November, 2022

Conan Shing

CPLEAP, University of British Columbia Okanagan

Take home message

  • Acute exposure to intermittent bouts of low oxygen (hypoxia) can elicit erythropoietin (EPO) production, which has potential to increase red blood cell production and possibly oxygen carrying capacity.
  • Eight 4-minute cycles of intermittent hypoxia appear to be sufficient to elicit a serum EPO level increase within hours of exposure.


  • -EPO is essential in stimulating red blood cell production and increasing oxygen carrying capacity. Thus, an increase in red blood cell mass can improve the body’s ability to transport and utilize oxygen for various activities of daily living and exercise.
  • Hypoxic exposure (low oxygen environments, e.g., high altitude) can elicit EPO production.
  • Both continuous and intermittent hypoxia may elicit increases in EPO suggesting intermittent hypoxia might be a time-efficient alternative for improving oxygen carrying capacity.

How the study was done

  • 7 healthy and recreationally active adults underwent 3 intermittent hypoxic exposure protocols (to induce a reduction in arterial oxygen saturation to 80%): five 4-minute cycles, eight 4-minute cycles, and a 120-minute continuous exposure with 4 minutes of normoxia (i.e., exposure to normal levels of oxygen) between the intermittent cycles.
  • Arterial oxygen was monitored in combination with ventilatory, blood pressure and other cardiorespiratory measures.
  • EPO levels were determined using venous blood samples collected at 2.5 and 4.5 hours post-hypoxic exposure for the 5-cycle protocol and at 4.5 and 6 hours post exposure for the 8-cycle and 120-minute protocols.
  • EPO levels for the control group was collected at 2.5 and 4.5 hours following the protocol.
  • Changes in EPO levels following hypoxic exposure was compared to a normoxic baseline.

What the researchers found

  • An increase in EPO was observed for all protocols with the greatest increases observed at 4.5 hours post exposure in both the 8-cycle and 120-minute hypoxic exposure protocols.
  • – While the 120-minute continuous exposure protocol elicited the greatest increase in EPO, the eight-cycle protocol elicited similar results (65% vs 76% increase), but only took 64 minutes to complete.
  • These findings indicate that brief successive exposure to hypoxia can elicit a significant change in EPO levels and may improve oxygen carry capacity.


  • As eight 4-minute cycles of intermittent hypoxia protocol (64 minutes to complete) elicited similar increases in EPO as 120 minutes of continuous hypoxic exposure, the finding suggests that the latter protocol may be a time-efficient method to elicit an increase in EPO production.
  • It remains unknown whether higher levels of hypoxia (greater decreases in oxygen) can elicit greater EPO production and subsequent red blood cell production.
  • Further studies investigating the response of endurance trained or clinical populations to intermittent hypoxia should be conducted to see if it could be a time-efficient method of naturally increasing EPO as any preexisting impairments may impact the observed responses.


Wojan, F., Stray-Gundersen, S., Nagel, M. J., & Lalande, S. (2021). Short exposure to intermittent hypoxia increases erythropoietin levels in healthy individuals. Journal of Applied Physiology, 130(6), 1955–1960.