July 2025

FLX PT NEWSLETTER #13

Happy Summer, Runners!
I’ve been loving the long days, warm evenings, and all the fun summer brings here in the Finger Lakes. I hope you’ve been soaking it in, too!

That said, this time of year can feel packed — between kids’ sports, clinic days, and family activities, it’s easy to feel like there’s not enough time (or energy) to do it all — including sticking to an ideal running schedule.

Recently, I noticed I was waking up tired despite getting a solid 8 hours of sleep. My runs felt unusually sluggish, I had brain fog, and even easy miles felt hard. At first, I chalked it up to life’s chaos. But if one of my patients came in describing the same thing, I’d encourage them to look deeper — so I decided to follow my own advice.

I brought it up to my primary care provider. She agreed to run a more comprehensive blood panel — and sure enough, my ferritin was low. Ferritin is a protein that stores iron in your body, and while my results were technically “normal” for the average adult, they weren’t optimal for a female endurance athlete. This was likely due to my high run training load, higher “life” load, as well as not eating as well as I should be.

Why Iron Matters for Runners

Iron plays a crucial role in oxygen transport — helping red blood cells deliver oxygen to your working muscles. Iron is also crucial in immune function, bone and brain health. Long story short, when your iron stores are low, your body can’t perform efficiently.

Most labs define normal ferritin levels as 13–150 ng/mL, but research and sports dietitians agree that runners should aim for at least 40 ng/mL to support performance and recovery.

Low Iron/ferritin can show up as:

• Sluggishness or heavy legs during easy runs

• Brain fog and unusual fatigue

• Shortness of breath

• Slower recovery

• Unexplained dip in performance

Runners at Higher Risk for Low Iron:

• Female runners (especially those with heavier menstrual cycles)

• Vegetarians or vegans

• High-mileage or competitive athletes (we lose iron through sweat and each foot strike)

• Teenage runners

• Anyone with a history of low iron

What You Can Do:

• Request yearly bloodwork that includes ferritin, hemoglobin, and iron panels — even if you feel "fine."

• Track trends over time — not just “normal” results. Optimal ferritin for runners is often ≥40 ng/mL.

• Eat iron-rich foods like lean red meat, lentils, spinach, and fortified cereals.

• Work with a Registered Sports Dietitian — especially one experienced with endurance athletes.

• Only supplement iron under medical supervision — too much can be harmful.

I see low iron/ferritin in runners more often than you might think — and I’ve experienced it myself. Knowing your numbers helps you train smarter, recover faster, and feel more like yourself again. Low iron/ferritin can also be a warning sign for under fueling which can lead you down a dark path!

So, at your next check-up, advocate for comprehensive bloodwork. And if something feels off, don’t brush it off — check in on your nutrition and get support from a professional who understands endurance athletes.

If you have questions or aren’t sure where to start, feel free to reach out! I’m always happy to help guide you — whether it’s reviewing your symptoms, recommending testing, or connecting you with a trusted sports dietitian.

Happy Running!

~Amanda Robertson

Interested in learning more about Iron? Here are some helpful references:

Clénin G, Cordes M, Huber A, Schumacher YO, Noack P, Scales J, Kriemler S. Iron deficiency in sports - definition, influence on performance and therapy. Swiss Med Wkly. 2015 Oct 29;145:w14196. doi: 10.4414/smw.2015.14196. PMID: 26512429.

Sim M, Garvican-Lewis LA, Cox GR, Govus A, McKay AKA, Stellingwerff T, Peeling P. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol. 2019 Jul;119(7):1463-1478. doi: 10.1007/s00421-019-04157-y. Epub 2019 May 4. PMID: 31055680.

Journal of Strength and Conditioning Research 29(2):p 559-565, February 2015. | DOI: 10.1519/JSC.0000000000000636

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