LAUSR

Eight 4-min cycles of intermittent hypoxia represent the shortest hypoxic exposure to increase erythropoietin (EPO) levels in young adults. The impact of aging on the EPO response to a hypoxic stimulus remains equivocal. Thus, the objective of this study was to determine the effect of the same intermittent hypoxia protocol on EPO levels in older adults. Methods: Twenty-two participants (12 women, age: 53±7 years) were randomly assigned to an intermittent hypoxia group (IH, n=11) or an intermittent normoxia group (IN, n=11). Intermittent hypoxia consisted of eight 4-min cycles at a targeted oxygen saturation of 80% interspersed with normoxic cycles to resaturation. Air was made hypoxic by titrating nitrogen into a breathing circuit. Intermittent normoxia consisted of the same protocol, but nitrogen was not added to the breathing circuit. EPO levels were measured before and 4.5 hours after the beginning of each protocol. Intermittent hypoxia lowered oxygen saturation to 82±3%, which corresponded to a fraction of inspired oxygen of 10.9±1.0%. There was a greater increase in EPO levels following intermittent hypoxia than intermittent normoxia (IH: 3.2±2.2 vs. IN: 0.7±0.8 mU·ml-1, p<0.01). A single session of eight 4-min cycles of hypoxia increased EPO levels, the glycoprotein stimulating red blood cell production, in older adults. Exposure to intermittent hypoxia has therefore the potential to increase oxygen-carrying capacity in a population with reduced red blood cell volume.