Leisure Time Physical Activity Among Non-Smoking, Normal Weight Adults: Assessing Prevalence of Central Adiposity, Insulin Resistance, and Systemic Inflammation

BACKGROUND: Physical activity (PA) has been examined as a preventive intervention against pre-diabetes, diabetes, and low-grade systemic inflammation, however, it remains unknown if normal weight individuals who do not engage in regular PA are at increased risk. METHODS: The National Health and Nutrition Examination Survey (NHANES) 2001-2006 were utilized. Three measures of PA (i.e., intensity level, the American College of Sports Medicine (ACSM) guidelines for frequency, intensity, and time/duration (FIT) of PA, and ACSM recommendations for MET-Mins Per Week) were analyzed in relation to elevated waist circumference, homeostatic model assessment for insulin resistance (HOMA), and immune system cells. In addition, the sample was stratified according to body mass index to determine if excess body weight reduces the benefits of PA. RESULTS: Normal and overweight individuals engaging in the highest levels of PA in all three measures displayed inverse associations with elevated waist circumference. Inverse relationships between PA and HOMA were insignificant. Engagement in vigorous intensity and the ACSM FIT guidelines produced inverse correlations with white blood cell count (WBC) and segmented neutrophil percent and number, while percent lymphocyte, monocyte, and basophil had direct correlations with MET-Min Per Week . CONCLUSIONS: Normal weight individuals engaging at the highest levels of PA had a decreased likelihood of an elevated waist circumference. Positive relationships between WBC and Elevated Waist Circumference were only seen in normal weight females. Future research using objective measures of PA is recommended to confirm our findings, and to clarify divergent results regarding immune system cells