Effects of 100-km ultramarathon on erythropoietin variation in runners with hepatitis B virus carrier

Completing an ultramarathon leads to an immediate postrace surge of erythropoietin (EPO). Patients with chronic liver disease may have high plasma EPO concentrations. This study aims to explore whether plasma EPO concentrations vary between hepatitis B virus carrier (HBVc) and non-HBVc runners during long distance running. Blood samples were collected from 8 HBVc and 18 non-HBVc runners at 3 different time points: 1 week before, immediately following, and then 24 h after the 100-km ultramarathon race. Samples were analyzed for plasma EPO levels. EPO concentration had a statistically significant rise immediately after the race (8.7 [7.1-11.9] mU·mL^-1to 23.7 [14.8-37.2] mU·mL^-1, P < 0.001) and maintained the high levels 24 h after the race finished (16.7 [11.5-21.0] mU·mL^-1, P < 0.001) in all participants. The mean of EPO concentration was 8.9 (5.7-13.2) mU·mL^-1in HBVc runners and was 8.7 (7.7-11.2) mU·mL^-1in non-HBVc runners in the prerace. In HBVc runners, plasma EPO levels were no different at baseline (P = 0.657) and increased in the same fashion in response to ultramarathon compared with non-HBVc runners. Plasma EPO levels between the two groups were not statistically different at any time point. Prolonged endurance exercise led to a significant increase in EPO. A comparable increase in EPO levels was observed in HBVc and non-HBVc runners during and 24 h after 100-km ultramarathon. However, a small sample size might have affected the ability to detect a difference if it does exist.