The effect of different exercise intensities on the fibrinolytic system.

The effects of moderate 30-min cycle ergometer exercise (aerobic metabolism) followed by short-term exercise at maximal capacity (anaerobic metabolism) on fibrinolytic activity were investigated in ten female and ten male healthy, untrained subjects. The following parameters of fibrinolytic activity were measured initially (t0), at the end of the aerobic phase (t1), at the end of the anaerobic phase (t2) and after a 30-min recovery period (t3): tissue plasminogen activator (PAt) activity, PAt concentration, plasminogen activator (PAt) activity, PAt concentration, plasminogen activator inhibitor (PAi) activity, and D-Dimer concentration. Moderate long-term exercise caused a slight but significant increase in PAt concentration and PAt activity (t1; P < 0.01), whereas short-term exercise at maximal capacity (t2) produced a substantial elevation in both these parameters (P < 0.01). This would suggest that PAt was not inhibited totally by PAi which would itself seem to be consumed during exercise. In addition, a slight exercise intensity-dependent increase in D-Dimer concentration was measured--circumstancial evidence not only for elevated fibrinolytic potential, but also for an actual increase in fibrin degradation (t2: P < 0.01). After t3 both PAt activity and D-Dimer concentration were still slightly but significantly increased. The results obtained in the tests of fibrinolytic activity showed no significant difference between the men and the women. It would seem that the release of PAt is more markedly stimulated by short-term intense physical exercise than by long-term moderate exercise and actually causes increased fibrin degradation.

Effects of an acute saline infusion on fluid and electrolyte metabolism in humans.

Several hormonal systems participating in body fluid and electrolyte homeostasis were investigated in six healthy volunteers in a supine body position during a period of 9 days and nights. Under strictly controlled conditions, striking circadian rhythms were observed for plasma levels of vasopressin, renin, aldosterone, guanosine 3',5'-cyclic monophosphate, cortisol, and epinephrine. Nocturnal decreases and diurnal increases in urine flow rate and urinary excretion of electrolytes were observed and closely paralleled the urinary excretion of urodilatin. During 48 h after an acute isotonic saline infusion (2 liters within 25 min) and after a 48-h control experiment the urinary excretion of H2O and electrolytes, and simultaneously the alterations in endocrine systems participating in body fluid homeostasis, were determined. Urine flow and urinary electrolyte excretion rates were significantly increased during 2 days after the saline infusion. The largest increase in urinary fluid and electrolyte excretion was observed between 3 and 22 h postinfusion. These long-term changes were paralleled by altered H2O and Na balances and also by elevated body weights that returned to baseline values with an approximate half-life of 7 h. These data suggest that vasopressin, atrial natriuretic peptide, and catecholamines are unlikely to be of major importance for the renal response to this hypervolemic stimulus. The renin-aldosterone system was suppressed during 2 days postinfusion. This suppression correlated with the effects of saline load on Na excretion. However, the closest relation with Na excretion was observed for the kidney-derived member of the atrial natriuretic peptide family, urodilatin, which was considerably increased during the long-term period up to 22 h postinfusion. Thus these data show that the human body in supine position requires approximately 2 days to regulate the amount of Na and H2O provided by an acute saline infusion. The data also suggest that urodilatin and the renin-aldosterone system might participate in the long-term renal response to an acute saline infusion and also in the mediation of circadian urinary excretion rhythms.

Influence of prolonged physical exercise on the erythropoietin concentration in blood.

Erythropoietin (EPO) and red blood cells were studied in 15 well-trained men before and several times after a marathon run. Changes in red blood cells reflected changes of plasma volume. Immediately after the run, red blood cells were increased due to haemoconcentration, whereas 31 h later the values were decreased due to haemodilution. The EPO concentration was increased 3 h, and more impressive 31 h, after the run. This long-lasting increase in EPO concentration after the marathon run would seem to be responsible for the increased red blood cell mass in long distance runners.

Effect of prolonged physical exercise on fluid regulating hormones.

Sixteen well-trained young men performed a test marathon to study the behaviour of atrial natriuretic peptide (ANP) and its second messenger cyclic guanosine monophosphate (cGMP) in relation to changes in plasma volume (PV) and plasma proteins, arginine vasopressin (AVP), renin, aldosterone, potassium and sodium. Blood samples were drawn under standardized conditions before and immediately after the run, as well as 3 h and 31 h after the run. Directly after the run, a two-and-a-half fold increase of plasma ANP and a twofold increase of plasma cGMP level were found, whereas PV decreased significantly by 7.4%. At this time renin-, aldosterone- and AVP-secretion were much stimulated. Thirty-one hours after the run, PV was markedly greater (10%) than before the race, whereas plasma proteins had returned to pre-exercise values. The ANP and cGMP were not significantly altered compared to the pre-race values. We have concluded that ANP and the other volume-regulating hormones may play an important role during and immediately after prolonged physical exercise but not in the longer recovery period. It seems that an influx of plasma proteins into the vascular space is responsible for the increased PV at this time.

Effect of prolonged physical exercise on the fibrinolytic system.

