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Annals of Vitamin and Metabolism
Summary
Background/Goals: Caffeine and creatine are 2 of essentially the most extensively out there and used compounds in sport. Though the usage of both shouldn’t be thought of a doping infraction, the proof does counsel ergogenic potential in sure sports activities. The aim of this paper is to evaluation the pharmacology and potential mechanism(s) of motion of caffeine and creatine as they pertain to doable use as an ergogenic assist in sport. Strategies: Earlier evaluation articles on caffeine and creatine use in sport have been screened for related info and references, and research for evaluation and up to date articles (2007 onwards) have been obtained and reviewed utilizing a PUBMED search with the phrases ‘caffeine AND exercise’, ‘creatine and creatine monohydrate AND exercise’, and applicable linked articles have been evaluated. Outcomes: Caffeine taken earlier than (3–6 mg/kg) or throughout (1–2 mg/kg) endurance train enhances efficiency, by way of central nervous system and direct muscle results. Creatine monohydrate supplementation at larger (approx. 20 g/day × 3–5 days) or decrease (approx. 5 g/day × 30 days) doses will increase skeletal muscle complete and phosphocreatine by 10–20%. Creatine supplementation seems to minimally however considerably improve high-intensity sport efficiency and the mass and probably power positive factors made throughout resistance train coaching over the primary few months. Conclusions: Though caffeine and creatine look like ergogenic aids, they accomplish that in a sport-specific context and there’s no rationale for his or her simultaneous use in sport. Larger doses of caffeine may be poisonous and look like ergolytic. There is no such thing as a rationale for creatine doses in extra of the suggestions, and a few athletes can get abdomen upset, particularly at larger creatine doses.
© 2011 S. Karger AG, Basel
Introduction
Caffeine and creatine are 2 extensively used compounds in sport and their use shouldn’t be at present thought of to be a doping infraction regardless of the truth that they look like ergogenic to sure kinds of sport efficiency in sure athletes (word: all athletes ought to verify up-to-date tips for his or her sport as these are topic to vary at any time). A part of the problem in classifying caffeine or creatine as doping brokers is that each of those are discovered naturally in all kinds of meals and drinks. As such, it’s doable for athletes to get 5 mg/kg of caffeine from espresso and 5 g of creatine from sure kinds of fish or meat, albeit at pretty excessive intakes. Clearly, though caffeine and creatine are biologically lively compounds that observe all features of pharmacology (pharmacokinetics, mobile organic results, and many others.), their presence in meals historically renders them as ‘nutraceuticals’ and never prescribed drugs. The latter designation is clearly semantic for each caffeine and creatine could be thought of pharmacological brokers in the event that they have been conceived and synthesized by a pharmaceutical firm.
The aim of the present evaluation is to supply an summary of the pharmacokinetics and mechanism(s) of motion, and to evaluation the proof for an ergogenic (work-enhancing) impact from each caffeine and creatine in a sport-specific context. It is vital for athletes to keep in mind that there are large interindividual variations that may affect the ergogenic results of any compound and the potential unwanted effects. Consequently, any athlete should take into account the moral, security and scientific proof for an ergogenic good thing about caffeine or creatine of their specific sport. Alongside these traces, I might advocate an athlete who’s contemplating caffeine or creatine as an ergogenic assist to first attempt them earlier than an necessary competitors to see if the profit (ergogenic potential) exceeds the danger (caffeine – tremor, creatine – gastrointestinal upset). There are a selection of critiques of each caffeine [1,2,3] and creatine [4,5,6,7] revealed up to now, and the present evaluation is an replace on the subject, together with new info since 2008. I don’t promote or settle for the usage of both of those compounds in athletes however it’s a person determination to make use of both in sport.
Caffeine
Overview
Caffeine is an alkaloid xanthine by-product (1,3,7-trimethylxanthine) present in, and added to, all kinds of meals and drinks (desk 1). A lot of the caffeinated drinks consumed all through the world include caffeine extracted from espresso beans or tea leafs, however caffeine can be eaten as chocolate derived from the cacao bean. Espresso and tea include all kinds of different chemical compounds with probably bioactive properties together with different alkaloids (theobromine, paraxanthine, theophylline) and polyphenols [tannins and flavonoids (chlorogenic acid)]. Consequently, the consumption of caffeine-containing tablets, drinks and different dietary supplements can’t be instantly equated to consumption of tea and occasional, from each a well being (see under), and probably ergogenic [1] perspective. Caffeine has been consumed in numerous meals and drinks for hundreds of years attributable to its perceived work-enhancing (ergogenic) and application results. Caffeine consumption additionally has quite a lot of different dose-dependent results within the nonhabitual client together with tachycardia, a slight enhance in blood strain, diuresis, and a advantageous tremor.
