See also: Effects of creatine
In recent years there has been a lot of talk about oral supplementation in creatine (creatine) and its alleged anabolic effects.
The thriving business that surrounds the world of supplements produces dozens of new products every year, promising and exceptional performances, amazing anabolic and anti-catabolic effects; in reality, only the exact knowledge of functional biochemistry can make the difference between a charlatan who recommends amazing products and a competent technician who does not sell dreams but "solid realities", to paraphrase a well-known commercial.
Synthesis and biochemistry of creatine
Creatine is an amino acid derivative - a tri-peptide to be exact - synthesized by the kidneys and liver from Arginine, Glycine and Methionine, which can also be obtained from food, especially red meat (907 g contains about 4 g).
The synthesis of creatine occurs in 2 steps:
1) Guanidine acetate is formed from arginine and glycine, a reaction catalyzed by the enzyme amidinotransferase-arginine.
2) a methyl group is transferred from the S-adenosinemethionine with guanidine acetate.
In humans, 1 kg of fresh muscle contains between 3 g and 4.6 g of creatine and 5 MMol of ATP.
Creatine is then taken from the skeletal muscles where it forms the Phosphocreatine (creatine phosphate), the high-energy phosphate compound.
The speed of the "ATPase it always depends on the reaction speed of the light "chains" of Myosin.
In addition, the body synthesizes 225g to 425g of creatine phosphate, thus up to 5 times the total synthesized ATP; therefore we are not talking about a small energy reserve.
But creatine phosphate, unlike ATP, cannot be reconverted, due to the reactivity of the group of Phosphoguanidine, in which the carboxyl group replaces the phosphate.
The cyclic compound derived from this process is the creatinine, then eliminated in the urine.
These are the functions that creatine phosphate performs inside the human skeletal muscle:
- rephosphorylates ADP more quickly
- favors a more rapid diffusion of high energy phosphates inside the cell
- contributes to the "buffer" of cellular acidosis during physical exercise
- the product of its hydrolysis plays a role in the activation of glycogenolysis and other catabolic pathways
The transport of creatine depends on the correct functioning of the "Sodium Pump", which in turn is activated by the "insulin, therefore this explains why the accumulation of creatine in the muscle increases with the concomitant ingestion of simple sugars.
Oral supplementation: how much to take ?!
According to ACSM, a dose of creatine 3g / day will have the same effect as a dose of 20g / day, obviously not in all individuals, and with concomitant carbohydrate ingestion.
In fact, most of the ingested creatine is retained by the body almost exclusively in the first days of supplementation; coinciding with retention, there is a substantial reduction in urine production in the first 3 days of supplementation, due to the biochemical peculiarity of creatine described above.
However, urinary excretion of creatine will always occur in relation to the quantity of muscle mass of the subject.
But how can it be that 3g express the same effects as 20 g?!: The amplitude of the intramuscular uptake of creatine is inversely proportional to the initial total muscle content of endogenous creatine in the individual, this means that the lower the initial concentration of creatine is , the greater the effects of the supplementation will be, remembering that the intramuscular increase of creatine is not generalized, but localized to the muscular districts solicited in exercise.
ACSM concludes by stating that 5 g of creatine accompanied by about 100 g of simple sugars (with a high glycemic index) are required for effective insulin stimulation: this simple daily "recharge" procedure ensures rapid intramuscular accumulation of creatine.
This is reduced when such supplementation occurs after prolonged exercise, due to the concomitant low insulin levels.
Creatine and exercise
Over the past 15 years, several clinicians and researchers have been dealing with the organic effects of exogenous creatine supplementation on training, with sometimes conflicting results.
According to some, supplementation delays fatigue, improves recovery capacity and increases the strength of muscle contraction during short bouts of maximal voluntary exercise; concomitant ingestion of glucose, taurine and electrolytes during training promotes large increases in fact. of upper extremity weight lifting volume and sprinting capacity.
According to ACSM, creatine supplementation does not increase maximal isometric strength, does not increase the rate of maximal strength production or performance in aerobic exercise, as recent studies confirm that creatine reduces the synthesis of IMP (Inosine Monophosphate) in human muscle. endurance exercises.
