Effects of exercise on the markers of iron status in serum of cross-country skiers

The study aim was to assess the within-subject, day-to-day variability for ferritin and soluble transferrin receptor (sTfR) concentrations in serum of 6 female and 8 male cross-country skiers aged 16-18 years under a regular training regimen throughout 8 consecutive days. The concentrations of iron status variables and creatine kinase (CK) activities were adjusted to plasma volume changes. Mean ferritin concentrations were 30.6 • 1.142[sup]±1[/sup] and 22.6 • 1.167[sup]±1[/sup] μg/l for men and women, respectively, the average within-subject, mean day-to-day variability coefficients (CV) being 13.4% in men and 15.2% in women. Mean sTfR was 2.14 • 1.050[sup]±1[/sup] and 2.62 • 1.047[sup]±1[/sup] mg/l, respectively, and mean day-to-day CV 6.5% and 4.6%. Mean CV for sTfR/logFerr were 6.0% and 7.4%, respectively. Neither index correlated with training loads or CK activities. Thus, the training performed once daily had no significant effect on ferritin concentrations on the following morning, so ferritin alone may prove insufficient in detecting iron deficiency in endurance athletes. The low variability of sTfR under endurance loads made it useful in detecting iron deficiency together with ferritin and the sTfR/logFerr index. Adjusting the concentrations of ferritin and sTfR by changes in plasma volume might be recommendable for endurance athletes

Physical fitness of schoolgirls with Turner syndrome

The aim of the study was to assess physical fitness of girls with Turner syndrome (TS) and to determine the relative contributions of age, body height, and body mass to performance in fitness tests. Girls with TS aged 10-18 years (n = 184), and age- and stature-matched healthy controls (n = 280) were studied with the use of the EUROFIT test battery. Girls with TS were significantly inferior to the control group in maintaining balance, standing broad jump, sit-ups, shuttle run, and endurance shuttle run (p < .001). No significant differences were found for plate tapping, but girls with TS were superior to their healthy mates (p < .001) in handgrip, sit-and-reach, and bent-arm hang. Unlike controls, body height in girls with TS had significant effects on handgrip strength (positive) and on plate tapping speed (negative), other contributions being relatively similar in both groups. It thus seems that the somatic specificity of girls with TS explains most differences in motor fitness. The identified motor deficiencies of girls with TS call for undertaking steps toward attracting those girls to motor activities

Day to day variability in the transferrin receptor/ferritin index in female athletes

Results: The error for ferritin concentration was nearly twice as high in athletes as in controls, that for sTfR concentration was identical in the two groups, and that for the sTfR/logFerr index was about 50% higher in athletes than in controls. Conclusions: The within subject, day to day error for the sTfR/logFerr index computed from data recorded for untrained subjects cannot serve as a reference value for training athletes. When the sTfR/logFerr index is used to monitor iron stores in athletes, an error value of 0.20 should be used, because determination of the index after a few days of rest may not be feasible