Effects of obesity, physical activity, and cardiorespiratory fitness on blood pressure, inflammation, and insulin resistance in the National Health and Nutrition Survey 1999-2002.

This study was designed to elucidate the effects of obesity, self-reported physical activity and cardiorespiratory fitness on blood pressure, inflammation, and insulin resistance.Data from 950 Caucasian subjects ranging in age from 19 to 49 years from the National Health and Nutrition Survey (NHANES), 1999-2002, were included to construct a population-based observational study. Cardiorespiratory fitness (VO(2) max) was predicted from a submaximal exercise stress test. Self-reported physical activity was measured by metabolic equivalent score transformed from a questionnaire. A structural equation model (SEM) was developed to examine the relationship between obesity, cardiorespiratory fitness, self-reported physical activity, and hypertension, inflammation, and insulin resistance. The model showed that obesity was positively linked to hypertension (B=0.50, P<0.001) and C-reactive protein (CRP; B=0.15, p<0.05), which in turn led to insulin resistance (B=0.44, P<0.05). Increased cardiorespiratory fitness was negatively associated with CRP (Γ=-0.23, P<0.01), but not correlated to hypertension after adjustment for potential confounding factors. No significant association was found between self-reported physical activity and hypertension, insulin resistance, and CRP.Obesity contributes to the development of hypertension, inflammation, and insulin resistance. Improved cardiorespiratory fitness might lead to clinical and biochemical improvement in insulin resistance by reducing the inflammatory state.