Ashenden, M. J., Gore, C. J., Parisotto, R., Sharpe, K., Hopkins, W. G, & Hahn, A. G.(2003). Effect of altitude on second-generation blood tests to detect erythropoietin abuse by athletes. Haematologica, 88, 1053-1062.

The model used to evaluate possible erythropoietin (EPO) enhancements in athletes' blood is based upon the On- and Off-model. It has been reported as being able to identify athletes who use or have used EPO. Blood parameters and model scores were retrospectively evaluated in:

• elite cyclists (N = 19) who lived and trained at 2,690 m above sea level for 26-31 days;
• elite Kenyan runners (N = 6) who lived 2,100 m above sea level but descended to compete at sea level competitions; and
• well-trained subjects (N = 39) who resided at sea level but slept at a simulated altitude of 2,650-3,000 m for 20-23 days of either consecutive or intermittent nightly exposure.

Upon reaching altitude On-model scores increased immediately, largely because of increased hemoglobin concentration. Upon returning to sea level, model scores did not return to previous sea level values after three weeks because of the persistence of the raised hemoglobin concentration for the On- and Off-model scores and a fall in reticulocyte percentage for Off-model scores. For the Kenyan runners, the On- and Off-model scores decreased within seven days of descent to sea level.

Implication. The use of the On- and Off-model scores as indications of EPO doping should be seriously questioned. Adaptive reactions to altitude living could cause false positives to be recorded if blood testing were performed at altitude or within three weeks of leaving altitude.

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