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Iron status in elite young athletes: Gender-dependent influences of diet and exercise
Abstract
Iron depletion seems to occur more frequently among athletes than in the general population and may affect performance capacity. Only little information is available about the prevalence of iron status abnormalities in young elite athletes and whether iron depletion is associated with gender, sport, age or nutrition- and exercise-related factors in this group. Hence, diet, exercise and haematological data from 193 elite athletes (96 males, 97 females; 16.2 ± 2.7 years) from 24 different sports were analyzed retrospectively. Most female athletes failed to meet the recommended daily allowance for iron, even though dietary iron density was higher than in males (5.75 ± 0.78 vs. 6.17 ± 0.98 mg/1,000 kcal; P = 0.001). Iron depletion (serum ferritin < 35 μg/L) occurred in 31% of male and 57% of female athletes (P < 0.001). Low haemoglobin (males: <13 g/dL; females: <12 g/dL) and haematocrit (males: <40%; females: <36%) values were equally prevalent in both genders [haemoglobin: 7.3% (males), 6.2% (females); haematocrit: 13.5% (males); 15.5% (females)]. In females, reduced ferritin levels were associated with a lower dietary iron density (5.9 ± 0.8 vs. 6.6 ± 1.1 mg/1,000 kcal; P = 0.002). Males with iron depletion had a significantly higher estimated energy expenditure (48.7 ± 7.0 vs. 44.4 ± 7.6 kcal/kg/day; P = 0.009).
... From dietary analysis, male and female athletes appear to approach or meet the recommended daily allowance (RDA) for iron [166][167][168]. However, mean intakes may not be as useful when working with individual athletes. ...
... Beals [167] examined iron intake in volleyball players and found 67% of athletes did not meet the RDA, even though the mean suggested the cohort met the RDA [167]. This is in agreement with a study of Koehler et al. [168] who reported mean iron intake for males to meet the RDA for iron with 19% not meeting the RDA and mean female values meeting the RDA, while 63% did not on an individual basis [168]. ...
... Beals [167] examined iron intake in volleyball players and found 67% of athletes did not meet the RDA, even though the mean suggested the cohort met the RDA [167]. This is in agreement with a study of Koehler et al. [168] who reported mean iron intake for males to meet the RDA for iron with 19% not meeting the RDA and mean female values meeting the RDA, while 63% did not on an individual basis [168]. ...
Female athletes tend to choose their supplements for different reasons than their male counterparts. Collegiate female athletes report taking supplements “for their health,” to make up for an inadequate diet, or to have more energy. Multivitamins, herbal substances, protein supplements, amino acids, creatine, fat burners/weight-loss products, caffeine, iron, and calcium are the most frequently used products reported by female athletes. Many female athletes are unclear on when to use a protein supplement, how to use it, and different sources of protein (animal vs. plant-based). This chapter addresses protein supplementation, amino acid supplementation, and creatine. In this chapter we also address the reported performance benefits, if any, of Echinacea, ginseng, caffeine, energy drinks, pre-workouts, and iron. The chapter concludes with a discussion on contamination of supplements and banned substances for competition. Competitive athletes should be aware of the banned substance list for their governing body and that over the counter (OTC) nutritional supplement products are not currently regulated by the food and drug administration (FDA). This lack of regulation may lead to supplements that are contaminated with banned substances.
... The prevalence of iron deficiency in athletes varies, with accounts of up to 35% in females and 11% in males having been reported [4]. In Japan's general population, Kusumi et al. reported that 18% of women aged between 20 and 29 were anemic, which is a higher prevalence than that seen in the United States (7.1% estimated for [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] year-old women) [9,10]. A previous report analyzing the annual prevalence of anemia in Universiade athletes in Japan revealed that the anemia prevalence decreased to 1.7% (from 13.3%) between 1977 and 2011, although their actual iron deficiency was not evaluated [11]. ...
... Age (years) 20 [20,22] 20 [20,22] 20 [19,21] Years of sports/athletics 15 [13,17] 15 [13,17] 15 [13,17] Body (serum ferritin levels ≤30 ng/mL) when compared to those with > 30 ng/mL of serum ferritin (Table 2). Significantly higher BMI and BF% were found in hypoferritinemia individuals when compared to the normal group (p < 0.05 for comparison of BMI and BF%) (Fig. 1). ...
... Although we found no anemia in the Kendo practitioners studied, a previous report on elite young athletes found a low incidence (~7%) of anemia in both males and females [21]. The iron status, however, exhibited a significant difference between genders -i.e., a significant higher proportion of iron deficiency was observed in female athletes in our study, which is consistent with previous reports [21,22]. ...
Background
Iron deficiency is widely recognized as being the cause of anemia in athletes, although iron status in athletes of Kendo , a traditional Japanese martial art based on swordsmanship and practiced as an educational sport, has not been widely investigated.
Methods
We performed a health assessment on anemia and serum ferritin levels, along with nutrient intake evaluation, for Kendo practitioners in a university in Japan.
Results
A total of 56 Kendo practitioners (39 male and 17 female) aged between 18 and 23 years participated in the study. No individuals exhibited WHO-defined anemia (less than 13 or 12 g/dL of hemoglobin levels in male or female), while hypoferritinemia (less than 30 ng/mL) was found in seven (41%) females but not in males. Significantly higher body mass index was found in the female athletes with hypoferritinemia compared to females with normo-ferritinemia in sub-analysis (median [interquartile range]; 25.6 [24.2, 26.9] versus 22.6 [21.7, 24.1], respectively. p < 0.05). No significant differences in the intake of iron were registered between males and females (with and without hypoferritinemia) using data from a food-frequency questionnaire survey.
Conclusion
No apparent anemia was found in adolescent Kendo practitioners, although this study confirmed the presence of hypoferritinemia in several female athletes. Careful follow-up, involving both clinical and nutritional assessment, will be necessary for them to prevent progression into anemia. A future study with larger cohorts in multiple sites is warranted to assess the prevalence of iron deficiency for validation and, if necessary, to devise a strategy for improving the iron status in Kendo athletes.
... However, there is a lack of consensus among clinical practitioners regarding the critical values and key markers to identify ID. For instance, various concentrations have been suggested to indicate ID using serum ferritin, including <12 μg/L (Di Santolo et al., 2008;Koehler et al., 2012), <16 μg/L (Landahl et al., 2005;Sandström et al., 2012;Sinclair & Hinton, 2005), and <20 μg/L (Dubnov & Constantini, 2004;Malczewska et al., 2000b). Therefore, it is difficult to draw definitive conclusions regarding the prevalence of ID, IDE, and IDA across studies. ...
... Increased iron requirements during growth and maturation in adolescence (Beard & Tobin, 2000); changes in dietary patterns (vegetarian diet and decreased energy intake; Beard, 2000); and exercise (Rowland, 2012;Schumacher et al., 2002) may further augment iron needs and promote a negative iron balance if the intake is inadequate. With intense exercise, usual avenues for iron depletion are potentially accentuated, through different mechanisms, such as gastrointestinal bleeding; foot-strike hemolysis; hematuria; and increased loss of iron in sweat, urine, and feces (Koehler et al., 2012). In addition, elevated postexercise hepcidin levels associated with inflammatory responses reduce intestinal absorption and macrophage recycling of iron, further contributing to the high number of athletes commonly diagnosed with ID (Peeling, 2010). ...
... Despite the general consensus that female athletes possess a heightened risk for compromised iron status (Dubnov & Constantini, 2004;Koehler et al., 2012;Landahl et al., 2005), research based on direct comparisons between female athletes and nonathletes has yielded equivocal prevalence data. In large cohort studies, a similar (27% vs. 30% [Di Santolo et al., 2008] and 52% vs. 48% [Sandström et al., 2012]) or lower (26% vs. 50% [Malczewska et al., 2000b]) prevalence of ID and slightly higher prevalence of IDA (8.6% vs. 5.8% [Di Santolo et al., 2008]; 8.6% vs. 3.3% [Malczewska et al., 2000b]; and 15.5% vs. 9.2% [Yasui et al., 2015]) have been reported in female athletes compared with nonathletes. ...
This study primarily aimed to quantify and compare iron status in professional female athletes and nonathletes. Furthermore, this study also aimed to identify differences in iron status according to sporting discipline and explore the relationship between ferritin concentration and weekly training volume in professional athletes. A total of 152 participants were included in this study, including 85 athletes who were members of senior teams (handball, n = 24; volleyball, n = 36; soccer, n = 19; and judo, n = 6) involved at the highest level of competition and 67 nonathletes. A significantly greater proportion ( p = .05) of athletes (27%) demonstrated iron-deficient erythropoiesis (IDE) compared with nonathletes (13%). There were nonsignificant differences ( p > .05) in the prevalence of iron deficiency (ID; 49% vs. 46%) and iron deficiency anemia (IDA; 2% vs. 4%) between athletes and nonathletes. Similarly, the prevalence of ID, IDE, and IDA was not significantly different between sports ( p > .05). Furthermore, training volume was negatively correlated with ferritin concentration in athletes ( r : −.464, moderate, p < .001). Professional female athletes are at a heightened risk of IDE compared with nonathletes; therefore, they should be periodically screened for ID to reduce the deleterious effects on training and performance. The similar prevalence of ID, IDE, and IDA found across athletes competing in different sports suggests that overlaps exist between handball, volleyball, soccer, and judo athletes regarding risk of disturbance in iron metabolism.
... Athletes are predisposed to iron deficiency due to iron losses through sweat, urine, foot-strike hemolysis, and inflammatory responses (6,7). Previous research has indicated that 4% to 70% of elite athletes exhibit poor iron status (8)(9)(10)(11). Children and adolescents also have greater dietary iron requirements that correspond with growth rates of bone and muscle, plasma volume, alterations to dietary intake, and the onset of menses in females (12,13). With the growing popularity of youth sports, an estimated 37% to 39% of American children are engaged in organized sports (14,15). ...
... Given the unique aspect of 8-to 16-year-old male and female athletes, the results of the present study contribute three primary findings to the existing literature. First, the prevalence of poor iron status is higher in 8-to 16-year-old athletes than previously reported in older athletes (8,11,34), and the prevalence of poor iron status is higher in females than males within this demographic (8,11,22). Second, the inter-individual consistency of ferritin, sTfR, and Hb biomarkers to classify poor iron status followed the classic model of progression from iron depletion (ferritin) to low iron levels (sTfR) to anemia (Hb). ...
... Given the unique aspect of 8-to 16-year-old male and female athletes, the results of the present study contribute three primary findings to the existing literature. First, the prevalence of poor iron status is higher in 8-to 16-year-old athletes than previously reported in older athletes (8,11,34), and the prevalence of poor iron status is higher in females than males within this demographic (8,11,22). Second, the inter-individual consistency of ferritin, sTfR, and Hb biomarkers to classify poor iron status followed the classic model of progression from iron depletion (ferritin) to low iron levels (sTfR) to anemia (Hb). Moreover, while the prevalence of iron depletion and low iron levels was higher in the females than the males, the prevalence of anemia was more equivalent between the female and male youth athletes ( Figure 1). ...
Objective: The purpose of this study was to determine the prevalence of poor iron status in young athletes throughout the stages of iron deficiency and assess sex differences with iron deficiency in relation to growth and development and dietary intake.
Methods: A cross-sectional analysis evaluated young male and female athletes (n = 91) between the ages 8 and 16 years. Anthropometric assessments, body composition, dietary intakes, and blood samples measuring ferritin, soluble transferrin receptor (sTfR), and hemoglobin (Hb) were examined. Prevalence was calculated as percentages, and independent samples t tests examined sex differences. Pearson product-moment correlation coefficient analyses quantified relationships among variables for the composite sample and each sex separately.
