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Clotting and Fibrinolytic Changes after Firefighting Activities


Medicine & Science in Sports & Exercise: March 2014 - Volume 46 - Issue 3 - p 448–454
doi: 10.1249/MSS.0b013e3182a76dd2
Clinical Sciences

Approximately 45%–50% of all duty-related deaths among firefighters are due to sudden cardiovascular events, and a disproportionate number of these fatalities occur after strenuous fire suppression activities.

Purpose The objective of this study is to evaluate the effect of strenuous firefighting activities on platelets, coagulation, and fibrinolytic activity and to document the extent to which these variables recovered 2 h after completion of the firefighting activity.

Methods Firefighters performed 18 min of simulated firefighting activities in a training structure that contained live fires. After firefighting activities, firefighters were provided with fluid and allowed to cool down and then recovered for 2 h in an adjacent room. Blood samples were obtained prefirefighting, postfirefighting, and 2 h postfirefighting.

Results Platelet number, platelet activity, and coagulatory potential increased immediately postfirefighting and many variables (platelet function, partial thromboplastin time, and factor VIII) reflected a procoagulatory state even after 2 h of recovery. Fibrinolysis, as reflected by tissue plasminogen activator, also was enhanced immediately postfirefighting but returned to baseline values by 2 h postfirefighting. In contrast, inhibition of fibrinolysis, as evidenced by a reduction in plasminogen activator inhibitor-1, was depressed at 2 h postfirefighting.

Conclusions Firefighting resulted in elevated coagulatory and fibrinolytic activity. However, 2 h postfirefighting, tissue plasminogen activator returned to baseline and coagulatory potential remained elevated. The procoagulatory state that exists after firefighting may provide a mechanistic link to the reports of sudden cardiac events after strenuous fire suppression activities.

1Illinois Fire Service Institute, University of Illinois Urbana-Champaign, Champaign, IL; 2Department of Health and Exercise Sciences, Skidmore College, Saratoga Springs, NY; 3Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL; 4Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL; and 5Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL

Address for correspondence: Denise L. Smith, Ph.D., Department of Health and Exercise Sciences, Skidmore College, 815 N. Broadway, Saratoga Springs, NY 12866; E-mail:

Submitted for publication January 2013.

Accepted for publication July 2013.

© 2014 American College of Sports Medicine