Changes in maximal exercise ventilation and breathing pattern in boys during growth: a mixed cross-sectional longitudinal study

The aim of this mixed cross-sectional longitudinal study covering a total age range of 11-17 years, i.e. the entire pubertal growth period, was (l)to specify the changes in maximal breathing pattern during incremental exercise; (2) to determine what parts of the changes are due to anthropometric characteristics, physical fitness and inspiratory or expiratory muscle strength; and (3) to determine if the role of these variables is identical before, during and after pubertal growth spurt. This study was conducted in 44 untrained schoolboys separated into three groups, with an initial age of 11.2 +/- 0.2 years for group A, 12.9 +/- 0.25 years for group B, and 14.9 +/- 0.26 years for group C. These children were subsequently followed for 3 years, during the same time period each year. The maximal inspiratory and expiratory pressures (P-I max and P-E max) were used as an index of the respiratory muscle strength. During an incremental exercise test, maximal ventilation ((V) over dot (E max)), tidal volume (V-T max), breathing frequency (f(max)), inspiratory and expiratory times (t(I max) and t(E max)) and mean inspiratory flow (V-T/t(I max)) were measured al maximal oxygen uptake ((V) over dot (O2max)). Our study showed that there was a marked increase with age in (V) over dot (E max), V-T max, and V-T/t(I) max, and no significant changes in f(max), t(I max) and t(E max). P-I max and P-E max showed a general trend towards an increase between 11 and 17 years. The study of the linear correlations between maximal breathing pattern and the anthropometric characteristics, physical fitness and inspiratory or expiratory muscle strength showed that, in the three groups of children, (1) lean body mass was the major determinant of (V) over dot (E max), V-T max and V-T/t(I max) and the relationships were significantly different before. during and after the pubertal growth spurt; (2) physical fitness was the main determinant of t(I max), t(E max)and f(max) before and after the pubertal growth spurt; and (3) maximal respiratory strength did not play a significant role. In conclusion, this mixed cross-sectional longitudinal study showed, at maximal exercise, a significant increase in (V) over dot (E max) during growth due only to a significant increase in V-T max and V-T/t(I max), and that the relationships of anthropometric characteristics and physical fitness with maximal breathing pattern change during growth.