Results: Iron depletion (low ferritin) was present in 65% and 86%, low iron levels (sTfR) in 51% and 68%, and anemia (low Hb) in 46% and 53% of the males and females, respectively. As iron deficiency progressed from low ferritin to high sTfR to anemia, prevalence decreased in both sexes, but always remained higher in females. Males were greater than females for weight, arm muscle size, and ferritin concentrations, while females were greater than males for biological maturity (p ≤ 0.05). Dietary iron intake was moderately to highly correlated (r = 0.543–0.723, p ≤ 0.05) with growth and development in females, but not males.
Conclusions: Prevalence of poor iron status was higher than expected, particularly in adolescent females. Since rapid growth combined with sports participation may create high demands for iron bioavailability, emphasis may need to be placed on dietary iron intake for young athletes, particularly females.
... al, the prevalence of iron depletion in various sport athletes was reported to be 57%. 16 This value compares with the results in this current study, as Koehler et. al. used a cut-off value of 35 ng/mL to define iron depletion. ...
... al. used a cut-off value of 35 ng/mL to define iron depletion. 16 The studies that report a much lower prevalence of iron depletion, such as the study by Milic et al. with a report of 18% iron depletion in various sport athletes, may be contributed to a much lower cutoff value for ferritin levels to be considered iron deficient. 17 The cut off value set by Milic et al. was 22 ng/mL, and therefore fewer athletes were included and categorized as iron deplete. ...
BACKGROUND: Iron deficiency is widely underdiagnosed in female college athletes and may limit their athletic performance. Routine screening is necessary to identify potential female athletes who might benefit from iron supplementation. A retrospective study on the prevalence of iron deficiency in female collegiate division I athletes is imperative to bring awareness to the prevailing problem. The objective of this study is to determine the prevalence of iron deficiency in female athletes presenting to a Division 1 Athletic Training Room for initial health screening evaluation from January 2017 to July 2022. METHODS: A retrospective chart review was performed for female athletes who presented for initial pre-participation examination health screening to a Division 1 Athletic Training Room The data collected included the patients’ age, BMI, menstrual history, ferritin, and hemoglobin lab values. The primary sports analyzed was swim and dive, soccer, basketball, track and field/cross country, softball, lacrosse, volleyball, high tech, tennis, golf, and cheerleading. Descriptive statistics were used to describe the prevalence of iron deficiency among female athletes and the Student’s t-test and Pearson correlation analysis are used to identify any potential risk factors for iron deficiency. RESULTS: There was a total of 336 participants. The prevalence of athletes with low initial ferritin values under 40 ng/mL at pre-participation examination was 194 (57.74%, n=336). The mean ferritin value at pre-participation examination was 43.18 ng/mL (n=336). Statistical analysis of the other variables collected in this study including body mass index, menstrual history and primary sport showed no significant differences in relationship to initial ferritin levels. Female athletes with low ferritin levels were more likely to receive iron supplementation (p=8.089e-18, 95% CI= -31.33142, -20.19980). An increase in ferritin levels was correlated with iron supplementation (p=0.0217, 95% CI= 1.45825, 18.34014) and hemoglobin levels were higher in female athletes with higher ferritin levels (p-value=0.04971, 95% CI=0.00546, 0.14506). Initial ferritin levels were positively correlated with hemoglobin levels (p=2.402e-11, 95% CI=0.26962, 0.46399). Statistical analysis showed an increase in ferritin levels with usage of contraception (p=0.0073, 95% CI= 3.15448, 20.05362). CONCLUSION: This study’s findings represent the importance of screening ferritin levels in all female collegiate athletes regardless of sport, BMI, or menstrual history due to the high prevalence of low ferritin values. There was an increase in ferritin levels with usage of birth control suggesting the need to further evaluate the impact of menstrual history and contraception usage on ferritin and hemoglobin levels. In these authors experience, it is uncommon for institutions to incorporate routine screening measures in place for screening all female athletes with a ferritin value and complete blood count at initial pre-participation examination.
... In contrast, in Western countries, a prevalence of up to about 20% in adolescent and menstruating women and 7% in young men has been described, with a much lower proportion of manifest iron deficiency anemia of just under 2% in women and less than one percent in men [17,18]. The prevalence of iron deficiency in competitive athletes is partly described as being much higher, ranging from 15 to over 57% in women and 3-31% in men [19,20]. Favoring factors for iron deficiency are, in addition to the female gender, insufficient and low-quality food intake, vegetarian and vegan diets, participation in endurance sports, and in sports that are associated with an increased risk of eating disorders [15,21]. ...
... In adult men, just one person suffered from iron deficiency. This observation is consistent with those of the studies mentioned in the introduction [1,2,4,[17][18][19][20] and suggests the recommendation for regular checks of iron levels in adolescent competitive athletes; adolescent women in particular should be monitored and treated more intensively. ...
Background:
Iron deficiency is a common phenomenon in sports and may lead to impaired physical performance. The aim of the study was to determine the frequency of iron deficiency in competitive athletes and to discuss the resulting consequences.
Methods:
The data of 629 athletes (339 male, 290 female) who presented for their annual basic sports medicine examination were investigated. Depending on age (<14 years, 15-17 years, ≥18-30 years), four groups ((I.) normal hemoglobin (Hb) and ferritin level (≥30 ng/mL for adults and 15-18-year-olds; ≥20 ng/mL, respectively, ≥15 ng/mL for adolescents and children), (II.) prelatent iron deficiency (ID) (normal Hb, low ferritin), (III.) latent ID (additionally elevated soluble transferrin receptor or decreased transferrin saturation) and (IV.) manifest anemia) were distinguished. In addition, the iron status and exercise capacity of different types of sports were compared.
Results:
Overall we found an iron deficiency of 10.9% in male (mainly in adolescence) and 35.9% in female athletes (emphasized in adolescence and young adulthood). There were no significant differences in iron status in regard to the different sport types or in maximum performance for the different groups of iron deficiency.
Conclusions:
Adolescent and female athletes are more likely to have an iron deficiency. Therapy concepts for athletes therefore should pay attention to iron-rich diets.
... ID is a common nutritional condition worldwide, and the number of cases with or without anaemia is 16% to 57% of female athletes and 1% to 31% of male athletes [6]. Although a high intake of iron is often promoted in athletes, the prevalence of ID is relatively high in athletes because iron absorption is negatively affected by physical exercise [7]. ...
... Although a high intake of iron is often promoted in athletes, the prevalence of ID is relatively high in athletes because iron absorption is negatively affected by physical exercise [7]. Haemoglobin and ferritin levels are lower in athletes compared to non-athletes [6]. The incidence of iron depletion in athletes who participate in endurance sports has been reported to be between 30% and 50%, and this is due to gastrointestinal bleeding, haemolysis, haematuria, and inadequate iron intake [8]. ...
Background:
Prevalence of iron deficiency is commonly reported among athletic population groups. It impairs physical performance due to insufficient oxygen delivery to target organs and low energy production. This is due to the high demand of exercise on oxygen delivery for systemic metabolism by the erythrocytes in the blood. Hepcidin, the key regulator of iron homeostasis, decreases to facilitate iron efflux into the circulation during enhanced erythropoiesis. However, acute anaemia of exercise is caused by increased hepcidin expression that is induced by stress and inflammatory signal. The study aimed to systematically review changes in serum hepcidin levels during resistance and aerobic exercise programmes.
Methods:
A systemic literature search from 2010 to April 2020 across seven databases comprised of Cochrane library, PubMed, Web of Science, Scopus, Embase, MEDLINE, and OpenGrey. The primary outcome was increased or decreased serum hepcidin from baseline after the exercise activity. Risks of bias were evaluated by using the National Institutes of Health (NIH) for quality assessment of before and after different exercise programmes.
Results:
Overall, twenty-three studies met the inclusion criteria. Out of the 23 studies, 16 studies reported significantly exercise-induced serum hepcidin elevation. Of the 17 studies that evaluated serum interleukin (IL)-6 levels, 14 studies showed significant exercise-induced serum IL-6 elevation. Changes in exercise-induced serum hepcidin and IL-6 levels were similar in both resistance and endurance exercise. Significant correlations were observed between post-exercise hepcidin and baseline ferritin levels (r = 0.69, p < 0.05) and between post-exercise hepcidin and post-exercise IL-6 (r = 0.625, p < 0.05).
Conclusion:
Resistance and endurance training showed significant increase in serum hepcidin and IL-6 levels in response to exercise. Baseline ferritin and post-exercise IL-6 elevation are key determining factors in the augmentation of hepcidin response to exercise.
... However, the cut-off of serum ferritin for iron deficiency in athletes is not yet established. Previous studies have used various cut-off values for serum ferritin to define iron deficiency in athletes: 12.0 ng/mL (14,18), 15.0 ng/mL (19), 17.0 ng/mL (20), 20.0 ng/mL (14,(21)(22)(23)(24)(25)(26), 25.0 ng/mL (13,19,27), 30.0 ng/mL (2,11,(28)(29)(30)(31)(32)(33), 35.0 ng/mL (18,34) or 40.0 ng/mL (35). Walker et al. suggested that it is important to recognize the differences between the clinical range and optimal range for athletes (36). ...
... However, the cut-off of serum ferritin for iron deficiency in athletes is not yet established. Previous studies have used various cut-off values for serum ferritin to define iron deficiency in athletes: 12.0 ng/mL (14,18), 15.0 ng/mL (19), 17.0 ng/mL (20), 20.0 ng/mL (14,(21)(22)(23)(24)(25)(26), 25.0 ng/mL (13,19,27), 30.0 ng/mL (2,11,(28)(29)(30)(31)(32)(33), 35.0 ng/mL (18,34) or 40.0 ng/mL (35). Walker et al. suggested that it is important to recognize the differences between the clinical range and optimal range for athletes (36). ...
For the evaluation of iron nutrition status, the measurement of serum ferritin levels is the most convenient and widely used technique for estimating stored iron. However, the cut-off value of serum ferritin for iron deficiency in athletes has not yet established. This study aimed to determine the cut-off value of serum ferritin to define iron deficiency in male college student runners. This study included 37–43 Japanese male college student runners for each month. Anthropometric measurements and blood collection were conducted from March to December 2018. In all months except May, significant negative correlations were observed between serum ferritin and transferrin levels, total iron binding capacity (TIBC), and unsaturated iron binding capacity. Furthermore, a significant association between serum ferritin levels and TIBC was observed by nonlinear regression analysis. The curvature radius and curvature were calculated using the data from 9 mo, and serum ferritin levels with the smallest curvature radius and the highest curvature in each month were identified. The serum ferritin levels were as follows: 35.0 ng/mL in March, 45.0 ng/mL in April, 40.0 ng/mL in June, 35.0 ng/mL in July, 35.0 ng/mL in August, 35.0 ng/mL in September, 35.0 ng/mL in October, 35.0 ng/mL in November, and 40.0 ng/mL in December. The average value was 37.2 ng/mL. In conclusion, the cut-off value of serum ferritin for defining iron deficiency in runners was determined to be 40.0 ng/mL in this study. This value (40.0 ng/mL) may be useful for iron deficiency screening in runners.
... Additionally, increased red blood cell (RBC) degradation is caused by the impact of foot strike in running activity and/or circulatory stress during exercise 6,7) . Furthermore, female athletes such as aesthetic athletes, long-distance runners, and vegetarians who have dietary problems, are extremely conscious of their physical body shape and often diagnosed with ID [8][9][10] . ...