Desk 1Caffeine content material of some frequent meals
Caffeine is absorbed with a time to peak plasma focus of 30–90 min and a half-life of about 5 h. Caffeine is metabolized by the cytochrome P450 oxidase system to quite a lot of xanthine metabolites [8], with about 1–3% excreted within the urine as free caffeine [3]. The latter truth is necessary from a drug testing perspective, for it’s the free caffeine that’s monitored for doping testing. Components corresponding to hepatic dysfunction, cytochrome P450 single-nucleotide polymorphisms [9], oral contraceptive use, and different medicine can alter metabolism and excretion of metabolites. The routine consumption of caffeine additionally influences metabolism by downregulating most of the physiological results (tachyphylaxis). For instance, a number of days of routine caffeine consumption attenuated acute ingestion-induced rise in coronary heart charge or blood strain [10], and the lipolytic results have been attenuated in girls throughout train [11]. In distinction to the above information, the ergogenic results of caffeine are related in each nonhabitual and routine caffeine customers [12].
The Worldwide Olympic Committee beforehand had caffeine on the banned substance record with urinary concentrations better than 12 mg/l thought of a doping infraction; nevertheless, the World Anti-Doping Company has subsequently eliminated it in 2004. A possible motive for removing from the banned record might be the truth that low doses of caffeine have been proven to be ergogenic and these ranges might be obtained with the routine consumption of many frequent foodstuffs (desk 1). As well as, it’s the free caffeine that’s used for monitoring and this variable exhibits a manifold interindividual variance in urine focus for a similar ingested dose.
Mechanism(s) of Motion
Caffeine was thought to disclose its ergogenic results by rising intracellular cyclic AMP by phosphodiesterase inhibition; nevertheless, this idea got here from research utilizing supraphysiologic concentrations (mM) that weren’t tolerable or seemingly even doable in people (µM) [3]. The present proof signifies that caffeine acts by way of its function as an adenosine receptor antagonist [3]. Adenosine receptors are extensively current in human tissue together with the mind, skeletal muscle and adipose tissue. Adenosine antagonism in adipocytes clearly results in elevated lipolysis and a rise in plasma free fatty acid (FFA) focus. Consequently, the ‘classical’ research evaluating the ergogenic potential of caffeine thought of that the discovering of a decrease respiratory change ratio throughout endurance train indicated that caffeine was rising plasma FFA focus, muscle uptake and fats oxidation which led to intramuscular glycogen sparing by way of the Randle impact [13,14]. This speculation grew to become properly established for over a decade, with a later modification that the sparing occurred primarily within the early rest-to-exercise transition; nevertheless, newer research confirmed no proof for glycogen sparing after long-term endurance train [2]. The rise in plasma FFA persistently noticed at relaxation is because of an adrenergic (epinephrine, norepinephrine) impact on adipocyte lipolysis; nevertheless, this impact is overridden by the adrenergic impact of train. Highly effective proof towards the Randle impact and adrenergic enhancement because the mechanism of motion of caffeine got here from the discovering that sufferers with excessive spinal twine lesions haven’t any enhance in epinephrine with caffeine or train and nonetheless present a caffeine-induced ergogenic impact on electrically stimulated cycle ergometer efficiency [15].
Caffeine is utilized in vitro and in situ to potentiate calcium launch from the sarcoplasmic reticulum and may result in a muscle caffeine contracture with supraphysiological concentrations [16]. We [17], and others [18], have proven and enhanced power output in people throughout low-frequency electrical muscle stimulation with caffeine, and we have now steered that this impact was attributable to enhanced calcium launch from the sarcoplasmic reticulum [17]. Particularly, we confirmed that acute caffeine administration (5 mg/kg) elevated low-frequency (20 Hz, simulating endurance train) electrically stimulated muscle power throughout a fatiguing protocol [17]. Low-frequency fatigue is felt to happen on the stage of calcium launch from the sarcoplasmic reticulum [19]. In distinction, caffeine didn’t improve energy output throughout electrically stimulated fatigue protocols utilizing high-stimulation frequencies (40 Hz, simulating high-intensity contractions) in our examine [17], or at a number of ranges of high-frequency stimulation in one other examine [18]. Fatigue at high-stimulation frequencies results in a lower in electrical exercise of the muscle attributable to conduction block from potassium accumulation and this sort of high-frequency fatigue shouldn’t be altered by caffeine [19]. In distinction, the modest enhance in plasma potassium focus that happens throughout endurance train was attenuated with caffeine consumption [20], and this might probably cut back conduction block-induced muscle fatigue [3].
