Aerobic Capacity and Exercise Performance in Young People Born Extremely Preterm

Abstract

The exercise capacity of a child may be described as the amount of sustainable physical exertion in a given activity. The aerobic capacity of the individual, commonly referred to as the maximally attainable oxygen consumption, may limit exercise capacity. Children and adolescents born extremely preterm have several developmental shortcomings that may reduce exercise capacity and ability to participate in physical activities in later life. The few studies examining exercise capacity after preterm birth used different test methods and had diverging results, with limited conclusions. The aim of this study was to compare aerobic capacity and exercise performance of children and adolescents born extremely preterm versus at term, and to relate the findings to selected perinatal and medical variables and to lifestyle factors. Children and adolescents born extremely preterm were studied in 2 different decades to address potential cohort effects. The study group included 2 population-based cohorts of subjects born at gestational age ≤28 weeks or with birth weight ≤1000 g in the years 1982–1985 and 1991–1992 in Norway. Standardized maximal treadmill exercise and pulmonary function tests were performed in 2002 in both the study group and comparable matched control subjects born at term. Background data were obtained from medical records and questionnaires. For the 1982–1985 cohort, 40 preterm and 40 control subjects were assessed; for the 1991–1992 cohort, 35 preterm and 35 control subjects were evaluated. Mean ages at examination were 17.6 years and 10.6 years for the 1982–1985 and 1991–1992 cohorts, respectively. Differences in measures of aerobic capacity between the preterm and term-born cohorts were not statistically significant. There was a modest (10%) but statistically significant reduction in average running distance among the preterm subjects. A similar and positive association between leisure-time physical activity and exercise capacity was found for both preterm and term-born adolescents; however, participation was lower in preterm subjects compared with control subjects. The association between leisure-time physical activity and exercise capacity was not observed in the 10-year-old subjects. There was no relationship between exercise capacity and either neonatal bronchopulmonary dysplasia or current forced expiratory volume in 1 second. During the 2 decades studied, differences had not changed between subjects born preterm and at term. These findings indicate that subjects born preterm can achieve normal exercise capacity and that their response to physical training may be comparable with peers born at term.