The Impact of Sibling Presence on Motor Competence and Physical Fitness: A Systematic Review

Objective: This systematic review examined whether siblings act as facilitators or barriers to children's motor competence and physical fitness. Methods: Following PRISMA guidelines, systematic searches were conducted in four databases (Web of Science, Scopus, SPORTDiscus, and MEDLINE/PubMed) up to September 2025. Results: Seventeen studies (total n = 116,827) met eligibility criteria. Eleven studies were rated fair quality and the remainder poor. Twelve studies assessed motor competence, four assessed physical fitness, and one addressed both. Children with older siblings often showed better coordination and motor skills, whereas some evidence indicated earlier gross motor development in only children and no consistent differences in fine motor skills. The presence of younger siblings was associated with lower motor skill scores in infants, while older siblings were linked to higher scores. Across motor competence outcomes, the available evidence is concentrated in object control and fine/hand motor skills, with comparatively fewer data on locomotor and stability domains. Regarding physical fitness, siblings generally exerted a positive influence across several dimensions, but these findings are based on a small number of studies, and results for cardiorespiratory fitness are conflicting. Conclusions: Given the heterogeneity in ages and measurement tools, along with the predominance of methodological constraints, readers should interpret the findings with caution. In summary, the available evidence suggests that having siblings may be associated with higher motor competence and some aspects of physical fitness, yet the certainty of evidence is limited by heterogeneity (age ranges and measurement tools) and methodological constraints.