Iron deficiency in athletes: Prevalence and impact on VO peak.

Background: Iron is an important micronutrient in pathways of energy production, adequate nutrient intake and its balance is essential for optimal athletic performance. However, large studies elucidating the impact of iron deficiency on athletes' performance are sparse.

Methods: Competitive athletes of any age who presented for preparticipation screening 04/2020-10/2021 were included in this study and stratified for iron deficiency (defined as ferritin level <20 µg/l with and without mild anemia [hemoglobin levels ≥11 g/dl]). Athletes with and without iron deficiency were compared and the impact of iron deficiency on athletic performance was investigated.

Results: Overall, 1190 athletes (mean age 21.9 ± 11.6 years; 34.2% females) were included in this study. Among these, 19.7% had iron deficiency. Patients with iron deficiency were younger (18.1 ± 8.4 vs. 22.8 ± 12.1 years, P < 0.001), more often females (64.5% vs. 26.8%, P < 0.001), had lower VO peak value (43.4 [38.5/47.5] vs. 45.6 [39.1/50.6]ml/min/kg, P = 0.022) and lower proportion of athletes reaching VO peak of >50 ml/min/kg (8.5% vs. 16.1%, P = 0.003). Female sex (OR 4.35 [95% CI 3.13-5.88], P > 0.001) was independently associated with increased risk for iron deficiency. In contrast, the risk for iron deficiency decreased by every life year (OR 0.97 [95% CI 0.95-0.99], P = 0.003). Iron deficiency was independently associated with reduced VO peak (OR 0.94 [0.91-0.97], P < 0.001) and lower probability to reach VO peak >50 ml/min/kg (OR 0.42 [95% CI 0.25-0.69], P = 0.001).

Conclusions: Iron deficiency is common in athletes (predominantly in female and in young athletes). Iron deficiency was independently associated with reduced VO peak during exercise testing and lower probability to reach a VO peak >50 ml/min/kg.