DOES ACUTE EXERCISE AFFECT THE SUSCEPTIBILITY OF LOW-DENSITY-LIPOPROTEIN TO OXIDATION

This study describes the effect of an acute exercise bout on the susce ptibility of isolated low density Lipoprotein (LDL) to in vitro oxidat ion. LDL was isolated from 23 subjects (exercisers, n = II; sedentary, n = 12) immediately before and after a single bout of exercise (30 mi n of treadmill work at 55% & 70% peak oxygen consumption (VO2 peak) fo r exercisers and sedentary, respectively). A statistically significant decrease in lag time for LDL oxidation was observed following exercis e compared to baseline (96.1 +/- 23.5 min vs. 92.1 +/- 23.3 minutes; n = 23, p less than or equal to .03) using a 5 mu M copper system. Ther e was a statistically significant increase in plasma myeloperoxidase ( MPG) levels following exercise compared to baseline values (1.58 +/- . 91 ng/dl versus 2.08 +/- 1.2 ng/dl; n = 12, p less than or equal to .0 3). These results suggest that the 30 min exercise bout at a moderate intensity and duration was a sufficient oxidative stress to increase t he susceptibility of LDL to in vitro oxidation. Additionally, the exer cise bout appeared to activate neutrophils, subsequently releasing MPO protein.