Effect of creatine on athletes

Abstract

Creatine is an amino acid. The vast majority is stored in skeletal muscle, and the form of storage in muscles is phosphocreatine (1, 2). Food sources of creatinine include meat and fish (1). An average 70-pound young man has a creatine pool of between 120 and 140 g (3), which varies according to muscle fiber type and muscle mass. Creatine is produced endogenously in the body. The place where it is most produced is the liver and kidneys (3). The increase in creatine use first started in Barcelona with the expression of the increased performance of Olympic athletes as a result of creatine supplementation (4). In a survey of 2100 athletes, it was determined that creatine use was most common in wrestlers with a rate of 29% (2). Even if no side effects are observed in creatine supplementation at appropriate doses, caution should be exercised about dehydration, venous thromboembolism (2, 1). Caution should be exercised in long-term use, especially in individuals with kidney and liver disease (1). Although it is stated that kidney dysfunction may occur with excessive creatine load in contradiction with this information; No decrease in glomerular filtration rate was observed in individuals who received five-year creatine supplementation (5). Creatinine has the ability to increase the volume of urine. The reason for this situation is explained as being due to its osmotic effect. Therefore, high fluid consumption is recommended in athletes using creatine (2).

Some of the benefits of creatine are; Increasing muscle strength, increase in muscle mass, strength adaptations (18). Creatine supplementation is recommended for use in short-term maximum-intensity exercises and anaerobic exercises, and during heavy exercise to conserve energy and gain strength (17,26). In addition, an increase in muscle strength with creatine supplementation is observed in both athlete individuals and non-athletes (18). The appropriate period for creatine supplementation is between 28 days and 10 weeks (3). The increase in muscle performance with creatine loading is explained in two ways: first, obtaining more phosphocreatine provides energy for short-term, high-intensity exercises such as sprinting, throwing-jumping and weightlifting by accelerating ATP regeneration. Latter; Phosphocreatine facilitates the passage of intracellular hydrogen ions required for lactate production, thus reducing fatigue (1). The daily amount of creatine taken with the diet is 1-2 g/day, and this amount saturates muscle creatine stores by 60-80% (4). A loading dose of creatine is usually used before daily dosing. Commonly accepted loading dose method: 20-25 g/day (1) for 5-7 days. In creatine supplementation, it affects the increase of intramuscular creatine depending on the initial levels of creatine stores (8). To achieve positive results after creatine supplementation, 0.03 g/day is recommended for 4-6 weeks (9). The creatine usage protocol is the use of 2-5 g/day of creatine for a total of 20-30 g for 4-5 days (11). Although long-term study results remain unclear, the safe long-term dose is stated to be 5g/day (10).

Potential ergogenic benefits of creatine supplementation: Increased single and repetitive sprint performance, increased work performed during maximum effort muscle contractions, increased muscle mass and strength adaptations during training, improved glycogen synthesis, increased anaerobic threshold, possible enhancement of aerobic capacity by increased binding of ATP from mitochondria , increased work capacity, improved recovery, greater training tolerance (18). In these two separate studies, a creatine supplement study was conducted on a sample group of 34 untrained men and a creatine supplement study was conducted on a sample group of 30 healthy individuals; Positive results have been obtained in exercise performance (14,15). The results of creatine studies conducted on veteran athletes, who have been training regularly throughout their lives and are generally defined as athletes over the age of 40, are quite contradictory (21, 22). While studies on veteran athletes using creatine supplements may result in negative cardiovascular outcomes, it is also observed that different results are obtained, including improved performance in exercise (22, 24). In a 14-week study conducted on healthy elderly people and 5 g/day creatine supplementation, an increase in lean body mass was observed (23). As a result of a 12-week study conducted on healthy elderly women and 5g/day creatine supplementation, it was found that there were positive effects on exercise performance along with an increase in lean body mass and muscle mass (24). In a 10-week study conducted on veteran athletes, it was determined that the group taking 0.1 g/kg creatine and 0.3 g/kg protein supplements had an improvement in lean body mass and exercise performance (25).

Different results of creatine supplementation are encountered in different sports branches. As a result of a study conducted with seventeen canoeists and creatine supplementation lasting 6 days, an increase in RM strength and a decrease in the strengthening time after optimal individual activation were observed (30). The creatine supplement research conducted with twelve taekwondo athletes lasted 6 weeks and as a result of the research, an increase in fat mass was detected (31). As a result of a 7-day study with twenty-four male football players supplemented with creatine, no significant difference was detected regarding body composition (32). As a result of the research conducted on creatine supplementation for 5 days with a sample group of 16 elite ice hockey players, performance improvement was detected (33).

Literature was reviewed for this research. The data of this research were obtained from Google Academic DergiPark and PubMed databases. The keywords used in these databases during the research were "creatine", "ergogenic support", "performance", "exercise" and "sports nutrition". As a result, studies have proven that creatine has an important place in sports nutrition and provides various benefits. When the literature is scanned, results of creatine supplement studies that give contradictory results are also encountered, and these contradictions are explained by the authors with many different claims. Many studies with large samples are needed on creatine supplementation. The studies to be conducted will contribute greatly to the literature, especially by addressing issues such as the causes of contradictory results, special groups, long-term studies, effects on various sports branches, and the positive and negative consequences of the dose to be used in creatine supplementation.