Introduction: Creatine (Cr) is an effective and safe ergogenic supplement that enhances post-exercise recovery, prevents injuries, supports thermoregulation, and provides benefits in rehabilitation, as well as spinal and cerebral neuroprotection for adults and older individuals. However, the evidence regarding its benefits in the pediatric population across various contexts has not been conclusive. Objective: Analyze the impact of different doses of Cr on physical performance and muscle function in children and adolescents in general through a systematic review of the literature. Materials and methods: This review followed the PRISMA reporting guidelines in the electronic databases of PubMed/Medline and Google Scholar. It included controlled clinical trials conducted between 1997 and May 2023 that assessed the effect of Cr supplementation on muscle function and physical performance in children and adolescents. A total of 20 studies were included. Results: The subjects included young high-performance athletes from different disciplines and children or adolescents diagnosed with pathologies affecting muscle function. Significant effects were found in athletes' physical performance and muscular function at various doses and periods of supplementation, unlike those involving a pathology, which mainly did not present improvements in these variables. Conclusions: Some reports suggest a positive effect on physical performance, specifically in young athletes. However, the Cr doses, posology, and administration protocols vary between studies.

Several chronic inflammatory processes are currently being studied in relation to other systems to better understand the regulation mechanisms and identify potential therapeutic targets. A significant body of evidence supports the role of the nervous system in regulating various immunological processes. This study investigates the relationship between pterygia and the sympathetic nervous system, focusing on their interaction in the inflammatory response and fibrogenic process. Sixteen surgical specimens of primary pterygia and four conjunctival tissue samples were examined, and their morphology was analyzed using hematoxylin–eosin and Masson’s trichrome stains. The gene expression of adrenergic receptors, as well as inflammatory and fibrogenic cytokines, was also assessed. Additionally, both adrenergic receptors and tyrosine hydroxylase were found to be localized within the tissues according to immunohistochemistry and immunofluorescence techniques. Increased expression of proinflammatory, fibrogenic, and adrenergic genes was observed in the pterygium compared to the healthy conjunctiva. Adrenergic receptors and tyrosine hydroxylase were localized in the basal region of the epithelium and within blood vessels, closely associated with immune cells. Neuroimmunomodulation plays a key role in the pathogenesis of pterygia by activating the sympathetic nervous system. At the intravascular level, norepinephrine promotes the migration of immune cells, thereby sustaining inflammation. Additionally, sympathetic nerve fibers located at the subepithelial level contribute to epithelial growth and the fibrosis associated with pterygia.