Changes in Breathing Reserves During Growth in Healthy Untrained Boys and Girls.

Background: The assessment of breathing reserve (BR) is essential to determine if ventilatory function is limited during exercise. Few studies reported the values of BR in healthy children and adolescents of both sexes. This study aimed to analyze the effects of age and sex on changes in BR in healthy untrained children and adolescents during growth. Methods: A study was conducted in 186 healthy untrained children and adolescents (10-16 years old). Maximal ventilation ($\dot{V}$_Emax) and maximal oxygen uptake ($\dot{V}$O_2max) were measured during a maximal graded test. Forced vital capacity and forced expiratory volume in 1 s (FEV₁) were also measured. BR was expressed as a percentage of theoretical maximal voluntary ventilation (MVV) which was obtained by multiplying FEV₁ by 35. The data were assessed by one-way analysis of variance (ANOVA) and two-way ANOVA supplement a Newman-Keuls test when P was significant (P < 0.05). Results: Height, weight, and lean body mass increased between 11 and 16 years old. For boys,$\hspace{0.17em}\dot{V}$O_2max, $\dot{V}$_Emax, FEV₁, and MVV increased (P < 0.05) between 12 and 16 years. For girls, $\dot{V}$O_2max increased (P < 0.05) only between 11 and 12 and 14 and 15 years. Increases in $\dot{V}$_Emax, FEV₁, and MVV were observed between 10 and 12 years and stabilized afterward. The BR in girls was higher than in boys (P < 0.05). There were no significant differences in BR at the same age correlated with sex during growth. Discussion: No significant changes were observed in BR as a function of age. BR changes during growth seem to be independent of changes in anthropometric characteristics.