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Physical Activity Level And Insulin Resistance In 6,500 Nhanes Adults: The Role Of Abdominal Obesity, James R Fowler

Theses and Dissertations

OBJECTIVE: This cross-sectional study investigated insulin resistance (IR) variation across physical activity (PA) levels in U.S. adults. METHODS: MET-minutes were utilized to quantify PA using 2 methods: 4 categories were based on relative MET-minutes, and 5 were based on U.S. PA guidelines. IR was indexed using the homeostatic model assessment (HOMA). Effect modification was tested by dividing waist circumferences into sex-specific quartiles, and then evaluating the relationship between PA and HOMA-IR within each quartile separately. RESULTS: Relative PA was associated with HOMA-IR after controlling for demographic and demographic and lifestyle covariates (F = 11.5, P < 0.0001 and F = 6.0, P = 0.0012, respectively). Adjusting for demographic and demographic and lifestyle covariates also revealed relationships between guideline-based PA and HOMA-IR (F = 8.0, P < 0.0001 and F = 4.9, P = 0.0017, respectively). Controlling for waist circumference with the other covariates nullified the relationship between PA and HOMA-IR. Effect modification testing showed that when the sample was delimited to adults with extra-large waists (Quartile 4), relative (F = 5.6, P = 0.0019), and guideline-based PA (F = 3.7, P = 0.0098) and HOMA-IR were related. PA and HOMA-IR were not related within the other quartiles. CONCLUSION: High levels of PA may play a meaningful role in glucose and insulin metabolism in those with abdominal obesity, but not in adults with smaller waists.