Erythropoietin, commonly referred to as EPO, is hormone in the body that stimulates red blood cell production and also aids in wound healing. The major effect on performance is increasing the amount of oxygen that can be delivered to the working muscles by the red blood cells, thus increasing one’s aerobic exercise abilities. This has lead synthetic EPO to be used as a performance enhancing drug in many endurance sports including cycling, where use has been a black eye for the sport.
Use of erythropoietin is not without it’s dangers. For one, it is a banned substance and thus, both immoral and illegal. Also by dramatically increasing the hematocrit, the volume percentage of red blood cells in a unit of blood, blood flow can decrease due to the increased viscosity of the blood. This thicker blood can also increase the likelihood of thrombosis (blood clot inside a blood vessel) and stroke.
However, use of synthetic EPO is not the only method of increasing red blood cell count in the body. Hypoxemia, or abnormally low oxygen content in the blood, stimulates the kidneys to produce erythropoietin resulting in increased hematocrit. Athletes can impose hypoxemia through intense exercise or through altitude training. The most effective method of altitude training is the live high, train low approach in which daily living occurs at elevation to stimulate EPO but training occurs lower to maximize workout performance. Live high, train high is another effective technique.
The most effective training method of improving red blood cell count is through VO2 max intervals. These intervals are intense, but not the same intensity of high intensity interval training. Maximum sustainable intensity for two to four minutes with approximately comparable rest periods an appropriate exercise prescription. A six-week program performed two times per week beginning with two-minute work intervals with four minute rests for four cycles and increases of the work interval by thirty seconds per week will result in an increased hematocrit.
As erythropoietin derived from amino acids, ensuring adequate high quality protein in the diet is essential for maximizing its effects. Iron, calcium and vitamins A and C are also important nutrients for optimizing erythropoietin’s production.
When endurance performance is the goal, maximizing red blood cell count is not the only limiting factor. A balanced endurance-training program will also improve central factors such as stroke volumes. Methods such as cardiac output (thirty to ninety minutes at a heart rate of one hundred and thirty to one hundred and fifty beats), tempo training (fifteen to twenty seconds at eighty to ninety percent effort with forty to forty-five seconds rest), and alactic-aerobic work (six to eight seconds of maximum effort with forty to sixty seconds rest) can all improve the foundational aspects of the aerobic system.
Lactate threshold, or the intensity at which the dominant energy system changes from aerobic to anaerobic, is another limiting factor to aerobic performance. This aspect can be improved by exercising at the lactate threshold for ten to twenty minutes at a time or in two-minute intervals above the threshold with five to eight minute rest periods.
Red blood cell count, increased by erythropoietin, can influence endurance performance. Hypoxemia is the mechanism that can increase release of this protein hormone and can be triggered by altitude or intense activity. However, hematocrit is not the only determinant of aerobic abilities and training each of the factors will lead to maximum performance.