Gender differences in the relationship between heart rate control and adiposity in young children: a cross-sectional study (EarlyBird 33).
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.
Krishnan
Binu
B
Department of Diabetes and Endocrinology, Derriford Hospital, Plymouth, UK.
Jeffery
Alison
A
Metcalf
Brad
B
Hosking
Joanne
J
Voss
Linda
L
Wilkin
Terence
T
Flanagan
Daniel E
DE
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