Moderate-intensity physical activity and fasting insulin levels in women -The cross-cultural activity participation study

OBJECTIVE - The purpose of this study was to determine the association betw een moderate-intensity physical activity (PA) and fasting insulin levels am ong African-American (n = 47), Native American (n = 46), and Caucasian wome n (n = 49), aged 40-83 years, enrolled in the Cross-Cultural Activity Parti cipation Study. Associations by race/ethnicity, levels of central obesity, and cardiorespiratory fitness were also examined. RESEARCH DESIGN AND METHODS - Physical activity scores were obtained from d etailed PA records that included all PA performed during two consecutive 4- day periods scheduled 1 month apart. Using MET intensity (the associated me tabolic rate for a specific activity divided by a standard resting metaboli c rate), PA was expressed as MET-min (the product of the minutes for each a ctivity times the MET intensity level) per day of energy expended in modera te (3-6 METs) and moderate/vigorous (greater than or equal to 3 METs) PA. F asting insulin levels were determined by radioimmunoassay. Data were analyz ed by multiple linear regression analysis. RESULTS - After adjusting for race/ethnicity, age, educational attainment, and site, an increase of 30 min of moderate-intensity PA was associated wit h a 6.6% lower fasting insulin level (P < 0.05). The association was simila r among races/ethnicities, centrally lean and centrally obese women, and wo men with low and high cardiorespiratory fitness levels. CONCLUSIONS - These findings lend support to the 1995 Centers for Disease C ontrol and Prevention and American College of Sports Medicine recommendatio ns for an accumulation of 30 min/day in moderate-intensity PA. They also co ntribute to the growing literature suggesting that moderate amounts of PA h ave a significant role in reducing the burden of hyperinsulinemia and diabe tes among ethnic populations at highest risk for these conditions.