Importance of aerobic fitness in cardiovascular risks in sedentary overweight and obese African-American women.

Background: Whether the level of aerobic fitness significantly impacts cardiovascular disease (CVD) risks in healthy, nondiabetic, overweight or obese African-American women remains uncertain.

Objective: To examine the clinical and metabolic risk factors of CVD in nondiabetic, sedentary overweight or obese African-American women with varying degrees of aerobic fitness.

Methods: Forty-eight African-American women, with mean age of 43 +/- 4.2 years and body mass index of 32.3 +/- 3.6 kg/m2, participated in the study. Fasting and 2-hr postprandial serum glucose, insulin, and C-peptide levels were obtained during oral glucose tolerance test. Insulin sensitivity was calculated by Homeostasis Model Assessment (HOMA-IR). Aerobic fitness was categorized empirically as very low aerobic fitness (VLAF; n = 17, VO2max < 21 ml/kg/min), low aerobic fitness (LAF; n = 12, between 21 and 24.4 ml/kg/min), and moderate aerobic fitness (MAF; n = 19, >24.4 ml/kg/min).

Results: Significant differences were found in serum glucose, insulin, and C-peptide levels, and HOMA-IR in the VLAF vs. LAF and MAF groups. Mean HOMA-IR was statistically greater in the VLAF and LAF when compared to MAF. Mean fasting serum cholesterol, triglycerides, and low-density lipoprotein cholesterol levels were higher in the VLAF group compared to the MAF group, whereas high-density lipoprotein cholesterol was lower in the VLAF group. Despite differences in the obesity indices and insulin resistance in the three groups, the atherogenic lipids and lipoproteins were within normal limits, irrespective of degree of VO2max.

Discussion: Modest aerobic fitness has significant impact on insulin sensitivity and atherogenic lipids and lipoprotein parameters and the overall risks for CVD in sedentary overweight or obese African-American women. Whether modest physical fitness translates into prevention of type 2 diabetes and CVD in African-American women remains to be determined.