at 85% of maximal oxygen consumption (VO2max) until voluntary exhaustion. The subjects were instructed to abstain from all caffeine-containing foods and beverages for 48 hours prior to each treadmill trial, to prepare as they would for an athletic competition (i.e., well rested, consuming a high-carbohydrate diet) and to prepare for each trial in an identical fashion.

Plasma concentrations of caffeine and paraxanthine (the major metabolite of caffeine) were similar in all three caffeine trials 60 minutes prior to, at the start of, and at the completion of exercise. Despite this, only ingestion of the caffeine capsules resulted in a significant increase in time-to-exhaustion (7.5-10 minutes compared with with the other four trials). There was no difference in time-to-exhaustion between the placebo, decaf, decaf+caffeine capsule, and regular coffee trials. These observations led the researchers to speculate that one or more of the numeorus compounds found in coffee may counter the ergogenic effect of caffeine.

However, the findings of Graham et al have not been replicated by other researchers.

McLellan and Bell, for example, took thirteen physically active subjects and had them consume on separate occasions:

  • Decaf coffee + placebo capsule
  • Decaf + caffeine capsule
  • Coffee (1.1 mg/kg caffeine) + caffeine capsule (5 mg/kg)
  • Coffee + caffeine caspule (3 mg/kg)
  • Coffee + caffeine capsule (7 mg/kg)
  • Colored water + caffeine capsule (5 mg/kg)

The subjects consumed the beverages 90 minutes prior to exercise testing. The capsules were consumed 30 minutes after the beverages, 60 minutes prior to the tests. The study was performed in double-blind fashion. Times to exhaustion were significantly greater for all trials with caffeine versus placebo. Mean exercise times (in minutes) were, in the same order as above:

  • 21.7
  • 29.0
  • 27.8
  • 25.1
  • 26.4
  • 26.8

McLellan and Bell, in other words, found no inhibitory effect of coffee on the performance-enhancing action of caffeine[2].

Nor did Wiles et al, who examined the effect of coffee on 1500 meter treadmill running. On separate occasions, eighteen male athletes were given 3 grams of coffee (containing approximately 150-200mg caffeine) or 3 grams of decaf 60 minutes prior to three different exercise trials[3]. These trials tested the following outcomes:

  • Time taken to complete a 1500 m run;
  • The speed at which athletes completed a 1-minute ‘finishing burst’ at the end of a high-intensity run;
  • Respiratory factors, perceived exertion and blood lactate levels during a high intensity 1500-m run.

The results showed that ingestion of caffeinated coffee decreased the time taken to run 1500 m, increased the speed of the ‘finishing burst’, and increased VO2 during the high-intensity 1500-m run. The average mean time to complete the run was 4.2 s faster following the ingestion of caffeinated coffee, with 14 of the 18 subjects experiencing faster mean times after the ingestion of caffeinated coffee. All ten of the subjects performing the second trial recorded faster speeds (mean speed increase = 0.6 km/h) during the final minute of their run after ingesting caffeinated coffee. In the third test, all six participating subjects produced a higher mean VO2 during the caffeinated coffee runs.

The celebrated exercise physiologist David Costill and co-workers also examined this issue way back in the 1970s[4]. They took nine competitive cyclists (two females and seven males) into the lab, and made them ride until exhaustion on a bicycle ergometer at 80% of VO2 max. One trial was performed an hour after ingesting decaf coffee, the other was performed one hour after consuming coffee containing 330 mg of caffeine. After taking the caffeinated coffee, the subjects were able to perform an average of 90.2 minutes of cycling as compared to an average of 75.5 minutes in the decaf trial.

