L.P.R. and V.P.L. were partly supported by the Portuguese Science Foundation (FCT), under Grant UID04045/2020. R.C. was partly supported by the Portuguese Science Foundation (FCT), under Grant UIDB/00447/2020 (unit 447). The research project was funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project TECH-Technology, Environment, Creativity and Health, Norte-01-0145-FEDER-000043.
The number of single-child families has been rising steadily in recent years, resulting in a
childhood absent of sibling relationships. Being an only child has been shown to have a negative
impact on physical fitness, somatic fitness, and motor development. In this study, we aimed to
understand how living with and without siblings can impact the motor competence of children. One
hundred and sixty-one children (87 boys, 74 girls) from 3.0 to 6.0 years of age (34 only children,
125 siblings) and with no known motor or cognitive disability were assessed using the Motor
Competence Assessment (MCA). Their standardized results on the three MCA subscales (stability,
locomotor, and manipulative) and total MCA were used to group them into high, average, and
low motor competence groups. Motor competence percentile distribution of the sibling and only
child group condition was compared using chi-square tests. Results showed a significative and
positive association between the sibling condition and the distribution between the three MC groups
(chi-square = 6.29; p = 0.043), showing that children in a household with siblings, independent of
their age and sex, show a clear tendency for developing better motor competence.
