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Guest Writer: Cindy Dallow, PhD, RD

So you’re training for an Ironman!?  You have your coach, your training plan and a big fat goal to work toward.  You have your maximum aerobic function (MAF), your heart rate (HR), your kilowatt (KW)/hour, and your sweat rate permanently implanted into your brain.  But have you thought recently about the importance of iron?  We hear and say the word all the time when we talk about our training (“I’m training for an ironman!”), but none of your training will do you any good if you are low in iron.

Say what?

That’s right – being low in iron can negate all the hard training you do! In fact, the iron content in your body’s tissues is one of the main factors determining your aerobic capacity, which of course greatly affects athletic performance.


If this is news to you I’m glad I have your attention now.  I know we hear it all the time – athletes worrying about sugar, fat, and sodium intake, but many should be more focused on iron intake. ESPECIALLY female athletes because of our menstruation cycles.

The body uses iron to produce oxygen transporters – such as hemoglobin and myoglobin – and to produce energy by serving as a cofactor to many energy-using enzymes. Strenuous training increases the physiological demand for oxygen which then increases the demand on the transport systems as well. Hemoglobin then carries oxygen from the lungs to all bodily tissues. Myoglobin in the muscle stores oxygen for use during exercise.

iron-coinIron deficiency anemia (IDA) is more common in athletes than sedentary individuals, and more common in female athletes than male athletes. Some studies suggest 20 – 50% of female athletes and 4-50% of male athletes have low iron stores (which is not IDA but can lead to IDA). Higher prevalence of low iron stores and IDA are seen in runners, swimmers, triathletes, rowers, and soccer players.

Symptoms of low iron stores include (but are not limited to):

  • shortness of breath,
  • early fatigue during exercise,
  • decreased motivation to train,
  • increased rating of perceived exertion (RPE),
  • decreased aerobic capacity,
  • decreased training adaptations,
  • decreased time to exhaustion,

Chronic fatigue is the most common symptom for iron depletion but it’s also a symptom of other conditions (and a common side effect of hard training). So be careful in diagnosing yourself with iron depletion!

A diagnosis of IDA or iron depletion Is made with a blood test and should be done at least 24 hours post-training or during a recovery period. You will need a complete blood count (CBC), serum ferritin, serum iron, transferrin saturation, and total iron binding capacity (TIBC). Discuss your results with a physician and a Registered Dietitian.

How to Prevent Iron Depletion and IDA

So how can you prevent iron depletion and IDA?  You can consuming adequate iron through food intake or by taking iron supplements.

Iron in food occurs in two different forms: heme and nonheme iron.  Heme iron is absorbed much more efficiently than nonheme iron. Oysters and beef are high in heme iron.  Grains, leafy greens, and lentils are high in nonheme iron. Vegetarians and vegans are at a higher risk for iron depletion but if they include iron-rich foods and/or take an iron supplement, they can easily maintain adequate iron stores.

How much do you need each day? The Dietary Reference intake (DRIs) for iron are 8 mg/day for males aged 18 – 50 and 18 mg/day for females 18 – 50. For both men and women over 50, the DRI is 8 mg/day.

If you want to take an iron supplement, look for ferrous sulfate or ferrous gluconate. These two forms are absorbed fairly well and are less expensive than other forms of iron., an independent laboratory analyzing and rating supplements for purity, nutritional content, and price, recommends the following approved iron supplements as the most affordable:

  • CVS Pharmacy Iron, 65 mg iron*, $10.49 for 200 tablets – CVS Pharmacy
  • Nature Made Iron, 65 mg iron, $9.99 for 100 tablets – Walmart
  • Nature’s Bounty, 65 mg iron, $4.54 for 100 tablets – Walmart
  • Spring Valley, 65 mg iron, $4.93 for 250 tablets – Walmart
  • *65 mg iron = 325 mg ferrous sulfate

As you can see, you do NOT need to spend a lot of money on iron supplements!

Do not take iron supplements and antacids or calcium supplements at the same time. It is best to space doses of these 2 products 1 to 2 hours apart, to get the full benefit from each medicine or dietary supplement. Do not take iron supplements with coffee or tea as the tannins in these beverages reduce the absorption of iron.

DO take iron with vitamin C-containing foods, such as orange juice, or with a vitamin C supplement. Vitamin C enhances the absorption of iron. Or simply take iron before bed on an empty stomach to maximize absorption.

Take Charge of your Iron

As you already know, your training and nutrition go hand in hand.  You put so much hard work into your swimming, cycling, and running, so it’s important to take in enough iron as to not negate your training!  If you think you might be low in iron, see your physician and get a blood test.  As an endurance athlete it never hurts to know your iron levels so you can monitor your intake and make sure it is not dipping over time. Otherwise, be sure to include lots of iron-rich foods in your diet and/or take an iron supplement.  This will ensure a strong and healthy you on your journey toward Ironman.

Happy training!

Cindy Dallow, PhD, RD
Cindy Dallow Nutrition and Wellness, LLC

5 Causes of Breathless Swimming

Ironman University Certified Coach, 16x Ironman Finisher, 8x Kona Finisher and author of "How To Swim Faster in 30 Days", Wendy Mader explains in detail, the 5 issues that can cause breathlessness in the water:

Not exhaling Immediately before you inhale
Dragging lower body
Kicking too much
Dropping your arm too soon when you rotate

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Post Author: Dave Erickson