Know Before You Go: Understanding Iron Deficiency in Runners
If you're a runner and you've ever felt like your legs just won't turn over, your workouts are flat, or you're constantly tired despite sleeping well and eating "healthy"—there's a chance something deeper is going on.
One of the most under-discussed performance limiters in distance running is iron deficiency, along with low Vitamin B12 and Vitamin D. These aren’t just medical issues—they’re performance issues. As a coach, I’ve seen firsthand how drastically low ferritin, hemoglobin, and B12 levels can affect an athlete’s ability to train and race effectively. But here’s the kicker: many runners never even consider this until they’ve been struggling for weeks or months.
Let’s break this down—not as a doctor (because I’m not), but as someone who’s done the research, talked to the experts, and seen how these numbers affect real athletes on real training plans.
Runners vs. General Population:
Why Bloodwork “Normals” Don’t Always Apply
When most people get blood work done, they’re measured against the general population. That’s a problem for runners. Why? Because the threshold for what’s considered “normal” medically might be well below what’s optimal for endurance performance.
Take ferritin, the marker most commonly used to assess iron storage. A general physician might say 30 ng/mL is “fine,” but for a female distance runner, that number might correlate with feeling like you’re dragging an anchor during every workout. Many experienced coaches and sport-focused practitioners look for 80–100+ ferritin in women and 100–150+ in men before they consider an athlete in the “good” or “great” zone.
Key bloodwork markers for runners to track include:
Ferritin (iron storage)
Hemoglobin and Hematocrit (oxygen transport)
Vitamin B12 (energy production and red blood cell health)
Vitamin D (bone health and injury prevention)
“I'm Tired” Isn’t Just Life—It Could Be Low Iron
Here’s the tricky part: runners often don’t notice a sudden drop. Symptoms like fatigue, irritability, poor recovery, and underwhelming race results creep in slowly. Many chalk it up to overtraining, lack of sleep, or stress. And while those things matter, so does your internal engine.
Common signs of low iron in runners:
Feeling flat or heavy-legged on runs
Needing more recovery time than usual
Shortness of breath during moderate efforts
Cold hands/feet or looking pale
Unexplained dip in performance despite consistent training
But waiting until symptoms appear can cost you weeks of progress. This is why I encourage a “know before you go” mindset: learn about these markers before you’re in trouble, and ideally, get a baseline test while you’re healthy and training well.
Testing Smarter: What to Know Before the Lab Draw
If you're considering getting labs done, go in informed. Many physicians will only test iron if you specifically ask—and they often won’t test ferritin, saturation, or Vitamin D unless you request it. Don’t assume a standard panel includes everything a runner needs to see.
Also remember: a single lab result is a data point, not a diagnosis. The real power comes in tracking trends over time—what your numbers look like when you’re feeling great versus when you’re not. Three tests across 9–12 months can give you invaluable insight into how your body responds to training, travel, stress, and seasonal changes.
If You Are Deficient: Training Adjustments That Help
If a runner’s iron levels are in the “danger” or “too low” zone—especially if they’re experiencing fatigue and poor performance—it’s time to adjust training. You cannot train through a deficiency and expect your body to bounce back. Here’s a sample protocol that’s been helpful:
6-Week Low-Iron Recovery Training Plan:
Week 1: 30–45 min easy runs only
Week 2–3: 45–60 min easy runs, add strides
Week 4: Same + gentle hill strides
Week 5: Light intro to speed, retest labs
Week 6: Resume normal training if numbers improve
This scaled-back approach gives your body space to recover and rebuild while staying active. Supplements may also be needed, but those decisions should always be made in consultation with a qualified healthcare provider.
Final Thoughts:
Take Your Health Seriously—It Fuels Your Running
This isn’t about fear. It’s about empowerment. As runners, we spend hours refining workouts, obsessing over gear, and fine-tuning our race calendars. But the truth is, your blood health may be the most performance-defining metric you're ignoring.
So be proactive. Talk to your doctor, but bring questions. Ask about ferritin, B12, and Vitamin D. Track your symptoms. Know your ranges. And don’t wait until you’re dragging in workouts to start caring about what’s happening on the inside.
Because no matter how dialed in your training plan is—if your iron is low, your performance will be too.
If you'd like a downloadable version of the iron ranges and recovery protocol mentioned here, shoot me a message—I'm happy to share the resource I use with my athletes.
Live What You Love,
~ Coach Dusty
