title: Blood viscosity responses to maximal exercise in endurance-trained and sedentary female subjects.
abstract: To assess whether the rheological properties of blood might be altered by exercise, we measured whole blood viscosity, plasma viscosity, and its components in healthy female subjects before, immediately after, and 1 h after maximal upright exercise using the Bruce graded exercise protocol. Forty-seven female subjects (15 sedentary, 14 who ran 5-15 miles/wk, and 18 who ran greater than 50 miles/wk), ages 18-43 yr, were evaluated. Whole blood viscosity, measured with a cone and plate viscometer, increased an average of 12.6% with exercise. The increase was greater than can be attributed to the observed 8.9% increase in hematocrit alone due to a coincident increase in plasma protein concentration. However, plasma viscosity did not rise to the degree expected, likely due to a disproportionate observed loss of fibrinogen from the protein pool. These changes were independent of conditioning level or aerobic capacity. In this cross-sectional study, there appears to be no adaptive adjustment in females to physical conditioning that results in changes in blood viscosity.
mesh_terms: D000328:Adult; D001798:Blood Proteins / Q000378:metabolism; D001809:Blood Viscosity; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006400:Hematocrit; D006801:Humans; D005082:Physical Exertion; D010809:Physical Fitness
chemical_list: D001798:Blood Proteins; D005340:Fibrinogen