JISSN | Full text | International Society of Sports Nutrition position stand: creatine ... - 0 views
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the energy supplied to rephosphorylate adenosine diphosphate (ADP) to adenosine triphosphate (ATP) during and following intense exercise is largely dependent on the amount of phosphocreatine (PCr) stored in the muscle
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Creatine is chemically known as a non-protein nitrogen
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It is synthesized in the liver and pancreas from the amino acids arginine, glycine, and methionine
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Approximately 95% of the body's creatine is stored in skeletal muscle
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About two thirds of the creatine found in skeletal muscle is stored as phosphocreatine (PCr) while the remaining amount of creatine is stored as free creatine
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The body breaks down about 1 – 2% of the creatine pool per day (about 1–2 grams/day) into creatinine in the skeletal muscle
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The magnitude of the increase in skeletal muscle creatine content is important because studies have reported performance changes to be correlated to this increase
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"loading" protocol. This protocol is characterized by ingesting approximately 0.3 grams/kg/day of CM for 5 – 7 days (e.g., ≃5 grams taken four times per day) and 3–5 grams/day thereafter [18,22]. Research has shown a 10–40% increase in muscle creatine and PCr stores using this protocol
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Additional research has reported that the loading protocol may only need to be 2–3 days in length to be beneficial, particularly if the ingestion coincides with protein and/or carbohydrate
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A few studies have reported protocols with no loading period to be sufficient for increasing muscle creatine (3 g/d for 28 days)
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Cycling protocols involve the consumption of "loading" doses for 3–5 days every 3 to 4 weeks
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Most of these forms of creatine have been reported to be no better than traditional CM in terms of increasing strength or performance
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Recent studies do suggest, however, that adding β-alanine to CM may produce greater effects than CM alone
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These investigations indicate that the combination may have greater effects on strength, lean mass, and body fat percentage; in addition to delaying neuromuscular fatigue
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creatine phosphate has been reported to be as effective as CM at improving LBM and strength
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Green et al. [24] reported that adding 93 g of carbohydrate to 5 g of CM increased total muscle creatine by 60%
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Steenge et al. [23] reported that adding 47 g of carbohydrate and 50 g of protein to CM was as effective at promoting muscle retention of creatine as adding 96 g of carbohydrate.
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It appears that combining CM with carbohydrate or carbohydrate and protein produces optimal results
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Studies suggest that increasing skeletal muscle creatine uptake may enhance the benefits of training
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Nearly 70% of these studies have reported a significant improvement in exercise capacity,
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Long-term CM supplementation appears to enhance the overall quality of training, leading to 5 to 15% greater gains in strength and performance
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Nearly all studies indicate that "proper" CM supplementation increases body mass by about 1 to 2 kg in the first week of loading
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short-term adaptations reported from CM supplementation include increased cycling power, total work performed on the bench press and jump squat, as well as improved sport performance in sprinting, swimming, and soccer
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Long-term adaptations when combining CM supplementation with training include increased muscle creatine and PCr content, lean body mass, strength, sprint performance, power, rate of force development, and muscle diameter
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subjects taking CM typically gain about twice as much body mass and/or fat free mass (i.e., an extra 2 to 4 pounds of muscle mass during 4 to 12 weeks of training) than subjects taking a placebo
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The gains in muscle mass appear to be a result of an improved ability to perform high-intensity exercise via increased PCr availability and enhanced ATP synthesis, thereby enabling an athlete to train harder
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there is no evidence to support the notion that normal creatine intakes (< 25 g/d) in healthy adults cause renal dysfunction
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no long-term side effects have been observed in athletes (up to 5 years),
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One cohort of patients taking 1.5 – 3 grams/day of CM has been monitored since 1981 with no significant side effects