... Athletes with low energy intake often have diets that lack iron 24) . Previous studies in female athletes have reported that low ferritin levels are associated with reduced dietary iron density 9) and that dietary iron interventions affect the overall body iron status 25) . Furthermore, female athletes who are at high risk of ID require more iron intake than sedentary women 26) . ...
Female rhythmic gymnasts with dietary problems are extremely conscious of their physical shape and often are diagnosed with iron deficiency (ID). Although there are several reports on training volume and quality throughout the year, there are few reports on the association between dietary intake and prevalence of ID. The aim of this study was to examine the association between the prevalence of ID, including erythropoiesis and hemolysis, and dietary intake for 10 months. A total of 19 Japanese collegiate elite female rhythmic gymnasts participated in five surveys in four different seasons: early pre-season (April), late pre-season (July and August), in-season (October), and off-season (January). Blood samples were collected to analyze body iron status including delta-aminolevulinic acid dehydratase (ALAD) activity, erythropoietin, and haptoglobin, and dietary intake were assessed. The definition of anemia was based on hemoglobin concentrations (<12.0 g/dL), and ID was diagnosed when one of the following clinical criteria or both were met: ferritin (< 12 ng/mL) and transferrin saturation (< 16 %). A higher incidence of ID (58%) was noted in July and August. ALAD was significantly higher in July to October than in April. Erythropoietin did not show any significant changes throughout the study. Haptoglobin was significantly lower in August than in January. Intakes of energy, protein, and iron were significantly lower in August than in April. Our findings suggest that inadequate intakes such as energy, protein and iron may concern with the high incidence of ID in August when the synthesis and destruction of red blood cells is enhanced in elite rhythmic gymnasts.
... Despite the biological importance, iron deficiency (ID) is a widely reported issue in athlete populations, with the documented prevalence reported at ~ 15-35% of female and ~ 3-11% of male athletes (Fallon 2004(Fallon , 2008Malczewska et al. 2001;Parks et al. 2017). However, smaller cohort studies report higher rates of compromised iron stores across a variety of sports settings, with the prevalence reported as > 50% in female, and up to 30% in male athletes (Koehler et al. 2012;Tan et al. 2012). Of note, female athletes tend to experience a greater incidence of ID (Beard and Tobin 2000), potentially a result of increased iron demand to account for menses (Pedlar et al. 2018). ...
... Active women are estimated to be twice as likely to present with IDNA compared to sedentary women (Sinclair and Hinton 2005), with 24-47% of exercising women experiencing IDNA (Rowland 2012). In 193 elite young (< 25 years) German athletes (mean age 16.2 years, ~ 50% female) across 24 different sports, the prevalence of low ferritin (< 35 ug/L) was almost double in females compared to males (57% vs. 31%) (Koehler et al. 2012). However, the incidence of low Hb (< 120 g/L or < 130 g/L for females and males, respectively) was similar (6.2% vs 7.3%). ...
Iron plays a significant role in the body, and is specifically important to athletes, since it is a dominant feature in processes such as oxygen transport and energy metabolism. Despite its importance, athlete populations, especially females and endur-ance athletes, are commonly diagnosed with iron deficiency, suggesting an association between sport performance and iron regulation. Although iron deficiency is most common in female athletes (~ 15–35% athlete cohorts deficient), approximately 5–11% of male athlete cohorts also present with this issue. Furthermore, interest has grown in the mechanisms that influ-ence iron absorption in athletes over the last decade, with the link between iron regulation and exercise becoming a research focus. Specifically, exercise-induced increases in the master iron regulatory hormone, hepcidin, has been highlighted as a contributing factor towards altered iron metabolism in athletes. To date, a plethora of research has been conducted, including investigation into the impact that sex hormones, diet (e.g. macronutrient manipulation), training and environmental stress (e.g. hypoxia due to altitude training) have on an athlete’s iron status, with numerous recommendations proposed for considera-tion. This review summarises the current state of research with respect to the aforementioned factors, drawing conclusions and recommendations for future work.
... [8][9][10] The prevalence rates of iron deficiency in exercising females in this age range from various cohort studies have been estimated to be as high as 50%. [11][12][13][14][15] This is due to the combined effect of menstrual blood loss in conjunction with several avenues for iron loss during exercise; which include: food-related energy deficits (purposeful or not), exercise-induced haematuria (blood in urine), gastrointestinal bleeding, sweating, haemolysis, increased inflammation, and transient elevations in hepcidin. [16][17][18][19] Research is currently ongoing as to the best strategies to overcome ID in exercising females encountering these issues. ...
Background
Patient perceptions of iron deficiency and efficacy of iron therapy may differ from the interpretations of doctors. Qualitative investigation at an individual level related may help define patient expectations and therapeutic targets. Therefore, we aimed to explore this concept in exercising females of reproductive age.
Methods
Exercising females (n = 403) who either (a) were currently experiencing iron deficiency, or (b) have experienced iron deficiency in the past were included. A survey comprising open-ended text response questions explored three ‘domains’: (1) the impact of iron deficiency, (2) the impact of iron tablet supplementation (where applicable), and (3) the impact of iron infusion treatment (where applicable). Questions were asked about training, performance, and recovery from exercise. Survey responses were coded according to their content, and sentiment analysis was conducted to assess responses as positive, negative, or neutral.
Results
Exercising females showed negative sentiment toward iron deficiency symptoms (mean range = −0.94 to −0.81), with perception that fatigue significantly impacts performance and recovery. Iron therapies were perceived to improve energy, performance, and recovery time. Participants displayed a strong positive sentiment (mean range = 0.74 to 0.79) toward iron infusion compared to a moderately positive sentiment toward oral iron supplementation (mean range = 0.44 to 0.47), with many participants perceiving that oral iron supplementation had no effect.
Conclusion
In Australia, women prefer an iron infusion in treatment of iron deficiency compared to oral iron.
... Athletes present a higher prevalence of iron deficiency, with 15-35% of female athletes and 3-11% of male athletes 5, 6 . Koehler et al. (2012) 7 reported that 30% of male athletes showed a suboptimal iron status (serum ferritin concentration < 35ng/mL) although 81% of male athletes satisfied the recommended dietary allowance criteria for elemental iron. Attenuated iron metabolism due to hepcidin, a liver-derived peptide hormone, contributes to iron deficiency in athletes 8 . ...
Purpose:
Exercise-induced hemolysis, which is caused by metabolic and/or mechanical stress during exercise, is considered a potential factor for upregulating hepcidin. Intramuscular carnosine has multiple effects including antioxidant activity. Therefore, this study aimed to determine whether long-term carnosine/anserine supplementation modulates exercise-induced hemolysis and subsequent hepcidin elevation.
Methods:
Seventeen healthy male participants were allocated to two different groups: participants consuming 1,500 mg/day of carnosine/anserine supplements (n = 9, C+A group) and participants consuming placebo powder supplements (n = 8, PLA group). The participants consumed carnosine/anserine or placebo supplements daily for 30.7 ± 0.4 days. They performed an 80-running session at 70% VO2peak pre-and post-supplementation. Iron regulation and inflammation in response to exercise were evaluated.
Results:
Serum iron concentrations significantly increased after exercise (p < 0.01) and serum haptoglobin concentrations decreased after exercise in both groups (p < 0.01). No significant differences in these variables were observed between pre-and post-supplementation. Serum hepcidin concentration significantly increased 180 min after exercise in both groups (p < 0.01). The integrated area under the curve of hepcidin significantly decreased after supplementation (p = 0.011) but did not vary between the C+A and PLA groups.
Conclusion:
Long-term carnosine/anserine supplementation does not affect iron metabolism after a single endurance exercise session.
... Buono et al. reported a significantly higher peripheral sweat rate in trained men and women compared with sedentary men and women [22]. In particular, women have an increased risk of low iron status as a result of exercise-related iron loss combined with iron loss due to menstruation [1,3,11,23,24]. Also, iron insufficiency can have a negative impact on physical performance, and athletes may suffer from non-specific symptoms such as fatigue, weakness, and lethargy [13,25,26]. The mechanisms that cause iron loss during exercise are hemolysis due to mechanical forces and oxidative stress, gastrointestinal and urinary tract bleeding due to microscopic lesions, and extreme sweating, which can result in iron deficiency [13]. ...
Iron is specifically important to athletes, and attention has grown to the association between sports performance and iron regulation in the daily diets of athletes. The study presents new insights into stress, mood states, fatigue, and sweating behavior among the non-anemic athletes with sweating exercise habits who consumed a routine low dose (3.6 mg/day) of iron supplementation. In this double-blind, randomized, placebo-controlled, parallel-group study, both non-anemic male (N = 51) and female (N = 42) athletes were supplemented either with a known highly bioavailable iron formulation (SunActive® Fe) or placebo during the follow-up training exercise period over four weeks at their respective designated clinical sites. The effect of oral iron consumption was examined on fatigue, stress profiles, as well as the quality of life using the profile of mood state (POMS) test or a visual analog scale (VAS) questionnaire, followed by an exercise and well-being related fatigue-sweat. Also, their monotonic association with stress biomarkers (salivary α-amylase, salivary cortisol, and salivary immunoglobulin A) were determined using spearman's rank correlation coefficient test. Repeated measure multivariate analysis of variance (group by time) revealed that the total mood disturbance (TMD) score was significantly lower (P = 0.016; F = 6.26) between placebo and iron supplementation groups over the four weeks study period among female athletes. Also, a significant reduction in tired feeling/exhaustion after the exercise (P = 0.05; F = 4.07) between the placebo and iron intake groups was noticed. A significant within-group reduction (P ≤ 0.05) was noticed in the degree of sweat among both male and female athletes after 2 and 4 weeks of iron supplementation, while athletes of the placebo intake group experienced a non-significant within-group reduction in the degree of sweat. Overall, the result indicates routine use of low dose (3.6 mg/day) iron supplementation is beneficial for non-anemic endurance athletes to improve stress, mood states, subjective fatigue, and sweating conditions.
... Comparing those who were classified as ID vs. non-ID, there were no differences in training load volume, anthropometric characteristics, or iron intake. Both groups reported an iron intake below the recommendations for females (18 mg/day) [5], but were similar to other female athlete groups [26,27]. Potentially then, reasons that an individual may become iron deficient within this group of international level, nonprofessional athletes may be more specific to the type and timing of iron sources within the diet. ...
Background:
While iron deficiency is commonly discussed in populations of professional female athletes, less is known about highly trained, sub-elite female athletes (e.g., those winning international age-group competitions) who generally have less access to medical and allied health support.
Methods:
Thirteen non-professional highly trained female endurance athletes provided training diaries and completed a blood test, where iron markers of haemoglobin (Hb), haematocrit (Hct), C-reactive protein (Crp), serum iron, serum ferritin, and transferrin were assessed. Resting metabolic rate (RMR) and body composition using dual-energy X-ray absorptiometry (DXA) were also obtained. Participants were classified as iron deficient (ID) if serum ferritin was <30 ug/L serum ferritin.
Results:
Six of the 13 females were classified as ID. Serum iron, ferritin, Hb, Hct, and ferrin were greater in the ID group (p < 0.05). Crp resulted in large to very large correlations with serum iron (r = -0.72), serum ferritin (r = -0.66), and transferrin (r = 0.70).
Conclusions:
In this population of highly trained female athletes, 46% were diagnosed with sub-optimal iron levels, which could have lasting health effects and impair athletic performance. The need for more education and support in non-professional athletes regarding iron deficiency is strongly advised.
