Clotting and fibrinolytic activity change during the 1 h after a submaximal run

To determine the changes in clotting and fibrinolytic activity during the 1-h period after an acute submaximal exercise at a specific relative exercise intensity to ascertain whether during this time there is a greater risk for developing a clot formation or thrombus. Ten healthy men reported between 0700 and 1000 h and ran at 70-75% VO2max or walked at 1.2 mph for 30 min in a random counter-balanced order. Venous blood was obtained at rest, immediately after, and every 20 min during the 1-h recovery. There were no differences in the resting parameters for each treatment. Walking did not alter the activity of any of the measures analyzed compared with rest. Clotting indicators activated partial thromboplastin time (APTT) was significantly decreased by approximately 2 s and remained at this level during the 1-h recovery, and factor VIII activity was elevated 66% immediately after the run and remained elevated at this level during the 1-h recovery period. Fibrinolytic indicators, t-PA, and D-dimers were significantly increased immediately after the run. However, t-PA demonstrated a quadratic negative slope during the 1-h recovery time. D-dimers remained elevated during the 1-h recovery time. These results suggest that running at 70-75% VO2max resulted in elevated clotting and fibrinolytic activity. However, the clotting activity was sustained during a time when fibrinolytic activity declined, which suggests a more favorable situation for clot formation during this time after exercise.