Exercise induces a change in plasma fibrinogen concentration: Fact or fiction?

This study examined the effect of exercise on plasma fibrinogen concentrati ons with simultaneous measurements of plasma volume changes. Eight moderate ly active males aged 26.6+/-3.6 years (mean+/-SD) completed maximal (VO(2)m ax) and submaximal (75% VO(2)max for 30 minutes) exercise trials separated by 7 days. Venous blood samples were obtained at rest, immediately postexer cise, and following 30 minutes of recovery. Whole blood was analysed for ha ematocrit and haemoglobin, while citrated plasma was assayed for fibrinogen levels. Values of haematocrit and haemoglobin before and after exercise we re utilised for the estimation of plasma volume changes. Plasma volume decr eased (p<0.05) immediately following both maximal (-17.7+/-5.1%) and submax imal (-14.3+/-3.1%) exercise, Exercise resulted in decreased plasma fibrino gen levels (maximal exercise: from 266.3+/-14.5 to 222.2+/-23.9 mg.dL(-1); submaximal exercise: from 239.5+/-45.4 to 209.7+/-42.4 mg.dL(-1)) only when postexercise raw data were corrected for the contraction of plasma volume. It is concluded therefore that changes in plasma volume in response to exe rcise should be taken into account when interpreting exercise effects on pl asma fibrinogen concentration. (C) 1999 Elsevier Science Ltd. All rights re served.