What is blood doping?

Blood doping involves techniques or substances that artificially boost the number of red blood cells in an athlete's body. This practice is banned in sports because it provides an unfair advantage by enhancing oxygen delivery to muscles.

The World Anti-Doping Agency (WADA) - an international organisation that coordinates the fight against doping in sport - defines blood doping as the misuse of methods or materials to increase red blood cell count. By increasing red blood cells, athletes can improve their endurance and recovery during activities.

Blood doping acts as a shortcut to building aerobic fitness, which is the body's ability to use oxygen efficiently during prolonged exercise. This allows performers to train harder and compete longer without tiring as quickly.

Methods of blood doping

Athletes use different approaches to achieve blood doping, focusing on raising red blood cell levels to transport more oxygen. The two main methods involve a hormone or direct blood manipulation.

Erythropoietin (EPO)

Erythropoietin (EPO) is a hormone naturally made by the kidneys to trigger the production of red blood cells. Some athletes inject synthetic EPO, which is an artificially produced version of this hormone, to stimulate extra red blood cell creation.

This method is popular among endurance athletes like cyclists, as it increases haemoglobin levels, allowing more oxygen to reach working muscles. As a result, performers experience better endurance and faster recovery from intense efforts.

Blood transfusions

In this method, blood is removed from the body, stored, and later reintroduced to elevate red blood cell counts. Unlike EPO, which prompts the body to make new cells, transfusions add existing red blood cells directly. This can make detection harder in some cases, leading athletes to switch from EPO to transfusions after blood tests for EPO became available.

The blood doping process

The process of blood doping through transfusions follows a specific timeline to maximise red blood cell levels just before competition. This method relies on timing to ensure high haemoglobin concentrations are preserved.

Steps in the blood transfusion process

1. Blood extraction - Several weeks before an event, blood is drawn from the athlete when their haemoglobin levels are at a peak.
2. Storage - The extracted blood is frozen to preserve the red blood cells and maintain high haemoglobin content.
3. Reintroduction - A day or two prior to the competition, the frozen blood is thawed and transfused back into the athlete's bloodstream.
4. Performance boost - This increases the overall red blood cell count, enhancing the blood's oxygen-carrying capacity.

Through this process, the athlete's aerobic capacity improves, enabling sustained performance with reduced fatigue.

Types of blood doping

Blood doping via transfusions can use the athlete's own blood or blood from another person, each with different risks.

Autologous and homologous transfusions

• Autologous transfusion - This involves using the athlete's own blood, which is extracted, stored, and reinfused. It reduces compatibility issues but is harder to detect.
• Homologous transfusion - Here, blood from a donor (another person) is used. This carries extra dangers, such as blood type mismatches that could cause severe reactions.

Homologous methods increase infection risks if blood is shared unsafely.

Benefits for athletes' performance

Blood doping provides significant advantages in sports requiring endurance, by enhancing the body's oxygen transport system.

Key performance improvements

• Increased oxygen delivery - More red blood cells mean greater haemoglobin availability, allowing muscles to receive more oxygen during exercise.
• Enhanced endurance - Athletes can maintain high-intensity efforts for longer periods without fatigue setting in.
• Faster recovery - Improved oxygen supply helps muscles recover quicker between training sessions or during multi-stage events like cycling tours.
• Aerobic fitness shortcut - It mimics the effects of high-altitude training or natural fitness gains, letting athletes work harder without the same level of legitimate preparation.

These benefits are why endurance sports, such as long-distance running or cycling, see higher instances of blood doping.

Risks and side effects

While blood doping can boost performance, it poses serious health dangers due to unnatural changes in blood composition.

Main side effects

• Thicker blood (viscosity) - Increased red blood cells make blood more viscous, or thicker, which strains the heart and raises the risk of clots.
• Cardiovascular issues - This can lead to heart attacks, strokes, or pulmonary embolism, which is a blockage in a lung artery caused by a blood clot.
• Infection risks - Sharing blood in homologous transfusions can transmit diseases, while poor storage or transfusion practices may cause infections.
• Kidney problems - Synthetic EPO overuse can damage the kidneys, the organs responsible for natural EPO production.

These dangers highlight why blood doping is not only unethical but also life-threatening.

Detection of blood doping

Detecting blood doping is challenging, but testing has evolved to catch cheats and maintain fair play in sports.

Testing methods and developments

• EPO detection - Introduced in 2000 for the Sydney Olympics, this involves initial blood screening followed by urine tests to identify synthetic EPO.
• Homologous transfusion tests - Since 2004, methods can spot transfusions using another person's blood by checking for foreign markers.
• Autologous challenges - Reliable tests for an athlete's own blood transfusions are not yet available, though WADA funds research to develop them.

Athletes caught doping face bans, fines, and loss of titles, reinforcing the importance of clean competition.