EFFECTS OF ENDURANCE TRAINING ON THE CIRCADIAN-RHYTHM OF FIBRINOLYSISIN MEN AND WOMEN

This randomized study compared the fibrinolytic circadian rhythm of he althy older men and older women (average age 66 +/- 5), before and aft er 6 months of endurance training versus stretching controls. Compared with men, women at baseline had similar rhythms for tissue plasminoge n 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 VO2max 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 wo men (N = 9), endurance training increased VO2max 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 activi ty-After endurance training there were no significant differences in t he fibrinolytic circadian rhythm of men versus women. Six months of no naerobic stretching had no effect on VO2max or fibrinolysis in men (N = 11) or women (N = 8). This study indicates that potentially favorabl e changes occur in fibrinolytic factors after endurance training in ol der men and older women.