Physical activity at 9-12 months and fatness at 2 years of age.

Previous research has shown that physical activity in early infancy does not predict later fatness, whereas in preschool children, such a relationship is found. The objective of this study was to investigate whether total energy expenditure (TEE) and behavior in late infancy are related to subcutaneous and total fatness in early childhood. Twenty-six infants were studied at 9-12 months and followed up at 2 years of age. Anthropometry, body composition, TEE, and behavior were measured in late infancy; skinfold thicknesses and total body fat were measured at 2 years of age. Infant TEE adjusted for fat-free mass was not related to later fatness. Infant behavior was related to later subcutaneous fatness, but not to total body fatness. Lower levels of infant activity were associated with greater skinfold thicknesses in childhood. Thus, by late infancy, physical activity level is related to subsequent skinfold thickness. Particular aspects of infant behavior appear to be more important than the sum of energy expended on activity. However, the relationship did not extend to total body fat.