IRON DEFICIENCY WITHOUT ANEMIA IN ATHLETES: IMPLICATIONS FOR PERFORMANCE, HEALTH, AND TRAINING

Objectives: This review synthesizes current evidence regarding the impact of IDNA on athletic performance. It also covers physiological mechanisms, diagnostic strategies, as well as potential nutritional and training implications. Methods: The literature search was conducted in the PubMed database. The search terms were related to iron deficiency, iron status, non-anemic states, athletes, performance, and endurance. Athletes with low iron stores and normal hemoglobin concentrations were the subject of this study, which included original research and reviews. Studies consisting of iron deficiency anemia (IDA) or non-athletic populations were excluded from the paper. A narrative synthesis was performed. Key Findings: IDNA is a common condition among athletic populations, which can be associated with reduced aerobic capacity. Affected athletes have a decreased probability of achieving high VO₂-based performance thresholds. Therefore, athletes should be seasonally screened for IDNA using ferritin with CRP. Diagnostic accuracy can be improved by selective use of transferrin saturation and soluble transferrin receptor (sTfR). Iron supplementation efficacy depends on the severity of iron deficiency. Performance benefits are most consistent in individuals with ferritin levels below 20 µg/L. Conclusions: Endurance performance and training efficiency are especially at risk of being negatively affected by IDNA. The research shows that athletes at a higher risk of IDNA should be advised to conduct regular screening. Moreover, there is a lack of analysis focused on ferritin cut-offs and intervention protocols that would benefit athletic populations.