The results of Graham et al, therefore, appear to be an anamoly. One posited explanation is that coffee beans from different regions and producers may vary widely in their content of non-caffeine components, and that the coffee used in the Canadian study may have featured an unusually large amount of substance/s with the potential to impair the actions of caffeine. In cell culture studies, de Paulis et al found certain derivatives of chlorogenic acid produced during the roasting of coffee interfered with the binding of caffeine to adenosine receptors. When high doses of these compounds were given to mice, the poor little buggers subsequently exhibited less activity and movement when placed in an open field box [5]. In earlier research, Tse isolated a cholinergic compound from both regular and decaffeinated coffee, purified it, and observed that injecting it into rats produced an abrupt decrease in blood pressure and heart rate[6].

Exactly what this all means in humans is unclear. Three of the four studies I could find examining regular coffee have found a performing enhancing effect. However, if you are using caffeine to boost performance before an important competitive event, and want to maximize the chances of experiencing such an ergogenic effect, the use of caffeine (i.e. NoDoz) rather than coffee would be wise.

Caffeine Study Results: Wide Variability

Another important point to keep in mind as we review the ergogenic effects of caffeine on performance is that research results in this area are subject to annoyingly wide variation, which makes it difficult to impart blanket recommendations.

For example, the research in its entirety supports ergogenic caffeine doses of 3-6 mg/kg, with dosages of 9 mg/kg typically showing no extra benefit. In fact, in some users the latter amount may impair performance due to negative effects such as confusion, light-headedness and an impaired ability to concentrate. But on an individual level, responses can vary widely. A study by the aforementioned University of Guelph team examined 3, 6 and 9 mg/kg doses of caffeine in non-users, low-users and regular consumers of caffeine and found no relationship between habitual use and effective dosage. The subjects, all well-trained distance runners, were instructed to abstain from caffeine for 48 hours prior to running to exhaustion at 85% VO2max.

Overall, the best results were seen with doses of 3-6 mg/kg, with 9 mg/kg delivering a lower mean improvement that was not statistically significant from placebo. However, these were the mean results of the group as a whole; individually, the data were not so clear cut. Two subjects, both caffeine users, had their best result with 9 mg/kg of caffeine, whereas three subjects actually ran longer with placebo than with 9 mg/kg of caffeine. The heaviest caffeine user had his longest run after 3 mg/kg of caffeine but the two nonusers in the study exhibited the greatest endurance with 6 mg/kg of caffeine. One subject had been previously tested in the same laboratory and had run a whopping 25.2 minutes longer with 9 mg/kg of caffeine than with placebo. Two years later he ran 21.15 min longer at the same power output. Some subjects, especially the lightest users and nonusers, complained of mental confusion and an inability to focus with the highest dose[7]. Given the results on this and numerous other studies, most folks should stick with doses of 3-6 mg/kg.

Several factors could contribute to the wide variation in caffeine/athletic performance research results, which we will discuss later. Those interested in using caffeine as an ergogenic aid are advised to read what follows remembering that it is a generalized summary, consult the cited research, then experiment with caffeine in their training to arrive at a protocol that works for them on contest day.

I would also like to emphasize that the information that follows is intended for healthy adults only. Athletic children and teenagers should focus on developing healthy nutrition habits (namely, a diet primarily of nutrient- and antioxidant-rich whole foods containing sufficient calories, protein, carbohydrates, essential fatty acids and appropriate non- stimulant supplements) and developing the skills and physical and psychological qualities necessary for optimal performance in their chosen sport.

Caffeine and Endurance

The first review I’ll summarize was published in the January 2009 issue of Journal of Strength and Conditioning Research[8]. Ganio et al sought to determine the effect of caffeine on sports endurance performance. Rather than gather up every single study they could find, they specifically sought out studies involving time trial formats rather than time-to- exhaustion tests. Many studies involving caffeine and endurance involved subjects given caffeine or a placebo then instructed to perform at a set pace or %VO2max for as long as possible. While this kind of test can indeed help to identify ergogenic effects, it bears little resemblance to real life sport activities, most of which are conducted over a set distance or within a set time frame. Ganio and colleagues, therefore, scoured the literature for studies examining the effect of caffeine on time-trial endurance (equal to or greater than 5 minutes). Their literature search revealed 21 eligible studies containing 33 trials.

