Can exercise make you anemic?

In this article:

• Can exercise cause anemia?
• Causes of exercise-induced anemia
• Symptoms of exercise-induced anemia 
• Who is at greater risk of exercise-induced anemia?
• How to prevent exercise-induced anemia

In this article

• Can exercise cause anemia?
• Causes of exercise-induced anemia
• Symptoms of exercise-induced anemia 
• Who is at greater risk of exercise-induced anemia?
• How to prevent exercise-induced anemia

Anemia develops when you don’t have enough red blood cells. When this happens, your body doesn’t circulate adequate oxygenated blood, which can lead to symptoms like feeling weak, dizzy, and fatigued. The CDC estimates that 2.8 million people in the U.S. have anemia.

If you are a high-intensity athlete or someone who exercises frequently, you might wonder: Can exercise cause anemia? Though rare, exercise-induced anemia, or sports anemia,  can occur among people who engage in intense physical activity regularly. Here, we’ll take a closer look at this phenomenon—what causes it, what symptoms to watch for, along with expert tips for how to manage and prevent it.

Can exercise cause anemia?

Yes, it’s possible for exercise to cause anemia. “Intense or prolonged exercise can lead to changes in iron levels, and in some cases, it can cause anemia, which is often referred to as ‘sports anemia,’” explains Sean Ormond, MD, interventional pain management physician at Atlas Pain Specialists.

Dr. Ormond, who treats athletes with various training-related issues (including exercise-induced anemia), says that the condition isn’t extremely common, but it does occur in a noticeable number of athletes, particularly ones who engage in high-endurance activities such as running, cycling, and swimming. “The prevalence can vary based on the type and intensity of the sport, as well as dietary factors,” he notes.

Although there is scant research on the prevalence of exercise-induced anemia among athletes of all types and demographics, a 2024 study looking at 1190 athletes found that up to 20% of them had anemia. Anemia was most likely to strike younger athletes and female athletes. Research from 2010 found that 28% of female marathon runners had anemia. 

Causes of exercise-induced anemia

There are several different ways that exercise can induce anemia. Let’s take a look at some of the most common causes of exercise-induced anemia.

Hemolysis

Hemolysis refers to the breakdown of red blood cells. If red blood cells are broken down at the same rate that the body makes red blood cells, the patient will not be anemic. If the body breaks down red blood cells too quickly, you won’t have enough red blood cells or hemoglobin in your body, causing anemia. Sometimes exercise can cause excessive red blood cells to be broken down.

This is often due to the repetitive physical impacts that can happen during exercise. “One major factor is the destruction of red blood cells due to the repetitive impact (especially in runners, hence ‘runner’s anemia’), where the cells burst from the constant pounding of the feet against the ground,” Dr. Ormond explains.

Gastrointestinal bleeding and sweating

Sometimes exercising can cause bleeding in your GI tract. “When exercising intensely, someone can have minor GI bleeding, so with a loss of blood, your labs may be positive for anemia,” says Danielle Kelvas, MD, a primary care physician based in Tennessee. It’s also possible to lose very small amounts of iron as you sweat, she adds.

Hematuria

Hematuria is when there’s blood in your urine. Blood in the urine can be microscopic, such that the urine will not appear pink or red, but is still losing red blood cells nonetheless. According to a 2021 narrative review, one cause of exercised-induced anemia is hematuria. This is most likely to happen in runners who experience bladder contusions as a result of the impacts of running. The athlete may be unaware that the bladder is hitting against the pubic bone. Other research has pointed to possible microscopic lesions developing in the urinary tract due to reduced circulation to your organs during high-intensity exercise, resulting in blood loss and iron loss.

Increased hepcidin concentration

Exercise temporarily increases the concentration of hepcidin, a hormone that regulates the body’s iron metabolism. “If hepcidin concentration increases briefly, then your blood concentration of iron decreases,” Dr. Kelvas explains. “We call this iron-restrictive anemia.”

Over-exercising

Overexerting yourself can cause you to burn excessive calories and nutrients, and if you aren’t properly replenishing, you may develop nutritional deficiencies like anemia. For instance, “overexercising in the setting of not eating enough protein and iron can result in anemia,” Dr. Kelvas says.

