Compression Socks Worn During Flight and Hemostatic Balance in Boston Marathon Runners on Oral Contraceptives

To investigate the effect of oral contraceptive (OC) use and compression socks on hemostatic activation in women flying cross-country to and from a marathon.

Prospective study.

2015 Boston Marathon.

Women were divided into non-OC using (CONTROL; n = 12), OC-using (OC; n = 15), and OC-using plus compression sock (OC + SOCK; n = 14) groups.

Women in OC + SOCK wore compression socks during flights to and from the marathon.

Venous blood samples were collected within 24 hours of arriving in Boston (EXPO), immediately after the marathon (RUN), and within 24 hours after a return flight home (Post-Flight) for analysis of thrombin-antithrombin complex (TAT), d-dimer, and tissue plasminogen activator (t-PA).

TAT did not increase with exercise (P = 0.48) and was not affected by group (P = 0.08) or the interaction between these 2 factors (P = 0.80). Group, time, and their interaction were significant for d-dimer (all P < 0.05) such that d-dimer increased with acute exercise to a greater extent (Δ d-dimer from expo to postrace = 909.5 ± 1021.9 ng/mL) in the OC + SOCK group relative to OC (Δ d-dimer = 240.0 ± 178.5 ng/mL; P = 0.02) and CONTROL (Δ d-dimer = 230.3 ± 120.3 ng/mL; P = 0.02). There was a significant effect of time, group, and the interaction on t-PA (all P < 0.01) such that t-PA increased with acute exercise to a greater extent (Δ t-PA from expo to postrace = 19.6 ± 10.0 ng/mL) in the CONTROL group relative to OC (Δ t-PA = 4.0 ± 1.8 ng/mL; P < 0.01) and OC + SOCK (Δ t-PA = 3.3 ± 1.2 ng/mL; P < 0.01).

Female runners using OCs did not exhibit disproportionately increased coagulation. The use of compression socks in women on OCs, surprisingly, resulted in a greater increase in d-dimer after exercise.