Women have smaller lungs and reduced expiratory flow rates compared to men. Also, women exhibit disproportionately smaller airways in relation to lung size (dysanapsis) compared to men. It is not known, if dysanapsis occurs during puberty. PURPOSE: To determine if the airways and lungs grow disproportionately during puberty in boys and girls. We hypothesized that during puberty dysanapsis would occur and boys would exhibit more dysanaptic growth compared to girls. METHODS: Nineteen pre-pubescent children (10 boys; 9 girls) performed pulmonary function tests (PFT) from a previous published study (Swain et al. 2010) ~5 years ago. These 19 children were recently recruited to perform follow up PFTs. PFTs included forced vital capacity (FVC) and forced expiratory flow at 50% (FEF50). Static pressure at 50% of FVC (Pst(l)50%)was estimated based on age (DeTroyer et al. 1978). Dysanapsis ratio was calculated (FEF50xFVC-1xPst(l)50%-1). Maturation was determined via Tanner stages. RESULTS: During puberty, boys were significantly more mature (4.1 ± 0.6 stage vs. 3.6 ± 0.5 stage, respectively) compared to girls. FVC and FEF50 increased (p<0.05) and FEF50/FVC and DR significantly decreased during puberty. FEF50 and FVC significantly increased and DR decreased (p<0.05) during puberty for both boys and girls. During puberty, boys had a significantly decreased FEF50/FVC compared to pre-puberty, while during puberty the FEF50/FVC of girls was not different (p>0.05) compared to pre-puberty. During puberty, boys had significantly larger FVC, but FEF50, DR, and FEF50/FVC were not different (p>0.05) compared to girls. Lastly, airway conductance (FEF50/Pst(l)50%) during puberty was not different (p>0.05) between boys and girls during puberty. CONCLUSION: These data suggests that dysanaptic growth occurs during puberty. In addition, the growth of the airways for boys lags behind the growth of the lungs during puberty compared to girls suggesting a sex difference in dysanaptic growth during puberty.

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