Heart rate variability in the healthy school-age children

Autonomic function can be measured assessing heart rate variability (HRV). The analysis by frequency domains allows to study sympathetic and parasympathetic activity (Shaffer et al., 2014). This methodology showed to be sensitive in discrimination of high-risk subjects in pathological conditions, such children born prematurely (Fyfe et al., 2015). However, data on physiological maturation of HRV in healthy children is lacking. The aim of this study was to evaluate the development of HRV in healthy children aged (5–10 years). We recorded the HRV in 25 infants, for 5 min, during awake state. The following parameters were calculated: total power, reflecting the global ANS activity; low frequency, reflecting a combination of sympathetic and parasympathetic nervous; high frequency, predominantly reflecting parasympathetic activity. We found total power (range 5.8–9.9, mean 8.16 ds 0.9), low (range 5.12–8.7, mean 7.07 ds0.9) and high (range 4.05–8.97, mean 7.03 ds1.22) frequency power, low and high frequency power ratio (range 0.4–3.2, mean 1.21 ds0.74), and sympathetic (range 28.2–76.4, mean 50.75 ds12.88) and parasympathetic (range 23.6–71.8, mean 49.26 ds12.88) activity percentages. We did not find an effect of age on HRV parameters.