Recommended Levels of Physical Activity and Insulin Resistance in Middle-Aged Women

Purpose The purpose of this study was to examine the relationship between recommended levels of physical activity (PA) and insulin resistance, as estimated by the homeostasis model assessment of insulin resistance (HOMA-IR) in middle-aged women without diabetes. Methods This was a cross-sectional study of 264 women located in the Mountain West region of the United States. Sedentary time and moderate-and vigorous-intensity PA were determined objectively, via accelerometry, over 7 days. HOMA-IR was calculated from fasting insulin and glucose. Body mass index (kg/m(2)) was calculated from measured weight and height; body fat percentage was assessed using air displacement plethysmography; and abdominal circumference was measured at the umbilicus. Moderate-and vigorous-intensity PA levels were based on recommendations for PA and health from the American College of Sports Medicine. Results Total time spent in sedentary activity was significantly related to insulin resistance. Time spent in moderate-intensity or vigorous-intensity activity, at recommended levels, was also significantly and inversely related to insulin resistance. However, after statistically adjusting for body fat percentage or abdominal circumference individually, the relationship between sedentary activity, moderate-intensity, or vigorous-intensity activity and HOMA-IR was eliminated. Conclusions Achieving recommended levels of PA is associated with lower HOMA-IR in healthy women without diabetes; however, adiposity accounts for part of this relationship.