Compression Socks Worn During Flight And Hemostatic Balance In Boston Marathon Runners On Oral Contraceptives

Abstract

Marathon running evokes acute parallel increases in markers of coagulation and fibrinolysis (i.e., hemostatic activation) such that hemostatic balance is maintained. However, other factors incident to marathon running (i.e., travel, oral contraceptive [OC] use) may disproportionately activate the coagulatory system, increasing blood clot risk in otherwise, healthy athletes. Compression socks are an established preventive measure to reduce blood clot risk with air travel, but their effect on thrombotic factors in athletes who fly to and from competitions has not been established. PURPOSE: This study investigated the effect of compression socks on hemostatic activation in OC using endurance athletes flying cross-country and running the 2015 Boston Marathon. METHODS: OC using women (n=29) traveling cross-country were divided into compression sock (SOCK; n=14) and control (CONTROL; n=15) groups in which SOCK participants wore compression socks during flights to (mean flight time 5.8±1.5hr) and from (mean flight time 6.1±1.3hr) the marathon. Venous blood samples were collected 24hr prior to flying cross-country to Boston, 1d before the marathon after flying, immediately after the marathon, and within 24hr following a return flight home. Samples were analyzed for coagulatory factor thrombin-antithrombin complex (TAT); fibrinolytic factor tissue plasminogen activator (t-PA); serum estradiol; and hematocrit. RESULTS: Baseline (pre-flight) TAT and t-PA did not differ between groups (all ps>0.13) and were not different from baseline after flying cross country to the marathon (all ps>0.92). T-PA increased after the marathon from baseline in CONTROL (+4.0±1.3 ng/mL) and SOCK (+3.3±1.3ng/mL) with no difference between groups (p=0.17). TAT was not different after the marathon from baseline (p=0.70). T-PA decreased to baseline levels after the return flight home in CONTROL (-4.4±1.6 ng/mL) and SOCK (-3.5±1.3 ng/mL); this response did not differ between groups (p=0.12). CONCLUSION: Compression socks worn during flight did not alter the balance of clot formation or breakdown at any individual time point in OC using women flying cross country before and after running a marathon. Future research is necessary to determine whether the timing of sock use influences their utility for blood clot risk reduction.