Physical Activity and Metabolic Alterations in Children and Adolescents Across Different Weight Groups: A Systematic Review.

Inadequate physical activity (PA) and increased sedentary time are key drivers of cardiometabolic disorders related to being overweight, and metabolomics offers a promising novel approach to study their associations. The aim of this systematic review was to assess the evidence on metabolites associated with PA and/or sedentary time among children and adolescents in different weight groups, integrating both intervention and observational studies to provide a comprehensive and broad synthesis of existing evidence. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, three databases (PubMed, Web of Science, and Scopus) were systematically searched for studies published from inception to December 2023 conducted in children and adolescents aged ≤ 18 years including metabolomics analyses focusing on PA, sedentary time, or cardiorespiratory fitness. Fifteen studies were included, and half of the studies were conducted in overweight individuals. Notable PA-induced or PA-associated alterations were seen in lipid, branched-chain amino acid and ammonia metabolism, and the citric acid and glucose-alanine cycles. The directions of the alterations seemed consistent across children and adolescents with normal body weight and overweight, but not in trained peers. Several metabolites and metabolite groups were identified as markers of higher PA and better cardiorespiratory fitness, reflecting favorable metabolic states in children and adolescents. However, there is still a great need for more in-depth metabolomics studies using state-of-the-art techniques in the fields of pediatric exercise science and public health. Training status, exercise modalities, and pubertal development are important covariates to consider in future studies.