Creatine is a nonessential dietary component that, when supplemented in the diet, has shown physiological benefits in athletes, in animal-based models of disease and in patients with various muscle, neurological and neuromuscular disease. (1)
Creatine is made in the body from the amino acids Arginine, Glycine and Methionine. This accounts for about half the body’s requirements. The balance is obtained from food, mainly fresh fish and meats. Almost 95% of it is stored in the skeletal muscles and the rest of it is stored in the brain, heart, testes and cells of other organs in the body.
The distribution of creatine throughout the body is largely determined by the presence of creatine transporters. These transporters not only serve to distribute creatine but serve as a clearance mechanism because of creatine 'trapping' by skeletal muscle. Creatine clearance also depends on renal elimination and degradation to creatinine. Other dietary components such as caffeine and carbohydrate can potentially affect pharmacokinetics by their influence on the creatine transporter. Disease and age may also affect the pharmacokinetics, but more information is needed. (1)
The body has its own ‘energy currency’ called ATP (Adenosine Tri Phosphate). This high energy molecule, ATP, is used for almost all the functions requiring energy expenditure. When ATP is used for energy expenditure, a phosphate is removed and it converts back to ADP (Adenosine Di Phosphate). Within the cell, Creatine exists as phosphocreatine and readily donates phosphorus to the low energy ADP and converts it back to the high energy ATP. This happens in the mitochondria where food is oxidized and converted into energy or ATP.
In a subject of 70 kg with a total creatine pool of 120 g, the daily turnover is approximately of 2 g. Exercising individuals and vegetarians may need higher amounts of Creatine as a supplement for Muscle Hypertrophy.
Creatine Supplementation EffectsCreatine administration increases creatine and phosphocreatine muscle concentration, allowing for an accelerated rate of ATP synthesis.Creatine enhances the possibility to maintain power output during brief periods of high-intensity exercises.Creatine supplementation in conjunction with resistance training augments gains in muscle strength and size.Increases in muscle fiber hypertrophy and myosin heavy chain expression have been observed with creatine supplementation.
Creatine supplementation increases acute weightlifting performance and training volume, which may allow for greater overload and adaptations to training.
Creatine supplementation may also induce a cellular swelling in muscle cells, which in turn may affect carbohydrate and protein metabolism. A carbohydrate or carbohydrate/protein-induced insulin response appears to benefit creatine uptake. (2)
Creatine supplementation affects muscle glucose metabolism in humans by increasing muscle glycogen storage.
In resting conditions and at high dosages (20 g) Creatine enhances Growth Hormone secretion, mimicking the response of strong exercise which also stimulates GH secretion (variable between individuals). For the majority, maximum Growth Hormone concentration occurred between 2 hrs and 6 hrs after the acute Creatine ingestion. (3)Creatine has a consistent ergogenic effect, particularly with exercises or activities requiring high intensity short bursts of energy. (4)
The increase in lean body mass often reported after creatine supplementation could be mediated by signaling pathway(s) involving IGF and 4E-BP1. (5)Creatine supplementation in combination with strength training amplifies the training-induced increase in satellite cell number and myonuclei concentration in human skeletal muscle fibres, thereby allowing an enhanced muscle fibre growth in response to strength training. (6)
Creatine supplementation (5gm/ day for 6 weeks) had a significant positive effect on both working memory (backward digit span) and intelligence (Raven's Advanced Progressive Matrices), both tasks that require speed of processing. These findings underline a dynamic and significant role of brain energy capacity in influencing brain performance. (7)
Resistance training of 12 weeks increases bone mineral density in older men (Age 71 years) and creatine supplementation (0.3 g/kg creatine for 5 d and 0.07 g/kg thereafter) may provide an additional benefit for increasing regional bone mineral content. The increase in bone mineral content may be due to an enhanced muscle mass with creatine, with potentially greater tension on bone at sites of muscle attachment. (8)
Creatine DosageCreatine dosage is a hotly debated aspect and various regimens are suggested. Human data are primarily derived from three types of studies: a) Acute studies, involving high doses (20 g/d) with short duration (< or = 1 week)b) Chronic studies involving lower doses (3-5 g/d) andc) Longer duration (1 year), or a combination of both. (4)
There appears to be a general consensus for using a loading dose of 0.3 gms / kg bodyweight for 5 days, followed by 0.03 gms / kg bodyweight thereafter for varying periods.
In a 6 weeks study, it was found that after loading 20 gm/day Creatine for 5 days, the Creatine levels can be maintained for 6 weeks with a maintenance dose of 2-5 g /day. If no Creatine was given as maintenance, the levels were much lower, but still remained higher than baseline (the levels before the loading dose). Glucose plus Creatine (but with a much smaller glucose intake than currently accepted) is potentially the most effective means of elevating total Creatine accumulation in human skeletal muscle. (9)
Creatine Supplement TimingIn a 10 weeks study in Australia, it was demonstrated that PRE and POST Workout supplementation with Creatine, Whey and Glucose showed greater increase in Lean Body Mass as compared to a Morning and Evening dose of the same quantity of supplements. The PRE and POST regimen also resulted in higher muscle Creatine and glycogen values after the training program. (10)
Most bodybuilders and athletes can get good results by taking Creatine and Glucose after a workout. This helps to reload glycogen into the muscles and speeds up recovery.
Those looking for more power during a weight training session can take Creatine pre workout also. However the increased power lasts only for a few seconds during the heaviest lifts.
Creatine SafetyTill recently there were many doubts about the safety of Creatine as a supplement. However recent clinical trials have confirmed the safety of Creatine for both short term and long term use. We have quoted below from some of the published reports:a) Trial of 310 days at a dose of 10g /day “Long-term supplementation of creatine did not lead to an increase of plasma urea levels or to a higher prevalence of micro-albuminuria.” (11)
b) Effective and safe ergogenic aid (long term use) “in healthy subjects, oral supplementation with creatine, even with long-term dosage, may be considered an effective and safe ergogenic aid” (12)
“In fact, most reports on side effects, such as muscle cramping, gastrointestinal symptoms, changes in renal and hepatic laboratory values, remain anecdotal because the case studies do not represent well-controlled trials, so no causal relationship between creatine supplementation and these side-effects has yet been established.” (12)
c) Does not affect Kidney Permeability (21 gms / day for 14 days) “This investigation shows that short-term, high-dose oral creatine supplementation enhances the excretion of potential cytotoxic compounds, but does not have any detrimental effects on kidney permeability. This provides indirect evidence of the absence of microangiopathy in renal glomeruli.” (13)
d) No adverse effect on Kidney and Liver functions with long term use (0.25 to 5.6 years in American Football Players) “Oral supplementation with Creatine Monohydrate (5 to 20 g) has no long-term detrimental effects on kidney or liver functions in highly trained college athletes in the absence of other nutritional supplements.” (14)
Common Adverse EffectsMost commonly reported adverse effects are nausea, gastro intestinal discomfort, diarrhoea and water retention. However, in a double blind placebo controlled trial of Creatine Monohydrate and Placebo, no significant differences in the adverse events were noted. (11)
ConclusionIn summary, the predominance of research indicates that creatine supplementation represents a safe, effective, and legal method to enhance muscle size and strength responses to resistance training. (2)References
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