Changes in erythropoiesis, iron metabolism and oxidative stress after half-marathon.
OBJECTIVE
In marathon runners changes in red blood cell count, haematocrit and haemoglobin in relation to haemodilution have been reported. Moreover, it has been hypothesized that strenuous exercise induces oxidant stress through several different mechanisms. This study investigated the haematological variables, iron status and oxidative indices before, immediately and 48 h after a race in 8 healthy trained males aged 33-44 years running a 21-km marathon in 79 +/- 3 min.


METHODS
The haematological parameters were determined by standard procedures. Erythropoietin and soluble-transferrin receptor were evaluated immunoenzymatically. Nontransferrin-bound iron (NTBI) was assayed by high-performance liquid chromatography after nitrilotriacetic acid chelation. Malonyldialdehyde (MDA) concentration was assayed colorimetrically.


RESULTS
The total number of reticulocytes rose significantly after the run with a significant increase in the high-RNA-content fraction (14 +/- 5, p < 0.0006). Erythropoietin rose by 26% (15.0 +/- 2.8 mU/ml, p < 0.004) and by 25% (14.9 +/- 2.13 mU/ml, p < 0.02) immediately and 48 h after the race, respectively. Serum iron and serum ferritin remained unchanged but NTBI and serum MDA increased significantly immediately after running (1.16 +/- 0.40 mmol/l, p < 0.0008; 0.76 +/- 0.16 mmol/l, p < 0.0001). Significant positive correlations at any time between MDA and polymorphonuclear neutrophils (p = 0.0005), MDA and NTBI (p = 0.0018), polymorphonuclear neutrophils and NTBI (p = 0.0008) and between lactate dehydrogenase and NTBI (p = 0.0212) were observed.


CONCLUSIONS
The erythropoietic changes observed in marathon runners are the results of several interacting mechanisms that involve either the haemopoietic system per se or erythrocyte haemolysis and oxidative stress.
Duca
Lorena
L
Department of Internal Medicine, University of Milan and IRCCS Ospedale Maggiore Hospital, Mangiagalli e Regina Elena Foundation, Milan, Italy.
Da Ponte
Alessandro
A
Cozzi
Mariarita
M
Carbone
Annalisa
A
Pomati
Mauro
M
Nava
Isabella
I
Cappellini
Maria Domenica
MD
Fiorelli
Gemino
G
D000328:Adult; D003627:Data Interpretation, Statistical; D004920:Erythropoiesis; D005293:Ferritins / Q000032:analysis; D005434:Flow Cytometry; D006801:Humans; D007124:Immunoenzyme Techniques; D007501:Iron / Q000097:blood / Q000378:metabolism*; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D009391:Nephelometry and Turbidimetry; D018384:Oxidative Stress / Q000502:physiology*; D011990:Receptors, Transferrin / Q000097:blood; D012016:Reference Values; D012156:Reticulocytes / Q000502:physiology; D012420:Running / Q000502:physiology*; D013997:Time Factors
D011990:Receptors, Transferrin; D008315:Malondialdehyde; D005293:Ferritins; D007501:Iron