Thirty of the 33 trials showed positive improvements in performance with caffeine, but only 15 were statistically significant (p 0.05 or less). The mean improvement in performance with caffeine ingestion was 3.2%; however, this improvement was highly variable between studies (-0.3 to +17.3%), possibly due to such factors as ingestion timing, ingestion mode, and subject habituation. The largest mean improvement (4.4%) was observed in studies involving stationary cycling, but again this may have been due to the much larger number of studies employing this mode of exercise compared to running, rowing, skiing and swimming.

The ingestion of caffeine was similarly ergogenic regardless of whether it was ingested around 60 minutes before or during exercise. The mean improvement was slightly greater when caffeine was ingested both before and during exercise (4.3%) compared with only before exercise (2.3%), but again this may be attributable to a greater number of trials examining the latter condition and/or wide variability.

The amount of caffeine commonly shown to improve endurance performance is between 3 and 6 mg/kg body mass; these amounts are equally effective when combined with a carbohydrate/electrolyte solution or water. Performance improvements with caffeine are maximized with amounts up to 6 mg/kg and are not generally improved with 9 mg/kg.

Early research suggested that the ergogenic effect of caffeine was due to increased fat oxidation and subsequent sparing of muscle glycogen. However, more recent research suggests that caffeine affects endurance performance largely through its antagonist effect on adenosine receptors in the brain. Acting through this mechanism, caffeine may modulate central fatigue and influence ratings of perceived exertion, perceived pain, and levels of vigor, all of which may lead to performance improvements. Caffeine is able to cross the blood-brain barrier and is a powerful antagonist of adenosine receptors in the central nervous system. As a result, caffeine counteracts the inhibitory effects of adenosine on neuroexcitability, neurotransmitter release, and arousal.

Chronic caffeine consumption in animal models results in upregulation of the number and an increase in the affinity of adenosine receptors within the central nervous system. This may result in an increased amount of caffeine needed to have the same antagonist activity on the receptors (termed ‘‘caffeine habituation’’). It is possible that the varied degree of improvements observed between studies may be attributable to lack of control over subject habituation.

The ergogenic effects of caffeine may be more pronounced in those who do not or rarely consume caffeine, whilst habitual users may require stronger doses to get an ergogenic effect. Bell and McLellan compared the effect of 5 mg/kg caffeine at 1, 3 and 6 hours prior to rides to exhaustion (in all the trials, Gatorade was also consumed 1 hour prior) and found that increases were greater for caffeine non-users (<50 mg caffeine per day) vs. users (>300 mg caffeine per day). Furthermore, the effect of caffeine in the nonusers was still evident 6 hours after ingestion of the drug, whereas in the users this was not the case[9].

It is not known how many days an endurance athlete should abstain from caffeine to maximize its ergogenic effects. Animal studies show increases in adenosine receptor number and affinity are maximized in seven days. Therefore, researchers recommend athletes abstain from caffeine ingestion for at least 7 days before competition. This should allow forwithdrawal symptoms (which may negatively affect performance) to subside and allow sufficient time for adenosine receptor downregulation to occur.

Caffeine in Power, Strength and Team Sports

The ergogenic effect of caffeine on endurance performance is well-known and widely accepted, but whether caffeine benefits power and strength-type activities is another story. While caffeine routinely enhances time-to-exhaustion and time trial performance in bouts lasting over 5 minutes, a performance-enhancing effect on shorter duration activities, or on repeated intermittent sprint activities is more elusive.

Does Caffeine Boost Strength?

If you’re hoping a couple of pre-workout espressos will help you set a new PR on the bench or squat, you’re bound to be disappointed. Yours truly found three studies examining the effect of caffeine on 1RM during dynamic weight training (the kind you and I perform in the gym with free weights and plate-loaded machines, as opposed to aeronautical-looking EMG-equipped laboratory apparatus).

