SHORT REPORT

Reliability of heart rate variability measures at rest and during light exercise in children

R J Winsley¹, N Armstrong², K Bywater² and S G Fawkner²

¹ Children’s Health and Exercise Research Centre, University of Exeter, Heavitree Road, Exeter EX1 2LU, Devon, UK
² University of Exeter

Correspondence to:
Correspondence to:
Dr Winsley
University of Exeter, Children’s Health and Exercise Research Centre, Heavitree Road, Exeter EX1 2LU, Devon, UK; r.j.winsley{at}exeter.ac.uk

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.

Keywords: reliability; children; heart rate variability; exercise

Abbreviations: HRV, heart rate variability; RMSSD, square root of the mean of the sum of the squares of the differences between adjacent R-R intervals; pNN50, the proportion of pairs of adjacent intervals differing by more than 50 ms; SDNN, standard deviation of all the R-R intervals; LF, low frequency power; HF, high frequency power; TP, total power; ICC, intraclass correlation coefficient

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