Hello Runner,
Welcome back to your weekly moment of endurance nutrition!
Happy Weekend!
How are you?
I'm fine!
My weekend was wonderful! I got some much-needed rest and celebrated my birthday exactly how I wanted to: surrounded by dear friends in a peaceful place full of delicious food.
After such a wonderful weekend, I started the week off right. I worked hard, trained as usual—the gym was empty because of the holidays, which was pure bliss—attended a dear friend's farewell party because she's returning to Brazil permanently, and traveled! Right now, I am in Galicia with my family. I took a week off to rest and spend time with my relatives.
Today, I want to talk about one of the most underestimated topics among runners, especially those who are already training well but don't understand why they continue to feel tired, aren't improving, or have low endurance.
One of the biggest mistakes I see among dedicated runners is:
→ They take care of their training and ergogenic resources, but many ignore iron deficiency.
The result? A persistent feeling of fatigue. A drop in pace. Their motivation goes down with it.
Worst of all, many think it's a lack of training and increase the load when the body actually needs support.
Why is iron so important for runners?
Iron is responsible for carrying oxygen to the muscles through hemoglobin.
As you probably know, running requires a lot of oxygen.
When your iron levels are good, your blood transports oxygen more efficiently, your body works better, and you run more lightly, breathe better, and maintain your pace.
What happens when levels are low?
You feel more tired, even if you sleep well.
Your pace drops inexplicably.
Recovery is slow.
Your heart rate rises more than normal.
In more severe cases, your body becomes iron-deficient, causing your performance to plummet.
Why Are Runners More Vulnerable to Iron Deficiency?
Several factors make runners more susceptible to significant iron deficiency. Some of these factors are:
The impact of running can cause microlesions in red blood cells.
These microlesions reduce iron levels in the bloodstream.Iron is lost through sweat and urine.
Runners tend to sweat and urinate more frequently due to running. This results in additional iron loss.Women are at greater risk due to menstruation.
Blood loss during menstruation causes additional iron loss.
Vegans and vegetarians need to pay special attention.
Those who follow these diets and do not consume all the necessary micronutrients tend not to reach their daily iron levels.
Poorly planned diets do not replace what the body loses.
In other words, eating well is not enough. You need to eat strategically.
How to know if you have an iron deficiency
The signs do not always appear at first. But you may suspect it if you feel:
Persistent fatigue (even after sleeping well)
Difficulty keeping up the pace
Loss of energy in the middle of workouts
Shortness of breath during light workouts
Excessive irritability or discouragement
⚠️ Ideally, you should have regular blood tests to monitor:
Ferritin
Hemoglobin
Transferrin
TSAT (transferrin saturation)
Ferritin below 30 ng/mL may already indicate a problem (even if you don't have anemia yet).
RECOMMENDATIONS
What to Do if Levels are Low
Adjust your diet with iron-rich foods
Lean red meat, egg yolks, beans, lentils, dark green vegetables.
Combine with vitamin C (increases absorption): orange, mandarins, lemon, kiwi, strawberry, broccoli, spinach, kale, bell peppers (especially yellow), cabbage, cauliflower, Brussels sprouts, tomatoes, sweet potatoes.
Avoid coffee and black tea immediately after iron-rich meals (they interfere with absorption).
Investigate causes and evaluate supplementation with a professional.
Not every runner needs supplements.
But some will only improve with controlled replacement.
Practical example
A runner I recently helped trained five times a week, ate a seemingly healthy diet, but was constantly exhausted.
Tests showed ferritin levels of 22 ng/mL.
After taking his medical history, I realized that he ate few vegetables, almost no legumes, and consumed some ultra-processed foods (especially when he was not at home).
After the first consultation:
→ We adjusted his diet: inclusion of iron-rich vegetables, inclusion of foods rich in vitamin C to improve iron absorption, and adjustments to the amount of protein.
→ We supplemented iron for 3 months.
The result?
His average pace dropped by 20 seconds/km.
Sleep improved.
He was able to progress to his first half-marathon.
Training well requires more than just willpower.
Your body needs the right biochemical structure to perform well.
Iron is one of those structures.
→ If you run frequently, experience persistent fatigue, or have difficulty improving, don't ignore these silent warnings.
Have you had your iron levels checked since you started running?
If you suspect your diet is hindering your running,
My 1:1 consultation can help you adjust your diet based on tests, training, and symptoms.
Reply with "I want help," and I'll explain how it works.
Track of the week 🎧️
This week's Track of the Week it's a brand new release from August. I discovered it recently and found it perfect for giving me a boost when running!
I've chosen the track Bus Stop Please (David Guetta & Morten Future Rave Remix) by Fatboy Slim, David Guetta, MORTEN, and Daniel Steinberg
Any questions or something you would like to share, drop me an email
Wishing you a great weekend and week ahead!
Here’s to health and good runs⚡️
Ana Paula Alonso