2. What is blood doping?
3. How does it work?
4. Respiratory physiology
5. The physiology of endurance sports
6. Ventilation during endurance sports
7. Cardiac output during endurance sports
8. Aerobic metabolism during endurance sports
9. Conclusion - blood doping kills
Aerobic metabolism is the final component examined here, which plays a part in the determination of VO2max. This occurs within the mitochondria when the pyruvate molecule is irreversibly converted to a form of acetic acid. This compound then enters the second stage of carbohydrate utilization known as the Krebs cycle. The most important function of the Krebs cycle is the generation of electrons (hydrogen) for transfer to the respiratory chain. Under normal conditions the transfer of electrons and subsequent release of energy are tightly coupled to ADP phosphorylation.
Endurance training improves the metabolic capacity of the trained muscle. More specifically, the mitochondria enlarge and even increase in number, as does the quantity of enzymes for aerobic energy transfer (Holloszy and Coyle 1984). There is also increased muscle capilliarization - this is 40% greater in trained athletes (Brodal et al 1976). If the increase in an athlete's VO2max is largely due to EPO abuse, and subsequent increases in haemoglobin levels, then the cellular adaptations mentioned here will not be sufficient to gain fully from the oxygen carrying capacity.