Iron deficiency

Iron deficiency is a shortage of iron that progresses through depletion, marginal deficiency and anemia.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 210.} Iron carries oxygen to working muscles, and even marginal deficiency may impair athletic performance.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 210.} Anemia develops when low stores persist and the body can’t make enough healthy red blood cells.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 210.}

Iron deficiency is the world’s most prevalent nutrition deficiency; in some studies, more than one in four female endurance athletes tested positive.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 210.} Symptoms include weakness, fatigue, irritability, poor concentration, headache and reduced exercise capacity, though some clients have no symptoms or get used to them.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 210.},^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 211.} Female athletes, women with heavy menstrual blood loss, distance runners and vegetarian athletes are at higher risk.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 211.}

In practice

• ISSA advises referring clients with nutrition deficiencies to a dietitian and working with their physician.^{3International Sports Sciences Association, Fast Track Study Guide: Nutrition, p. 1.}
• Iron supplements are outside a trainer’s scope of practice: only a doctor or registered dietitian should recommend them, because absorption varies and excess iron can cause harm.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 211.},^{4USA Triathlon, Complete Triathlon Guide, p. 41.}
• USA Triathlon recommends annual blood tests to check female athletes for signs of anemia.^{4USA Triathlon, Complete Triathlon Guide, p. 41.}
• The body absorbs about 15% to 35% of heme iron from meat, fish and poultry, compared with 2% to 20% of nonheme iron.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 211.} Vitamin C-rich foods and pairing with meat increase nonheme absorption; tea, calcium and phytates reduce it.^{2Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 211.}
• Helms and colleagues identify iron as an especially common shortfall in female athletes, particularly when energy intake is restricted.^{5Helms et al., The Muscle & Strength Pyramid: Nutrition, 2nd ed., p. 108.}