IMPROVEMENT OF INSULIN SENSITIVITY BY SHORT-TERM EXERCISE TRAINING INHYPERTENSIVE AFRICAN-AMERICAN WOMEN

African American women have a high prevalence of insulin resistance, n on-insulin-dependent diabetes mellitus, obesity, and hypertension that may be linked to low levels of physical activity. We sought to determ ine whether 7 days of aerobic exercise improved glucose and insulin me tabolism in 12 obese (body fat >35%), hypertensive (systolic blood pre ssure greater than or equal to 140 and/or diastolic blood pressure gre ater than or equal to 90 mmHg) African American women (mean age 51+/-8 years). Insulin-assisted frequently-sampled intravenous glucose toler ance tests were performed at baseline and 14 to 18 hours after the 7th exercise session. There was no significant change in maximal oxygen c onsumption, body composition, or body weight after the 7 days of aerob ic exercise. The insulin sensitivity index increased (2.68+/-0.45.10(- 5) to 4.23+/-0.10.10(-5) [min(-1)/pmol/L], P=.02). Fasting (73+/-9 to 50+/-9 pmol/L, P=.02) and glucose-stimulated (332+/-58 to 261+/-45 pmo l/L, P=.05) plasma insulin levels decreased. Additional measures relat ed to the insulin resistance syndrome also changed with the 7 days of exercise: basal plasma norepinephrine concentrations were reduced (2.4 6+/-0.27 to 1.81+/-0.27 nmol/L, P=.02) and sodium excretion rate incre ased from 100+/-13 to 137+/-7 mmol/d (P=.03); however, there was no ch ange in potassium excretion or 24-hour ambulatory blood pressure. We c onclude that a short-term aerobic exercise program improves insulin se nsitivity in African American hypertensive women independent of change s in fitness levels, body composition, or body weight. The present stu dy indicates that short-term exercise can improve insulin resistance i n hypertensive, obese, sedentary African American women and confirms p revious reports that a portion of the exercise-induced improvements in glucose and insulin metabolism may be the result of recent exercise.