School-aged children who were very premature may exhibit reduced exercise capacity despite having near-normal lung function, researchers from Australia report in the August issue of Pediatrics.
Dr. Lucia Jane Smith from Children's Hospital at Westmead, Sydney, and colleagues assessed the lung function and fitness of 126 children (mean age, 10) who were born weighing less than 1,000 grams before 32 weeks' gestation in 1992-1994, as well as in 34 term-born age-matched control children.
"The most striking finding in this study," the investigators say, "was that the exercise capacity of children who were born very preterm was half that of term-born control subjects despite the fact that mean values of lung function of these children were within the reference range."
The premature group, relative to the term group, had a significantly lower forced expiratory volume in 1 second (FEV1) -- 85% vs 95% predicted -- and a significantly higher mean percentage of predicted residual volume -- 141% vs 99%.
Exercise capacity was assessed by the 6-minute walk and the 20-meter shuttle run. There was no difference between groups on the 6-minute walk test.
However, "the mean completed shuttle stage reached by the preterm group was 48% lower than the shuttle stage reached by the control group (2.8 vs. 5.6)," Dr. Smith and colleagues found.
They concluded that these findings demonstrate significant impairment in exercise capacity in school-aged children who were very premature, despite evidence of only mild small airway obstruction and gas trapping.
The impaired exercise capacity, they point out, seems to be "out of proportion to the degree of airflow limitation." Why this is so, "and whether it can be improved with a training program," requires further study.
Reuters