title: Gender differences in the relationship between heart rate control and adiposity in young children: a cross-sectional study (EarlyBird 33).
abstract: BACKGROUND
  The role of the autonomic nervous system in the complex link between insulin resistance and cardiovascular risk remains unclear. Increased sympathetic nervous system activity has been implicated in the pathophysiology of insulin resistance but is confounded by a number of factors.
  
  
  METHODS
  We have therefore examined the relationship among cardiac autonomic control, insulin resistance, habitual physical activity, resting energy expenditure (REE), and anthropometric variables in a subset (107 boys, 101 girls, age 9 +/- 0.25 yr) of the EarlyBird cohort. Cardiac autonomic activity was assessed using time domain and power spectral density analysis methods of heart rate variability. Insulin resistance was measured using homeostasis model assessment of insulin resistance (HOMA2-IR).
  
  
  RESULTS
  Girls, in comparison to boys, showed significantly higher resting heart rate and lower systolic blood pressure (BP); were more insulin resistant; undertook less physical activity, and had lower fat-free mass and REE. Increasing fasting insulin and increasing insulin resistance were associated with increasing BP.
  
  
  CONCLUSIONS
  The data suggest early gender differences in predictors of cardiac autonomic control. Pubertal staging was not undertaken in this study, and we plan to evaluate this in future studies to further clarify these associations.
authors.affiliation: Department of Diabetes and Endocrinology, Derriford Hospital, Plymouth, UK.
authors.forename: Binu
authors.initials: B
authors.lastname: Krishnan
authors.forename: Alison
authors.initials: A
authors.lastname: Jeffery
authors.forename: Brad
authors.initials: B
authors.lastname: Metcalf
authors.forename: Joanne
authors.initials: J
authors.lastname: Hosking
authors.forename: Linda
authors.initials: L
authors.lastname: Voss
authors.forename: Terence
authors.initials: T
authors.lastname: Wilkin
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Flanagan
mesh_terms: D050154:Adiposity; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure; D002648:Child; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D012737:Sex Factors