title: Heart rate variability, adiposity, and physical activity in prepubescent children.
abstract: OBJECTIVE
  This study aimed at examining the associations between weight status, body fat mass, and heart rate variability in prepubescent children, adjusting for physical activity levels.
  
  
  METHODS
  A cross-sectional investigation in which a total of 50 Caucasian pre-pubertal children (21 normal weight; 8 overweight; 21 obese), aged 6-10 years (8.33 ± 1.14), including both boys (n = 24) and girls (n = 26), were recruited from local schools. Total body fat and trunk fat were evaluated through dual-energy X-ray absorptiometry. Free-living physical activity levels were evaluated by accelerometer. Short-term heart rate variability acquisition was performed; time- and frequency-domain parameters were analysed. Logarithmic transformations of the low-frequency (LnLFnu), high-frequency (LnHFnu) normalized units and low-frequency/high-frequency (LnLFnu/HFnu) ratio were computed.
  
  
  RESULTS
  Adjusting for age, Tanner stage, and moderate to vigorous physical activity levels, obese children compared to normal weight children showed a significant decreased LnHfnu (3.8 ± 0.2 vs 4.1 ± 0.2 %) and both higher LnLFnu (4.0 ± 0.4 vs 3.7 ± 0.3 %) and LnLFnu/LnHFnu ratio (1.1 ± 0.1 vs 0.9 ± 0.1). LnHFnu showed significant negative correlation with waist circumference (r = -0.598; P = 0.000), total body fat (r = -0.409; P = 0.011) and trunk fat (r = -0.472; P = 0.003). Both LnLFnu and LnLFnu/LnHFnu ratio showed positive correlations with waist circumference (r = 0.455; r = 0.513) and trunk fat (r = 0.370; r = 0.415).
  
  
  CONCLUSIONS
  A higher amount of body fat mass, particularly central fat, was shown to be related to decreased parasympathetic modulation in time-domain heart rate variability. This finding highlights the potential cardiovascular risk that excessive fat mass may represent even at very young age.
authors.affiliation: School of Health, University Fernando Pessoa, Porto, Portugal, andrem@ufp.edu.pt.
authors.forename: Andre Filipe
authors.initials: AF
authors.lastname: Santos-Magalhaes
authors.forename: Luisa
authors.initials: L
authors.lastname: Aires
authors.forename: Clarice
authors.initials: C
authors.lastname: Martins
authors.forename: Gustavo
authors.initials: G
authors.lastname: Silva
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Teixeira
authors.forename: Jorge
authors.initials: J
authors.lastname: Mota
authors.forename: Luis
authors.initials: L
authors.lastname: Rama
mesh_terms: D015502:Absorptiometry, Photon; D050154:Adiposity / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology; D011627:Puberty / Q000502:physiology; D012727:Sex Characteristics; D055105:Waist Circumference
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