Abstract
Exercise increases clotting and fibrinolytic activity in humans. This has also been
reported for oral contraceptive agents (OCA). We studied the effects of strenuous
exercise and OCA on a number of hematological variables in 20 highly trained female
athletes. Ten had been using OCA for more than a year (users). The other ten served
as the control group (non-users). All subjects were exercised to exhaustion by means
of a graded exercise test on a bicycle ergometer. Biochemical and cellular assays
for the determination of plasma volume changes and used to standardize the intensity
of exercise were performed in pre- and post-exercise blood samples. Procoagulant activity
of factors XII, XI and VII were determined. High molecular weight kininogen (HMWK),
α2 -macro-globulin, and C1 -esterase inhibitor were quantified by rocket Immunoelectrophoresis
using monospecific antisera. Synthetic chromogenic peptide substrates were used for
the determination of plasminogen, prekallikrein, α2,-antiplasmin, and antithrombin III. The two groups examined were anthropometrically
and physically very well matched. The pre-exercise results of the groups of users
demonstrated a significantly higher factor XII and plasminogen level, together with
a significantly lower C1-esterase inhibitor level compared to the pre-exercise data
of the group of non-users. No significant differences in pre-exercise values of factor
XI, factor VII, HMWK, α2-macro-globulin, prekallikrein, α2-antiplasmin, and antithrombin III were observed between the groups. Exercise induced
a significant decrease in all clotting and fibrinolytic variables, except factor VII
and α2-antiplasmin in the group of users. In the group of non-users, significant post-exercise
decreases were observed in factor XII, HMWK, prekallikrein, and α2-macro-globulin only. Results indicate a potentiating effect of OCA on post-exercise
hemostatic and fibrinolytic changes.
Key words
oral contraceptives - exercise - clotting - fibrinolysis - training
