The aim of the study was to assess the effect of physical exercise on the changes in concentrations of ferritin and soluble transferrin receptor (sTfR) in plasma in course of 10 consecutive days of a training camp. Ten female elite judoists, aged 17-23 years, participated in the study. Mean concentration of ferritin for the 10 day period was 62.8 x 1.633(+/-1) microg/l, the within-subject, day-to-day variability being very high (13-75%). Ferritin concentrations were significantly correlated with the training load on the preceding day (r = 0.397; p < 0.001). Mean level of sTfR was 2.56 x 1.291(+/-1) mg/l and its within-subject variability was much lower (4-16%). Although the training loads had an effect on the intravascular hemolysis as indicated by a significant, negative correlation between load scores and haptoglobin concentration (r = -0.282; p < 0.01), the latter was not correlated significantly with sTfR levels. It was concluded that the soluble transferrin receptor is a more stable indicator of iron status under high training loads since, unlike ferritin, it does not respond to the workload on the preceding day. Moreover, the intravascular hemolysis observed in athletes does not affect the sTfR levels in plasma.
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