Astorino and Rohman tested the effect of caffeine (6 mg/kg, 60 minutes prior to exercise) on one-repetition maximum in the bench press and leg press. The subjects were resistance trained men with a mean daily coffee consumption of 110 mg. No difference in bench press or leg press 1RM strength was observed; eleven men lifted at least 10 kg more weight with caffeine, yet 8 lifted more with placebo, and 3 showed no difference between treatments[10].

Beck et al found that a supplement containing numerous ingredients (guarana, green/black tea extract, various herbs, vitamin C, B vitamins, cinnamon) including caffeine at a dose of 2.4 mg/kg taken 60 minutes preexercise increased bench press 1RM by a mean 2.1 kg in men regularly participating in strength training. However, no change was observed in leg extension 1RM nor mean and peak power from the Wingate test. Two minutes after testing for their 1RM on the bench and leg extension, each subject performed a set to failure with 80% of their 1RM. Caffeine had no effect on the total volume of weight lifted (80%RM x repetitions achieved) in the leg extension, but resulted in a small and statistically non- significant 5% increase in bench press total volume[11].

While the tiny 2.5 kg increase in bench press 1RM met the mathematical criteria for “significance”, seasoned lifters would hardly consider a 2.5 kg gain significant; natural strength can easily vary from day to day by this amount. Furthermore, the study design precludes embracing these results as proof of caffeine’s ergogenic effect. Because of their short duration, it is feasible (and common) for caffeine studies to be performed in “crossover” fashion, i.e. each subject undergoes placebo and caffeine treatments on separate occasions. This study, however, used a protocol in which all subjects underwent initial testing, then 48 hours later were randomized to either a placebo or caffeine group. Hence, the 2.5 kg gain in the bench press could easily have been due to a “learning” effect in some individuals from having performed a 1RM in the bench only 2 days earlier.

When the same researchers later tested a similar supplement, this time using a crossover protocol (so that all subjects were tested in both the placebo and caffeine conditions), they found no differences in bench press 1RM (nor running time to exhaustion)[12]. For some reason, the researchers used untrained subjects in their second study, introducing a new variable (lack of regular training) that may or may not have confounded the results. Nevertheless, the evidence for any claim that caffeine may increase maximal strength must be considered extremely weak.

Caffeine may however increase performance in later bouts of higher intensity activities. To address this issue, Astorino et al recently reviewed caffeine studies involving resistance training, team sports (which often feature intermittent bursts of intense activity) and power-based activities[13].

Eleven of 17 eligible studies revealed significant improvements in team sports exercise and power-based sports with caffeine, but the effects were more common in elite athletes who did not regularly ingest caffeine. Mean improvement in these studies was 6.5%.

As for resistance training, six of 11 studies revealed significant caffeine-induced improvements, usually in the form of increased number of repetitions or higher EMG-measured torque.

Caffeine dosages used in the positive studies ranged from 110 mg to 7mg/kg body weight.

Again, there was considerable variability across studies, suggesting only some individuals may experience improved performance with acute caffeine intake.

One potential explanation for the equivocal data regarding caffeine’s ability to alter high-intensity exercise may be differences in subjects’ training status. Of the studies revealing a significant improvement in short-term high-intensity exercise performance, many included trained athletes and not untrained, recreationally active, or weight training college students. It is likely that athletes have greater motivation to perform fatiguing exercise and can provide more consistent performance day-to-day , which may reduce variability and thus increase statistical power. In some studies, subjects were low-caffeine consumers (<100 mg per day) which may have potentiated the ergogenic effect of the drug compared with subjects tolerant to the effects of caffeine.

Also, most of the research with caffeine is conducted in free-living subjects who are instructed to refrain from caffeine for a set period prior to the start of the experiment and to maintain their usual dietary and lifestyle habits prior to each experimental trial. However, as the subjects are not living in a closely monitored ward situation, their exact compliance with these requirements is not known.

