Can Breath Holding Increase EPO? What Research Shows

Erythropoietin (EPO) is a hormone produced mainly by the kidneys in response to low oxygen levels. It stimulates the bone marrow to produce and mature red blood cells, increasing the blood's oxygen-carrying capacity.

Because breath holding lowers blood oxygen, it is often said to "boost EPO." Research shows that repeated maximal breath holds can cause a short-term rise in EPO of around 24%. But a short-lived rise in EPO is not the same as a lasting increase in red blood cells, and newer research has not shown that breath holds reliably produce that kind of adaptation. This article explains what the research does and doesn't show.

What Is Erythropoietin (EPO) and What Does It Do?

• Erythropoietin (EPO) is a naturally occurring hormone
• About 90% of EPO is secreted by the kidneys
• EPO stimulates production and maturation of red blood cells in the bone marrow
• This increases the oxygen-carrying capacity of the blood

Erythropoietin, or EPO, is produced when oxygen levels in the body are low. This occurs naturally at high altitude. Like any hormone, imbalance can also be caused by sickness or overtraining.

Raised EPO and red blood cell levels can be seen in some sleep apnea patients. These people stop breathing periodically during sleep, and their blood oxygen saturation can drop substantially, night after night, for years.

Low blood oxygen stimulates the production of erythropoietin. It is one of the body's protective mechanisms. When tissues are short of oxygen for long enough, the body releases and matures new red blood cells to compensate.

EPO and Blood Doping

EPO is essential for the production of red blood cells. A healthy red blood cell count supports aerobic power and oxygen-carrying capacity.

Synthetic EPO is available as a pharmaceutical. It regulates the concentration of red blood cells and hemoglobin in the blood. It is used to treat anemia.

It is also used in blood doping, when athletes inject EPO to boost their aerobic capacity.

Blood doping is banned. It can result in long bans from competition. It has tainted events like the Tour de France. Since the Sydney Olympics in 2000, EPO testing has been commonplace.

Blood doping can also be fatal. When EPO concentration is too high, the bone marrow produces too many red blood cells. This causes the blood to thicken. Thick blood is difficult for the heart to pump, slowing blood flow and affecting blood pressure.

The full long-term effects of unregulated synthetic EPO use are not known. But young athletes have suffered clotting and strokes, and some have died from heart attacks.

Supporting Healthy Red Blood Cell Production

If you want to support healthy red blood cell production, start with your diet. Your body needs certain nutrients to make red blood cells, especially when it is under endurance exercise stress.

Key nutrients include:

• Iron
• Vitamin B12
• Folate (vitamin B9)
• Vitamin C, which helps your body absorb iron

If you suspect your iron or red blood cell count is low, get a blood test and talk to your doctor before taking iron supplements, as too much iron can be harmful.

Heat exposure has also been studied. Men's Health has reported on research suggesting that sauna use may influence EPO.

Does Exercise Increase EPO?

EPO production increases when the body is low in oxygen. In one study, EPO rose after exercise that caused arterial oxygen saturation to drop below about 91% (Roberts et al., 2000).

At sea level, most people will not reach this level of desaturation during normal training. Breath holding after an exhalation is one way to create a temporary drop in blood oxygen.

What Happens to EPO During Breath Holding?

Breath holding lowers blood oxygen for a short time. In one study, repeated maximal breath holds raised EPO by 24%, with levels returning to baseline within around 5 hours. The effect is real but short-lived.

Acute Response vs Lasting Adaptation

When people talk about breath holding and EPO, they are often mixing up two different things.

The acute response happens during and shortly after breath holding. The spleen contracts within seconds, releasing stored red blood cells and briefly raising hemoglobin for a few minutes. EPO can rise over the following hours, then returns to normal.

A lasting adaptation would mean a sustained increase in total red blood cell mass. At altitude, this generally requires many hours of low oxygen every day for weeks. A few minutes of breath holding creates a much smaller and shorter hypoxic signal.

When Patrick McKeown wrote The Oxygen Advantage, much of the evidence on breath holding and blood came from studies of free divers. These showed spleen contraction during breath holds, short-term rises in EPO, and higher hemoglobin in experienced divers compared with untrained people. Those findings were real, but they did not show that breath holds cause lasting changes. Experienced divers may differ for other reasons, including years of very intense, prolonged breath holding.

Newer research has tested this more directly. In a controlled 2022 study, six weeks of daily static breath holds did not raise EPO, hemoglobin mass or VO2 peak (Bouten et al., 2022). So far, research has not shown that breath holds reliably raise red blood cell mass.

What This Means for Athletes

Breath holding does cause a short-term EPO response, but it should not be relied on to increase red blood cells or oxygen-carrying capacity.

There are other reasons athletes use breath hold training. It can help strengthen the breathing muscles, provide controlled exposure to air hunger, and create a brief altitude-like training stimulus. Some studies also suggest benefits for fatigue resistance during repeated sprints. See our guides on aerobic capacity and altitude training to learn more.

You can track your breathing by measuring your BOLT score. BOLT measures how quickly you feel the first clear urge to breathe during a comfortable breath hold. It is a useful personal baseline for tracking progress, but it does not measure EPO, red blood cells or performance.

Note: Strong breath holds are not suitable for everyone. Avoid them if you are pregnant or have a heart condition, high or low blood pressure, epilepsy, diabetes, pulmonary hypertension or another serious medical condition, unless cleared by your doctor. Never practice breath holds in or under water.

Research: What Studies Show About Breath Holding and EPO

Study 1: Repeated Breath Holds Raised EPO by 24% for a Few Hours

Results showed that EPO concentration increased by 24%, peaking at three hours after the final breath hold and returning to baseline two hours later.

Exercise protocol: Three sets of five maximum duration breath holds, with each set separated by ten minutes of rest.

de Bruijn R, Richardson M, Schagatay E. "Increased erythropoietin concentration after repeated apneas in humans." Eur J Appl Physiol 2008; 102:609-13.

Study 2: Exercise-Induced Low Oxygen Increased EPO by 24 to 36%

Researchers from the Human Performance Laboratory, University of Calgary, Canada, investigated the relationship between decreased oxygen concentration during exercise and erythropoietin production. This study involved hard exercise at altitude, not breath holding.

Five athletes cycled for three minutes at supramaximal intensity at two different elevations: 1,000m and 2,100m. Oxygen saturation of hemoglobin dropped below 91% for approximately 24 seconds at 1,000m and for 136 seconds at 2,100m. EPO levels increased by 24% and 36% respectively following the exercise.

Roberts D, Smith DJ, Donnelly S, Simard S. Plasma-volume contraction and exercise-induced hypoxaemia modulate erythropoietin production in healthy humans. Clinical Science. 2000.

Study 3: Six Weeks of Static Breath Holds Did Not Change Hemoglobin Mass

Twenty-two men were randomly assigned to a control group or to six weeks of daily static breath holds (five maximal breath holds per day). The breath-hold sessions did not produce an acute rise in EPO, and after six weeks there was no change in resting EPO, hemoglobin mass, VO2 peak or 3 km cycling time trial performance. The researchers concluded that longer or more intense sessions with a stronger hypoxic stimulus are probably needed.

Bouten J, Debusschere J, Lootens L, et al. Six weeks of static apnea training does not affect Hbmass and exercise performance. J Appl Physiol. 2022;132(3):673-681.

The Bottom Line

Breath holding can cause a brief rise in EPO and a short-term release of red blood cells from the spleen. But the research so far does not show that breath holds reliably increase red blood cell mass over time. If you practice breath hold training, do it for the benefits that are better supported, and learn more in our guide to the benefits and science of breath holding.