Haematological status of middle- and long-distance runners.

1. Haematological investigation and blood volume measurements were carried out on forty male middle and long distance runners and twelve non-athletes. 2. The distribution of haemoglobin concentration, packed cell volume, erythrocyte count, total ironbinding capacity, serum and erythrocyte folate and serum vitamin B12 concentrations were essentially the same in atheletes and non-athletes. The mean serum iron concentration was higher in non-athletes than in athletes. There was no difference in the above measurements between athletes taking iron and/or folate and athletes not taking these supplements. 3. Blood volume and total body haemoglogin were on average 20% higher in the atheletes than in the non-athletes. 4. There was no correlation between haemoglobin concentration and blood volume in athletes. The evidence of this study suggests that haemoglobin concentration and blood volume are independently controlled. 5. 2,3-Diphosphoglycerate concentration in the erythrocytes was higher in the athletes than in the non-athletes; the mean values were 15-9 and 14-2 mumol/g of haemoglobin respectively.