Photo Credit: Viacheslav

The following is a summary of “Impact of physical activity and intensity on clot mechanical microstructure and contraction in middle-aged/older habitual runners,” published in the March 2025 issue of BMC Neurology by Zaldua et al. 

Exercise temporarily increases clot mass and strength, regulated by fibrinolysis. Cardiovascular diseases impair fibrinolysis, leading to larger clots and weaker contraction. 

Researchers conducted a retrospective study on clot microstructure and contractile forces in middle-aged/older runners after 2 exercise intensities.  

They analyzed blood samples from 28 runners (≥40 years) before, immediately after, and 1-hour post-run. About 14 completed a 3 km high intensity run after a 10 km moderate run. They measured clot biomarkers (d_f, gel time, G’_Max, CF_max) and plasma markers. 

The results showed both exercise intensities altered PT, APTT, FVIII, and D-dimer, indicating hypercoagulability. D_f was higher after a short intense exercise but returned to baseline after 1 hour. CF_max decreased over time at both intensities, with a further drop after 1 hour, suggesting ongoing fibrinolysis. 

Investigators found that exercise temporarily induced an intensity-dependent hypercoagulable state, leading to denser clots and reduced contractile force due to fibrinolysis. These findings may help guide safe rehabilitation exercise for cerebrovascular patients. 

Source: bmcneurol.biomedcentral.com/articles/10.1186/s12883-025-04074-y