title: Exercise induces in vivo platelet activation in patients with coronary artery disease and in healthy individuals.
abstract: Recently, conflicting results have been published about a possible relationship between platelet activity and exercise-induced myocardial ischemia. The present study was performed to investigate platelet behavior during a graded symptom-limited bicycle ergometer test both in relation to the intensity of exercise and to exercise-induced myocardial ischemia. Plasma concentrations of platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) were measured by radioimmunoassays in 53 patients who had had acute myocardial infarction 10 weeks before the study and, for comparison, in 9 healthy individuals. In the whole group of the 53 patients there was no significant alteration in platelet-specific proteins during exercise, whereas physical activity induced a 2- to 3-fold increase in beta-TG and PF4 levels in the controls. However, on differentiation of the patients as to their individual exercise performance, significant exercise-associated platelet activation was demonstrable in those who reached more than 75% of their calculated maximal working capacity, whereas no correlation was found between platelet activity and exercise-induced myocardial ischemia. Thus, the results from this study indicate that in vivo platelet activation is a physiological phenomenon which occurs when a certain degree of physical intensity is exceeded, independent of the precipitation of myocardial ischemia.
mesh_terms: D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000503:physiopathology*; D003327:Coronary Disease / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D010978:Platelet Factor 4 / Q000032:analysis; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D001620:beta-Thromboglobulin; D010978:Platelet Factor 4