Reduced Exercise Capacity in Adults Born at Very Low Birth Weight: A Population-based Cohort Study
Jun Yang, Michael Epton, Sarah Harris, L. John Horwood, Rachel A. Kingsford, Richard W. Troughton, Charlotte Greer, Brian A. Darlow
Abstract
Abstract Rationale Population-based data regarding the consequences of very low birth weight (VLBW) and bronchopulmonary dysplasia (BPD) on adult exercise capacity are limited. Objectives To compare exercise capacity in a national VLBW cohort with term-born controls and explore factors contributing to the differences. Methods At 26–30 years of age, 228 VLBW survivors and 100 controls underwent lung function tests, cardiopulmonary exercise testing, and assessment of resting cardiac structure and function using echocardiography. Data on self-reported physical activity were collected. Measurements and Main Results Compared with controls, adults with VLBW demonstrated reduced oxygen uptake, work rate, and oxygen pulse at peak exercise (9.3%, 10.7%, and 10.8% lower, respectively) and earlier anaerobic threshold (all P < 0.0001), with all mean values within normal range. VLBW survivors showed reduced physical activity, impaired lung function (reduced FEV1, FEV1/FVC, and DlCO), altered left ventricular structure and function (reduced mass, size, stroke volume, and cardiac output), and reduced right atrial and ventricular size. Adjustment for the combination of three sets of covariates (physical activity with body mass index, lung function, and cardiac structure and function) explained most of the exercise group differences. Beyond the effects of physical activity and body mass index, lung function and cardiac structure and function contributed approximately equally. BPD with other prematurity-related perinatal factors (ventilation, antenatal steroids, extremely low birth weight, and extreme preterm) were not associated with a reduced exercise capacity. Conclusions Exercise capacity was significantly reduced in adults with VLBW, which we speculate is from combined effects of impaired lung function, altered heart structure and function, and reduced physical activity. Perinatal factors including BPD were not associated with a reduced exercise capacity.