... В практике спорта очень мало чётких рекомендаций потребления микроэлементов с пищей для спортсменов различной квалификации, возраста и пола [10,11,15,23]. Точно сказать, сколько алиментарного железа (Fe), меди (Cu) и марганца (Mn) необходимо, чтобы удовлетворить потребность организма в микроэлементах, можно лишь после изучения баланса микроэлементов в организме спортсменов, что является наиболее актуальной на сегодняшний день. ...
Introduction. As you know, trace elements play an important role in the life of every living cell. Deficiency of trace elements or their unbalanced ratio in food can lead to profound metabolic disorders and cause the development of a number of diseases, including "sports anemia". The content of trace elements in the blood depends on the nature of muscle activity, its volume, intensity and fitness of the body. Under the influence of systematic training, in parallel with the growth of muscles and their need for oxygen, the content of iron, copper, and manganese in the blood cells increases. At the same time, the physical performance of athletes also increases. In the practice of sports, there are very few clear recommendations for the consumption of microelements with food for athletes of various qualifications, age and gender. It is possible to say exactly how much alimentary iron (Fe), copper (Cu) and manganese (Mn) is necessary to satisfy the body's need for microelements only after studying the balance of microelements in the body of athletes, which is the most relevant today. The purpose of this study was to study the daily balance of microelements in the body of swimmers of high qualification categories. Research methods. The elemental profile of the organism of the examined contingent was established on the basis of urine analysis (morning, middle portion collected in a special container). The analysis was carried out by inductively coupled argon plasma mass spectrometry (ICP-MS) on a Nexion 300D + NWR213 device (PerkinElmer, USA), as well as the effectiveness of prescribed drugs was assessed by indicators of capillary blood. Hemoglobin and serum iron were determined using the appropriate standard kits, hematocrit and erythrocytes were determined using conventional methods. Statistical processing of the obtained data was carried out using Microsoft Excel XP software packages (MicosoftCorp., USA) and Statistica 6.0 (StatSoft Inc., USA). Results. In our studies, it was found that the total loss of iron in most cases significantly exceeded the intake of iron with food. During the period of active rest, the absorption of iron from food increased. In most cases, his balance was positive. Through the correct selection of foods rich in trace elements, you can try to influence the balance of trace elements in the body. Conclusion. Thus, the complexes we offer to a greater or lesser extent have a positive effect on a number of important indicators, and are recommended for the prevention of anemia and, also, are highly effective and, therefore, very promising products for improving physical performance.
... Depending on the criteria used, 16% to 57% of female endurance athletes and 1% to 31% of male endurance athletes are ID. [2][3][4][5][6][7][8][9] However, the factors that predispose athletes to develop ID are not well understood. ...
Purpose:
Inflammatory cytokines including interleukin-6 can upregulate hepcidin and decrease iron absorption. Endurance exercise is associated with transient increases in cytokines, which may alter the risk of iron deficiency (ID). This study examined whether chronic elevations in basal levels of cytokines and hepcidin were associated with ID in highly trained runners.
Methods:
Fifty-four collegiate runners (26 males and 28 females) living at ∼1625 m were recruited from an NCAA Division I cross-country team for this prospective cohort study. Over 2 seasons, fasted, preexercise blood draws were performed in the morning 4 times per season and were analyzed for hemoglobin concentration, ferritin, soluble transferrin receptor (sTfR), hepcidin, and 10 cytokines. Stages of ID were defined using ferritin, sTfR, and hemoglobin concentration. During the study, a registered dietician provided all runners with iron supplements using athletic department-created guidelines.
Results:
Fifty-seven percent of females and 35% of males exhibited stage 2 ID (ferritin <20 ng/mL or sTfR >29.5 nmol/L) at least once. Cytokines, ferritin, and sTfR exhibited changes through the 2 years, but changes in cytokines were not associated with alterations in hepcidin, ferritin, or sTfR. In males and females, lower ferritin was associated with lower hepcidin (both P < .0001). One female exhibited higher hepcidin and lower iron stores compared with other individuals, suggesting a different etiology of ID.
Conclusion:
ID is common in highly trained collegiate runners. In general, the high prevalence of ID in this population is not associated with alterations in basal hepcidin or cytokine levels.
... As previously noted, evaluation of Fe status is usually performed indirectly using several indicators [25]. These include: serum ferritin, transferrin saturation and hemoglobin concentration, which are the most commonly used parameters to assess Fe status indirectly [26][27][28][29]. However, some indicators such as ferritin or transferrin saturation could be altered by inflammation or diurnal fluctuations [30,31]. ...
Iron (Fe) is one of the most widely studied trace mineral elements. Fe metabolism and homeostasis could be altered by physical training. The aim of this study was to analyze the influence of long-term physical training on serum, plasma, urine (extracellular), erythrocyte and platelet (in-tracellular) Fe concentrations. Forty men from the same geographical area divided into a training group (TG; n = 20; 18.15 ± 0.27 years) and a control group (CG; n = 20; 19.25 ± 0.39 years) participated in this study. The TG was composed of soccer players of the highest youth category. The CG consisted of young people who did not follow any training routine and had not practiced any sport for at least the previous six months. The TG showed higher plasma and serum Fe concentrations (p < 0.05), but lower concentrations in erythrocytes and platelets compared to the CG (p < 0.01). Due to the differences observed in the extracellular and intracellular compartments, it seems necessary to perform a global Fe analysis to assess Fe status.
... Prevalence rates range from zero to 17% in males and 24-42% in females. However, some studies report that up to 65% of males and 86% of females present with deficient iron levels [181][182][183] . ...
The Female Athlete Triad (Triad) and the more encompassing Relative Energy Deficiency in Sport (RED-S) are disorders caused by low energy availability (LEA). LEA is a state of insufficient energy intake by an athlete relative to their energy expenditure. Persistent LEA results in the deleterious consequences to health and performance that comprise RED-S. With respect to both the Triad and RED-S, researchers have called for more education of those involved with sport, particularly coaches, to help reduce the incidence of these disorders. Recent studies have shown that as few as 15% of coaches are aware of the Triad, with up to 89% unable to identify even one of its symptoms. RED-S is a more recently established concept such that coach knowledge regarding it has only begun to be assessed, but the results of these initial studies indicate similar trends as for the Triad. In this review, we synthesize research findings from 1986 to 2021 that pertains to LEA and RED-S, which coaches should know so they can better guide their athletes.
... Hasil uji hubungan antara asupan zat besi dengan prestasi belajar responden ditampilkan pada Tabel (Koehler et al., 2012). Pada penelitian ini jenis kelamin menjadi variabel yang tidak dikendalikan karena semua jenis kelamin baik laki-laki dan perempuan dimasukkan menjadi responden. ...
Latar belakang: Penurunan kadar haemoglobin menyebabkan gangguan mekanisme neurotransmitter yang berpengaruh terhadap kecerdasan dan prestasi belajar. Asupan zat besi dan prestasi belajar yang rendah merupakan permasalahan pada remaja yang berpengaruh pada kualitas SDM di masa mendatang. Tujuan: Menganalisis hubungan antara asupan zat besi dengan prestasi belajar siswa SMA Muhammadiyah I Surakarta. Jenis penelitian adalah observasional dengan pendekatan cross sectional. Sampel penelitian 33 siswa yang dipilih dengan systematic random sampling. Kriteria inklusi responden adalah siswa SMA Muhammadiyah 1 Surakarta laki–laki dan perempuan kelas X dan XI. Kriteria eksklusi responden adalah siswa yang sakit, sedang berpuasa, dan sedang melakukan diet tertentu. Data asupan zat besi diperoleh dari wawancara langsung kepada responden menggunakan metode food record selama 7 hari berturut-turut. Data prestasi belajar diperoleh dari rata-rata nilai UKK semua mata pelajaran. Uji hubungan antara asupan zat besi dengan prestasi belajar menggunakan uji Rank Spearman. Hasil: berdasar nilai p uji hubungan antara asupan zat besi dengan prestasi belajar siswa adalah 0,767. Simpulan: tidak terdapat hubungan signifikan antara asupan zat besi dengan prestasi belajar. Meskipun asupan zat besi diketahui mampu mempengaruhi kemampuan kognitif dan prestasi belajar, namun ada berbagai faktor lain yang kemungkinan berpengaruh secara langsung terhadap prestasi belajar.
... Estimates of iron deficiency prevalence vary from 15 to 35% [106][107][108] of female athletes to some studies suggesting rates > 50% [36,109,110]. Non-medical stakeholders, including the athlete herself, coaches, and parents, often misunderstand the interpretation of iron studies or want a single laboratory marker of iron deficiency. ...
Optimal nutrition is an important aspect of an athlete’s preparation to achieve optimal health and performance. While general concepts about micro- and macronutrients and timing of food and fluids are addressed in sports science, rarely are the specific effects of women’s physiology on energy and fluid needs highly considered in research or clinical practice. Women differ from men not only in size, but in body composition and hormonal milieu, and also differ from one another. Their monthly hormonal cycles, with fluctuations in estrogen and progesterone, have varying effects on metabolism and fluid retention. Such cycles can change from month to month, can be suppressed with exogenous hormones, and may even be manipulated to capitalize on ideal timing for performance. But before such physiology can be manipulated, its relationship with nutrition and performance must be understood. This review will address general concepts regarding substrate metabolism in women versus men, common menstrual patterns of female athletes, nutrient and hydration needs during different phases of the menstrual cycle, and health and performance issues related to menstrual cycle disruption. We will discuss up-to-date recommendations for fueling female athletes, describe areas that require further exploration, and address methodological considerations to inform future work in this important area.
... In adolescent female endurance athletes, suboptimal iron status is mainly attributed to low iron intake and low iron bioavailability in combination with high requirements associated with training and blood loss (e.g., increased red cell mass, menstruation, haematuria, haemolysis) [62,63]. In contrast, suboptimal iron status in adolescent male athletes is associated more with high physiological requirements (i.e., training and growth) than with diet. ...
Adolescence (ages 13–18 years) is a period of significant growth and physical development that includes changes in body composition, metabolic and hormonal fluctuations, maturation of organ systems, and establishment of nutrient deposits, which all may affect future health. In terms of nutrition, adolescence is also an important time in establishing an individual’s lifelong relationship with food, which is particularly important in terms of the connection between diet, exercise, and body image. The challenges of time management (e.g., school, training, work and social commitments) and periods of fluctuating emotions are also features of this period. In addition, an adolescent’s peers become increasingly powerful moderators of all behaviours, including eating. Adolescence is also a period of natural experimentation and this can extend to food choice. Adolescent experiences are not the same and individuals vary considerably in their behaviours. To ensure an adolescent athlete fulfils his/her potential, it is important that stakeholders involved in managing youth athletes emphasize eating patterns that align with and support sound physical, physiological and psychosocial development and are consistent with proven principles of sport nutrition.
... Iron concentration has various regulatory functions for oxidative protein and enzymes involved in cellular energy production (Beard, 2001). Previous literature has shown that participation in intensive training may induce iron deficiency that may be associated with performance reduction (Koehler et al., 2012;Oliveira et al., 2017;Reinke et al., 2012). On the other hand, high oxygen transport capacity and oxygen uptake, which are prerequisite for success in sports, can be improved by increasing the red cell mass and consequently the haemoglobin concentration within the blood. ...
