The Role of Latent Iron Deficiency and Its Subsequent Correction in Adolescent Boys' Functional Performance

Abstract

Background. Iron deficiency remains the most frequent nutrient deficiency in the world. Its negative impact on the physical and psychomotor development determines the importance of its timely, fast, and complete correction. Thus, the clinical efficacy of iron supplementation and its effect on body function, especially in latent iron deficiency (LID), is still insufficiently studied.Objective. The aim of the study is to identify the effect of iron supplementation in various dosages on functional performance of healthy adolescent boys but considering the initial iron levels.Methods. The study covered teenage boys 12–17 years old from I and II health groups studying in Samara Cadet Corps. All children were divided into groups according to the examination results (CBC, serum ferritin level): study group — 20 children with iron deficiency (3 children with iron deficiency anemia (IDA) were not included in this analysis), and the control group — 99 children. All children received iron supplements for 30 days: children with LID — 2.5 mg/kg/day, healthy children — 15 mg/day.Results. Normalization of serum ferritin was achieved only in 75% (16) of children after 30 days of iron intake. The mean timed expiratory capacity was 20" (16 ± 25) in healthy and 17.5" (11.25 ± 21.75) in iron deficiency (p = 0.081) group. There is a tendency to prolong the breath retention time on exhalation after supplementation in LID group (p = 0.068). The recovery time of heart rate before supplementation was 118.8 ± 71.7" in study group and 168.0 ± 98.5" in control group (p = 0.045) according to the results of the Martin – Kushelevsky test. After supplementation it has decreased only in study group (p = 0.009). The children's muscle strength in compared groups did not differ before (p = 0.486) and after (p = 0.567) supplementation, however, it has increased in the control group regarding the initial values (p = 0.003). Physical fitness indicators in both groups did not differ before supplementation. Study group significantly improved the running time by 60 m (p = 0.038) after supplementation. Control group has shown positive dynamics for three indicators: pulling out from suspension on high bar (p = 0.019), long jump (p = 0.026), and running at 60 m (0.018). Moreover, there were no differences between study and control groups after supplementation.Conclusion. Iron deficiency has moderate negative effect on adaptive respiratory and cardiovascular capabilities and fatigue. Iron supplementation mainly improves the indicators of cardiovascular system in case of iron deficiency, and indicators of muscle strength and physical fitness in case of normal iron levels.