Purpose: Although fibrinolysis increases with acute exercise, it decreases rapidly during the postexercise period. Therefore, the time point at which blood samples are collected postexercise could affect reported tissue plasminogen activator (t-PA) and/or plasminogen activator inhibitor-1 (PAI-1) levels. The purpose of this study was to determine the time course of t-PA and PAI-1 changes after acute maximal exercise.
Methods: Eight healthy males performed a graded maximal exercise test on a treadmill. Venous blood samples were collected using an indwelling catheter before exercise and at 1, 2, 4, 6, 8, and 10 min postexercise. Mean differences in t-PA activity, t-PA antigen, and PAI-1 activity at each time point were assessed using a repeated measures ANOVA. Post hoc means comparisons were performed by contrasting the 1-min postexercise value against all other time points.
Results: Both t-PA activity and t-PA antigen significantly increased from pre- to postexercise (P < 0.05). t-PA activity did not change from 1 to 2 min postexercise but decreased significantly at 4 min postexercise. Likewise, t-PA antigen remained elevated from 1 to 2 min postexercise but decreased at 4 min postexercise. PAI-1 decreased from pre- to postexercise but did not change during the 10-min postexercise period.
Conclusion: To accurately evaluate the t-PA response to acute exercise, blood samples should be collected within 2 min after the cessation of exercise.
Human Energy Research Laboratory, Department of Kinesiology, Michigan State University, East Lansing, MI
Address for correspondence: Christopher J Womack, Ph.D., FACSM, 3 IM Sports Circle, East Lansing, MI 48824; E-mail: email@example.com.
Submitted for publication January 2004.
Accepted for publication July 2004.