The aim of this study was to examine the changes in blood parameters caused during Small-Sides Games (SSGs)
in U20 elite players in professional league. The sample consisted of eight U20 Greek Super League elite level
soccer players, aged 18.3 ± 1 years old, who participated in six SSG’s (4 vs 4 + 2 GK), each lasting 4 min with 3
min rest. The size of the pitch was 30m in length and 20m wide and the SSGs took place in a pitch with artificial
turf. Blood samples were collected before and immediately after the six SSGs to examine any potential changes
of the haematological profile and the levels of cell damage. The Wilcoxon Test (Z) and the Effect Size (r) were
used to compare the repeated measures of the variables (pre-post), while the Pearson correlation index (r) was
used to test the correlation between the variables. The results showed a significant decrease in the second
measurement in Rbc (p < .05), Hgb (p < .05), Mcv (p < .01), Mch (p < .05) and Mchc (p < .05). On the contrary,
Hct, Rdw and iron concentration did not show a significant change (p > .05). Regarding the elements of the
leukocyte series a significant increase was observed in Wbc (p < .01), Neutrophils (p < .05), Plt (p < .05), and
Pct (p < .01). On the contrary, a significant decrease was observed in Lymphocytes (p < .05) and Pdw (p < .05).
Finally, Monocytes, Eosinophils and Pct did not show any statistically significant change. Overall, the results
showed that exercising through high intensity SSGs can cause specific metabolic effects on the haematological
profile of soccer players. Soccer teams need to incorporate the monitoring of haematological parameters of
players while planning their training program, as this information can influence the performance and overall
wellbeing of players.
... In addition, very low intakes of calcium and vitamin D were observed. Gymnasts in both groups failed to meet RDAs for both of these micronutrients, which is in agreement with previous studies conducted on elite gymnasts [55,61,68]. Vitamin D deficiency and insufficiency is common in children worldwide. ...
The aim of this study was to analyze dietary intake and body composition in a group of elite-level competitive rhythmic gymnasts from Spain. We undertook body composition and nutritional analysis of 30 elite gymnasts, divided into two groups by age: pre-teen (9–12 years) (n = 17) and teen (13–18 years) (n = 13). Measures of height, weight, and bioimpedance were used to calculate body mass index and percent body fat. Energy and nutrient intakes were assessed based on 7-day food records. The two groups had similar percentages of total body fat (pre-teen: 13.99 ± 3.83% vs. teen: 14.33 ± 5.57%; p > 0.05). The energy availability values for pre-teens were above the recommended values (>40 kcal/FFM/day) 69.38 ± 14.47 kcal/FFM/day, while those for the teens were much lower (34.7 ± 7.5 kcal/FFM/day). The distribution of the daily energy intake across the macronutrients indicates that both groups ingested less than the recommended level of carbohydrates and more than the recommended level of fat. Very low intakes of calcium and vitamin D among other micronutrients were also noted. The main finding is that teenage gymnasts do not consume as much energy as they need each day, which explains their weight and development. Moreover, they are at a high risk of developing low energy availability that could negatively impact their performance and future health.
... Dietary iron is an essential nutrient for human health and for maintaining athletes' performance [45]. Low levels of iron have commonly been found, above all, in female, mainly young, athletes with low caloric or iron intakes, and consequently, these athletes have hematological indices below the reference values [46,47]. ...
Adolescent high-performance gymnasts are considered to be at risk for low energy intake. The aim of the present study was to determine the effects of implementing a nutritional education program during the sports season on the nutritional status and nutrition knowledge of the female artistic gymnasts from the Technification Center of the Balearic Islands (n = 24; age, 14.1 ± 2.3 years). A quasi-experimental intervention design was applied, which consisted of implementing a nutritional education program of seven sessions given during eight months. Measurements of nutritional intake, nutrition knowledge, and anthropometric parameters, as well as hematological and biochemical blood parameters, were performed. Gymnasts reported low energy and carbohydrate intakes, with significant increases during the study (energy, 28.3 ± 1.4 vs. 32.8 ± 1.4 kcal kg−1, p = 0.015, carbohydrate 3.20 ± 0.20 vs. 3.92 ± 0.22 g kg−1, p = 0.004). The average values for parameters such as hemoglobin, ferritin, lipoprotein, and vitamin C and E levels in the plasma were within normal ranges. Low intakes of most of the food groups were observed during the study, with similar initial and final values. Nutrition knowledge did not change as a result of the study (28.0 ± 1.7 vs. 31.1 ± 1.3, p = 0.185). In conclusion, gymnasts reported low energy intakes. However, blood markers and most of the anthropometrical parameters measured were within normal ranges. The nutrition education program implemented did not produce significant improvements in the dietary habits or nutritional knowledge of gymnasts.
... [5,6] An athlete's nutritional needs usually encompass a higher energy requirement to account for greater energy expenditure, increased protein and carbohydrate requirements to support lean muscle mass maintenance and glycogen stores, as well as an increased requirement for certain micronutrients. [7,8,9] In young athletes, nutrients identified as of concern due to insufficient intake include carbohydrates (especially during exercise), vitamin E, vitamin D, calcium, iron, magnesium and zinc [10,11,12,13] and low intake may cause poor performance during competition and also result in deficiencies affecting health. [14] Recovery from a bout of exercise is integral to the athletes' training regime as without proper recovery of the nutrients such as carbohydrates, protein and electrolytes, the performance may be hampered.2Consumption of a diverse diet is advised to ensure nutrient adequacy. ...
... 29 different sports were represented by the participating athletes. Due to varying samples sizes, the athletes were clustered into the following sport groups as done before (Koehler et al. 2012;Zinner et al. 2015;Tomschi et al. 2018): endurance sports (n = 23) [triathlon (n = 1), long distance running (n = 12), middle distance running (n = 9), heptathlon (n = 1)]; return and team sports (n = 34) [badminton (n = 1), baseball (n = 8), basketball (n = 1), ice hockey (n = 1), soccer (n = 9), handball (n = 7), tennis (n = 1), table tennis (n = 4),]; combat sports (n = 28) [boxing (n = 2), judo (n = 17), karate (n = 2), wrestler (n = 5), taekwondo (n = 2)]; aesthetic and individual sports (n = 24) [fencing (n = 18), horse riding (n = 2), dancing (n = 2), race driver (n = 1)]; and strength and power sports (n = 30) [sprint (n = 8), bob-sledge (n = 1), highjump (n = 1), canoe (n = 2), lifesaver swimming (n = 1), rowing (n = 1), pole-vault (n = 13), and javelin (n = 1)]. ...
Purpose
Measures of arterial stiffness (AS) and central blood pressure (BP) are indicators for cardiovascular health and possess a high prognostic value in the prediction of cardiovascular events. The effects of physical training are widely unexplored in the context of competitive, high-performance sports. Therefore, we aimed to present possible reference values of brachial and central BP and of AS of adult elite athletes compared to a control group.
Methods
A total of 189 subjects participated in this cross-sectional study. Of these were 139 adult elite athletes (70 male, 69 female) performing on top-national and international level, and 50 control subjects (26 male, 24 female). Resting brachial and central BP and aortic pulse wave velocity (PWV) were measured and were compared in terms of sex, sport category, and age of the athletes.
Results
Results show no difference between athletes and controls in any parameter. Women exhibit lower brachial and central BP and AS values compared to men. PWV is positively correlated with age. Evaluation of the parameters according to the different sport categories showed that endurance athletes exhibit lower BP and PWV compared to other athletes.
Conclusions
This study presents brachial and central BP and PWV values of athletes, suggesting that high-performance sport does not negatively impact AS. The proposed reference values might support a more detailed evaluation of elite athlete’s cardiovascular and hemodynamic system and a better assignment to possible risk groups.
... Parks et al. [55] found the prevalence of anemia at PPE (Pre Participation Examination) was 5.7% and found that only 2.2% of female athletes indicated iron deficiency anemia and 30.9% indicated iron deficiency without anemia. A similar study reported which reported a prevalence of anemia for females at PPE in1067collegiate athletes was 3.6%, which is slightly lower [64].Females tend to have lower concentrations of iron status biomarkers than males [65][66][67][68]. Ahmadi et al. concluded that the intake of iron and calories were low in female athletes in team ball sports [60],. ...
Background: Iron deficiency is the most prevalent form of malnutrition and the most common cause of iron deficiency anemia in female athletes across worldwide. It has been shown to impact overall health as well as the physical performance of female athletes.
Objective: To provide a literature review on the prevalence of iron deficiency with or without anemia in female athletes and to understand its effects on health and sports performance.
Methods: International databases Google Scholar, PubMed and MEDLINE were searched using combinations of the keywords: ‘iron deficiency’, ‘iron status’, ‘iron-deficiency anemia’, ‘female athletes’, ‘sports performance’, ‘causes’, ‘health consequences’. Studies were conducted only on female athletes from 2000 to 2020 and published in English included in the present study. The present study included varied study designs like cross-sectional studies or surveys, controlled clinical trial studies, descriptive studies, comparative studies, retrospective, and correlational studies.
Results: A total of 11 studies have been included in this review based on inclusion and exclusion criteria. Most of the studies had reported low hemoglobin levels and low iron status in female athletes (15 to 35 years) of different sports. It has been found that there was a high prevalence of iron deficiency with or without anemia in female athletes. Conclusion: It concluded that female athletes are at higher prevalence of developing iron-deficiency and anemia. Iron deficiency (with or without anemia) may severely affect an athlete’s ability to perform at an optimal level. Proper health education to increase knowledge about anemia, as well as its causative factors, iron store screening, appropriate nutritional education and iron supplementation are warranted.
... Parks et al. [55] found the prevalence of anemia at PPE (Pre Participation Examination) was 5.7% and found that only 2.2% of female athletes indicated iron deficiency anemia and 30.9% indicated iron deficiency without anemia. A similar study reported which reported a prevalence of anemia for females at PPE in1067collegiate athletes was 3.6%, which is slightly lower [64].Females tend to have lower concentrations of iron status biomarkers than males [65][66][67][68]. Ahmadi et al. concluded that the intake of iron and calories were low in female athletes in team ball sports [60],. ...
... La suplementación con hierro fue mayor en jugadoras de balonmano femenino (8.0% vs 14.7%) sin llegar a ser estadísticamente significativo. Este resultado puede deberse a que el hierro se considera uno de los suplementos más importantes para las deportistas femeninas debido a las pérdidas menstruales (Koehler et al., 2012;Peeling, Dawson, Goodman, Landers y Trinder, 2008). Por lo tanto, los valores bajos de hierro pueden reducir la capacidad de generar fuerza que afecta el rendimiento deportivo (Rodenberg y Gustafson, 2007;Zoller y Vogel, 2004). ...
Suplementación Deportiva en Balonmano: Efecto de la Cafeína e Influencia del CYP1A2 y ADORA2A en el Rendimiento Deportivo en Jugadores de Élite de Balonmano
... 4 13 14 18 Iron deficiency in athletes is thought to be caused by reduced dietary iron and increased requirements associated with exercise. 19 Iron deficiency is more common in females than males across studies as well as in our study 18 20 and it is known that the onset and duration of menstruation affect iron status. 21 The roles of several minerals and trace elements in improving athletic performance have been studied, with iron and magnesium having the strongest quality evidence. ...
Objectives
To compare laboratory test results and lung function of adolescent organised sports participants (SP) with non-participants (NP).
Methods
In this cross-sectional study, laboratory tests (haemoglobin, iron status), and flow-volume spirometry were performed on SP youths (199 boys, 203 girls) and their NP peers (62 boys, 114 girls) aged 14–17.
