Exercise does not induce oxidative stress in trained heart transplant recipients

Purpose: The objectives of this study were twofold: 1) to determine the eff ect of incremental exercise to volitional fatigue on plasma levels of lipid peroxidation (malondialdehyde) in heart transplant recipients (HRT) and 2) to examine blood antioxidant capacity in HTR by assessment of antioxidant enzyme activities and vitamin E levels. Methods: Seven endurance-trained HT R (mean +/- SD; age 39.7 +/- 12.8 yr) and seven endurance-trained healthy, age-matched control subjects (HC) (mean age 40.6 +/- 10.7 yr) performed a s ymptom-limited incremental exercise test on a cycle ergometer. Venous blood samples were obtained at rest, exercise, and during recovery and analyzed for plasma levels of malondialdehyde (MDA) as well as markers of blood anti oxidant capacity. After exercise and during recovery, all dependent measure s were corrected for plasma volume changes induced by exercise. Significanc e was established at (P < 0.05). Results: No group differences existed in p lasma levels of MDA at rest. Further, graded exercise did not alter plasma levels of MDA in either group. Resting erythrocyte glutathione peroxidase ( GPX) activity was significantly lower and erythrocyte superoxide dismutase (SOD) activity was higher in HTR compared with HC. Finally, at rest, no gro up differences existed in plasma GPX activity or vitamin E levels. Conclusi ons: Graded exercise to fatigue does not promote an increase in oxidative s tress in blood of exercise trained HTR. Therefore, physical exercise does n ot appear to pose an oxidative-stress risk for these patients.