Along with the ergogenic advantages of caffeine instantly on skeletal muscle, there are additionally central (mind and spinal twine) results from caffeine administration that will improve train efficiency throughout endurance train (for a evaluation, see Tarnopolsky [15]). Numerous research have proven that the score of perceived exertion is decrease with caffeine administration versus placebo throughout endurance train. In reality, the most effective recognized impact of caffeine is the promotion of wakefulness and this may occasionally forestall the central notion of fatigue (central fatigue speculation). Along with a discount within the central notion of fatigue, a discount in ache has been demonstrated in a number of research following caffeine administration [15].
Caffeine and Train Research
The preliminary research within the late Nineteen Seventies confirmed that caffeine administration (approx. 5 mg/kg) improved endurance cycle efficiency in open-ended [14] and closed-ended [13] biking duties. Subsequently, many laboratory-based research have proven both a better energy output for a given time period (closed-ended research) or a better time to exhaustion (open-ended research). A lot of research have additionally discovered enhancements in endurance sports-specific efficiency together with operating, cross-country snowboarding, and biking (for a evaluation, see Graham [1] and Tarnopolsky [3]). The overwhelming majority of those research have used caffeine doses within the vary of three–6 mg/kg taken roughly 1 h previous to train. Extra not too long ago, research have reported that a lot decrease doses of caffeine (1.0–2.0 mg/kg), particularly when taken later throughout an endurance train process, have enhanced efficiency [21]. These findings are in step with athlete anecdotes reporting enhancements in efficiency with the consumption of flat cola kind merchandise throughout endurance biking. A number of gels at the moment are being produced with roughly 50 mg of caffeine per serving.
The proof for an ergogenic impact of caffeine on high-intensity efficiency is scant in comparison with the info with endurance duties. Numerous research have discovered no enchancment in 30-second all-out dash biking efficiency with caffeine administration and there’s no proof of enchancment in single-effort power or energy maneuvers [3]. One examine has reported enhancements in repetitive high-intensity biking (2-min sprints adopted by a 4- to 5-min energy output take a look at) [22], and this might be associated to a lower in ache notion.
Potential Facet Results and Different Well being Points
There have been numerous epidemiological research wanting on the potential well being penalties from routine caffeine consumption with variable reviews over the many years suggesting a possible hyperlink to heart problems or sure kinds of most cancers. Nevertheless, the overwhelming majority of research don’t discover any relationship between routine espresso consumption (3–8 cups per day) and any unfavourable well being penalties [23]. The US Meals and Drug Administration considers caffeine to be usually acknowledged as protected. It is vitally necessary to notice that there’s a distinction between the consumption of espresso, tea, chocolate and cocoa and that of caffeine-supplemented merchandise. The vital situation is that espresso and tea include over 1,000 organic compounds together with the polyphenol chlorogenic acid that has potential useful results corresponding to antioxidant properties and slowing of glucose absorption. In distinction, caffeine per se seems to have a unfavourable impact on insulin sensitivity [24], and could be anticipated to predispose in the direction of kind 2 diabetes. From a dietary consumption perspective, there’s very sturdy proof that consumption of espresso, even in excessive day by day doses, really lowers the danger of kind 2 diabetes [23].
There are additionally some people who’re delicate to the nervousness and tremor that may be induced with acute caffeine consumption and athletes who get significantly nervous or who develop a tremor could want to keep away from caffeine-containing merchandise previous to train. The latter level could be significantly necessary in accuracy sports activities corresponding to biathlon the place tremor could also be an ergolytic impact. Caffeine can be very well-known to advertise wakefulness and consumption too late within the day could have a serious insomnia impact that would exacerbate ‘pre-race jitters’. Caffeine additionally has a diuretic impact in nonhabitual customers; nevertheless, that is extra obvious at relaxation and research have demonstrated that there isn’t a dehydrating impact from caffeine consumption throughout endurance train. For the routine caffeine client, it might even be smart to not acutely cease taking caffeine on the morning of train for acute caffeine withdrawal can result in a major headache which might be ergolytic to efficiency.
