Iron: The Performance Enabler You Might Be Missing

MUSINGS FROM A COACH - 16 APRIL '26

A research note, sent to me by one of my coach mentors, written by Dr. Jeff Rothschild (PhD in Sport Nutrition and Sport Nutritionist at High Performance Sport New Zealand) inspired me to touch on the subject of iron. Whether you coach athletes or are one, iron is a topic that deserves more attention than it typically gets.

Dr. Rothschild makes a distinction I love: iron isn't a performance enhancer, it's a performance enabler. When it's low, nothing else you do fully works. Training adaptation stalls. VO₂max drops. Endurance capacity tanks. And the frustrating part? You might not even know why you feel flat. Iron is critical for hemoglobin, oxygen transport, and energy production at the mitochondrial level. When it's missing, you're essentially trying to run an engine without fuel.

The numbers are sobering. Iron deficiency affects up to 17% of male endurance athletes and up to 50% of female endurance athletes. Female athletes carry higher risk due to menstrual losses compounded by training-induced absorption issues. But male athletes aren't immune - high training load, sweat losses, GI stress, and inadequate dietary intake all increase risk regardless of sex. You can be deficient before you're anemic.

He goes on to write that Iron deficiency progresses in stages. By the time hemoglobin drops - which is what most standard blood panels flag - you've already been running on compromised stores for a while. Stage 1 begins with depleted ferritin. Stage 2 is iron deficiency without anemia. Stage 3 is full iron deficiency anemia. Stages 1 and 2 are where most athletes are quietly underperforming without explanation.

Dr. Rothschild recommends testing with a healthcare provider, not guessing. Key markers include serum ferritin, transferrin saturation, soluble transferrin receptor (sTfR), and CRP to contextualize the results. He also stresses standardizing conditions: morning, well-hydrated, no hard training in the prior 24 hours, no muscle-damaging work in the 2–3 days prior. Also, be aware that a few things can skew results, such as "...inflammation, illness, or heavy training, potentially masking low iron stores. High values can also indicate hemochromatosis (excess iron stores), which should not be left untreated."

Testing frequency depends on history and risk factors - athletes with prior deficiency or high training loads may test up to four times per year. And if you're doing an altitude camp, you can put a testing and supplementation protocol in place to ensure successful adaptation and benefits from that camp (read more here).

From my experience and knowledge learning from USPOC Dieticians for years, it's important to be consistent when testing as well as getting enough testing to notice trends. An example of a recommended set of blood work would be the standard CBC (to look at your RBC, Hemoglobin and Hematocrit), iron panel plus ferritin. I also like to know Vitamin D levels as well. I'm NOT a Dietician, so I always recommend athletes work with one or their Doctor to chart the best testing combinations and frequency.

As Dr. Rothschild puts it simply: "Repleting low iron can do wonders for your performance, recovery, and overall wellbeing. But if your iron levels are fine, supplementing isn't a gain — it's a risk."

As athletes, I think this is worth investigating. Maybe one test a year works fine for us. Or maybe repeated testing each quarter is better. Regardless, I think it's important for each of us to start learning about our own levels and track trends throughout the season, or season to season.

Gratefully,

Mark

CEO Team MPI