Results
Haemoglobin concentration <120/130 g/L was found in 5.8% of SP and 5.1% NP (OR 1.20, 95% CI 0.54 to 2.68). Ferritin concentration below 15 µg/L was found in 22.7% of both SP and NP girls. Among boys ferritin <30 µg/L was found in 26.5% of SP and 30.2% of NP (OR 0.76, 95% CI 0.40 to 1.47). Among SP iron supplement use was reported by 3.5% of girls and 1.5% of boys. In flow-volume spirometry with bronchodilation test, 7.0% of SP and 6.4% of NP had asthma-like findings (OR 1.17, 95% CI 0.54 to 2.54); those using asthma medication, that is, 9.8% of SP and 5.2% of NP were excluded from the analysis.
Conclusions
Screening for iron deficiency is recommended for symptomatic persons and persons engaging in sports. Lung function testing is recommended for symptomatic persons and persons participating in sports in which asthma is more prevalent.
... The rate of iron deficiency (ID) is higher in elite athletes, particularly female athletes participating in certain types of sports and sports that require particular diets that may affect iron levels [5,6]. For athletes and women in general, ID both without and with anemia (IDA) should be avoided given the decrease in physical activity/performance and increased fatigue that can accompany ID [7,4,8]. ...
Iron deficiency anemia (IDA) due to malnutrition and/or blood loss is a common condition, especially in women of reproductive age. Intense exercise can induce anemia via an inflammatory response, but whether intense exercise affects the efficacy of iron supplementation to treat IDA is unclear. Here, we show in a mouse model of IDA that acute intense swimming increased IL-6 levels in the blood, but did not affect the maximum elevation of plasma iron following oral administration of 0.5 mg/kg Bw iron. However, compared with the control group without intense exercise, acute intense swimming was associated with a significant decrease in plasma iron 2 and 4 h after iron loading that could be attributed to rapid iron absorption in peripheral tissues. In the chronic experiment, IDA mice administered 0.36, 1.06, or 3.2 mg/kg Bw iron per day that were subjected to 11 intense swimming sessions over 3 weeks showed significantly decreased recovery levels for hemoglobin and red blood cell count during the early phase of the experimental period. At the end of the experimental period, significant, dose-dependent effects of iron, but not the main effect of intense exercise, were seen for recovery of hemoglobin and red blood cell counts, consistent with the acute exercise study. These results suggested that intense exercise in the presence of IDA does not inhibit iron absorption from the gastrointestinal tract and that iron supplementation can enhance the recovery process even after intense exercise.
... Learning takes place, fundamentally, through the imitation of the behaviours of parents by their children, and through open communication between them in the process of growth and maturation . The research by Koehler et al. (2012) focused on iron depletion that would occur more frequently among athletes than in the general population. But they mentioned that there was little information available on the prevalence of iron status abnormalities in young athletes and whether the depletion of iron was associated with factors related to gender, sports, age, or nutrition. ...
The objective of this article is to know the state of health of a sample of adolescents and how it relates to toxic habits and personal relationships. Likewise, it is presented how can influence eating habits, sports practice and interpersonal relationships in their general health status. The research has carried out through a survey of 56 questions to 470 adolescents, between 13 and 18 years old, of both sexes, of different schools in the province of Cordoba, Spain. These results have been subjected to a statistical model widely used in health and social sciences in general, called Structural Equations Model (SEM), through the SPSS program, v. 23 and AMOS. SEM is widely used in the social sciences to estimate regression models (usually multi-equational). The estimated model shows a significant global acceptability based on the usual statistical tests and goodness-of-fit measures. In this regard, these results are: CMIN = 17.554 with 33 degrees of freedom (DF) and a probability level, p = 0.987, which is higher than any reasonable level of significance (α = 0.05, 0.10, even 0.20). Likewise, FMIN = 0.038, CFI = 1.000 and RMSEA = 0.000. The main recommendation of this research aimed at improving good eating and healthy habits, and to avoid toxic habits of adolescents, is to begin the education in the family, in coordination with their school and high school.
... Interestingly, the inclusion of the athlete's sport did not improve the model (<1% of the variance). This is partially supported by research demonstrating the prevalence of iron deficiency in female athletes across various sports appears to be similar (Koehler et al. 2012;Ponorac et al. 2019). While it is acknowledged that only a limited number of sports have been studied here (n = 7), it is likely that the type, frequency, and duration of training completed may have a greater impact on the decay in serum ferritin rather than the sport per se. ...
The long-term decay rate of serum ferritin post-iron infusion in athletic populations is currently unknown. Here, we modelled the decay rate of serum ferritin in female athletes after an intravenous iron infusion (n = 22). The post-infusion serum ferritin response and the rate of decay was highly variable between athletes; however, we demonstrate that follow-up blood testing at 1 (154 μg/L; 77–300 μg/L) and 6 months (107 μg/L; 54–208 μg/L) post-infusion is appropriate to observe treatment efficacy and effectiveness.
NoveltyFemale athletes should have serum ferritin assessed at 1 and 6 months following an intravenous iron infusion to determine efficacy and effectiveness.
... Iron depletion is one of the most prevalent nutrient deficiencies among female athletes because of low dietary iron intakes, increased menstrual losses, elevated hepcidin, erythropoiesis, and foot strike hemolysis. It has been reported that 57% of female adolescent athletes, from a variety of sports, had depleted iron stores using a serum ferritin cutoff of ,35 mg$L 21 (33). Iron deficiency, with or without anemia, has been linked to increased levels of perceived exertion, feelings of fatigue, decreased VȮ 2 max, and increased blood lactate levels after exercise, all of which have a negative impact on performance (20). ...
Adequate nutrition generally promotes training adaptations and thus optimal performance. Adolescence is characterized by a pubescence growth spurt, increasing energy and nutrient needs. Most team sports literature focuses on male athletes, with little on adolescent female team sports. Adolescent female athletes are at an increased risk of inadequate energy, and micronutrient intakes because of the pursuit of high fitness levels, and society pressures. This may cause hormonal irregularities, delayed development, poor bone health, and increased risk of injury. This review synthesizes information on the nutritional needs of adolescent female team sport players for performance and health.
... [4][5][6] As a result, athletes are almost three times as likely to be iron depleted when compared to non-athletes, 7 a risk that is even further exacerbated in certain groups, such as female adolescent athletes, among whom as much as 58% may suffer from iron depletion. 7,8 Iron depletion, even in the absence of anemia, can result in suboptimal athletic performance, [9][10][11] which can be reversed by means of iron supplementation or dietary intervention. [12][13][14][15][16] Considering the wide-spread prevalence of iron status abnormalities among athletes and its detrimental effects on performance, along with the potential dangerous side effects of unmonitored supplementation, 6 regular screening and monitoring of iron status are common practice among athletes. ...
Objectives
Iron depletion is common around the world and among certain risk groups in developed countries. The overall purpose was to test the suitability of a novel plasma collection card for minimally invasive iron status assessment.
Methods
Twenty participants (10 f/10 m) participated in this cross‐sectional study. Ferritin and hemoglobin were measured from blood collected from a forearm vein, serving as reference method. Blood was also collected from the fingertip using the NoviplexTM Plasma Prep Card as well as capillary collection tubes.
Results
There was substantial concordance between ferritin measured from samples collected via NoviplexTM and venous ferritin (concordance correlation coefficient (CCC) = 0.96) with a mean bias of −0.8 ng/mL. Storing NoviplexTM cards at room temperature for 2 weeks resulted in slightly lower but good concordance when compared to venous ferritin (CCC = 0.95). Capillary hemoglobin (CCC = 0.42) and hematocrit (CCC = 0.25) were in poor agreement with venous data.
Conclusions
NoviplexTM cards offer a suitable alternative for a minimally invasive ferritin screening in the field when compared to capillary collection tubes. Despite overall substantial concordance with the reference method, findings indicative of iron status abnormalities should be confirmed in venous samples.
... More advanced iron deficiency, i.e., iron-deficient erythropoiesis, was found in a relatively low percentage of athletes (2.3%; n = 21) and only three (0.3%) subjects in the group of over 900 athletes showed iron deficiency anemia. The prevalence of iron deficiency in male athletes in previous studies ranged from 2.9 to 31.0%, [28,29,[54][55][56][57][58][59][60], although the comparison of these results is difficult due to different criteria used (ferritin, or sTfR/logFerr index) as well as application of various cut-off values of ferritin (from 20 to 35 µg/L). Comparing our results to others who used the same ferritin threshold (<30 µg/L), a higher frequency of ID (27%) was observed in elite rowers and professional soccer players [60], while in large cohorts of Australian male athletes only 3-4% of subjects had a decreased ferritin concentration [58,59]. ...
In athletes, no reliable indices exist for an unambiguous evaluation of hematological and iron status. Therefore, the utility of some new red blood cell (RBC) parameters was explored in 931 elite male athletes aged 13–35 years. To diagnose iron status, the values of ferritin and soluble transferrin receptor (sTfR), total iron binding capacity (TIBC), and basic blood morphology were determined in blood. The new hematological markers included among others: mean cellular hemoglobin content in reticulocytes (CHr), percentage of erythrocytes (HYPOm) and reticulocytes (HYPOr) with decreased cellular hemoglobin concentration, percentage of erythrocytes (LowCHm) and reticulocytes (LowCHr) with decreased cellular hemoglobin content, mean volume of reticulocytes (MCVr), and percentage of erythrocytes with decreased volume (MICROm). Despite adverse changes in reticulocyte hypochromia indices (CHr, LowCHr, HYPOr; p < 0.001) in the iron depletion state, the area under the receiver operating characteristic curve (AUC-ROC) values calculated for them were relatively low (0.539–0.722). In iron-deficient erythropoiesis (IDE), unfavorable changes additionally concern microcythemia indices in both reticulocytes and erythrocytes (MCVr, MCV, MICROm, and red cell volume distribution width—RDW), with especially high values of AUC-ROC (0.947–0.970) for LowCHm, LowCHr, and CHr. Dilutional sports anemia was observed in 6.1% of athletes. In this subgroup, only hemoglobin concentration (Hb), hematocrit (Hct), and RBC (all dependent on blood volume) were significantly lower than in the normal group. In conclusion, the diagnostic utility of the new hematology indices was not satisfactory for the detection of an iron depletion state in athletes. However, these new indices present high accuracy in the detection of IDE and sports anemia conditions.
... I ron deficiency (ID) is the most prevalent nutritional disorder worldwide and continues to be a prevailing health issue in athletes (1). Existing literature reports the incidence of ID to be up to 17% in male and 50% in female endurance athletes across various cohort studies (2)(3)(4)(5)(6). It has been established that ID impairs an individual's oxygen transport and energy metabolism, with severe cases (i.e., anemia) linked to decreases in work capacity and maximal oxygen consumption (V O 2max ) (7). ...
Purpose:
This study examined postexercise inflammatory, hepcidin, and iron absorption responses to endurance exercise performed in the morning versus the afternoon.
Methods:
Sixteen endurance-trained runners (10 male, 6 female) with serum ferritin (sFer) < 50 μg·L completed a 90-min running protocol (65% vV˙O2max) in the morning (AM), or the afternoon (PM), in a crossover design. An iron-fortified fluid labeled with stable iron isotopes (Fe or Fe) was administered with a standardized meal 30 min following the exercise and control conditions during each trial, serving as a breakfast and dinner meal. Venous blood samples were collected before, immediately after, and 3 h after the exercise and control conditions to measure sFer, serum interleukin-6 (IL-6), and serum hepcidin-25. A final venous blood sample was collected 14 d after each trial to determine the erythrocyte iron incorporation, which was used to calculate iron absorption. Linear mixed-modeling was used to analyze the data.
