PHYSICAL FITNESS AND THE HYPERTRIGLYCERIDEMIC WAIST PHENOTYPE

Abstract

A hypertriglyceridemic waist (HTGW) phenotype (waist girth > 89 cm, triglyceride [TG] > 170 mg/dL) has been associated with the metabolic triad of elevated insulin, [Apo B], small dense low density lipoprotein cholesterol (LDL-C) and angiographically defined coronary heart disease (CHD) in a small sample of Caucasian men. The HTGW has not been reported for women, and the degree to which physical fitness (PF) modifies these associations between the HTGW and CHD risk factors is unknown. PURPOSE: To determine the prevalence of HTGW and the influence of PF on the relationship between HTGW and CHD risk among 137 healthy women (M ± SD, 54 ± 9 yr; 28 ± 6 kg/m2). METHODS: PF was quantified as total time during a maximal graded treadmill exercise test. Body mass index (BMI) was computed as weight (kg) ÷ height2 (m) and waist girth (cm) was measured level with the iliac crest. Standard automated assay procedures were used to determine fasting TG, Apo B and insulin concentrations. We defined the HTGW as waist girth > 88 cm and TG > 150 mg/dL. The metabolic triad was defined as higher than median levels of insulin (> 31pmol/L), Apo B (> 69 mg/dL) and LDL-C (> 84 mg/dL) among women with a BMI < 25. We computed the median Framingham 10-yr risk score (FRS; 4%) among women with BMI < 25 as a surrogate of future CHD risk. RESULTS: The sample prevalence of HTGW was 11%. Apo B (P = 0.04) and insulin (P = 0.0001) increased across quintiles of waist girth, and LDL-C (P = 0.004) increased across quintiles of TG. The prevalence of the metabolic triad was highest (67%) among women with TG > 150 mg/dL and waist > 88 cm, and lowest (22%) among women with TG < 150 mg/dL and waist < 88 cm. HTGW women had less favorable CHD risk factors than their non-HTGW counterparts. Among the HTGW group, fit (> 6.5 METs) women had more favorable CHD risk factors than unfit women. The odds of > 4% FRS among HTGW versus non-HTGW women was 2.8 (95% confidence interval [CI] = .78–8.5). Among the HTGW group, the odds of > 4% FRS among fit versus unfit women was 0.28 (95% CI = .02–3.5). CONCLUSIONS: HTGW exists in women and is associated with increased CHD risk as previously reported among men. PF favorably modifies associations between HTGW and CHD risk factors and should be considered in the clinical interpretation of HTGW and individual CHD risk. Supported by NIH WHI-SIP #22W-U48/CCU409664