Ventilatory variables in normal children during rest and exercise

The aim of this study was to provide a complete description of normal venti lation at rest and exercise in children and to determine how best to correc t for body size. One-hundred and six children aged 8-17 years (55 male) underwent incrementa l bicycle exercise testing from rest to exhaustion in 3 min, 15 W.m(-2) ste ps and thence through 9 min recovery. All variables were calculated using h elium dilution mixed expired gas analysis together with measures of alveola r gas concentrations from continuous measurement at the mouth, all via an A MIS 2000 quadrupole mass spectrometer. Surface area was the best single measure to correct for body size but alway s explained <37% of the variance. Thus for example, surface area corrected oxygen consumption at rest in males was greater than females. Data is prese nted at rest, each work load and at "maximum" exercise. When presented per watt of work at each work load, this permits comparison of adaptability to exercise between sexes and age groups. Exercise appears to terminate when r espiration reaches 45 and 40 breaths.min(-1) in males and females respectiv ely and when alveolar oxygen concentrations rise. This simple protocol and near complete data set ought to permit accurate co mparison with disease groups.