Influence of long-distance trail running on blood hemostasis at the World Mountain Trail Running Championship 2023. A pilot study

Background: Severe exercise performed over longer duration can involve multiple prothrombotic alterations in blood coagulation markers. Standard coagulation tests are not robust in identifying hyper- or hypocoagulability due to indirect determination of changes in hemostasis and fibrinolysis. Conversely, viscoelastic tests might do so. Objectives: The aim of this pilot study was to assess the exercise-induced changes in coagulatory and fibrinolytic processes by applying viscoelastic tests in a mountain ultramarathon. Seven elite athletes participating in the World Mountain and Trailrunning Championship 2023 were examined. The 86.9 km track involved 6500 m of climbing and 6920 m of descent. Methods: Venous blood samples were taken the day prior to and within 3 hours following the competition. Plasma coagulation tests and whole blood viscoelastic coagulation tests (ClotPro) were used to assess changes in hemostasis. Results: Plasma coagulation testing revealed prolonged prothrombin time, with correlatively decreased factor (F)V, FVII, and FX activities. As a consequence of increased intrinsic coagulation factor activities (FVIII, FIX, FXI, and FXII) and von Willebrand factor, activated partial thromboplastin time was shortened. In addition, plasminogen decreased, whereas α2-antiplasmin and D-dimer showed significant elevations. Maximal lysis, examined by viscoelastometric tests, was observed to be slightly diminished postrace, whereas fibrin polymerization increased. Conclusion: The trail-long race generated substantial alterations in coagulation that were linked to a higher inflammatory state, with characteristic increases in FVIII, von Willebrand factor, and fibrinogen levels. Viscoelastic coagulation monitoring used in our study was able to reflect the summation of pro- and anticoagulants, as well as pro- and antifibrinolytic changes, in hemostasis.