Sports Anemia: Can Exercise Make You Anemic?

Recently, some elite athletes have reported experiencing symptoms of anemia. The prevalence of such cases has raised an important question among fitness enthusiasts. Can exercise make you anemic? This post explains the connection between sports and anemia, including the most effective treatment options for sports-related anemia.

What is sports anemia?

To understand sports anemia, you must first know what anemia is. In people with anemia, the body doesn’t have enough red blood cells (RBCs). These cells transport oxygen around the body.

There are many potential causes of anemia. However, studies show that over half of all cases of anemia are related to low iron levels in the body. Iron is essential for the production of hemoglobin, a protein in RBCs, so low iron counts reduce RBCs and hemoglobin production.

In some cases, athletes may have “false anemia.” This occurs when the number of RBCs is normal or even slightly increased in the athlete, but the amount of fluid in the bloodstream is significantly increased due to changes induced by exercise. The extra fluid dilutes the blood, making the hematocrit (a measure of the percentage of the blood that’s taken up by red blood cells) look lower than normal. Although this is commonly called “sports anemia,” this condition is not truly anemia, as the athlete has enough RBCs to transport normal amounts of oxygen in the body.

It’s also possible for intense physical training to lead to anemia through a few different mechanisms.

Causes of sports anemia

Athletes may also experience true anemia, which can be caused or exacerbated by intense physical training in some people. This can occur in several different ways, including:

Hemolysis

Hemolysis is the breakdown of RBCs. When they’re broken down more quickly than they can be replenished, anemia results. In sports, hemolysis may occur due to:

• Repeated trauma: When the feet hit the ground repeatedly during running or other sporting activities, the impact can cause breaks in the capillaries (very small blood vessels) of the foot, causing RBC breakdown.

• Vasoconstriction: During intense exercise, blood vessels to the muscles open widely to allow for intense muscle activity. Blood flow to some other areas, such as the kidneys, is severely reduced in order to prioritize blood flow to the muscles. In areas where the blood vessels are extremely narrowed, there’s more friction against the RBCs, which can lead to their breakdown.

• Metabolic shifts: During intense exercise, there are a variety of shifts in blood chemistry. The acid level of the blood increases and adrenaline levels rise. Body temperature also goes up, and there’s a decrease in levels of blood cholesterol. All of these changes make RBCs more fragile and vulnerable to damage.

Hematuria

This condition occurs when healthy red blood cells are excreted in the urine. It is mainly caused by the following factors:

• Direct renal impact and trauma (DRIT) – DRIT may occur in sports like soccer, wrestling, and football, where direct impacts may occur to the area of the kidneys (in the mid-back). This can damage the kidneys, leading to bleeding.

• Prolonged impact on the bladder wall – this may occur due to repeated impact on the bladder wall and the base of the bladder during running, jogging, or swimming, causing tears that lead to internal bleeding.

Gastrointestinal bleeding

It’s been established that strenuous exercise can lead to digestive tract injury. This occurs because of a severe decrease in blood flow to the digestive tract when exercising, along with the biochemical changes induced by exercise. Over time, the lining of the digestive tract may become damaged, leading to internal bleeding. Even if this bleeding is at a very low level and is not apparent, the loss of blood through the intestines may eventually lead to anemia.

Inflammation

Intense exercise causes inflammation throughout the body. Inflammation interferes with the ability of the body to use iron to make red blood cells, which can lead to anemia. It can also reduce the body’s ability to absorb iron in the digestive tract, which can deplete iron stores and lead to iron deficiency anemia.

Symptoms of sports anemia

In general, the symptoms of anemia are similar, no matter what the cause is. They can include:

• Loss of endurance. You may not be able to exercise for as long as you used to.

• Chronic fatigue. You may feel extremely tired, which can make strenuous exercise difficult.

• Irritability. You may find that you become more easily agitated, even by small annoyances.

• Irregular heartbeat. You may feel chest palpitations or an increased heart rate, which may be more noticeable when engaging in exercise.

• Trouble concentrating. It may be difficult to think clearly or to concentrate on activities.

Talk to your doctor immediately if you experience any of these sports anemia symptoms. Even if you feel that it’s likely that you have anemia, it’s important that you never take any medications, including iron supplements, without consulting your doctor. In some cases, anemia can be a sign of a serious underlying disease, so it’s important that you get a professional medical evaluation before you begin treating your condition.

