Why may athletes require additional levels of iron?

Athletes tend to consume more and often healthier food than the rest of us, however, they place their bodies under considerable stress, draining them of iron. Iron performs an essential role in the transportation of oxygen from the lungs to all parts of the body. Oxygen is required for muscular activity. Myoglobin (the muscle's iron-containing compound) makes oxygen available to meet the requirements of physical activity and sport. Through chemical reaction iron is involved in the production of energy.