Iron deficiency can hurt performance before anemia appears

Low iron stores can impair energy and endurance even when hemoglobin still looks normal.

Iron does more than help make hemoglobin. It also supports myoglobin and enzymes involved in mitochondrial energy production. As iron stores fall, fatigue, breathlessness and reduced endurance can appear before hemoglobin drops enough to meet the definition of anemia.

Athletes are more vulnerable because training can increase iron losses through sweat, gastrointestinal bleeding, red blood cell breakdown and menstruation. Low energy intake can further reduce iron intake. Ferritin helps assess stored iron, but inflammation can temporarily raise it, so symptoms and a single test should not be interpreted in isolation.

Do not self-prescribe high-dose iron: excess iron can cause gastrointestinal problems and may be harmful. If persistent fatigue or an unexplained performance decline continues despite adequate sleep and recovery, ask a clinician about blood testing and use supplements only when deficiency is confirmed.

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