Abstract
Lung growth as determined by changes in lung volumes in adolescent men aged 17-19 years is poorly documented in the literature. This study was designed to investigate lung growth in a population of shipyard workers. One hundred and ninety eight apprentices participated in a longitudinal study. Lung volumes including FRC by helium dilution and anthropometric measurements including thoracic dimensions were obtained. In this growing population, lung growth exceeded the growth in stature. The subdivisions of TLC showed a greater increase in FRC than IC and was shown not to be due to lowering of the diaphragm. Lung growth was associated with an increase in the thoracic dimensions which contributed to the description of lung size in this age group. To determine whether the elastic properties of the respiratory system may have contributed to the change in the thoracic dimensions and lung growth, a cross-sectional study was undertaken. Two subgroups of men were selected from the longitudinal study; one group had large lung volumes, the other small lung volumes. Static lung compliance and elastic recoil were measured and tracheal dimensions obtained from chest X-rays. The level of physical activity reported by each individual was not associated with their lung size; neither was their respiratory muscle strength as measured by maximal respiratory pressures. Lung growth was not associated with changes in lung elasticity, although men with larger lungs did have more distensible lung tissue. There was no correlation between lung and tracheal size in agreement with the concept of dysanaptic growth (r = 0.16; p > 0.05) It was concluded that growth of the chest wall, with the consequent increase in thoracic dimensions, was accompanied by an increase in lung volume (r = 0.52; p < 0.05). The lung developed within the enlarged thoracic cavity by actual tissue growth rather than expansion of existing structures.