Creatine Monohydrate Supplementation – “creatine as an ergogenic aid”
Introduction
Creatine is a guanidine compound synthesized from the amino acids arginine and glycine within the liver and kidney. Arginine and glycine kind guanidinoacetate within the kidney utilizing the enzyme arginine-glycine amidinotransferase, and the guanidinoacetate is transformed to creatine with methionine-mediated methylation utilizing guanidinoacetate methyltransferase. Creatine can be current in meat and fish (desk 2). Commonplace cooking has a minimal impact on reducing creatine content material by way of conversion to creatinine [25]. Plasma creatine is transported into tissues through an X-linked creatine transporter. Over 90% of creatine is taken up into skeletal muscle and creatine is present in excessive focus in skeletal muscle (130 mmol/kg dry muscle mass). Roughly 65% of intracellular creatine is phosphorylated (phosphocreatine) and the rest exists as free creatine. Within the rest-to-exercise transition, phosphocreatine supplies a fast retailer for the rephosphorylation of ADP and capabilities as a temporal power buffer offering the vast majority of the power for the primary 6–8 s of muscle contraction earlier than anaerobic glycolysis turns into predominant (fig. 1). The creatine kinase response additionally has a buffering function as depicted in determine 1. The temporal power buffering can be linked to an activation of mitochondrial respiration forming a creatine phosphocreatine shuttle referred to as a spatial power buffer [26].
Desk 2Creatine content material of some frequent meals
Fig. 1Creatine-phosphocreatine power buffering throughout anaerobic train. ATP = Adenosine triphosphate; ADP = adenosine diphosphate; H+ = proton (acidity); PCr = phosphocreatine; Cr = creatine.
There are a selection of different mobile results of creatine, together with a rise within the expression of numerous genes probably attributable to cell swelling [27]. A few of these different mobile results could also be liable for the intensive variety of research demonstrating useful results from creatine supplementation in quite a lot of animal and human fashions of neurologic illness [28]. The curiosity in creatine supplementation for sport got here from a seminal paper in 1992 the place Roger Harris et al. [29] demonstrated that 5 days of oral administration of creatine monohydrate (20 g/days) elevated muscle complete and phosphocreatine by roughly 15–20%. Subsequent analysis demonstrated related will increase in creatine and phosphocreatine after 30 days of low-dose (3 g/day) creatine administration and after a loading dose (20 g/day for six days) and a pair of g/day for 1 month [30]. The elevated creatine ranges in muscle slowly return to regular after 5–8 weeks after cessation of supplementation [30]. The quantity of intramuscular creatine varies between people with vegan vegetarians having low ranges and people consuming excessive fish or meat diets having elevated ranges. The maximal muscle focus of complete creatine is about 160 mmol/kg/dry muscle weight [29]. Given {that a} muscle biopsy could be required to verify for creatine loading and that probably ergogenic elevations might be discovered for unexplained causes in some individuals (genetic variations in creatine transport capability) or in these consuming excessive quantities of fish or meat, creatine supplementation shouldn’t be on the World Anti-Doping Company banned record.
Creatine Supplementation and Train Efficiency
Dash and high-intensity train efficiency depends closely on the creatine-phosphocreatine system within the first 10 s of contraction (for a evaluation, see Terjung et al. [5]). Based mostly on the well-known temporal power buffering capability of this method, the logical speculation was that if creatine shops might be elevated, there might be a prolongation of anaerobic power supply in short sprinting exercise. The benefit of the phosphocreatine system is that power may be supplied at a fast charge and, in distinction to anaerobic glycolysis the place lactate is produced, the proton is definitely buffered from this response (fig. 1). The preliminary research have been centered on high-intensity biking for 10–30 s and a number of other confirmed a slight enhance in energy output throughout this time interval [31,32,33] (for critiques, see Kreider [4] and Terjung et al. [5]). The advance in high-intensity biking efficiency was within the order of 1–2% in lots of research, and that is significantly obvious with repetitive sprinting exercise in a laboratory setting (for critiques, see Kreider [4] and Terjung et al. [5]). Though a few % enchancment could appear pedestrian, it must be famous, nevertheless, that the distinction between the first and eighth in lots of sprinting occasions on the Olympic stage is lower than a fraction of a proportion and an enhancement of 1% might imply the distinction between a gold medal and never even making the ultimate. There have been an enormous variety of research evaluating biking, swimming and a bunch of different high-intensity sporting actions with most, however not all, displaying a slight however statistically vital and physiologically related enchancment in efficiency [34,35] (for a evaluation, see Kreider [4]).
