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 ˙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 women (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 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 ˙VO2max 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.
Departments of Laboratory Medicine, Medicine and Psychiatry, and Behavioral Sciences, University of Washington; the Geriatric Research, Education, and Clinical Center (GRECC); and the Seattle Veterans Administration Medical Center, Seattle, WA
Submitted for publication April 1995.
Accepted for publication February 1996.
The authors thank Jay Bryan, Michael Davis, Valerie Larson, and Robert Ward for their expert assistance.
This study was supported by PHS Grants K02 MH01158 (MVV); MH45186 (MVV); MH33688 (MVV); AG10943 (RSS); GCRC RR-37 (RSS, MVV); and by the Department of Veterans Affairs.
Address for correspondence: Wayne L. Chandler, M.D., Department of Laboratory Medicine, SB-10, University of Washington, Seattle, WA 98195.