Breathing pattern and occlusion pressure during exercise in pre- and peripubertal swimmers

In two groups of young swimmers (prepubertal stage: group A; peripubertal stage: group B), the ventilatory response to graded exercise work with a cycle ergometer was studied. Ventilatory variables (ventilation, V̇E, tidal volume, VT, respiratory frequency,f, ratio between inspiratory period and total breath duration, TI/TTOT, and mean inspiratory flow, VT/TI) as well as mouth occlusion pressure measured at 100 msec (P 0.1), effective impedance of the respiratory system (P 0.1/ VT/TI), inspiratory power for breathing (Ẇ) and O 2 uptake (V̇ O 2 ) were measured during the third minute of each work load. At the same level of exercise both groups showed identical values of VT/TI, but V̇E was higher in group A individuals. This resulted from higher values of respiratory frequency with higher TI/TTOT ratios. P 0.1, P 0.1/( VT/TI) and Ẇ were also much higher during work load in group A than in perpubertal subjects. When the above results were related to the same percentage of V̇ O 2 max, P 0.1, Ẇ, respiratory frequency and duty cycle did not differ within both groups. However, V̇E, VT and VT/TI were lower in group A subjects with a higher P 0.1/( VT/TI) ratio. Further corrections of VT, VT/TI and P 0.1/( VT/TI) ratios by body weight cancelled all these differences. In conclusion, our results strongly suggest that biometric factors only determined interindividual differences in ventilatory response to exercise in prepubertal and peripubertal swimmers.