Creatine is one of the most demanded supplements in recent years, and it is also true that creatine is one of the ergogenic aids with the highest number of scientific publications. Today, it is estimated that more than 2.5 million kilograms of creatine are consumed with sales exceeding 200 million dollars. The turning point came in the 1990s, when several top athletes confessed to creatine supplementation.

More than 75% of American football players regularly consume creatine and 90% of weightlifters and bodybuilders consume creatine monohydrate. But even athletes such as Linford Christie, who won the gold medal in the 100m sprint at the 1992 Barcelona Olympics, or the swimmer Mark Andrew Foster have publicly stated that they consume creatine.

What is Creatine?

Creatine was discovered in 1835 by the French scientist Chevreul, and the name derives from the Greek word kreas (meat). But due to problems in detection, it was not until 1847 that Liebig was able to confirm the presence of creatine as a constituent of meat.

At the beginning of the 20th century, research into creatine intake began. These early studies showed that not all of the creatine ingested was eliminated in the urine, indicating that the body retained some of it. In 1923, Hahn and Meyer estimated the total creatine content of a 70 kg man to be approximately 140 g.

The creatinecreatine, also called α-methyl guandine-acetic acid, is a nitrogenous amino acid. Endogenous creatine synthesis consists of three amino acids: glycine, arginine y methionine. Endogenous creatine synthesis is 1-2 g/d, and is mainly produced in the liver and in second place in the pancreas and the kidney. Approximately 1-2 g/d of creatine is obtained from dietary intake, mainly from fish and meat.

Daily creatine demands are met by intestinal absorption of creatine from the diet and by de novo biosynthesis of creatine. Creatine will therefore originate from the liver and intestine, accumulating in tissues containing creatine kinase (CK). The 90% of creatine enters skeletal muscle via a transporter protein, in a mechanism mediated by Na+ K+ ATPase dependent on the extracellular concentration of Na+ and Cl-.

In resting muscle cells, creatine is phosphorylated by creatine kinase (CK) to form PCr. To this end, ATP formed by glycolysis and oxidative phosphorylation reacts with creatine to form ADP and PCr.

• In resting muscle cells, creatine is phosphorylated by creatine kinase (CK) to form PCr. To this end, ATP formed by glycolysis and oxidative phosphorylation reacts with creatine to form ADP and PCr.

• During the exerciseWhen muscle ATP is consumed, the high-energy phosphoryl group of PCr is transferred to ADP to restore ATP. Creatine is recycled or transformed into creatinine (Crn).

The daily creatine requirement for a 70 kg person is considered to be around 2g. A person following a Mediterranean diet usually ingests 0.25 to 1 g per day. Crn exchange is proportional to muscle mass and increases with high intensity physical exercise.

Approximately 95% of the total mass of creatine is found in skeletal muscle, the 5% are mainly found in the heart, brain and testicles.

Cr and PCr concentrations correlate with the glycolytic capacity of the different types of muscle fibres. In this respect, the PCr content is 5-30% higher in type II fibres than in type I muscle fibres. This is in agreement with the high levels of muscle PCr observed in sprinterswhose muscles also contain a higher proportion of type II fibres. In people over 70 years of age, there is a decrease in 5% concentrations of PCr, which may be explained by the decrease in type II muscle fibres with age.

How do I take creatine to improve performance?

Several studies advocate that in principle a loading dose of 0.3 g/kg/day would be necessary. This loading dose should be maintained within four to seven days. After the loading dose, a maintenance dose of 0.04-0.07 g/kg/day should be introduced. Other authors question whether the loading dose is necessary, as the same long-term results are obtained by consuming 0.04 or 0.03 g/kg/day from the start of supplementation.

The International Society of Sports Nutrition (ISSN) supports an acute or loading phase creatine intake of approximately 0.3 g/kg/day, maintaining this loading for at least three days. It appears that the ergogenic effect of creatine decreases after periods of more than 2 months of supplementation, so a 2-4 week washout is recommended, every 6-8 weeks of supplementation.

