Résumé
1. 10 trained males were studied for the changes in white, red blood cell counts, Hemoglobin concentration, Hematocrit value, Blood Glucose, Lactate and Triglycerides concentration after 5000-m-running. 2. There was a slight but significant increase in RBcs, WBcs counts and hemoglobin [%], this may be due to the low intensity of the load [rate of running] which was not enough to stimulate the sympathetic system to a greater extent. It is also possible that the athletes were well-trained and adapted 3. The slight increase in the blood cells led to a minimal increase of hematocrit and hence blood viscosity will not increase to the extent of increasing the blood flow and so the blood flow to muscle is not affected. 4. There was significant increase of blood lactate concentration which means that anaerobic glycolysis is an important element in this race, at least in the final sprint. So the anaerobic power of the athlete is an influencing element in the race the aerobic power. 5. The non-significant change in triglycerides denotes that lipids are not the main fuel for the energy needed in the race. This is in accordance with other studies. 6. There was insignificant increase of glucose concentration which denotes that inspite of this long race Hypoglycaemia did not happen. 7. In conclusion, it may be said that the anaerobic power of the long distance runner is very important to improve his record, so the trainer must put in consideration this fact in his training programm as he does for the aerobic power, Also a high carbohydrate diet for few days before training and race is very important