[Platelet morphology and physical stress (author's transl)].

The morphology of thrombocytes of 45 volunteers in varying conditions of training was analysed under physical stress. The probands were divided in three groups of 15 each. Group X (aged 20-26 years) had occasional gymnastics training. Group Y (aged 44-52 years) was without any physical training, and Group Z consisted of athletes (aged 22-25 years) in good training condition. By means of the platelet aggregation test (PAT), thrombocyte changes were classified in 5 stages: solitary stage (I), accumulation stage (II), degranulation stage (III), fibrin forming stage (IV), irreversible aggregation stage (V). The probands were subjected to ergometer stress in exact dosage. With the exception of the athletes, all blood smears showed a decrease in stage I (solitary), and considerable increase in stages II-V. 5, 30, or 60 min after stress, the return of irreversible aggregates (PAT V), of platelet changes in the fibrin-forming stage (PAT IV), and in the degranulation stage (PAT III), was markedly delayed in Group Y (untrained older persons) when compared with the group of well-trained athletes. The observation may offer an explanation for some cases of acute thrombotic cardiac death among trained athletes. On the other hand, it may prove the better adaptation of the thrombocytic system during physical stress when athletes are in good physical condition.