Effect of Obesity, Physical Activity, and Cardiorespiratory Fitness on Blood Pressure, Inflammation, and Insulin Resistance in the National Health and Nutrition Survey 1999-2002

BACKGROUND AND AIMS: This study was designed to elucidate the effects of obesity, self-reported physical activity and cardiorespiratory fitness on blood pressure, inflammation, and insulin resistance. METHODS AND RESULTS: 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 ( =-0.23, P