Regarding the ideal time to take this supplement, Noonan et al. recommended, in the acute phase, during training days, to distribute the dose as follows: 25% of the dose at breakfast, 25% one hour before training and the remaining 50% just after training. On rest days it would be sufficient to divide the doses into four equal doses. Then, in the maintenance phase, a single dose would be taken just after training or with the meal on rest days. On the other hand, Antonio et al. more recently analysed the difference between an intake immediately before and immediately after training. This study concluded that creatine intake immediately after training produced better results in increasing fat-free mass, decreasing fat mass and improving 1-RM (one-repetition maximum, or maximum weight that can be lifted once) in the bench press exercise.

Nowadays, many elite or popular athletes do not perform the initial overload and usually maintain a dose of 0.1g/kg/day. This is a more convenient way of supplementing creatine, with a duration of 4-6 weeks and a week's rest.

It is recommended that supplementation be accompanied by foods rich in medium to high glycaemic carbohydrates and protein, as creatine transport is mediated by insulin.

There are different forms of creatine, but most of these forms do not show the strength or performance gains that creatine does. creatine monohydrate.

How does creatine help my performance?

The effects of creatine on sports performance are diverse and we can point out that the benefits according to the publications are:

• Firstly, we will find benefits in explosive sports, in those exercises of 2-30 seconds of high intensity and that have intermittent short breaks between sets.

• Studies show that after 5-7 days of creatine supplementation, an improvement in muscle strength and power is achieved. It should be noted that this effect has been observed more in men than in women. This may help to support a greater training load, improving physical performance in competition. In fact, a study by Claudino et al. with football players showed that supplementation with

with creatine prevented the decline in muscle power as the season progressed.

• Thanks to the osmotic effect achieved with creatine (between 0.5-1 litre of weight can be saved), a better tolerance to sports at high temperatures can be achieved.

What side effects can I get from taking creatine?

• Weight gain. Most studies, between 60 to 70%, show an increase in body weight, around 1 to 2 kg. It has been observed that this increase in body mass could only partly be attributed to the increase in water volume by 55%.

• Muscle cramps. A few studies, almost anecdotal in nature, have reported the occurrence of muscle cramps, attributing it to a potentially adverse effect on the water-electrolyte balance. However, it would be more accurate to consider that the reason for such a process is the result of increased exercise intensity.

• Digestive disorders. Some studies have shown the appearance of gastrointestinal side effects after creatine administration, such as diarrhoea, stomach discomfort and vomiting. In my experience, when diarrhoea appears in athletes, I usually lower the dose slightly and increase it very gradually.

• Alteration of liver function. Therefore, we can currently indicate that, in healthy individuals, oral creatine supplementation at usual doses does not cause significant changes in liver function tests. However, it seems reasonable to monitor liver function in individuals on a creatine supplementation regimen.

• Alteration of renal function. Some studies have shown an increase in creatinine excretion after supplementation with Cr. However, these variations were not significant. However, renal function should be monitored in individuals undergoing high doses of creatine and, in general, creatine supplementation should be used with caution in individuals at risk of renal dysfunction.

• Effects on muscle enzymes. Elevations in creatine phosphokinase have been observed in some studies, but it is possible that this was due to increased sporting activity.

Como conclusión de este post, podría deciros que la Creatina es un suplemento deportivo que presenta evidencia suficiente para su utilización en el deporte profesional y popular, para mejorar el rendimiento. La creatina es un suplemento es seguro si se utiliza a la dosis adecuada (0,1g/kg/día) durante el tiempo adecuado (4-6 semanas)  con su fase de descanso (1 semana). La aplicación de la Creatinina tiene beneficios tanto en deportes anaerobios, como aerobios.

BIBLIOGRAPHY:

"Creatine as an ergogenic supplement in athletes". Quirós-Romero, D. Bernabéu-Álvarez, C. Herrera Fajardo, L.SANUM 2022, 6(2) 64-70.

Ergogenic aids in sport. Santesteban Moriones V, Ibáñez Santos J Nutr Hosp 2017;34:204-215.

Course Pharmacology and supplementation in sport. Ergogenic aids I. Jordi Ribas Fernández 2009.

Ergogenic supplements: the evidence beyond a fad. Martorell et al. ARS MEDICA Journal of Medical Sciences Volume 46 number 2 year 2021.

Dr. Alberto Sacristán