The effect of a test marathon race on plasma fibrinolytic activity (FA) was studied in 16 endurance athletes before, immediately after, 3 h, and 31 h after the run. Tissue plasminogen activator (t-PA) activity increased about 31-fold immediately after the run. Similar increases were found in t-PA antigen concentration. Plasminogen activator inhibitor (PAI) was not detectable immediately after the race and was significantly decreased 3 h (P less than 0.05) and 31 h (P less than 0.01) later. B beta 15-42 peptide increased by 0.63 pmol.ml-1 (P less than 0.001), D-dimer by 68.3 ng.ml-1 (P less than 0.05). Euglobulin lysis time (ELT) was reduced from 109 to 18 min (P less than 0.001). The increased t-PA activity and t-PA antigen concentration disappeared in the course of the first 3 h after exertion. ELT also reached its pre-exercise levels at this time. Thirty-one hours after the race ELT and t-PA antigen levels were slightly but significantly reduced (P less than 0.05), whereas B beta 15-42 peptide remained increased (P less than 0.05). t-PA activity was unchanged compared with pre-exercise values. It seems that the exercise-induced FA is mainly caused by the marked increase of t-PA antigen and t-PA activity.

Influence of prolonged physical exercise on plasma volume, plasma proteins, electrolytes, and fluid-regulating hormones.

Fluid-regulating hormones [arginine vasopressin (AVP) and aldosterone] as well as electrolytes, plasma volume (PV), and plasma proteins were studied in 16 well-trained male amateur runners (mean age 31.8 years) before t0), immediately after (t1), and 60 min (t2) and 22 h (t3) after a marathon run. Immediately after the run PV was significantly decreased by 12.1%, whereas the concentration of plasma proteins increased by 13.9%, sodium by 5.8 mMol.l-1, and potassium by 0.58 mMol.l-1, respectively. Aldosterone increased by 1089 pg/ml and AVP by 9.0 pg/ml. PV was significantly increased 22 h after the run by 10.6% (P less than 0.001) and plasma proteins were increased by 1.0% (P greater than 0.05), whereas aldosterone and AVP as well as electrolytes returned to control values. At t1, and particularly at t2 and t3, the total plasma protein concentration increased much more than could have been expected from changes of PV. It is suggested that this phenomenon was caused by an influx of proteins into the vascular space. This might also be the reason for the expanded PV especially in the longer recovery period at t3. The volume-regulating hormones (AVP and aldosterone) may play an important role during and immediately after the run but not in the longer recovery period (t2 and t3).

[The hemostatic and fibrinolytic system in normal subjects and myocardial infarct patients. Effect of a standardized aerobic and anaerobic ergometric stress test]. / Hämostase- und Fibrinolysesystem bei Gesunden und Herzinfarktpatienten. Einfluss einer standardisierten aeroben und anaeroben ergometrischen Belastung.

After clinical examination, 14 asymptomatic post-infarction male patients and 12 healthy control persons, aged 35-62 years, underwent two bicycle-ergometry tests. After a 20-min aerobic test of moderate intensity both groups had slight activation of the clotting system simultaneously with favorably increased fibrinolytic activity. After stepwise submaximal aerobic exercise, postinfarction patients had marked activation of the thrombocytic system; beta-thromboglobulin rose significantly from 36 to 102 ng/ml. But compared to the results in healthy persons, fibrinolytic activity was significantly reduced in the postinfarction patients (euglobulin lysis time 135 and 100 min, respectively). In three patients with unfavorable reactions of the hemostasis and fibrinolysis systems, ischemic changes or multifocal ventricular extrasystoles were recorded in the ECG after the second exercise test. These results indicate that intensive physical exercise in postinfarction patients can change the dynamic equilibrium between hemostasis and fibrinolysis in the direction of an increased clotting tendency. For this reason postinfarction patients and elderly untrained persons, especially those with an increased coronary risk factor, should avoid endurance training involving anaerobic exercise. On the other hand, moderate training at aerobic level favorably influences the hemostatic equilibrium in both healthy and postinfarction patients.

Blood platelet activation and increase in thrombin activity following a marathon race.

To see whether strenuous prolonged exertion increases blood platelet activation and thrombin activity in healthy well-trained men, 16 male amateur runners (mean age 31,8) were studied. A marathon race (mean time 2 h 44 min 30 s) caused a significant increase in plasma beta-thromboglobulin (beta-TG), platelet factor 4 (PF4), fibrinopetide A (FPA) and factor VIII (F VIII) activity. Sixty min after exertion beta-TG and F VIII activity were still significantly elevated. FPA continued to rise, reaching peak values 60 min after the run. 22 h after finishing the race F VIII activity was still significantly elevated. The study has demonstrated the great inter-individual variability of marathon race-induced haemostatic changes. The elevation of beta-TG varied from 42% to 156%, F VIII from 112% to 625%, and in three runners FPA reached more than 900% of its pre-exercise value. In some individuals the haemostatic changes observed could be potentially unfavourable for coronary heart disease prevention.