Objectives: To investigate the reliability of heart rate variability (HRV) measures at rest and during light exercise in children.
Methods: Short term (five minute) HRV was assessed in 12 children (11-12 years of age). HRV measures were collected at rest with the children supine, breathing at 12 breaths/min, and during exercise on a cycle ergometer while exercising at 25% of peak oxygen uptake. Both resting and exercise data were collected twice from each child.
Results: Intraclass correlation coefficients were low to moderate for most measures with wide confidence intervals for each variable in both resting and exercise conditions. Random variation (typical error) within repeated measurements ranged from 31% to 187%.
Conclusions: These preliminary findings suggest that HRV measures are unreliable at rest and during light exercise in children aged 11-12 years. Tighter control of extraneous influences is recommended.