Iron, Hemoglobin, and Running Performance

I know how important it is to prevent anemia and low hemoglobin levels when you’re active. When I was 19, I decided to take running seriously. I got a coach and followed a structured plan. After a couple of months, I started feeling constantly tired and sleepy. I had no energy for training, and studying at university became a struggle — I felt like my brain wasn’t working. My coach sent me for a blood test, and the sports doctor found that my hemoglobin was at the lower end of the normal range. He explained that I needed higher hemoglobin levels to perform well and prescribed iron supplements.

One month later, my hemoglobin increased from 118 to 132, and I felt like a different person. I could run better, study better, and be productive again.

Why Hemoglobin Matters for Performance

The higher your hemoglobin (within the normal range), the more oxygen your tissues receive. More oxygen to the brain means better cognitive function. More oxygen to the muscles means greater endurance and aerobic capacity — allowing you to run faster and longer.

But hemoglobin production requires iron, not just circulating iron in your blood but also stored iron — ferritin. The body prioritizes essential functions and will maintain basic iron levels for daily survival. If your iron stores are low, your body will limit hemoglobin production, keeping you at the bare minimum. As a result, if you try to train with low hemoglobin, your body will shut you down — you’ll feel exhausted and unmotivated.

This is why I always ask my runners to get a blood test at least once a year and share their results with me. Many doctors only check if your values fall within the “normal” range. But normal doesn’t mean optimal.

Key Blood Markers for Endurance Athletes

Hemoglobin (Hb)

• Below 130 (women) / 140 (men): Low for performance, limiting aerobic capacity.

• 130-140 (women) / 140-150 (men): Acceptable; you’ll have enough energy for daily life.

• Above 140 (women) / 150 (men): Good for endurance training.

• 150-160 (women) / 160-170 (men): Very good — optimal for high-performance athletes.

Erythrocytes (Red Blood Cell Count)

• Directly linked to hemoglobin levels. The closer they are to the upper range, the better your oxygen transport.

Ferritin (Iron Storage)

• The normal range varies between labs (often 20-330 ng/mL).

• Above 100 ng/mL: You’re fine.

• Above 200 ng/mL: Ideal for endurance athletes.

• Caution: Very high ferritin can indicate inflammation, so proper interpretation is necessary.

Why Iron Matters for Runners

Hemoglobin, erythrocytes, and ferritin play a crucial role in oxygen transport. Low values will limit aerobic capacity and lead to fatigue, poor recovery, and reduced performance.

Additionally, hard training destroys red blood cells — a process called exercise-induced hemolysis. The body must continuously produce new erythrocytes, which requires sufficient iron levels.

Can You Get Enough Iron From Food?

It depends.

1. Animal vs. Plant-Based Iron:

   • Heme iron (from meat) has high bioavailability.

   • Non-heme iron (from plants) has low bioavailability—meaning vegetarians are at a higher risk of deficiency.

2. Iron Absorption Varies:

   • If you have gut issues, iron absorption can be impaired.

   • Certain foods (e.g., tea, coffee, dairy) inhibit iron absorption, while vitamin C enhances it.

3. Training Increases Iron Demand:

   • High mileage increases iron needs.

   • Women lose additional iron during menstruation, increasing their risk of deficiency.

Who Likely Needs Iron Supplements?

• Men with good absorption, eating iron-rich foods, and training moderately → likely get enough from diet.

• Women with good absorption, eating iron-rich foods, and training moderately → may benefit from supplements during their period.

• High-mileage runners (80+ km per week) → often need supplementation.

• Vegetarian runners → at high risk of deficiency and likely need supplements.

A blood test will help determine if supplementation is needed and what dosage is appropriate.

Choosing the Right Iron Supplement

Iron absorption from supplements varies by person and by form (e.g., ferrous sulfate, ferrous bisglycinate). Trial and testing are necessary to find what works best for you. I discovered that encapsulated iron works well for many.

While other nutrients like vitamin B12 and copper also influence hemoglobin production, they are typically sufficient in a healthy diet. However, some individuals have trouble absorbing vitamin B12, which can be checked with a blood test.

Final Thoughts

I can’t prescribe supplements, but I often recommend iron to women and both male and female runners with high mileage. If you’re running a lot, it’s hard to get enough iron from food alone — unless you’re eating a 200g steak every other day.

The first step? Check your blood test and see where you stand.