Results:
Overall, exercise significantly increased the concentrations of IL-6 (4.938 pg·mL; P = 0.006), and hepcidin-25 concentrations significantly increased 3 h after exercise by 0.380 nM (P < 0.001). During the PM trial, hepcidin concentrations exhibited diurnal tendency, increasing 0.55 nM at rest (P = 0.007), before further increasing 0.68 nM (P < 0.001) from prerun to 3 h postrun. Fractional iron absorption was significantly greater at breakfast after the AM run, compared with both the rested condition (0.778%; P = 0.020) and dinner in the AM run trial (0.672%; P = 0.011).
Conclusions:
Although exercise resulted in increased concentrations of IL-6 and hepcidin, iron was best absorbed in the morning after exercise, indicating there may be a transient mechanism during the acute postexercise window to promote iron absorption opposing the homeostatic regulation by serum hepcidin elevations.
Iron is needed for many biological processes but can be extremely harmful when intake is excessive. Exercise brings about iron deficiency as iron in the body is being utilised during the process.
This study was aimed to determine the effect of short-term exercise on iron status and haematological parameters in male subjects.
A total of 47 apparently healthy male subjects aged 17–26 years were investigated. Pre and post-exercise blood samples were collected. Full blood count was carried out using standard laboratory procedures, while serum iron and total iron binding capacity (TIBC) were estimated spectrophotometrically.
The obtained results showed non-significant changes of serum iron and total iron binding capacity (TIBC) post-exercise when compared to pre-exercise (P > 0.05). There was a non-significant decrease (P > 0.05) in the post-exercise levels of white blood cell (WBC), red blood cell (RBC), haemoglobin (HB), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), mean platelet volume (MPV) and unsaturated iron binding capacity (UIBC) compared with pre-exercise. An non-significant increase (P > 0.05) was observed in the post-exercise levels of haematocrit (HCT), mean cell volume (MCV), platelet (PLT), serum iron, and total iron binding capacity (TIBC) compared with pre-exercise. The haematological parameters also showed some variations, but none of these findings were clinically significant.
Active erythropoiesis and thrombopoiesis are associated with exercise and there is a depletion of iron store levels immediately after exercise. We, therefore, recommend that iron supplements and an adequate diet be taken by athletes immediately after exercise to ensure a long and healthy life.
Comprehensive and up to date, this textbook on children’s sport and exercise medicine features research and practical experience of internationally recognized scientists and clinicians that informs and challenges readers. Four sections—Exercise Science, Exercise Medicine, Sport Science, and Sport Medicine—provide a critical, balanced, and thorough examination of each subject, and each chapter provides cross-references, bulleted summaries, and extensive reference lists. Exercise Science covers growth, biological maturation and development, and examines physiological responses to exercise in relation to chronological age, biological maturation, and sex. It analyses kinetic responses at exercise onset, scrutinizes responses to exercise during thermal stress, and evaluates how the sensations arising from exercise are detected and interpreted during youth. Exercise Medicine explores physical activity and fitness and critically reviews their role in young people’s health. It discusses assessment, promotion, and genetics of physical activity, and physical activity in relation to cardiovascular health, bone health, health behaviours, diabetes, asthma, congenital conditions, and physical/mental disability. Sport Science analyses youth sport, identifies challenges facing the young athlete, and discusses the physiological monitoring of the elite young athlete. It explores molecular exercise physiology and the potential role of genetics. It examines the evidence underpinning aerobic, high-intensity, resistance, speed, and agility training programmes, as well as effects of intensive or over-training during growth and maturation. Sport Medicine reviews the epidemiology, prevention, diagnosis, and management of injuries in physical education, contact sports, and non-contact sports. It also covers disordered eating, eating disorders, dietary supplementation, performance-enhancing drugs, and the protection of young athletes.
Objectives:
Anemia is a common condition in long-distance runners (LDRs). Recently, not only iron deficiency (ID) but also energy deficiency has been considered as a risk factor for anemia in athletes but no evidence has yet been established. The aim of this study was to investigate the prevalence of anemia and ID and the influence of body mass index (BMI) on anemia in high-school LDRs.
Methods:
The participants were 406 male and 235 female elite Japanese LDRs who competed in the All-Japan High-School Ekiden Championship 2019. They submitted their anthropometric data and results of a blood test within five days after the competition. The prevalence of anemia and ID and the influence of BMI on anemia were assessed retrospectively.
Results:
Mean hemoglobin concentrations (Hb) were 14.8 ± 0.9 g/dl in males and 13.2 ± 0.9 g/dl in females. The prevalence of anemia (Hb < 14 g/dl in males and < 12 g/dl in females) was significantly higher in males (16.3%) than females (6.4%), but males also showed higher prevalence of non-iron deficiency anemia (NIDA) than females (11.6% and 3.0%, respectively). No significant gender difference was found in the prevalence of iron deficiency anemia (IDA) (4.7% in males and 3.4% in females). ID (serum ferritin level < 25 ng/ml) was significantly more prevalent in females (37.4%) than males (18.5%). A binary logistic regression analysis revealed that low BMI was a contributor to anemia in females (odds ratios: 0.577 (95% CI: 0.369-0.901), p = 0.012).
Conclusion:
In Japanese high-school LDRs, one in six males was anemic, but most males did not have ID. Conversely, one-third of females were diagnosed with ID. Lower BMI was identified as a risk for anemia in females, suggesting that leanness may also lead to anemia in females.
An iron deficient athlete is likely to develop iron deficiency anemia, a pathology that may lead to a decrease in performance. If adult athletes, women and men, are aware of the need for regular monitoring, young people under 18 are not necessarily aware of the risks associated with competitive sports practice in the presence of anemia. Even if the guidelines are well known and described, a lack of regular monitoring is found for the aforementioned age group. In junior female athletes practicing basketball, a significant rate of iron deficiency or even iron deficiency anemia was found during annual analyses. The authors wish to emphasize the importance of regular medical and laboratory follow-up for younger athletes who often no longer have a pediatrician and no attending physician.
Introduction:
Iron plays a significant role in energy production. However, it is not uncommon for athletes to be diagnosed with iron deficiency (ID), suggesting a correlation between performance and iron regulation. As a result, the International Olympic Committee has recommended iron screenings during health evaluations for elite athletes. Furthermore, athletes participating in esthetic sports are at increased risk for suboptimal iron intake due to disordered eating. Therefore, the purpose of this study was to investigate the distribution of serum ferritin (SF) in a cohort of elite ballet dancers and determine associations between vitamin D, anthropometric measures, stress injury, and dietary preferences.
Methods:
Electronic health records of 40 elite ballet dancers (22 female, 18 male), age 19 to 38 years old, from the 2020 to 2021 pre-participation physical screening were examined. Chi squared comparisons were calculated to evaluate the association between SF and additional variables (ie, gender, age, height, weight, body mass index, vitamin D, stress injury history, and dietary preferences). SF values were compared to published normal and athletic population data.
Results:
58.97% of participants displayed normal or above SF values (>50 ng/ml), while 41.02% displayed minimal (<50 ng/ml) to depleted (<0.12/ng/ml) SF values. Approximately, 68% of the female dancers were ID and did not meet the minimal value needed for athletes. Females were more likely to have lower SF distributions (x2 [4] = 15.6377, P = .004) compared to male dancers. Additionally, dancers who reported dietary preferences (ie, vegetarian) were more likely to display lower SF distributions (x2[4] = 13.3366, P = .010).
Conclusion:
Over half of the female elite ballet dancers were ID which is consistent with current research. Females were at a significant higher risk compared to male dancers who reported dietary preferences. These findings suggest iron screenings should be considered in elite dancer populations.
Iron deficiency (ID) and iron deficiency anemia (IDA) are global health problems. Iron is the number one nutritional deficiency in the world and the top-ranking cause of anemia. ID refers to low iron stores and inadequate availability, whereas anemia refers to low hemoglobin. Endurance athletes are at a high risk for anemia and nutritional deficiencies related to the intensity and duration of training. Progressive decreases in iron stores can result in symptoms of fatigue, weakness, and performance decline with or without true anemia. Although iron deficiency is not related to all anemias, IDA is the most prevalent form seen in the athletic population. The most common causes of iron deficiency, with or without anemia, are often multifactorial including poor dietary iron intake and decreased absorption, as well as various types of blood loss. A good history and physical examination are necessary to rule out more serious medical illnesses as well as screen for low iron. Healthcare providers must be astute clinicians to interpret the laboratory studies for various types of anemia and different stages of iron deficiency, particularly in the context of athletic participation. Intense exercise, endurance training, and illness have significant, yet predictable, effects on test results. General treatment of anemia and nutritional deficiencies in endurance athletes is individualized to both the athlete and the underlying cause(s). IDA and ID treatment is specifically focused on dietary changes and, when indicated, oral or parenteral supplementation.KeywordsAnemiaHemoglobinHemolysisFerritinHepcidinIron deficiencyExerciseEndurancePseudoanemia
Introduction: Migraine is a common, complex neurological disease characterized by the presence of a strong genetic component. Genome-wide association studies (GWAS) have identified gene variants involved in migraine development. In addition, it is known that epigenetic mechanisms, such as DNA methylation, play an important role in inflammation disorders. The aim of our study was to investigate global DNA methylation levels in migraine patients with C677T polymorphism of the MTHFR gene. Materials and methods: MTHFR C677T genotyping analysis (36 patients and 32 controls) was performed using TaqMan technology (Thermo Scientific, USA). Global DNA methylation was determined by the quantitative analysis of 5-methylcytosine (Zymo Research, Germany). Results: In individuals with TT genotypes, the percentage of methylated cytosine (5mC) was significantly lower in the migraine group compared to the control group (P=0.001). Conclusions: Our results suggest that epigenetic approaches can be used to study the migraine pathogenesis. In addition, reduced methylation levels can be ameliorated by the dietary supplementation with vitamins B6, B9, B12, which may be a strategy for migraine prevention and management in patients with MTHFR C677T polymorphism.
Currently, there is no doubt about the prevailing influence of the level of physical activity of an individual on the functional state of the body. However, the available literature data on the impact of physical stress on the body's supply of trace elements and their distribution in tissues are largely contradictory. This review of available literature data provides an insight into the relationship between physical activity and microelement homeostasis. The influence of human physical activity on the exchange of toxic (lead, cadmium, Nickel, etc.) and essential trace elements, such as iron, selenium, copper, cobalt, chromium, and zinc is reviewed. Based on the analyzed works, it is concluded that in order to correct the metabolic and microelement status of a person during physical activity, the most reasonable and necessary is the modulation of homeostasis of zinc and selenium.
Professional rugby league (RL) football is a contact sport involving repeated collisions and high-intensity efforts; both training and competition involve high energy expenditure. The present review summarizes and critiques the available literature relating the physiological demands of RL to nutritional requirements and considers potential ergogenic supplements that could improve players’ physical capacity, health, and recovery during the preparatory and competition phases of a season. Although there may not be enough data to provide RL-specific recommendations, the available data suggest that players may require approximately 6–8 g·kg−1·day−1 carbohydrate, 1.6–2.6 g·kg−1·day−1 protein, and 0.7–2.2 g·kg−1·day−1 fat, provided that the latter also falls within 20–35% of total energy intake. Competition nutrition should maximize glycogen availability by consuming 1–4 g/kg carbohydrate (∼80–320 g) plus 0.25 g/kg (∼20–30 g) protein, 1–4 hr preexercise for 80–120 kg players. Carbohydrate intakes of approximately 80–180 g (1.0–1.5 g/kg) plus 20–67 g protein (0.25–0.55 g/kg) 0–2 hr postexercise will optimize glycogen resynthesis and muscle protein synthesis. Supplements that potentially improve performance, recovery, and adaptation include low to moderate dosages of caffeine (3–6 mg/kg) and ∼300 mg polyphenols consumed ∼1 hr preexercise, creatine monohydrate “loading” (0.3 g·kg−1·day−1) and/or maintenance (3–5 g/day), and beta-alanine (65–80 mg·kg−1·day−1). Future research should quantify energy expenditures in young, professional male RL players before constructing recommendations.
