Exercise-induced increase in hydrogen peroxide plasma levels is diminishedby endurance training after myocardial infarction

We have investigated the influence of physical training on exercise-induced changes in free radical activity in patients after myocardial infarction. Seventeen patients admitted to the cardiac rehabilitation center performed a bicycle ergometry before and after a 3-week endurance training program. T he oxygen consumption and carbon dioxide production were measured and the E CG and the systemic blood pressure were monitored during the tests. Blood s amples for acid-base equilibrium, lactic acid levels and hydrogen peroxide concentrations were collected directly before and after each exercise test. Exercise-induced increases in systolic blood pressure, heart rate and rate -pressure product as well as lactic acid concentrations were significantly less marked during the bicycle ergometry performed after the rehabilitation program. During the initial exercise test hydrogen peroxide levels increas ed significantly from 7.15 +/- 0.74 mu mol/l before to 9.09 +/- 1.04 mu mol /l 3 min after the test (P = 0.0229). In contrast, no significant changes i n hydrogen peroxide concentrations were observed during the exercise test p erformed after the training (6.31 +/- 1.05 mu mol/l before the test, 5.85 /- 1.08 mu mol/l after the test, P = 0.201). These observations suggest tha t physical training may have a beneficial influence on free radicals' gener ation in patients after myocardial infarction. (C) 1998 Elsevier Science Ir eland Ltd. All rights reserved.