Fig. 3: Erythropoietic changes in 20 male participants before, during and after 60 days of bed rest HDT.

a Participants remained hemoconcentrated at all time points during bed rest. Reambulation uncovered lower RBC concentration. b EPO was decreased at all time points during bed rest. EPO increased at reambulation. c Total hemoglobin mass was decreased after 60 days of bed rest and at recovery Day 7. Sixty days of bed rest caused a 77.2 g loss in tHb mass attributed to hemolysis and blood draws. Data expressed as changes from baseline. Shaded area represents the bed rest HDT phase. BDC: Baseline Data Collection; HDT: Head-Down Tilt; R: Recovery or Reambulation. Error bars: 95% Confidence Interval. *p < 0.05 compared to baseline.