|Posted on Saturday, February 28, 2004 - 03:53 pm: |
What do we know about Iron uptake/requirements in endurance athletes. I have read many abstracts on the topic but would like to hear what forum readers have noticed. Even if it is anecdotal evidence. What happens if an athlete is taking Dr. Rx Iron supplements and stops. How long before we would expect to see a drop in performance (higher hr) for a given wattage? When Dr. Rx supplements are resumed, what is the time line before we see performance return to previous levels?
I personally have seen a number of Ironman distance male/female athletes experience Iron related issuses.
Any feedback is appreciated.
|Posted on Sunday, February 29, 2004 - 09:03 am: |
The first recommendation of course is not to discontinue Dr. Rx Iron supplements until the Dr. suggests to do so. The Dr. will typically recommend discontinuing iron supplementation only when blood tests show that it is ok to do so (normal Ferritin levels).
Iron stores take a long time to deplete, and a long time build. If you are low on iron it may take several months for increased iron intake either through dietary intake or supplements to have the desired effect on Ferritin scores. Iron supplements should not be taken without a doctor’s prescription. Too much iron causes problems as well.
Athletes who run are at a greater risk of iron deficiencies because of "runners anemia", low iron in runners caused by red blood cells literally being crushed in the feet upon the impact of each running stride, as well as through bleeding in the GI and Urinary tracts. Iron is also lost through sweat. I am not aware of any studies that have correlated specific decreases in iron levels with specific decreases in power output. Generally the physical result of low iron is fatigue, manifested both in decreased power, but mostly in decreased time to fatigue at any given power output.
Men require about 10 mg of iron per day, females and teenagers about 15mg/ day. Athletes need only slightly more. It isn’t important to be concerned with exactly what drop in iron will potentially cause what effect, since this would be different for each individual, with the exception of going below the minimum daily intake. Additionally, discovering the exact correlation would require daily blood testing, which is interesting scientifically, but entirely impractical otherwise. Obviously achieving the required daily intake is paramount, and one would not want to experiment with how low they could go before fatigue symptoms present. It is important to meet the daily minimum requirements of iron intake. If high heart rate and fatigue symptoms appear, look at iron as one of the possible causes or contributors.
The bottom line; If a person is certain they taking in less than the minimum intake of iron needed in one day, then increasing dietary intake of iron is important. Check with a dietition or Dr. for a dietary analysis. If a person suspects they are low on iron, only a blood test will show whether or not this is true, and only subsequent blood tests will show if iron levels (Ferritin) levels have responded to either supplements or dietary intake.
With myself, I was shown 3 years ago to be on the low side of normal for Ferritin levels, which is a little low for athletes. My dietary intake of iron was good, and increased dietary iron intake had no effect on my Ferritin levels over several months so the Doc. prescribed iron supplements. It took 5 months for my iron levels to increase. I now take an iron supplement every day. But that’s only me. I have a deficiency in absorbing iron. Others may not.
|Posted on Monday, March 01, 2004 - 12:39 pm: |
My experience with low iron levels is that when you notice, it's too late. It's better to be proactive in this area and keep your ferritin levels up so recovery time doesn't increase.
Falling off the track is easier than getting back on.
And not all iron supplements are created equal. This is especially important for endurance athletes. There are many out there but few directly affect your ferritin level. And this is important as low ferritin levels gone uncorrected lead to iron deficiency problems.
One last comment.....unless you speicifically request a ferritin level when you get your blood work done, chances are that it will NOT be checked. It's not a standard test but can prove to be valuable to athletes.
|Posted on Tuesday, March 02, 2004 - 09:27 pm: |
Thanks Mike and Chris for your thoughts.
I wonder how many individuals have problems absorbing iron? I suspect that if we were to assess a large population, we might be surprised how large a percentage experience this condition.
|Posted on Wednesday, March 03, 2004 - 08:31 am: |
In my experience there aren’t many who have a deficiency in absorbing iron. There may be a great deal of people who don't consume enough iron though, but this would not likely be the case with red meat eaters.
|Posted on Monday, March 29, 2004 - 09:30 am: |
Dr. Doug Clement at UBC did a lot of work on iron levels in athletes in the 1980's and he found that over 85% of female endurance athletes and 50% of male endurance athletes that he tested were low in iron stores measured by serum ferritin. He defined low as below 20 (pernicious anemia is lower than 10 and normal is 20 - 250). He recommended supplementation with ferrous fumarate or ferrous gluconate of 300 mg of elemental iron per day until the reading was above 50.
His possible reasons for these low numbers were that the body cannot absorb iron very well through the wall of the gut and that endurance athletes, especially menstruating females, destroy a lot of red blood cells during exercise.
