Change in Physical Activity and Heart Rate Variability from Adolescence to Young Adulthood in Persons Born Preterm with Very Low Birth Weight

Abstract

Heart rate variability (HRV), a marker of autonomic dysfunction, decreases with age but few studies have examined HRV longitudinally. Further, studies have shown gestational age, birth weight and physical activity (PA) may influence a person’s HRV. The purpose of this study is to compare PA and HRV between 108 preterm/very low birth weight (PT/VLBW) participants and 20 full term/normal birth weight (FT/NBW) peers from adolescence and young adulthood. HRV was determined from a 5-minute resting ECG using Nevrokard Software. The root square mean of the standard deviation (RMSSD), high frequency (HF), and low frequency/high frequency (LF/HF) ratio were used to reflect HRV. Average total hours and vigorous hours per week for the past year were estimated from the Modifiable Activity Questionnaire. Repeated Measures ANOVA demonstrated no between group differences but significant within group differences indicating a decrease in HRV from adolescence to young adulthood (p<0.001). Mann-Whitney U tests found significantly lower vigorous PA at adolescence as well as total and vigorous PA at young adulthood (p<0.05) in PT/VLBW compared to their FT/NBW peers. However, no associations were evident for PA in adolescence or change in PA and change in HRV from adolescence to young adulthood.