Inflammation

Endurance athletes or those who exercise intensely may experience upticks of inflammation in the body. This can lead to anemia for some people, says Kevin Huffman, DO, doctor of osteopathic medicine and founder of American Bariatric Consultants. “Iron absorption can also be disturbed by inflammation associated with exertion,” Dr. Huffman explains.

Symptoms of exercise-induced anemia 

Symptoms of exercise-induced anemia are the same symptoms as iron deficiency anemia. “Symptoms can include fatigue, weakness, dizziness, shortness of breath, and reduced exercise performance,” says Dr. Ormond.

Oftentimes anemia is asymptomatic, especially at first. When it has symptoms, iron deficiency anemia can affect many areas of your body. Some of the possible symptoms of anemia include:

• Feeling weak
• Fatigue, which can be excessive
• A restless feeling in your legs
• Shortness of breath
• Feeling like you’re going to faint
• Chest pain, especially during exercise
• A desire to eat non-food items like dirt or ice, a condition called pica
• Skin that feels cold when touched
• Fast heart rate
• Low blood pressure
• Pale skin

What to do if you notice any of these symptoms? “If you notice these symptoms, especially in the context of increased or intense training, it might be worth checking your iron levels,” Dr. Ormond recommends. “Monitoring your performance and overall well-being can be a good indicator; if you’re feeling unusually drained or your workouts are suffering, it might be a sign.”

Who is at greater risk of exercise-induced anemia?

Certain types of athletes are more at risk. “Endurance athletes, such as marathon runners, cyclists, and swimmers, are particularly prone due to the high volume and intensity of their training,” says Dr. Ormond. “Female athletes may also be at higher risk due to menstrual bleeding and blood loss combined with high exercise levels.” Finally, athletes who don’t maintain a well-balanced diet with adequate iron intake are at increased risk, says Dr. Ormond. 

How to prevent exercise-induced anemia

Although exercise doesn’t usually cause anemia, if you’ve been anemic in the past or if you are concerned about it happening in the future, you might want to consider some preventive techniques to reduce your risk of exercise-induced anemia, such as: 

Monitor your iron levels

If you exercise strenuously, your healthcare provider may periodically run blood tests to check your serum ferritin (a protein that stores iron in the blood) and serum iron levels—along with a complete blood count test to identify any other abnormalities. “Regular monitoring of serum iron levels and working with a nutritionist or a sports physician can help in managing and preventing exercise-induced anemia effectively,” explains Dr. Ormond.

Adjust your diet

Lifestyle changes, such as eating iron-rich foods, can help remedy low iron levels. Dietary iron sources include lean red meat, iron-fortified cereal, oysters, nuts, legumes, tofu, sardines, chicken, tuna, spinach, broccoli, and mushrooms.

Time your exercise and iron consumption

Eating an iron-rich diet is key in preventing anemia from developing. But when you exercise, it’s all in the timing. The German Journal of Sports Medicine recommends eating iron-rich foods in the morning, prior to exercise. You should also consume coffee and tea separately from eating foods with iron because these beverages can decrease iron absorption. 

Increase vitamin C intake

Iron-containing foods, like red meat and dark green leafy vegetables, on their own, aren’t enough if you want to maximize absorption. You’ve got to combine these with vitamin C-rich foods like citrus fruit and tomatoes. “Vitamin C helps the gut to absorb metabolized iron,” Dr. Kelvas explains.

Try an iron supplement

Certain people may need a dietary supplement on top of lifestyle changes, especially women who lose iron through menstruation. However, it’s important to take the right amount of iron for your body, and iron supplements have side effects like constipation. As such, it’s best to discuss options with your healthcare provider.

Add in rest days

“It’s crucial to balance exercise routines to avoid overtraining and to ensure proper nutrition,” says Dr. Ormond. “In some cases, rest and recovery might be necessary to help the body replenish its iron stores.”

Regular exercise is healthy and should be practiced regularly, but days off are important. “Rest days and proper recovery techniques as part of a training plan eases body stress and replenishes iron stores,” says Dr. Huffman. Ask a healthcare professional about the best fitness schedule for your body and to maintain healthy iron levels.

Consider lower-intensity exercises

Exercise-induced anemia rates “increase with longer-distance running, cycling and swimming, which require a high cardiovascular fitness,” Dr. Huffman shares. As such, it can be helpful to break up these higher-intensity exercises with other types. Consider strength training, yoga, Pilates, and power walking.