An additional explanation is that genetic variation may at least partially explain differences between individuals in their response to caffeine. Research suggests that variations in genotype may alter caffeine metabolism and possibly the magnitude of performance in response to caffeine. Caffeine is metabolized in the liver by cytochrome P450 1A2, which shows marked variation between individuals. A single substitution in the gene causes some persons to be “slow” caffeine metabolizers, whereas those who are homozygous for the allele metabolize caffeine more rapidly. The elucidation of exactly what influence genetic factors have upon the individual performance response to caffeine requires further research.

Further Considerations for the Athlete

Caffeine Abstinence Before Competition

As a strategy, if the athlete decides to stop consuming caffeine before competition to optimize its benefits during competition, he or she should reduce caffeine consumption at least 1 week before competition to be completely free from withdrawal effects. To avoid negative effects on training, the dose should be gradually reduced over 3 or 4 days, instead of quitting abruptly. Resuming caffeine on the day of competition will again provide the desired ergogenic effects, as it would for a nonuser.

Caffeine Effects and Hydration Status

The common belief that a diuretic effect of caffeine leads to dehydration and causes impaired athletic performance has been disproved by numerous studies[14]. A recent study examined body fluid, temperature regulation or electrolyte indices during twelve days of controlled caffeine ingestion (3 mg/kg caffeine daily for the first 6 days, and either 0, 3 or 6 mg/kg on days 7-12). On day 12, the subjects walked for 90 minutes on a 5% gradient in 37.7C heat. No changes were noted in the aforementioned indices[15,16].

Caffeine and Post-Workout Recovery

A recent study by researchers at RMIT University over the border in my old home Victoria, examined the effect of consuming caffeine, not pre-workout, but post-workout[17]. The aim of the study was to see what effect this had on glycogen replenishment after exhaustive exercise. On the evening prior to the experiment, seven endurance-trained cyclists and triathletes performed high intensity intermittent cycling and then consumed a low-carbohydrate meal to induce a glycogen-depleted state. The following morning subjects reported back to the lab and rode until volitional fatigue.

Upon completion of this ride subjects consumed either carbohydrate or the same amount of carbohydrate plus caffeine during four hours of passive recovery. A total of 4 g/kg of carbohydrate was consumed within 5 minutes of stopping exercise and again after 60, 120 and 180 minutes. During the caffeine trial, the same carbohydrate ingestion regimen was followed along with a total of 8 mg/kg caffeine administered in two equal doses immediately post exercise and after 2 hours of recovery. Muscle biopsies and blood samples were taken at regular intervals throughout recovery. Muscle glycogen levels were similar at exhaustion and increased by a similar amount (~80%) after 1 h of recovery. After 4 hours of recovery, however, the carbohydrate + caffeine treatment resulted in higher glycogen accumulation (313 vs. 234 mmol.kg-1 d.w., P<0.001). The overall hourly rate of re-synthesis for the 4 hour recovery period was 66% higher with the caffeine treatment.

So should you start chugging down coffee and NoDoz after glycogen-depleting exercise? That depends on how sensitive you are to caffeine, and whether you prefer to spend your evenings sleeping soundly or staring wide-eyed at the ceiling. According to the researchers, several of the athletes in the study reported difficulty sleeping the night after the trial, hardly surprising seeing they’d consumed the equivalent of 5-6 cups of strong coffee. Several of the others, however, fell asleep during the recovery period and reported no adverse effects. As one of the researchers noted, the next logical step is to repeat the study using a lower dosage of caffeine and see if enhanced glycogen resynthesis still occurs[18].

Unless you are going to be performing a second bout of intense exercise later in the day, my advice would be to reserve caffeine for pre-event use (and peri- in the case of longer events).

Caffeine and Creatine

Creatine has become one of the most popular supplements among strength athletes and recreational weight trainers. In early studies showing ergogenic effects of creatine, the powdered creatine was often mixed into warm drinks such as tea (which contains caffeine, albeit at much lower amounts than coffee) to increase solubility. So it was rather surprising when a couple of subsequent papers claimed caffeine impaired the absorption/actions of creatine.

