IRON (Fe) The Most Crucial Atom For An Endurance Athleteâ€™s Success Joe I. Vigil, Ph.D.
Essential Ingredients of a Successful Athlete ¾ Ability to Set Achievable Goals ¾ Interaction With a Competent Coach ¾ Good Nutritional Habits ¾ An Effective Improvement Training Plan ¾ Consistency in Training (Compounding)
Essential Ingredients of a Successful Athlete, Continued 他 Adequate Recovery 他 A Positive Mental Attitude (PMA) on Life and All Mini-Environments Exposed To
Athletes’ Adaptation to Distance Running ¾ Increased Blood Volume ¾ Increased Number of Red Blood Cells (RBC), Which Contain Hemoglobin (Hb) — Iron is Part of the Hb Structure ¾ Increased Stored Fuels in the Cells ¾ Increased O2 Storage Capability in Muscles (Via Myoglobin Which Contains Iron)
Athletes’ Adaptation to Distance Running, Continued ¾ Increased Number of Enzymes Used for Complete Fuel Metabolism (Iron is Part of Cytochrome Enzyme Structure) ¾ Decreased Resting Pulse
Importance of Iron in Distance Running 他 Hypothesis: Inadequate body iron reserves compromise the magnitude of adaptation to the training process. 他 This limits the quality and quantity of high-level endurance work output. 他 Thus, it is not just doing the training that builds fitness, rather it is adapting to the training stimulus by building a bigger engine. This engine requires iron.
Lowered Hb Can Impair Aerobic Performance ¾ Example I: Decreasing Hemoglobin from 16 to 15 gms/dl ¾ Oxygen content decreases from 21.09 to 19.79 ml/dl—This is a 6.2% decrease (1.3/21.09 x 100) in oxygen content.
Lowered HG Can Impair Aerobic Performance, Continued 他 Example II: Decreasing Hemoglobin from 14 to 13 gms/dl 他 Oxygen content decreases from 18.49 to 17.9 ml/dl. This is a 7.0% decrease (1.3/18.49 x 100) in oxygen content. 他 Decreasing Hb from 14 to 13 gms/dl will decrease VO2MAX by 3%. If VO2MAX decreases from 68 to 66 ml/kg/min, it can slow Marathon pace from 2:26:26 to 2:30:36.
Possible Mechanisms of Iron Deficiency/ Depletion in Endurance Runners ¾ Decreased Dietary Intake (More So In Women Than Men) ¾ Decreased GI Iron Absorption* ¾ Increased Sweat Loss ¾ Loss of Myoglobin Iron (Rhabdomyolysis)
¾ Increased Gastrointestional Loss (Ulcers, Hypoxia) * Of Greatest Importance
Possible Mechanisms of Iron Deficiency/ Depletion in Endurance Runners, Continued 他 Increased menstrual Loss (Women) 他 Loss of Hemoglobin Iron From Hemolysis*
* Of Greatest Importance
Functional Monitoring of Iron Status Hemoglobin (Hb) ¾A protein normally occupies 1/3 of RCB (MCHC). ¾ 98.5% of the blood’s O2 is chemically bound to Hb for transport to metabolizing tissue. ¾ As Hb changes, so does VO2MAX. ¾ It is not just training that affects VO2MAX
remember the interaction between good health and fitness.
Functional Monitoring of Iron Status, Continued 他 Normal range of Hb for men is 15-18 gms/dl. 他 Normal range for women is 12-15 gms/dl.
Hemotalogical Aspects of Overuse 他 Iron deficiency causes overtraining in many runners: 他 Iron is part of the hemoglobin molecular structure. 他 Hemoglobin carries 98.5% of blood oxygen. 他 More than half of the enzymes of aerobic metabolism contain iron.
Hemotalogical Aspects of Overuse, Continued 他 Thus, a decrease in iron stores can yield a decrease in aerobic capacity (VO2MAX). 他 Excessive impact stresses can cause hemolysis due to extravascular compression and intravascular acidosis.
Hemolysis in Runners ¾ Blood Acidity Increases ¾ RBC Transit Velocity Increases ¾ Extravascular Compression of Major Working Muscles ¾ Increases in Plantar Surface Compression of Foot Strike ¾ Mean Life of RBC in Runners is 80 days versus 120 Days in Sedentary Populations
Iron Inadequacy Is A Common Problem ¾ Occurs in 10-25% of the US Population ¾ Caused primarily by increased refining and processing of food, plus a decreased use of cast iron cooking utencils (we are a “Teflonized” society!). ¾ Deficiency of iron is more common than any other nutrient. ¾ Elite Runners (especially women) tend not to eat red meat.
Iron Depletion Vs. Iron Deficiency 他 Iron Depletion Subnormal body iron stores, most easily seen as decreased serum ferritin levels. 他 Iron Deficiency
Inadequate iron supplies to permit normal erythrocyte and hemoglobin levels in the blood.
