Objective: This study intended to identify pulmonary and exercise-related effects of chronic lung disease of infancy (CLD) versus prematurity (PRE) without CLD in children 5 to 7 years old who were born prematurely (24-30 weeks of gestation) with very low and extremely low birthweight of 500 to 1500 g (VLBW, ELBW).
Subjects: Seventeen CLD and 14 PRE were compared with 24 term controls (CON). The premature children had no overt manifestations of a neuromuscular disease.
Methods: Pulmonary function at rest and following exercise, and aerobic exercise performance were measured.
Results: Peak V̇O2 and maximal aerobic power were not different among the groups, but O2 uptake at a given mechanical power was higher in the CLD than in PRE and in CON (P < 0.05). At rest, forced vital capacity was significantly lower in CLD than in PRE (P < 0.05) and CON (P < 0.0005), and FEV1 and FEF25-75 were lower in CLD than CON (P < 0.0005 and P < 0.005, respectively). Exercise-induced bronchoconstriction (EIB) was more prevalent among the 2 premature groups (P < 0.05).
Conclusions: Our children 5 to 7 years old born at VLBW or ELBW, with or without CLD, have some degree of pulmonary dysfunction at rest and following exercise and a higher prevalence of EIB with no reduction in maximal aerobic exercise performance. The findings suggest that the pulmonary limitations are associated with low birthweight even in the absence of CLD. The higher O2 uptake at a given mechanical power in the CLD group may cause early fatigability during prolonged exercise, even when aerobic performance is normal.
From the *Children's Exercise and Nutrition Centre and the †Neonatology Unit, Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
Received for publication June 2004; accepted July 2005.
Supported by a grant to the Children's Exercise and Nutrition Centre, McMaster University, by the Hospital for Sick Children's Foundation, Toronto, Ontario, Canada.
Reprints: Susi Kriemler, MD, Exercise Physiology, Department of Movement Science, Swiss Technical Institute and University of Zurich, Winterthurstr. 190, 8057 Zurich, Switzerland (e-mail: email@example.com).