Most research have additionally reported an acute enhance in fat-free mass after 5–7 days of creatine administration (for a evaluation, see Terjung et al. [5]). We’ve discovered that this impact is larger in males versus girls and the impact in males is roughly 1.5 kg [36]. This acute enhance in fat-free mass is because of a rise in intracellular water; nevertheless, together with resistance train coaching, the rise in fat-free mass is expounded to a rise in muscle mass. In reality, the overwhelming majority of research which have evaluated the co-administration of creatine plus resistance train have demonstrated better enhancements in fat-free mass and a few measures of power as in comparison with resistance coaching and placebo in each younger [37,38,39,40] and older [41,42,43] adults (for a evaluation, additionally see Terjung et al. [5]).
Conceptually, one wouldn’t count on a rise in endurance efficiency from creatine loading, and the rise in fat-free mass might be ergolytic in weight-supported actions corresponding to operating or climbing in biking. In distinction to the pretty constant proof displaying that acute creatine supplementation can improve high-intensity sprinting efficiency, most research exhibit no convincing proof for an ergogenic impact from creatine loading (for a evaluation, see Terjung et al. [5]). In reality, one subject examine confirmed that creatine administration worsened train efficiency in a cross-country run [44].
Creatine Supplementation and Facet Results/Well being Points
There is no such thing as a complement within the historical past of the world that has acquired extra unhealthy press within the lay literature than creatine. Maybe one of many causes is that there’s a small proportion, however quantitatively massive quantity, of power/energy athletes who’re prone to taking actually harmful anabolic medicine and when any unfavourable well being penalties happen with them, they search for a extra acceptable scapegoat. One other situation I’ve seen is that the phrase ‘supplement’ has a unfavourable connotation and other people generally love unhealthy press. For instance, I used to be very shocked when the Lancet and the New England Journal of Drugs readily revealed anecdotal case reviews of ‘side effects’ from creatine supplementation [45,46]. The Lancet paper was on an athlete reportedly taking creatine who had pre-existing renal failure [46], and the New England Journal of Drugs paper reported {that a} younger man bought interstitial nephritis after 30 days of creatine supplementation at 20 g/day) [45]. The topic within the former examine was additionally taking the drug cyclosporine, which is a widely known nephrotoxic agent, and but they concluded that creatine, and never the apparent wrongdoer cyclosporine, was the trigger. The latter publication indicated that the individual was additionally taking nonsteroidal inflammatory medicine, that are one of many main causes of interstitial nephritis in younger wholesome males. A part of the confusion seemingly comes from the usage of serum creatinine as a marker of renal perform. Creatine and phosphocreatine are nonenzymatically transformed to creatinine inside the cell. Since many of the physique’s creatine is saved contained in the muscle, there’s a pretty constant relationship between 24-hour urinary creatinine excretion and muscle mass (1 g creatinine in approx. 20 kg of muscle). If there is a rise in creatine consumption and creatine shops enhance, there’s a proportionate enhance in plasma creatinine because of the enhance in supply to a pool with a usually functioning nephron. Potential research utilizing creatine for as much as 5 years in wholesome individuals [47,48,49,50] and people with illness [51,52] have uniformly proven no opposed results of creatine supplementation on renal perform.
One other very fascinating situation was the press that was unfold all over the world quickly stating that creatine causes most cancers. An investigative report on this anecdote on a French meals company web site was touted as a ‘clinical trial’ by some information businesses and it was subsequently proven that this ‘report’ was a hyperbole of a extremely theoretical hypothesis based mostly upon nonphysiological natural chemistry involving cooking creatine, creatinine and sugars at excessive temperatures for lengthy durations [53]. In reality, individuals are at a far better danger from this course of taking place after they charcoal barbeque meats. Sadly, the stability of proof for unfavourable press is slim to none and these anecdotes seem to supersede the publications actually evaluating potential unwanted effects (for a evaluation, see Terjung et al. [5]).
