Undiagnosed low iron is one of the main causes of inconsistent training, lack of progress, and disproportionate fatigue.

As such, getting your ferritin checked is one of the easiest ways to ensure low iron isn’t impacting your training or overall health.

Even if you don’t have symptoms of low iron, getting tested is still a smart idea.

That’s because, like everything in the human body, individual differences can mean one person’s low ferritin is another’s normal.

Likewise, “optimized” and low iron levels can fall into a pretty wide range. It’s important to know what your ranges look like.

As an example, if you take a ferritin test when you’re feeling great and crushing your workouts, you’ll now know what a “good” ferritin level is for you.

Then, if you start to experience symptoms of low iron or poor training, you can get your levels checked and compare these to what they were when you were feeling good.

To provide a specific example, let’s assume that your ferritin level when feeling great was 55ng/ml.

You re-test when you’re feeling sluggish or experiencing symptoms and your ferritin level is now 40ng/ml.

The lab and your doctor are going to tell you that iron isn’t a problem. But, you know from historical data that this is low for you and can then make appropriate changes.

Establishing a baseline and periodically monitoring your iron is an easy way to ensure your levels are always where they need to be.

It’s important to remember that not all individuals who have low iron will experience symptoms.

Further, athletes may have a more difficult time discerning the difference between normal training fatigue and the symptoms of low iron.

That said, here are things you should look out for…

• Fatigue
• Shortness of breath
• Joint pain
• Headaches
• Sore or swollen tongue
• Weakness

Your ferritin is going to come back with a number expressed as ng/ml.

Most general practitioners and advice will say having low ferritin constitutes a number below 16ng/ml.

However, like most things when it comes to running, research has shown that runners require higher ferritin levels to maintain performance.

Thus, most running experts consider having low ferritin to constitute values below 25ng/ml.

If your ferritin levels are between 25 and 50 ng/ml then you’re in what I’d call the “cautionary zone”.

While not considered low, you should be paying attention to your levels and supplementing to make sure you don’t dip below the low iron thresholds.

In my experience coaching elite runners, a ferritin level less than 50 ng/ml in women and less than 60 ng/ml in men are good targets to ensure there’s no impact on performance.

Again, while these numbers are not considered low by medical professionals, they can impact your running.