Are muscular and cardiovascular fitness partially programmed at birth? Role of body composition

Abstract

Objective: To determine whether birth weight is associated with handgrip strength and cardiovascular fitness in adolescence and, if so, how these associations are influenced by current body composition.

Study design: A total of 1801 adolescents (983 females), age 13 to 18.5 years, from the AVENA (Alimentación y Valoración del Estado Nutricional de los Adolescentes Españoles [Food and Assessment of the Nutritional Status of Spanish Adolescents]) study were evaluated. Handgrip strength and cardiovascular fitness were assessed using the handgrip test and the 20-m shuttle run test, respectively.

Results: Birth weight was positively associated with handgrip strength in females after controlling for current age, gestational age, breast-feeding, and adolescent body mass index (P = .002), body fat percentage (P < .001), or waist circumference (P = .005), but not after controlling for fat-free mass. The associations were similar yet weaker in males. Females with high birth weight (>90th percentile) had greater handgrip strength than those with normal (10th to 90th percentile) or low (<10th percentile) birth weight, after adjusting for body fat percentage (P = .004). All of the differences became nonsignificant after adjusting for adolescent fat-free mass. Birth weight was not associated with cardiovascular fitness.

Conclusions: High birth weight is associated with greater handgrip strength in adolescents, especially in females, yet these associations seem to be highly explained by fat-free mass.