Who is at a greater risk of sports anemia?

Generally, premenopausal female athletes are at an increased risk for anemia, including sports anemia, as women lose blood every month through menstruation. Pregnant athletes are also at a high risk because pregnancy uses a lot of iron.

You may also be at a higher risk for developing sport-induced anemia if you've been diagnosed with another chronic condition, such as cancer, diseases of the kidney, liver, or thyroid gland, or inflammatory bowel diseases such as ulcerative colitis. 

How is sports anemia diagnosed?

Your doctor will perform various tests to determine if you have sports anemia. The first step is to check whether you have anemia. If so, additional testing is used to determine the cause of your anemia. The tests done may include:

• A physical examination along with a medical and dietary history

• Tests for anemia, which may include a complete blood count (which tests the amounts of different types of cells in your blood), hemoglobin level, or hematocrit (a test of the percentage of your blood volume that’s taken up by red blood cells)

• Bilirubin level. Bilirubin is a breakdown product of red blood cells. Increased bilirubin levels could indicate that red blood cells are breaking down more rapidly than normal.

• Tests of iron levels in the body. These may include serum iron (which tests the amount of iron in your blood), ferritin (a protein which stores iron in the body), transferrin (a protein which transports iron throughout the body), and total iron binding capacity (which tests the ability of proteins in your blood to bind to iron and carry it around your body).

• Tests of vitamin B12 and folate levels. These two nutrients are important in making red blood cells, and low levels can lead to anemia.

• Urine analysis to check for blood in the urine

• Endoscopic exams to check for sources of bleeding in the digestive system

Sports anemia treatment options

If you have anemia, the treatment will depend on the specific cause. Some of the treatment options may include:

• Dietary modification – if your iron levels are low, you may be able to address this by increasing your intake of iron-rich foods such as meat, fish, legumes, and dark green leafy vegetables. You may also benefit from eating more foods that contain nutrients like folate and vitamin B12.

• Iron supplements – your physician will advise on the safest supplements to take for better iron intake.

• Changing shoes – if your sport involves running or other impacts on the soles of your feet, then wearing footwear that properly cushions and supports your feet may help to reduce the impact, which can help to protect your red blood cells from breakdown.

• Healthy movement patterns – in some cases, you may be able to reduce the impact on your body by changing how you perform your sport, which can also help protect your red blood cells from breakdown.

• Moderation of your workouts – in some cases, you may need to consider scaling back the intensity of your physical training to allow your body to recover normal levels of red blood cells.

It’s important to consider that not all cases of “sports anemia” involve true anemia. If you’re experiencing dilution due to increased fluid in your blood, then this may not require any treatment.

Recovering from sports anemia

The time it takes to recover from sports anemia depends on the specific cause and on the severity of your case. It may take weeks to months to recover normal levels of red blood cells. It’s important to stay diligent about following your treatment plan. Once your anemia is addressed, you’re likely to experience improved physical performance along with better quality of life.

The lowdown

Sports anemia is a condition in which there aren’t enough red blood cells to properly transport oxygen around the body. It can be triggered in a variety of ways, including the breakdown of red blood cells due to impacts and blood flow changes, blood loss related to chronic minor trauma, or inflammation induced by strenuous exercise. Female athletes are at a greater risk for sports anemia, but male athletes can also experience this. 

If you’re having any symptoms of sports anemia, talk to your doctor for a professional evaluation and an appropriate treatment plan.

Frequently asked questions

Which specific sports can induce sports anemia?

Almost any sport can potentially cause sports anemia if the training is intense enough. Endurance sports are more likely to induce anemia because of sustained changes in blood flow and increased inflammation. Sports that involve forceful striking of the foot against the ground, such as running, or those that involve direct hits to the area around the kidneys, such as boxing, also carry a significant risk of anemia.

Is the evidence on sports anemia conclusive?

Anemia in athletes can have multiple different causes. In some cases, athletes may experience a “false anemia” related to an increase in fluid volume in the bloodstream. However, true anemia can also result from intense physical training. In addition, athletes can experience medical problems unrelated to their athletic training, and this may also lead to anemia in some cases.

Is meat an iron-rich food?

In general, meat is an excellent source of iron. The best sources include beef (particularly beef liver), oysters, and sardines, though chicken and turkey also contain iron. There are also many plant foods that contain iron, including beans, lentils, dark leafy greens, and tofu.