Dietary Sources of Iron 他 Heme Iron:
Exists in meat and liver and is quite easily absorbable. 他 Non-Heme Iron: Found in egg yolks, dried fruits, baked beans and molasses, soybeans, spinach, broccoli, lima beans, sweet potatoes, Brussels sprouts. Non-heme iron is poorly absorbable.
Absorption of Iron Into The Body 他 Absorbable iron is in the ferrous state (Fe**) 他 Heme iron does exist in the Fe** state and thus absorbs easily. 他 Vegetable sources of iron are typically in the ferric state (Fe***), and thus must be acidified for conversion to Fe**.
Absorption of Iron Into The Body, Continued 他 Enhancers of Fe*** Vitamin C, Citric Acid, Orange Juice, Apple Sauce, etc. 他 Inhibitors of Fe***
Phosphoprotein (Egg Yolks), Bran Fiber, Polyphenols (Coffee, Tea)
Functional Monitoring of Iron Stores ¾ A protein which chemically binds Iron is found in almost all living cells. ¾ Because it also circulates in the plasma, plasma ferritin levels mirror total iron stores. ¾ Ferritin is the body’s most accurate indicator of iron stores.
Functional Monitoring of Iron Stores, Continued 他 <20ng/ml:
Inadequate Bone Marrow Iron
他 20-30ng/ml: Sizable Iron Depletion 他 >50ng/ml:
他 Beware of hemochromatosis (iron storage disease), which has the same symptoms as anemia.
Iron Supplementation in Distance Running 他 Distance running is an aerobic event, requiring adequate transportable O2 in the bloodstream, and Hb mediates this transport. 他 More than 50% of the enzymes for aerobic metabolism are iron-containing; part of the getting fit process thus involves producing more mitochondrial enzymes for aerobic metabolism.
Iron Supplementation in Distance Running, Continued 他 Distance runners may not get adequate dietary intake of iron-making supplementation potentially worthwhile. 他 Since iron absorption occurs in the first part of the small intestine, breakdown of iron-containing pills often does not occur quick enough to ensure absorption. 他 Liquid iron is suggested as the optimal means for non-dietary iron intake.
Iron Supplementation in Distance Running, Continued 他 My experience with 35 years of working with distance runners suggests that when ferritin levels are below 30ng/ml, 1mg elemental iron per kg body weight per day serves to maintain ferritin levels at or above 30ng/ml. 他 Examples: 50 kg (110 lbs) Woman needs 50 mg Iron 60 kg (132 lbs) Man Needs 60 mg Iron
Iron Supplementation in Distance Running, Continued 他 One teaspoon of liquid iron has 45mg elemental iron: 他 The woman could take 1 tsp. per day; the man, 1-1/2 tsp. per day, with orange juice. 他 Beware of hemochromatosis (iron storage disease) which has the same symptoms as anemia.
Functional Monitoring of Iron Status Heptaglobin (Hp) 他 A plasma protein, produced by the liver, which chemically binds to hemoglobin released into plasma, when red blood cells rupture (hemolysis) due to impact stress or extravascular compression. 他 The resulting Hb:Hp complex gets transported to the liver, where the hemoglobin is metabolized and the iron conserved.
Functional Monitoring of Iron Status, Continued Heptaglobin (Hp) 他 Excessive hemolysis
Functional Monitoring of Iron Status, Continued Urine Hemosiderin (Hs) 他 Kidney tubules reabsorb filtered hemoglobin in an attempt to prevent its loss. 他 Metabolism converts hemoglobin to hemosiderin. 他 Normal kidney cell growth and replacement causes cell sloughing, which forms part of urine sediment.
Functional Monitoring of Iron Status, Continued Urine Hemosiderin (Hs) 他 Centrifugation of the urine specimen and staining the sediment reveals the presence of Hs. 他 A positive hemosiderin test
Functional Monitoring of Iron Status, Continued Reticulocytes 他 These are 1-2 day old red blood cells. 他 Their elevation implies an increased release of young red blood cells from bone marrow due to a recent loss (as with hemolysis). 他 If elevated to >75,000 per liter, this suggests a vigorous response to a recent red cell loss, but also implies adequate iron stores.
Functional Monitoring of Iron Status, Continued Reticulocytes 他 A low reticulocyte count, coupled with low Hb, suggests low iron stores or iron loss (check ferritin, Hp, Hs).
Summary: What Are The DEF’s? D = Dissolved Oxygen Only 1.5% of the total in the blood— inadequate—we need oxygen bound to hemoglobin.
E = Erythroprotein The protein hormone from the kidney that stimulates hemoglobin production, which transports 98.5% of the blood oxygen.
F = Ferritin Carries iron for hemoglobin production.
Hemotalogy WBC (k/dl)
(4.5 – 11.0)
(4.0 – 5.2)
(12.0 – 16.0)
(35 – 47)
(140 – 400)
(80 – 100)
(30 – 50)
(32 – 36)
Iron Presentation Vocabulary Cytochrome System