One other anecdotal ‘side effect’ I hear nearly day by day is that, ‘…creatine will damage your liver’. I’m nonetheless unsure the place this comes from besides maybe from a report stating that liver transaminases have been a bit larger in American soccer gamers taking creatine [40]. Once more, this misinterpretation relies upon a lack of information of physiology for these athletes have been additionally lifting extra weights and consequently had larger creatine kinase values, and other people typically overlook that AST and ALT are additionally present in excessive abundance in skeletal muscle and can’t be used as a marker of hepatocellular injury within the presence of a excessive creatine kinase stage. We’ve discovered that for some motive, creatine monohydrate triggered liver irritation in mice, however not rats [54]. We and others have used γ-glutamyltransferase and bilirubin as non-muscle markers to obviously present that acute and intermediate (6 months) creatine supplementation had no impact in youthful and older people [36,43,50], or these with neurological issues [49,52].
There was some concern that since creatine supplementation led to a rise in intracellular water that this might end in dehydration in athletes. In distinction, a number of research have evaluated this idea and located it to not be true and the consensus is that no dehydration happens [55]. Some, however not all, research have discovered that creatine supplementation triggered gastrointestinal upset. We’ve accomplished many randomized, double-blind research utilizing creatine and have discovered that about 5% of all topics expertise some gastrointestinal upset. Nevertheless, we have now additionally noticed that this facet impact is normally associated to not dissolving creatine and taking it on an empty abdomen, and that is nearly invariably eradicated by dissolving or mixing it properly (i.e., in yoghurt or different viscous meals) and taking it in divided doses at breakfast and supper.
There are an rising variety of papers displaying that creatine supplementation could have a useful impact in a variety of issues together with muscular dystrophy, polymyositis, regular getting older, Parkinson’s illness, Huntington’s illness, mind hypoxia (stroke, cerebral palsy), and congestive coronary heart failure [56,57]. We and others have discovered that creatine supplementation can enhance power and fat-free mass in kids and adults with muscular dystrophy [51,58], and this was confirmed utilizing a meta-analytical strategy [59].
Conclusion
For an athlete wishing to take creatine or caffeine as an ergogenic assist you will need to take into account many components. Firstly, you will need to attempt something that you just want to soak up competitors in coaching to see how your physique reacts to the substance in query. Secondly, though neither creatine nor caffeine are ‘banned’ substances, you will need to verify with present WADA tips for ANY substance {that a} high sport athlete consumes. Thirdly, analysis research report the common response and inside the inhabitants there are responders and nonresponders; consequently, if one thing doesn’t seem to give you the results you want, don’t take it.
Scientifically, the stability of the proof signifies that the consumption of caffeine at 2–6 mg/kg earlier than train or 0.75–2.0 mg/kg throughout train will improve endurance train efficiency. There is no such thing as a sturdy proof that caffeine consumption will improve high-intensity dash or power efficiency, however actually no proof that it might hurt efficiency. Some athletes, particularly those that are nonhabitual caffeine customers, could expertise some gastrointestinal upset, pre-exercise diuresis or tremor that will inhibit efficiency. For routine caffeine customers, it might seemingly not be smart to withhold caffeine within the 8–12 h earlier than train for the withdrawal unwanted effects (headache) could inhibit efficiency.
The stability of the proof means that creatine loading (5 g 4 occasions a day for 4–5 days OR 3 g/day for 30 days) will improve repetitive high-intensity dash efficiency and should improve efficiency in sports activities with high-intensity bursts of energy. Moreover, most research do present that creatine administration enhances the power and muscle mass positive factors throughout a resistance train program as in comparison with placebo (no less than over the primary 4–6 months of a coaching program). There is no such thing as a convincing proof that there’s an ergogenic profit from creatine loading for endurance athletes. Some athletes (approx. 5%) expertise gastrointestinal upset with creatine administration.
Though there’s little rationale for taking each caffeine and creatine concurrently as ergogenic aids, some have reported that the acute consumption of each negated the ergogenic advantages [60].
Disclosure Statemement
Dr. Tarnopolsky is the co-founder and chief scientific officer of Life Sciences Nutritionals (we don’t make any merchandise containing both caffeine or creatine).
“creatine as an ergogenic aid”