Acute hyperhydration reduces athlete biological passport OFF-hr score

Anecdotal evidence suggests that athletes hyperhydrate to mask prohibited substances in urine and potentially counteract suspicious fluctuations in blood parameters in the athlete biological passport (ABP). It is examined if acute hyperhydration changes parameters included in the ABP. Twenty subjects received recombinant human erythropoietin (rhEPO) for 3 weeks. After 10 days of rhEPO washout, 10 subjects ingested normal amount of water (approximate to 270mL), whereas the remaining 10 ingested a 1000mL bolus of water. Blood variables were measured 20, 40, 60, and 80min after ingestion. Three days later, the subjects were crossed-over with regard to water ingestion and the procedure was repeated. OFF-hr was reduced by approximate to 4%,approximate to 3%, and approximate to 2% at 40, 60, and 80min, respectively, after drinking 1000mL of water, compared with normal water ingestion (P<0.05). Forty percent of the subjects were identified with atypical blood profiles (99% specificity level) before drinking 1000mL of water, whereas 11% (n=18), 10% and 11% (n=18) were identified 40, 60, and 80min, respectively, after ingestion. This was different (P<0.05) compared with normal water intake, where 45% of the subjects were identified before ingestion, and 54% (n=19), 45%, and 47% (n=19) were identified 40, 60, and 80min, respectively, after ingestion. In conclusion, acute hyperhydration reduces ABP OFF-hr and reduces ABP sensitivity.