Obesity and Postexercise Oxidative Stress in Older Women

PURPOSE: This study compared lipid peroxidation values in nonobese and obese postmenopausal women before and after acute maximal aerobic exercise (AX). METHODS: Blood samples were collected in nonobese (22.1 +/- 0.9% body fat) and obese (40.8 +/- 0.9% body fat) women (61-75 yr, N = 34) before and immediately after a maximal graded treadmill test. Lipid hydroperoxides (PEROX), cholesterol, and thiol profiles were measured. Oxygen consumption (V(O2), respiratory exchange ratios (RER), and minute ventilation (VE) values were determined before and during exercise. RESULTS: PEROX levels were not different between the nonobese and obese groups at baseline (2.4 vs 2.8 nmol.mL(-1), respectively) or post-AX (2.8 vs 3.2 nmol.mL(-1), respectively) (P > 0.05). When expressed as DeltaPEROX (nmol.mL(-1))/DeltaVO(2) (mL.kg(-1).min(-1)), to account for different exercise durations, the obese group had a greater lipid peroxidation response compared with the nonobese group (0.13 vs 0.02 (nmol.mL(-1)).mL(-1).kg(-1).min(-1), respectively; P < 0.05). Regression analysis revealed that when baseline PEROX and body fat values were controlled, age, exercise intensity, and duration were significant contributors to the DeltaPEROX/DeltaV(O2) after AX (R(2) = 0.536 P < 0.05). CONCLUSION: For a given oxidative challenge (exercise-associated oxygen utilization), older, obese women were at a greater risk for oxidative stress compared with nonobese counterparts.