High red blood cell count

high red cells can increase the delivery of oxygen to your tissues, and can make you feel full of energy. However, past a point, the increased number of cells in your blood causes the blood to become thickened and kinda gluggy. This puts a HUGE strain on the heart, and can cause heart attacks and heart failure. Do not consider taking hormones such as EPO (erythropoietin) to increase your red cells- it is a dangerous practice and is illegal in sports and in the courts (it is a prescription medicine only). Altitude training provides enough stimulus for the body to increase blood cells to get the beneficial effects, but not enough to cause the adverse effects (provided it is done responsibly). Hope this helps! Aj :)