The first of these studies was published in 1996[19]. Nine recreationally active males were studied before and after 6 days of placebo, creatine (0.5 g/kg daily), or the same dose of creatine plus caffeine (5 mg/kg daily). The subjects were then tested on an isokinetic leg extension dynamometer; testing consisted of three consecutive maximal isometric contractions and three interval bouts of 90, 80, and 50 maximal voluntary contractions performed with a rest interval of 2 minutes between bouts.

Muscle ATP concentration remained constant over the three experimental conditions, while creatine and creatine + caffeine increased muscle phosphocreatine concentration by 4-6%. Dynamic torque production was increased by 10-23% by creatine but was not changed by creatine + caffeine. Torque improvement during creatine was most prominent immediately after the 2-minute rest between the exercise bouts. According to the researchers, who initially expected that caffeine would enhance the effects of creatine, “The data show that [creatine] supplementation elevates muscle [phosphocreatine] concentration and markedly improves performance during intense intermittent exercise. This ergogenic effect, however, is completely eliminated by caffeine intake.”

In order to understand why caffeine would impair the effect of creatine supplementation, the researchers conducted another study[20]. Ten students were assigned in random crossover fashion to five experimental protocols, each lasting 8 days and separated by a washout period of 5 weeks (muscle creatine levels return to baseline around 4-5 weeks after cessation of supplementation). Exercise tests were performed before and after creatine supplementation (4 × 5 g/daily for 4 days), short-term caffeine intake (5 mg/kg daily for 3 days), creatine supplementation + short-term caffeine intake, acute caffeine intake (5 mg/kg) or placebo.

Maximal torque, contraction time from 0.25 to 0.75 of maximal torque, and relaxation time from 0.75 to 0.25 of maximal torque were measured during an exercise test consisting of 30 intermittent quadriceps contractions (2 seconds stimulation, 2 seconds rest) induced by electrical stimulation. Compared with placebo, creatine shortened relaxation time by 5%; in contrast, caffeine increased relaxation time by 10%. When caffeine was combined with creatine, relaxation time increased by 7%.

Skeletal muscle relaxation after a contraction is initiated by a reduction in sarcoplasmic calcium ion concentrations, and the researchers speculated that caffeine may interfere with this process in a detrimental manner. Relaxation time increases as a muscle fatigues, and in this study caffeine amplified the effect of fatigue on relaxation time. As the researchers point out, theoretically muscle relaxation rate is important to power production during sprint-type exercise. During fast repetitive concentric muscle contractions, recovery time from the previous contraction is critical to maximal force output during the next contraction.

However, this study involved subjects whose muscles were wired up and given electrical stimulation to induce contraction. Neither this nor the previous study measured power output or performance during a “real life” activity such as cycling, running, or dynamic weight lifting. If these results held, then performance in subsequent bouts of maximal sprint exercise would be expected to be impaired by caffeine. While one oft-quoted study did indeed show a statistically significant reduction (7%) in peak power output on the last of 4 x 30 second “Wingate” sprints following caffeine ingestion[21], numerous other studies involving Wingate protocols have shown no difference; some have even found benefit.

Vanakoski et al studied seven trained athletes in a randomized, placebo-controlled, double-blind crossover fashion[22]. The treatments were: placebo, a single oral dose (7 mg/kg) of caffeine, repeated oral doses (3 x 100 mg/kg daily) of creatine for 3 days, or the combination of caffeine and creatine before physical exercise. Supplement administration was followed 70 minutes later by 3 repetitive 1-minute exercise bouts on a stationary bike at maximal speed. This was followed by 45 minutes of cycling at a constant speed and workload. Neither creatine nor caffeine, alone or in combination, improved maximal pedaling speed, maintenance of maximal speed or total work output during the 1 -minute bouts, when compared with placebo.