My experience with the National Team and my club team in xc skiing has shown this to be true. Many of my skiers have low serum ferritin, even though they may not show a low hemoglobin. This has resulted in low energy, low VO2 max and a low capacity to handle high training loads. After supplementation (it usually takes 3-6 months to change the levels significantly)my skiers are racing faster, have higher VO2 maxes and can handle a higher training load and recover faster. There is no doubt in my mind serum ferritin should be tested in all endurance athletes and that most of them should be supplementing iron for the entire time of their career. There is no way that you can absorb enough iron by eating meat or leafy green vegetables if your serum ferritin is low. You would have to eat hundreds of steaks and hundreds of head of lettuce.
|Posted on Monday, March 29, 2004 - 07:21 pm: |
In my experience I have found that those athletes who follow good dietary habits are not candidates for iron supplementation, but that most athletes, despite claiming to or attempting to, don’t follow a good diet 100% of the time.
Many athletes don’t make the basic recommendation of eating a few pieces of fruit per day, as well as large servings of vegetables and the right balance of meats, grains, and milk/ soy type products.
However, compared to the 80’s when Clement did this work referred to in the previous post, serious athletes, in general, now are eating better than 10 or 20 years ago, but still most leave much to be desired in proper nutrition.
It isn’t true that to get enough iron an athlete would need to eat “hundreds of steaks” since one 3 ounce steak has about 3mg of heme iron, so “hundreds of steaks” would amount to hundreds of milligrams of dietary iron per day, which would most likely cause constipation, and at least really bad gas. The supplement form of iron is not absorbed nearly as well as from food. 200mg of Ferrous Fumarate has 66mg of elemental iron, and not all of this is absorbed. 300 mg of elemental iron per day is achieved with 3 200 mg tablets of Ferrous Fumarate per day, but this can also cause constipation so dosage may need to be reduced for some individuals. 300 mg of elemental iron per day is definitely aggressive iron supplementation, and not at all typical of a maintenance dose. The reference did appropriately clarify that this dose is discontinued once serum Ferritin reached 50.
After 6 months or so when iron levels have normalized, supplementation is not required, and the athlete should be able to maintain serum Ferritin levels through diet.
It would be difficult to raise an athletes low serum Ferritin levels (close to 20 and increase to above 50) with diet alone, specifically if the athletes continued to train hard without sufficient recovery time. But again, once iron levels are normal, a healthy diet should maintain iron levels.
heme iron is the better absorbed of the two types of iron; heme, from animal products, and nonheme, from plant products.
The daily iron intake for non-athletes is around 8mg for men and 18mg for woman. Various sources recommend increasing this by 30% for athletes. (I’ve included a link to one source at the bottom here) A 3000 calorie per day balanced diet provides more than enough iron for those without a specific deficiency in absorbing iron.
This is still well within the means of dietary intake, especially the comparatively larger caloric intake of well-trained athletes (3500 – 5000 calories). Amongst the cyclists, triathletes’, and pro hockey players I have worked with, low iron levels are not common for those with good dietary habits, and those who don’t overtrain. The exception is females and particularly female runners.
I would hesitate to suggest that all athletes all the time always require iron supplements, not only because this makes an assumption about a population without testing individuals, but because of the prevalence of poor dietary habits and training too hard too often, many athletes iron levels are low. This means that although many have measured low iron levels in many athletes, that it should not be concluded that all athletes are low on iron. It does mean that all athletes should be tested to see what iron levels are before making dietary or supplement recommendations. An athlete should not take iron supplements unless prescribed by a physician, and whether or not iron supplementation is prescribed, serum Ferritin levels should be followed throughout the annual training and competitive plan of athletes. Three tests per year should suffice, but a sports medicine doctor should determine this.
The main problem is “getting behind the 8 ball” so to speak. If an athlete begins intensive training with poor nutrition and thus through poor nutrition and hard training depletes iron levels, it will be difficult to manage low iron even with good diet, once iron is low. However, slowly progressing into hard training with normal iron and getting the required recovery from hard training should prevent most athletes from experiencing low serum Ferritin levels, the expected exception being female runners. Female runners may benefit from a higher percentage of running time being deep water running, being that hemoglobin is destroyed through the impact of land running.
It seems that as with most things, prevention is the best cure. Athletes should not begin intensive training until iron levels are normal, favorably on the high side of normal, before engaging in intensive exercise. At all times, but imperatively so during periods of intensive training, diet should be as good as it can possibly get without exception.
As I stated in previous posts, interestingly, I happen to be an individual that requires iron supplementation due to a supposed genetic deficiency in absorbing iron. So I know all to well the tribulations of low serum Ferritin and hemoglobin levels. Nonetheless, after 10 years of having athletes serum Ferritin levels measured, the athletes with low levels also trained too hard too often, began hard training with low iron, or were female runners.
I know that my field experience only represents but a tiny portion of athletes, but this information that I provide here is worth consideration.
|Posted on Sunday, February 05, 2006 - 01:13 pm: |
hi thnx for the help. It would of been nice if you guys could of provided me with the direct answer for the question. I hope you guys really review over this note and make the proper corrections.
Thnx For Everything
|Posted on Sunday, February 05, 2006 - 03:13 pm: |
I am a little bit confused , because the last post on here was from Chris March 2004.
And this post from you is from today.
So the question is not anymore that clear to me after all this time and you may be able to help us out here.
So sorry for no answer at that time.