Iron metabolism in boys involved in intensive physical training.

The purpose of the present study was to compare some haematological and iron-related parameters of prepubertal boys (10-12 years old) involved in intensive physical training program in preparation for the national championship with nontrained age-matched subjects. For this purpose, iron stores, haemoglobin, ferritin and serum transferrin receptor concentrations were taken into account. The athletes' dietary intakes were similar to the respective intakes in the control group. Mean ferritin concentration was similar in investigated groups of boys at the start of the study, but significant changes between those groups occurred during the 8 months of study. Compared with the control group, the trained ones have shown significantly higher serum transferrin receptor concentration during the competition period of the training season, just when they reached maximum performance capacity. Similarly, significant difference in total body iron, estimated as the sum of the individual's red blood cells iron and iron stores, between investigated groups occurred only during the competition period. The main finding of this study is that the endurance training in boys brings about significant decrease in serum ferritin, as well as iron stores in the body. Haematological parameters and iron status of trained children revealed latent anaemia (15%) or even manifest anaemia (9%). These findings indicate high prevalence of nonanaemic iron deficiency in young athletes and bear relationship to swimming training.