If you’re an endurance athlete struggling with fatigue, slower recovery or declining performance, your iron stores could be part of the problem.
Iron deficiency is one of the most common nutritional issues affecting runners, cyclists, triathletes, swimmers and other endurance athletes. In fact, many athletes have a normal haemoglobin level but still have low ferritin, which can negatively impact training and performance.
Understanding the difference between iron deficiency and iron deficiency anaemia is essential if you want to perform at your best.
What is ferritin?
Ferritin is a protein that stores iron inside your body’s cells. A ferritin blood test measures how much iron your body has in reserve.
Think of ferritin as your iron “fuel tank.”
Your body relies on these iron stores to:
- Produce haemoglobin, which carries oxygen around your body.
- Produce myoglobin, which stores oxygen in your muscles.
- Support energy production.
- Help muscles recover after training.
- Maintain a healthy immune system.
When ferritin levels become low, your body has fewer iron reserves available. This often occurs before anaemia develops, meaning you may notice symptoms despite having a normal full blood count.
Why do endurance athletes need higher ferritin levels?
Unlike the general population, endurance athletes place much greater demands on their bodies.
Regular endurance training increases the need for iron because your body is continually repairing tissues, producing new red blood cells and adapting to training.
This is why sports physicians and sports dietitians often recommend maintaining higher ferritin levels than those considered adequate for the general population.
A ferritin level that is “normal” on a pathology report may not be enough to support optimal athletic performance.
Why are runners and endurance athletes at greater risk of iron deficiency?
1. Increased red blood cell production
As fitness improves, your body produces more red blood cells to transport oxygen to working muscles.
Making these red blood cells requires iron.
2. Foot-strike haemolysis
Every time a runner’s foot strikes the ground, a small number of red blood cells are damaged.
Although the loss is tiny with each step, thousands of foot strikes over weeks and months can contribute to reduced iron stores.
3. Sweat losses
Iron is lost through sweat.
While these losses are relatively small, they accumulate in athletes completing high training volumes.
4. Gastrointestinal blood loss
Long-distance running can temporarily reduce blood flow to the digestive system, occasionally causing microscopic bleeding during prolonged exercise.
5. Reduced iron absorption after training
Following intense exercise, the hormone hepcidin increases.
Hepcidin temporarily reduces your body’s ability to absorb iron from food, making it more difficult to replace iron losses if meals are poorly timed.
6. Increased nutritional requirements
Training more means your body requires more energy, more nutrients and more iron to support recovery and adaptation.
Symptoms of low ferritin in athletes
A low ferritin athlete may experience:
- Persistent fatigue
- Slower running pace despite consistent training
- Reduced endurance
- Poor recovery between sessions
- Shortness of breath during exercise
- Heavy legs
- Brain fog or poor concentration
- Frequent illness
- Feeling cold
- Restless legs
- Hair loss
Many runners initially blame these symptoms on overtraining, when low iron stores may actually be contributing.
What ferritin level is best for endurance athletes?
General pathology reference ranges are designed for the wider population—not athletes.
Many sports medicine practitioners consider:
- Below 30 µg/L: Iron deficiency requiring investigation.
- 30–50 µg/L: May contribute to symptoms or reduced performance in some endurance athletes.
- Above 50 µg/L: Often considered a more appropriate minimum target for athletes undertaking regular endurance training.
Some sports physicians aim for ferritin levels between 50–100 µg/L before major training blocks or competitions, particularly for athletes with a history of iron deficiency.
Remember, there is no single “perfect” ferritin number. Your blood results should always be interpreted alongside your symptoms, training load and overall health.
Should athletes take iron supplements?
Not without appropriate testing.
Taking iron supplements unnecessarily can be harmful because excess iron accumulates in the body.
Instead, speak with your GP if you’re experiencing symptoms. Your doctor may recommend tests including:
- Ferritin
- Full Blood Count (FBC)
- Serum iron
- Transferrin saturation
- C-reactive protein (CRP), if inflammation is suspected
Working with a sports dietitian can also help identify dietary factors that may be contributing to low iron stores.
Best foods to increase iron intake
Iron-rich foods include:
- Lean beef and lamb
- Kangaroo
- Chicken
- Fish and seafood
- Eggs
- Tofu
- Lentils and beans
- Iron-fortified breakfast cereals
- Pumpkin seeds
- Cashews
- Spinach and other leafy greens
To improve iron absorption:
- Include vitamin C-rich foods such as oranges, kiwi fruit, berries, tomatoes or capsicum with meals.
- Avoid tea and coffee around iron-rich meals.
- Eat regular meals to support recovery throughout your training week.
When should runners have their iron checked?
If you’re an endurance athlete, speak with your healthcare team about iron testing if you:
- Feel unusually fatigued.
- Notice declining performance.
- Have heavy menstrual periods.
- Follow a vegetarian or vegan diet.
- Have previously experienced iron deficiency.
- Are increasing your training volume.
- Are preparing for a marathon, ultramarathon or Ironman.
Early detection can prevent more significant performance declines later in the season.
The bottom line
Low ferritin in athletes is extremely common, particularly among runners and other endurance athletes.
Because endurance training places greater demands on your body, athletes often require larger iron stores than the general population to support oxygen transport, energy production and recovery.
If you’re experiencing persistent fatigue, declining performance or slow recovery, don’t assume it’s simply part of training. Having your iron status assessed may provide valuable answers and help you return to feeling and performing at your best.
Optimise Your Performance with Feed Your Future Dietetics
At Feed Your Future Dietetics, we provide evidence-based sports nutrition support for runners, cyclists, triathletes, swimmers and endurance athletes across Australia.
With over 10 years of experience, we help athletes optimise their nutrition, interpret blood test results, prevent nutrient deficiencies and fuel for performance, recovery and long-term health.
All consultations are delivered conveniently via Telehealth, making expert nutrition support accessible wherever you live in Australia.
Whether you’re preparing for your next marathon, tackling an Ironman or simply wanting to improve your endurance, we’re here to help.
Book your appointment with Feed Your Future Dietetics today and discover how personalised sports nutrition can help you train harder, recover faster and perform at your best.