In fact, the benefits of supplementation would be evident only in short duration exercises, at very high intensity, especially if performed in succession and separated by very short recoveries.
Furthermore, a creatine supplementation would not favor aerobic performance, as in swimming or marathons, but would nevertheless produce a positive effect on short sprints rigorously performed during or after "endurance" tests.
Positive effects of creatine supplementation have also been demonstrated on F.E. (Explosive Force).
Creatine and muscle fiber
Specifically, the most comprehensive study is carried out by ACSM, with the following results:
resting phosphocreatine is 5-15% higher in type 1 fibers (STF or slow) than in type 2 fibers (FTF or fast)
during a 10-30 "" sprint exercise, the degradation rate is higher in FTF fibers than in STF fibers
in sprint recovery, STF fibers resynthesize phosphocreatine faster than FTF fibers
however, after oral supplementation, FTF fibers increase total phosphocreatine content to a greater extent than STFs
creatine supplementation is not associated with "true" hypertrophy, but increases the intramuscular phosphocreatine content by 20%, ie from 70/90 MMol to 85/105 MMol per kg of alipidic mass, also taking into account the fact that 1 g of creatine "binds" about 4Mol of ECW (Extracellular Water)
further studies have shown a relationship between muscle hypertrophy in strength exercises (Squat) and supplementation - 1.5 g / day - with 1) whey protein taken in conjunction with creatine, 2) creatine taken with sugars, 3) sugars taken individually and 4 ) whey proteins taken individually: the improvements in strength performance and the "hypertrophy of the lower train in the squat exercise" occurred only in cases 1 and 2, reinforcing the thesis according to which it is the "sugar intake is the key to optimal intramuscular uptake of creatine
a study on training and supplementation for 8 weeks of creatine - 0.25 g / kg alipid mass - in vegetarians showed that: the baseline values of phosphocreatine before the study were lower in vegetarians - 117 MMol - than in non-vegetarians. vegetarians - 130 MMol-, and that supplementation produced an increase in phosphocreatine and TC (Total creatinaeatine), an increase in strength in isokinetic work and in% 1RM at the bench press and a greater hypertrophy in STF and FTF in vegetarians than in non-vegetarians. vegetarians, to demonstrate the above, i.e. that it is precisely the pre-supplementation creatine basal values that optimize the production and intramuscular uptake of phosphocreatine
Health effects of supplementation
Creatine can cause nausea and vomiting only when taken concomitantly with other substances.
Studies of up to 5 years on the effects of creatine supplementation on the kidney have not shown a harmful increase in the rate of creatine presentation in the nephron. High creatine supplements in very short times intensify renal excretion of Urinary Methylamine And Formaldehyde, without however causing detriment to renal permeability, provided that no renal microangiopathies are present.
Studies conducted up to 4 years on the effects of creatine supplementation on the liver have not shown a relationship between liver disorders, elevated SGOT and GPT levels and creatine.
Creatine supplementation protects cardiac cells from oxidative stress in rats, lowers plasma Total Cholesterol, Triglycerides and VLDL values in humans.
Creatine decreases the neurotoxicity of Glutamate and the energy alterations in shots of "Hippocampal Anoxia"
In patients undergoing post-surgical rehabilitation with an inadequate diet, creatine supplementation increased the diameter of the STF and FTF fibers by 43%; this effect was maintained for 5 years!
In a state of potential thermal stress, it has been noted that creatine largely influences water balance, sweating and thermo-regulation; ACSM therefore recommends those individuals who train in hot / humid conditions or perform very intense exercises not to take creatine.
NB: although creatine supplementation has no side effects, this does not mean that it is harmless, and future studies will prove it.
Supplementation and sex
The various studies conducted in recent years agree that the intramuscular accumulation of creatine is not dependent on female or male sex.
Age and supplementation
Although they need further scientific and clinical explanation, studies show that older individuals do not respond to supplementation like younger people.
Finally, regarding the controversial association of caffeine to oral creatine supplementation, researchers agree that the concomitant ingestion of caffeine greatly reduces the effects of exogenous creatine.
In light of the above overview, I believe that a wise creatine supplementation advice should at least adhere to a thorough study of the basic sciences and the competence of the technician.
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