Heart rate recovery after maximal exercise is impaired in healthy young adults born preterm.

Abstract

The long-term implications of premature birth on autonomic nervous system (ANS) function are unclear. Heart rate recovery (HRR) following maximal exercise is a simple tool to evaluate ANS function and is a strong predictor of cardiovascular disease. Our objective was to determine whether HRR is impaired in young adults born preterm (PYA). Individuals born between 1989 and 1991 were recruited from the Newborn Lung Project, a prospectively followed cohort of subjects born preterm weighing < 1500g with an average gestational age of 28weeks. Age-matched term-born controls were recruited from the local population. HRR was measured for 2min following maximal exercise testing on an upright cycle ergometer in normoxia and hypoxia, and maximal aerobic capacity (VO2max) was measured. Preterms had lower VO2max than controls (34.88 ± 5.24 v 46.15 ± 10.21ml/kg/min, respectively, p < 0.05), and exhibited slower HRR compared to controls after 1 and 2min of recovery in normoxia (absolute drop of 20 ± 4 v 31 ± 10 and 41 ± 7 v 54 ± 11 beats per minute (bpm), respectively, p < 0.01) and hypoxia (19 ± 5 v 26 ± 8 and 39 ± 7 v 49 ± 13bpm, respectively, p < 0.05). After adjusting for VO2max, HRR remained slower in preterms at 1 and 2min of recovery in normoxia (21 ± 2 v 30 ± 2 and 42 ± 3 v 52 ± 3bpm, respectively, p < 0.05), but not hypoxia (19 ± 3 v 25 ± 2 and 40 ± 4 v 47 ± 3bpm, respectively, p > 0.05). Autonomic dysfunction as seen in this study has been associated with increased rates of cardiovascular disease in non-preterm populations, suggesting further study of the mechanisms of autonomic dysfunction after preterm birth.