Contrasting results were obtained by British researchers who had fourteen trained male subjects perform treadmill running to exhaustion at an exercise intensity equivalent to 125% VO2max. Three trials were performed, one before 6 days of creatine loading (0.3 g/kg daily), and two further trials after the loading period. One hour before the post-loading trials, caffeine (5 mg/kg daily) or placebo was ingested in cross-over, double-blind fashion. The mean time to exhaustion was significantly longer in the caffeine trial (222.1 seconds) than both baseline (200.8 s) and placebo (198.3 s) trials[23].

It’s probably safe to assume that the vast majority of individuals taking creatine are doing so, not for performance enhancement, but for aesthetic bodybuilding purposes. The aforementioned studies were of short duration and tell us nothing about what sort of muscle gain or body composition changes may occur with longer term creatine use.

One study, from the University of Oklahoma, did run for a longer duration, but it involved a supplement containing, not just caffeine and creatine, but several other ingredients[24]. It also did not examine the effects of creatine and caffeine separately. This single-blinded, placebo-controlled study examined the effects of a pre-workout supplement known as Game Time® or placebo combined with three weeks of high-intensity interval training (HIIT) on aerobic and anaerobic running performance, training volume, and body composition[23].

Twenty-four moderately-trained recreational athletes were assigned to either Game Time® (which contains Cordyceps sinensis, Arginine AKG, Kre-Alkalyn, Citrulline AKG, Eleutherococcus senticosus, Taurine, Leucine, Rhodiola Rosea, Sodium Chloride, Valine, Isoleucine, Caffeine, Whey Protein Concentrate) or placebo. The supplement/placebo powders were consumed thirty minutes prior to all testing and training sessions. Training comprised of a three-week HIIT program three days per week, and testing was conducted before and after the training. Each training session consisted of five sets of two-minute running bouts with one minute of rest between each bout.

Both the Game Time® and placebo groups demonstrated significant increases in VO2max from pre- to post-training resulting in a 10.3% and 2.9% improvement, respectively. Critical velocity (maximal running velocity that can be maintained for an extended period of time using only aerobic energy stores) increased for the supplement group by 2.9%, but remained unchanged in the placebo group. Anaerobic running capacity increased for the placebo group by 22.9% and for the Game Time® group by 10.6%. Training volume was 11.6% higher for the supplement versus placebo group. As for body composition changes, bodyfat decreased from 19.3% to 16.1% for the Game Time group and decreased from 18.0% to 16.8% in the placebo group. Lean body mass increased from 54.2 kg to 55.4 kg for the Game Time® group and decreased from 52.9 kg to 52.4 kg in the placebo group (p = 0.694).

Again, it must be noted that this study involved numerous other ingredients and did not separately examine the effects of caffeine and creatine. Also, Game Time® contains 100 mg of caffeine, a much lower dose than what is typically used for ergogenic purposes.

While commentators on both sides of the fence of confidently assert that caffeine “does/does not/does too!” impair the actions of creatine, the research so far is equivocal. More research is required to determine for sure if, and under what conditions, caffeine anatagonizes the actions of creatine.

Summary of Key Points

  • The amount of caffeine commonly shown to improve endurance performance is between 3 and 6 mg per kg of body weight; these amounts are equally effective when combined with a carbohydrate/electrolyte solution or water.
  • Acute ingestion should occur around 60 minutes before and, if practical, during competition.
  • Given the available evidence, endurance athletes should abstain from caffeine use at least 7 days before competition to maximize its ergogenic effect.
  • Because some individuals react differently to caffeine than others, it is recommended athletes try caffeine while training before using it in competition. In the midst of an important race is not the ideal time to discover that caffeine upsets your stomach or gives you a sudden overwhelming urge to empty the contents of your nethermost regions.
  • Caffeine research consistently shows improvement in endurance performance. Improvements in team sports and power-type activities are much more erratic. Based on current research, caffeine does not appear to increase maximal strength in weight lifting exercises.

Anthony Colpo is an independent researcher, physical conditioning specialist, and author of the groundbreaking books The Fat Loss Bible and The Great Cholesterol Con. For more information, visit TheFatLossBible.net or TheGreatCholesterolCon.com

References

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