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Creatine Monohydrate Herb Desciption: Uses, Benefits & Side Effects
Common Trade Names
Multi-ingredient preparations: Advanced Genetics, ATP Advantage, BioTech, Champion's Choice, GNC Pro Performance Labs, ISP Nutrition, Joe Weider, Labrada, Metaform, MMUSA Xtra Advantage, Muscle Tribe, Nature's Best, Universal Nutrition, VitaLife Sport Products
Common Forms
Available in effervescent powder, gum, liquid (serum, 2,500 mg [2.5 g] per dose), powder (1 tsp contains 5 g), and tablets (2.5 g, 5 g).
Source
Creatine is found in such dietary sources as red meat, milk, and fish. The human body also synthesizes endogenous creatine in the kidneys, liver, and pancreasChemical Components
Creatine is an amino acid that's synthesized from arginine and glycine. The highest levels of creatine are found in skeletal muscle, mostly in the form of creatine phosphate. High levels also occur in cardiac and smooth muscle, brain, kidneys, and spermatozoa; data suggest that creatine amounts in muscle vary.
Actions
Ingestion of creatine monohydrate increases cellular levels of creatine and creatine phosphate, which maintains high intracellular levels of adenosine triphosphate (ATP), the principal energy source for muscle contraction. As ATP stores become depleted, muscle fatigue ensues. Regeneration of ATP stores at a rate similar to that of ATP hydrolysis may delay onset of muscle fatigue. The phosphate from creatine phosphate is transferred to adenosine diphosphate, restoring ATP and releasing free creatine. Creatine phosphate also transfers ATP equivalents from within the mitochondria to the cytoplasm, where ATP is needed for cellular metabolism.
Studies of oral absorption of creatine show that it increases the plasma creatine pool. Low doses of creatine monohydrate produced only a moderate rise in plasma creatine levels, whereas higher doses resulted in a larger increase. Repeated dosing maintained plasma levels. Oral supplementation also significantly increased total creatine content of skeletal muscle, with the greatest changes in those subjects who had low initial total creatine content.
Reported Uses
Creatine is used to enhance exercise performance. It's been shown to improve short-term or intermittent high-intensity exercise performance, such as weightlifting and short-distance running.
Creatine continues to be studied in relation to many other types of exercise, including isokinetic torque; isometric force; arm, cycle, and kayak ergometer performance; high-intensity prolonged exercise; and endurance tasks at lower intensity both inside and outside the laboratory . Positive results with the use of creatine have been difficult to replicate consistently, sample sizes have generally been small, subjects range from highly trained athletes to sedentary individuals, and various doses and sources of creatine have been used in the clinical trials.
An interesting preliminary study of patients with muscular dystrophies suggests some value of creatine in improving daily activities .
Dosage
The amount of creatine ingested in a nonvegetarian diet is 2 g/day P.O. The recommended dose to achieve an ergogenic effect is a loading dose of 15 to 20 g/day P.O. taken for the first 5 days and then 5 tolO g/day P.O. as a maintenance dose. Other dose recommendations are 5 to 30 g/day P.O. or 2 to 4 g P.O. as a long-term supplement. Most clinical trials have used a dose of 20 to 25 g/day P.O. for 5 days and then measured exercise performance. Because creatine is a low-molecular-weight compound and readily excreted by the kidneys, ingestion of doses over 20 g/day P.O. is not valuable.
Adverse Reactions
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GI: abdominal pain, bloating, diarrhea.
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GU: renal dysfunction.
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Musculoskeletal: muscle spasms.
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Other: dehydration, weight gain (perhaps caused by water rather than increased muscle mass).
Interactions
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Caffeine: May reduce or abolish ergogenic effect of creatine. Avoid administration with creatine.
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Glucose: May increase creatine storage in muscle. Increase in muscle creatine accumulation because of carbohydrate ingestion may result from a stimulatory effect of insulin on muscle creatine transport. Avoid administration with creatine.
Contraindications And Precautions
Avoid using creatine in pregnant or breast-feeding patients; effects are unknown. Use cautiously in patients with renal disease.
Special Considerations
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Monitor young athletes for overuse or abuse of creatine.
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Urinary excretion of creatine does not indicate declining renal function. It correlates with the increase in muscle creatine storage seen during creatine supplementation and reflects the increased rate of muscle creatine degradation to creatinine. Renal dysfunction associated with creatine use has been reported . In both cases, renal function normalized after creatine supplementation was discontinued.
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Urge the patient with renal disease to avoid creatine supplements.
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Athletes participating in a resistance-training program may benefit from creatine supplementation because it allows them to complete workouts at a higher level of intensity and strength.
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Creatine is not on the International Olympic Committee's drug list, but some consider it in a gray zone between doping and substances allowed to enhance performance.
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Advise the patient to avoid long-term (more than 30 days) use of creatine until effects are known.
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Instruct the patient to discontinue supplementation or to take smaller daily doses if muscle spasms occur. Increased intracellular water content can lead to muscle spasms and tightened muscles. Athletes should avoid combinations of diuretics along with creatine supplements in an effort to control the water weight.
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Inform the patient that creatine is useful only for exercise that is intense and of short duration or when short bursts of strength are need in weightlifting and sprinting.
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Advise the parents of athletes who may take this agent about its action, potential adverse effects, and proper use.
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The FDA recommends that a health care provider be consulted before creatine is used.
Points of Interest
Low-dose supplementation for 30 days results in increased total muscle creatine stores at a much lower rate than aggressive and higher loading doses. Most creatine uptake appears to occur during the first few days. The kidneys readily excrete creatine not retained by tissues. Because the storage of and response to creatine are varied, 20% to 30% of patients may not respond to creatine supplementation.
A single 5-g dose of oral creatine monohydrate is equivalent to the creatine content of about 2.41b (1 kg) of uncooked steak.
Responses to a national poll of professional athletes indicated that the use of creatine is greatest with football players, with baseball players being the second largest group of professional athletes who consume creatine.
Commentary
Although studies have shown that creatine supplementation improves high-intensity intermittent exercise performance, its use in enhancing aerobic exercise or endurance exercise performance is unclear and probably insignificant. Improvement in strength is probably related to an increase in the rate of phosphocreatine resynthesis from creatine stores during recovery between short-duration, high-intensity exercise. Physical strength improvements, although statistically significant, are generally minor and beneficial only to the highly trained athlete who is engaged in specific intermittent activities. Most other forms of exercise, such as low-intensity longer-duration workouts, have revealed negative results .
Because the normal creatine content of muscle varies, response to creatine supplementation also varies. It appears that patients who start with low creatine levels benefit more from supplementation than those with higher baseline creatine levels. The long-term safety of creatine is unknown. If creatine was held to FDA drug-testing standards, it would be in phase 2 of clinical trials and not yet generally available to the public . Until further trials are conducted, use of creatine cannot be recommended.
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