The Effects of Physical Exercise on the Concentrations of Ferritin and Transferrin Receptor in Plasma of Male Judoists

Abstract

The aim of the study was to assess the within-subject (day-to-day) variability for iron status variables: ferritin (ferr) and soluble transferrin receptor (sTfR) concentrations in plasma and the sTfR/log ferr index in athletes subjected daily to high physical loads. Blood was sampled in the morning from 8 healthy male elite judoists, aged 20 - 31 years, for 10 consecutive days while at training camp. Mean concentrations of ferritin and sTfR in plasma for the 10 day period were 32.0. 1.771(+/-1) and 2.41. 1.324(+/-1) mg/l, respectively. The average within-subject, day-to-day variability for ferritin was 27.4 % (range: 16 - 44 %), and was much lower for sTfR (6.7 %; range: 4 - 15 %). Ferritin concentrations were significantly, albeit weakly, correlated with training loads on the preceding day (r = 0.256; p < 0.05) and with creatine kinase (CK) activities on the same day (r = 0.397; p < 0.001), while sTfR did not correlate with either training loads or CK activities. Mean day-to-day variability for the sTfR/log ferr index was 11.8 % (range: 5 - 21 %), i.e. markedly lower than for ferritin. Although the physical load-induced changes in iron metabolism indices in male subjects were similarly oriented as in the earlier reported female ones representing the same sport, the magnitude of those changes was less pronounced than in the females. This was evidenced by a markedly lower within-subject day-to-day variability in ferritin, still significant but weak correlation between load magnitude and ferritin levels, and a significant, negative correlation between ferritin and sTfR concentrations, not found previously in the female athletes. However, despite lower variability in ferritin than in women, the exercise-induced ferritin increases in male athletes might make a reliable assessment of iron stores in them difficult. The present results confirm our earlier reports that sTfR levels are stable under high physical loads, thus making them a useful indicator of iron status. Also sTfR/log ferr index is of a much higher diagnostic value than ferritin, despite high variability of the latter. That index is particularly valuable in detecting iron-deficient erythropoiesis.

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

“…Physical exercise may considerably increase ferritin levels as reported for cross-country skiers [21] or female triathletes [23] and those exercise-induced increases may persist for several days [12,27], which may affect the day-to-day variability. Similar observations were made by us in male and female judoists in whom the within-subject, day-to-day variability averaged 27.4 and 46%, respectively, highest individual values amounting to 44 and 75%, respectively [14,16]. Thus, the day-to-day variabilities in ferritin concentrations found in this study in cross-country skiers were much lower than the abovementioned values for other athletes.…”

“…Significant correlations between ferritin concentrations and training loads, as well as CK activities observed in male judoists [16], and a lack of such correlations in this study, support the view that the loads applied to cross-country skiers brought about only minor muscle damages which increased the permeability of cell membranes but without inducing an inflammatory process. It suggests that the exercise-induced ferritin increase would be due to stimulation of ferritin synthesis as a response to an acute-phase stimulus and not to increased liberation of ferritin from myocytes due to increased membrane permeability.…”

“…An alternative explanation would be that the loads applied to cross-country skiers were too small to induce a response like that observed in judoists [16]. That view might be supported by a rather low correlation between CK and training loads in this study (r<0.…”

“…Earlier studies on male [16] and female [14] judoists revealed a marked day-to-day variability of ferritin levels under high physical loads and demonstrated that the soluble transferrin receptor (sTfR) was a much more stable indicator of iron metabolism in speedstrength athletes under such conditions compared with ferritin alone. The lack of similar studies on endurance athletes prompted us to determine the within-subject, day-to-day variability under conditions of varying training loads for the following iron status indices: concentrations of ferritin and of soluble transferrin receptor (sTfR), and for the ratio of those expressed as the sTfR/log ferr index in male and female cross-country skiers during a training camp.…”

Circulating soluble transferrin receptor concentration decreases after exercise-induced improvement of insulin sensitivity in obese individuals

“…The concentration of sTfR increased immediately after exercise, as found in several studies. [11][12][13][14][15][16][17][18] The study of the long-term concentration of serum sTfR was carried out in a group of elite rugby players during a competitive season. 19 The sTFR concentration increased during the competition period and decreased at the end of the season.…”