Effects of endurance training on the circadian rhythm of fibrinolysis in men and women

This randomized study compared the fibrinolytic circadian rhythm of healthy older men and older women (average age 66 ± 5), before and after 6 months of endurance training versus stretching controls. Compared with men, women at baseline had similar rhythms for tissue plasminogen activator (t- PA) activity and plasminogen activator inhibitor 1 (PAI-1) activity, but lower levels of total t-PA antigen. In men (N ≃ 16), endurance training increased V̇O(2max) 15% (P < 0.001), while decreasing PAI-1 activity 37% (P = 0.034) and total t-PA antigen 18% (P = 0.0003) between midnight and 6 a.m., but did not affect t-PA activity. In women (N = 9), endurance training increased V̇O(2max) 18% (P = 0.003), and increased t-PA activity 20% (P = 0.027) and total t-PA antigen 55% (P = 0.007) between 10 p.m. and 4 a.m., but had no effect on PAI-1 activity. After endurance training there were no significant differences in the fibrinolytic circadian rhythm of men versus women. Six months of nonaerobic stretching had no effect on V̇O(2max) or fibrinolysis in men (N = 11) or women (N = 8). This study indicates that potentially favorable changes occur in fibrinolytic factors after endurance training in older men and older women.