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Objectives and questions: Creatine is considered as one of the most investigated nutritional supplements worldwide and especially popular among young athletes with an estimated market value of USD 515.2 million in 2024. With nearly 67,000 publications listed on Pubmed, the European Food Safety Authority as well as the International Federation of Sports Nutrition have released recommendations that the intake is safe and effective.

Aim of this study was to perform a systematic literature review on clinical trials in healthy, young athletes taking Creatine Monohydrate in long-term with a minimum duration of 3 months.

Material and methods: A systematic literature review was performed on the 16th of September 2024 searching MEDBASE, EMBASE, PubMED and Google Scholar. The search terms were “creatine AND (sports OR athlete)” and all clinical – prospective as well as retrospective – studies were included. Inclusion criteria consisted of healthy athletes up to the age of 40 years of age, with a minimum intake of creatine of 3 months.

Results: 5,099 articles were identified, of which 405 studies looked for the effect in healthy subjects of which 363 did not meet inclusion criteria. A total of 21 articles, including 704 subjects at a mean age of 23.1±3.1 years of age were left for inclusion, of which one each focused on weight training, American football, soccer, resistance training, basketball, handball or swimmers and three on aerobic training. In the remaining 9 publications the type of sports was not specified. The follow up was on average 314.4±488.7 days.

For outcome three studies analyzed the performance such as sprint test, 8 described the fat free mass and change in body fat percentage and six studies focused on one repetition maximum. Ten studies focused their research on blood changes. One group performed muscle biopsies and showed the change in satellite muscle cells and fibres, as well as myonuclei.

Discussion and conclusions: Creatine is considered as the worldwide best investigated nutritional supplement and praised in recreational athletes with annually increasing market value and consumption. Although the literature shows no major complications it lacks to describe long-term effects such as improvement in performance or one repition maximum among young, healthy athletes.