Every runner eventually loses their motivation. It’s a natural part of participating in any sport. For some runners, however, the problem runs deeper than their motivation. Some runners – particularly female distance runners – may have their iron levels to thank for the exhaustion plaguing them during their runs. Runner’s anemia, which can develop from either iron depletion or iron deficiency, often sneaks up on athletes. And though it takes time to develop, it is important for runners of all levels to know what causes the issue and how to spot the symptoms.
What is Anemia?
Anemia usually refers to a condition in which a person does not have enough iron in their blood. Runner’s anemia, however, is a specific condition that can refer to one of three things: low iron, low hemoglobin, and low ferritin. This may sound confusing, but the three issues are fairly straight-forward. Low iron means that the body is using more iron than the person is bringing in. Low hemoglobin – which carries oxygen to muscles through the blood – means that a person’s muscles are not getting the oxygen they need to work properly. And low ferritin means that a person’s body is low on stored iron, which usually resides in bone marrow.
Endurance runners are more likely to develop Runner’s anemia and for good reason. Endurance sports cause an increase in red blood cell development which means they need to consume more iron to keep their blood iron and hemoglobin levels balanced. Jarring impacts – such as footfalls – also physically break up red blood cells. This is called footstrike hemolysis. Intense workouts also increase the body’s production of hepcidin, which blocks a person’s system from absorbing iron. This – combined with the iron lost through sweat and, for some, menstruation – puts endurance runners at risk for Runner’s anemia.
The first symptom most runners will notice is constant and persistent exhaustion. Caffeine and rest do little when a body is low on iron because neither solution provides the boost to cellular energy that iron does. Some doctors refer to this as “lethargy”. Runners and coaches may mistake it for a loss of motivation, particularly when it affects long-term and endurance runners.
If a runner is suffering from iron depletion and has low ferritin levels, they may experience other symptoms. Low ferritin levels can lead to high blood lactate levels. It also leads to a runner’s limbs feeling heavy, slows their recovery from workouts and injuries, and causes tight muscles. Low ferritin will lead to exhaustion and low motivation just as iron deficiency does. These, in turn, will decrease a runner’s performance and increase their risk of overuse injuries such as shin splints or stress fractures.
Continuous anemia can affect more than a runner’s energy levels. It can reduce a person’s ATP which is the chemical that allows cells to carry out their jobs. It can also harm cardiac health by reducing a person’s VO2 Max, which is the amount of oxygen a body uses during exercise. A high VO2 Max level indicates that a body uses a lot of oxygen and uses it well. Anemia makes this hard to do. In addition to all of this, prolonged anemia can cause thyroid health issues which then unbalance a runner’s hormone levels.
While the symptoms of Runner’s Anemia are fairly easy to detect, a diagnosis requires comprehensive blood testing. Most doctors will simply test the level of iron and hemoglobin in an athlete’s blood. If a runner suspects that they are suffering Runner’s Anemia, they need to insist that the blood tests look at their serum ferritin levels as well. Ferritin levels are the best way to detect iron depletion, which will not show up in general blood work.
Runner’s anemia is, thankfully, easy to treat. That said, iron levels are very important to competitive athletes, so a doctor should absolutely be involved in any recovery plan that involves taking iron supplements or drastically changing an athlete’s diet.
Although the treatments for Runner’s anemia are fairly straightforward, sufferers may not see improvements for 4-8 weeks. Their bodies have to restore depleted iron or balance the levels of iron and hemoglobin in the blood. These things take time and may cause the symptoms to come and go. If a runner’s symptoms persist after 8 weeks, they should check back in with their doctor for more testing. Athletes must also be sure that their doctor takes into account the increased rate at which runners use iron. Levels that appear “normal” in non-athletes can still indicate a dangerously low level of iron, ferritin, or hemoglobin for runners.
Most treatment options can be administered at home without a doctor’s guidance. These include dietary changes and iron supplements, as well as cooking in cast iron cookware. We’ll go over a few of them now.
Iron supplements are most often sold in pill form, but these are not easily absorbed by our bodies. The most easily absorbed version is liquid ferrous sulfate or ferrous gluconate. Athletes may have to specifically request these versions as most doctors opt for solid pills. Our bodies only absorb about 15% of the iron we consume, however, so runners will benefit from increasing their chances of absorption as much as possible.
There are two types of dietary changes that runners may have to make. One change involves adding iron-rich foods to their meals while the other requires them to cut out certain substances that reduce iron absorption. Omnivores can easily increase the iron levels in their meals while vegetarians and vegans may require a little more time to find the best combination of foods to meet their iron intake needs.
Examples of animal-sourced iron-rich foods are red meat, eggs, and oysters. Non-animal sources include spinach, oatmeal, dried fruit, and whole grain enriched cereals.
In addition to consuming more iron, runners may have to avoid substances that reduce their ability to absorb iron. These include caffeine, calcium, and NSAIDs (Non-Steroidal Anti-Inflammatory Drug). Most over-the-counter painkillers are considered NSAIDs and caffeine can be found in chocolate, coffee, and many teas. It is easy for most people to avoid these substances, but calcium is a little bit tricker. Calcium is important for athletes and should not be avoided completely. It should just be consumed at different times than any iron sources a runner is relying on.
A few other changes that runners may want to consider include increasing their vitamin C intake and timing their heaviest iron-consumption times around the hepcidin spikes produces by their workouts. Vitamin C boosts iron absorption, so once a doctor recommends a vitamin C supplement it can be taken with any iron source the runner chooses. Hepcidin decreases a body’s ability to absorb iron. It is also, unfortunately, a byproduct of intense endurance workouts. Post-workout hepcidin spikes usually happen 3-6 hours after the workout is over. Runners should either take their iron first thing in the morning before their workouts or immediately after their workouts before their levels spike.
- Jama Network, Runner’s Anemia
- The Long Distance Runner’s Anemia: A paper from a coach to his athletes
- The Globe and Mail, How Your Iron Levels Affect Your Athletic Performance
- NCBI, Runner’s Anemia and Iron Deficiency
- BJSM, Athletes’ Anaemia
- Australian Red Cross, Iron Deficiency Without Anaemia