Blood donation
Question:
I am a passionate marathon cyclist and am planning to take part in a long-distance ride. Can I allow myself to donate blood beforehand? How long does it take for the body to regenerate the one litre of blood taken? How severe is the loss of performance in the meantime?
Answer from Dr Merkl:
Since the EPO debate at the latest, every cyclist knows that red blood cells have a decisive influence on endurance performance. The reason for this is the function of these blood cells to transport oxygen from the lungs to the working muscles. The more oxygen reaches the working muscles, the more efficient the organism is. According to studies by sports medicine specialist Professor Bodo Hollmann, maximum oxygen uptake was restored 72 hours after a blood sample of 430 millilitres was taken. In another study, a 12 per cent reduction in oxygen uptake was observed after 900 millilitres of blood had been taken. In general, it can be said that the last blood donation should take place at least four weeks before the planned sporting activity. Taking an iron supplement can promote haematopoiesis.
Haematocrit value
Question:
Is the UCI's setting of the haematocrit value at 50 percent actually scientifically proven? On the laboratory reports of the blood counts that I have done from time to time by my GP, the scale for normal values for men goes up to 54. My personal value was last at 49.9. I take nothing in addition to this except vitamin E and red wine in small quantities.
Answer from Dr Merkl:
In healthy adults, the haematocrit value (= proportion of red blood cells in the total blood volume of a sample) is between 44 and 46, in women between 41 and 43. However, the fluctuation range is very individual and depends on many external factors. Under normal conditions, a highly trained athlete has more red blood cells overall. However, as they have up to two litres more fluid in their circulation at the same time, the haematocrit value is more likely to fall than rise. Altitude training or EPO intake raises the value, which improves endurance. However, as the viscosity (thickness) of the blood also increases as a result, a higher haematocrit value places a strain on the heart and can lead to an undersupply of the organs.
Inhibited blood clotting
Question:
I am undergoing treatment with the drug Marcumar because of a thrombosis in my lower leg. Can I go on longer cycling tours of medium to high intensity again after the therapy?
Answer from Dr Merkl:
Thrombosis is the formation of a blood clot from clumped red blood cells. This can be caused by disturbed blood flow, damage to the vessel wall or a pathological change in the blood composition. The drug Marcumar influences the blood composition in such a way that the clotting process only functions to a limited extent ("artificial haemophiliac"). In the event of a fall injury - for which the risk is high in cycling - this can lead to unstoppable internal and external bleeding. There is also a risk of internal haemorrhaging during strenuous physical exertion, especially with high blood pressure. If you are taking Marcumar, you should therefore only exercise at a relaxed pace and on the ergometer. However, once you have stopped taking the medication, I consider cycling to be an effective way of preventing thrombosis. This is because endurance training leads to a relative thinning of the blood, and the work of the muscles also improves the blood flow.
