Iron is a particularly important mineral for endurance athletes due to its role in binding oxygen, which is circulated through the lungs and to the working muscles. Unfortunately, our bodies absorb only about 15% of the iron we ingest, and distance runners do just about everything possible to deplete the iron that they do consume.
Iron is lost through sweat and gastrointestinal irritation. It is temporarily lost through "footstrike hemolysis" (bursting blood cells through foot impact with the ground). Iron absorption is inhibited by calcium, coffee, tea, carbonated beverages and non-steroidal anti-inflammatories (all that ibuprofen some of you swallow). Women lose a substantial amount of iron through menstruation, making them more susceptible to iron depletion, but it is a concern for all distance runners-male and female.
Anemia, clinical iron deficiency, is not rare among runners, but even more common than iron deficiency is "iron depletion" due to low ferritin stores. Ferritin is an iron-containing protein that is primarily responsible for iron storage in the bone marrow. It is common among distance runners to have acceptable hemoglobin and hematocrit counts even when ferritin levels are severely depleted. For less active people, low ferritin levels are much less significant and don't often draw the attention of medical professionals.
However, the results of low ferritin levels for distance runners are significant. While iron depletion rarely results in the general lethargy associated with true iron-deficiency anemia, distance runners with low ferritin will likely experience abnormal exhaustion, increased blood lactate, slow recovery, declining performances, heavy legs, muscular tightness, loss of motivation, and substantially increased risk of injury. Does any of this sound familiar?
And there's more. Overuse injuries (the type of injuries distance runners get) double with ferritin levels under 20 and triple with levels under 12. I think it's safe to suggest that iron depletion is rarely considered to be the root cause of these injuries. Instead we focus on mileage, running surfaces, shoes and the other usual suspects. If you were nodding your head thinking the previous symptoms sound like a checklist of your most recent season, go get your serum ferritin tested.
At South Eugene High School, we became aware of the consequences of low iron in the spring of 2001 when three of our female distance runners all came back from blood tests with ferritin levels below 10 ng/ml. All three had all run their best times two years before but had been plagued with injuries and frustration since. During those two years, they had multiple blood tests, but the doctors never checked their serum ferritin levels.
Within four weeks of beginning an aggressive supplementation program, all three felt substantially more energy while running; their enthusiasm and joy for running returned, and they began to run much faster. Within two months, their levels were between 35 and 55 ng/ml. All three went on to compete collegiately and ran times far superior to what they ran in high school.
Since that initial experience, we have suggested that all the girls on the team have complete iron tests. Only five out of the dozens who have been tested, have been within the acceptable range for serum ferritin, and those five were either big meat eaters or had been taking supplemental iron for years. Half of the girls tested have been below 12 ng/ml.
Saturday, January 23, 2010
The Importance of Iron
This past week I read a really good article on iron intake and iron stores by coach Jeff Hess. It is something that is unfortunately misunderstood and undervalued in how much it can impact performance, by too many coaches, athletes, and even the medical community. It can affect males as well as females, particularly in those with heavy training loads - as well as those living at altitude - who do not include regular intake of red meat and/or sufficient iron supplementation. I have referenced it in passing - coach Scott Simmons, to name just one, has all of his athletes, both professional and collegiate, tested quarterly for ferritin levels - and the timing of seeing this article seems like a great opportunity to explore it more in depth. I will post some pertinent passages below, but the entire article is certainly well worth taking the time to read and digest.