It is the joint position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine that micronutrient supplements are unnecessary for athletes who consume a diet providing high energy availability (EA) from a variety of nutrient-dense foods, but that vitamin and mineral supplements may be necessary in athletes who consume suboptimal amounts of micronutrients. However, inadequate EA, or macronutrient intake needed for energy expenditure associated with exercise, is commonly reported, especially in the female population and may result in micronutrient deficiencies. Moreover, current literature, although limited, reports that athletes’ knowledge is lacking regarding adequate macro- and micronutrient intake and needed supplementation. Correction of deficiencies via supplementation may be needed to restore physiologic processes but may not lead to improved performance. Athletes and coaches should be aware of these issues and work together to improve nutrition knowledge and determine if the athlete is at risk for low EA or nutritional deficiencies.
Thyroid disease is common in the general population, especially in women, and also may be prevalent among athletes. Autoimmune disorders are the most common cause of thyroid disorders in countries with iodine-fortification programs; however, thyroid dysfunction can be brought on by nutritional factors, including insufficient energy intake and iodine, selenium, iron, and vitamin D deficiency. Additionally, strenuous exercise may be associated with transient alterations in thyroid hormones. While the development of thyroid related disorders has the potential to impact health and peak performance, typical clinical manifestations are highly variable, lack specificity, and are frequently confused with other health problems. The assessment process should focus on anthropometric changes, biochemical tests (thyroid panel), personal and family history, examination for appropriate signs and symptoms, and diet and environmental assessment that includes adequacy of energy, iodine, iron, selenium, and vitamin D intake/status along with excess stress and exposure to environmental contaminants and dietary goitrogens.
The rate of metabolic processes increases during physical activities, which leads to increased consumption of macronutrients and trace elements. We studied the elemental composition of hair in 54 young wrestlers with different levels of physical activity (high, medium, and low). The proximal parts of hair strands with a length of 3–4 cm were used for elemental analysis. The analysis was performed by inductively coupled plasma mass spectrometry (ICP-MS). It was found that physical activity led to increased contents of a number of chemical elements in hair. As an example, intensive physical exertion is associated with increased levels of the macronutrients Ca, Mg, P, K, and Na; essential trace elements Fe, Mn, Co, and Mo; conditionally essential trace elements B, Li, and Sb; as well as the toxic elements Pb and Cd. The contents of the toxic elements Cu, Se, and Hg were reduced. It can be suggested that the metabolism of macronutrients is most susceptible to changes during training in wrestling. The increased level of macronutrients in hair reflects the intense metabolic activity in wrestlers rather than an excess of these elements. This article discusses the possible causes and correlations of these changes. The indicators of the metabolism of macronutrients and trace elements in athletes must be controlled by sports physicians because of the increased risk of disorders associated with a number of elements, in particular, electrolytes. A personalized approach to the determination of the elemental status in athletes is necessary, since different types of sports have different impacts on the metabolism of macronutrients and trace elements. This will provide a precise assessment of the effects of increased physical activity on the individual indicators of metabolism and the detection of disorders, which can lead to reduced levels of physical reserves and decreased adaptation potential and an increase in the risk of disease and injury.
Iron deficiency is commonly diagnosed by serum ferritin [sFer] determination, iron deficiency anaemia from reduced mean cellular volume (MCV). [sFer] shows a high variance if inflammation or liver dysfunction are present. Athletes often present with hypoferritinaemia. This study was designed to evaluate the relation of total body haemoglobin mass (tHb) which is commonly elevated in athletes to [sFer]. In the present study 56 trained (TR), 72 moderately trained (MT) and 31 untrained (UT) male individuals were investigated for peak oxygen uptake (max), serum iron, [sFer], soluble transferrin receptor [sTfr], serum erythropoietin [EPO], haemoglobin concentration [Hb], haematocrit (Hct), MCV, tHb, blood volume (BV), and plama volume (PV). TR and UT individuals differed significantly in max, tHb, PV, and BV (all p<0.01). [sFer] correlated negatively with tHb (r=-0.31,p<0.05), BV (r=-0.38,p<0.05) and max (r=-0.54,p<0.01) but not with EPO, [Fe], [sTfr], MCV, [Hb], Hct, and PV. Since a negative correlation of [sFer] and tHb was found, an iron storage shift from the reticuloendothelial system (RES) to the erythroid system could have occurred. This is only pathological if functional iron deficiency occurs, as suggested by increased [sTfr]. Possible causes of functional iron deficiency are gastrointestinal microhaemorrhage, menstrual blood loss and EPO-doping. True iron deficiency should be treated by dietary means or iron supplementation. Iron misuse instead has severe side-effects and uncritical addition of iron to the athlete's nutrition should be avoided.
There is still debate in the literature on whether or not endurance athletes tend to have low iron stores. In this article, we propose that endurance athletes really are at risk of becoming iron deficient due to an imbalance between absorption of dietary iron and exercise-induced iron loss. The purpose of this article is to present a critical review of the literature on iron supplementation in sport. The effect of iron deficiency on performance, its diagnosis and suggestions for treatment are also discussed.
Studies of the nutritional status of athletes in various disciplines have shown that male, but not female, athletes clearly achieve the recommended dietary intake of iron (10 to 15 mg/day). This reflects the situation in the general population, with menstruating women being the main risk group for mild iron deficiency, even in developed countries. Whereas the benefit of iron supplementation in athletes with iron deficiency anaemia is well established, this is apparently not true for non-anaemic athletes who have exhausted iron stores alone (prelatent iron deficiency); most of the studies in the literature show no significant changes due to supplementation in the physical capacity of athletes with prelatent iron deficiency. However, the treatment protocols used in some of these studies do not meet the general recommendations for the optimal clinical management of iron deficiency, that is, with respect to adequate daily dosage, mode of administration and treatment period. For future studies, we recommend a prolonged treatment period (≥3 months) with standardised conditions of administration (use of a pharmaceutical iron preparation with known high bioavailability and a dosage of ferrous (Fe++) iron 100 mg/day, taken on an empty stomach).
Currently, decisions regarding iron supplementation are best made on the basis of taking care of individual athletes. We believe that there are sufficient arguments to support controlled iron supplementation in all athletes with low serum ferritin levels. Firstly, the development of iron deficiency is prevented. Secondly, the nonspecific upregulation of intestinal metal ion absorption is reverted to normal, thus limiting the hyperabsorption of potentially toxic lead and cadmium even in individuals with mild iron deficiency.
Anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are the most prevalent forms of anemia and often occur concurrently. Standard tests of iron status used in differential diagnosis are affected by inflammation, hindering clinical interpretation. In contrast, soluble transferrin receptor (sTfR) indicates iron deficiency and is unaffected by inflammation. Objectives of this prospective multicenter clinical trial were to evaluate and compare the diagnostic accuracy of sTfR and the sTfR/log ferritin index (sTfR Index) for differential diagnosis using the automated Access(®) sTfR assay (Beckman Coulter) and sTfR Index. We consecutively enrolled 145 anemic patients with common disorders associated with IDA and ACD. Subjects with IDA or ACD + IDA had significantly higher sTfR and sTfR Index values than subjects with ACD (P < 0.0001). ROC curves produced the following cutoffs for sTfR: 21 nmol/L (or 1.55 mg/L), and the sTfR Index: 14 (using nmol/L) (or 1.03 using mg/L). The sTfR Index was superior to sTfR (AUC 0.87 vs. 0.74, P < 0.0001). Use of all three parameters in combination more than doubled the detection of IDA, from 41% (ferritin alone) to 92% (ferritin, sTfR, sTfR Index). Use of sTfR and the sTfR Index improves detection of IDA, particularly in situations where routine markers provide equivocal results. Findings demonstrate a significant advantage in the simultaneous determination of ferritin, sTfR and sTfR Index. Obtaining a ferritin level alone may delay diagnosis of combined IDA and ACD.
To examine the correlation of peak oxygen uptake (VO2 peak), velocity at lactate threshold (V(LT)), and running economy (RE) in a group of Special Force Squad members.
VO2 peak, V(LT), and RE of 120 male elite special force police squad members (VO2 peak, 57.4 +/- 4.3 mL minute(-1) kg(-1); age, 28.9 +/- 5.2 years; body mass index, 24.2 +/- 1.6 kg m(-2)) were tested using an incremental treadmill protocol (2.4 m second(-1), increase 0.4 m second(-1) every 5 minutes). Running velocities at the first lactate inflection point (V(LT)) and blood lactate concentration at 4 mmol L(-1) (V4) were determined. RE was defined as oxygen uptake in mL kg(-1) minute(-1) at 3.2 m second(-1).
Analysis revealed little or no correlation between V4, V(LT), VO2 peak, and RE (r = 0.02-0.35; p = 0.01-0.80).
(1) VO2 peak, V(LT), and RE do not correlate in elite squad members. (2) All 3 variables should be assessed when comparing inter- and intraindividual differences in endurance performance of Special Force Squad members.
It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance. This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of sports dietitians. Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins, as well as contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged. Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise, maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia. Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density, may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution, and only after careful product evaluation for safety, efficacy, potency, and legality. A qualified sports dietitian and in particular in the United States, a Board Certified Specialist in Sports Dietetics, should provide individualized nutrition direction and advice subsequent to a comprehensive nutrition assessment.
It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance. This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of the sports dietitian. Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins and to contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged. Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise, maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia. Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution and only after careful product evaluation for safety, efficacy, potency, and legality. A qualified sports dietitian and, in particular, the Board Certified Specialist in Sports Dietetics in the United States, should provide individualized nutrition direction and advice after a comprehensive nutrition assessment.
In order to determine whether dietary inadequacies can explain the sub-optimal iron status widely documented in endurance-trained athletes, the food intake records of Fe-deficient and Fe-replete distance runners and non-exercising controls of both sexes were analysed. In all the male study groups the mean dietary Fe intake met the recommended dietary allowances (RDA; > 10 mg/d (US) Food and Nutrition Board, 1989). However, both female athletes and controls failed to meet the RDA with regard to Fe (< 15 mg/d) and folate (< 200 micrograms/d). There was no difference in the total Fe intakes of Fe-deficient and Fe-replete athletes and the controls of each sex. However, Fe-deficient male runners, but not female runners, consumed significantly less haem-Fe (P = 0.048) than their comparative groups. This suggests that the habitual consumption of Fe-poor diets is a factor in the aetiology of athletes' Fe deficiency.
To determine whether physical exercise affects biochemical indices of nutritional status, we compared four groups of male athletes (total n = 427) with two control groups (n = 150). Data about their nutrient intake for 1 month were obtained from a 122-item food frequency questionnaire. An estimate for leisure energy expenditure (EE) was calculated from a 15-item physical activity questionnaire. Athletes were grouped according to their EE (ModEE and HighEE athletes) and weight (light = less than 75 kg; heavy = greater than or equal to 75 kg), and controls according to their weight. Mean energy intake in ModEE and HighEE athletes was 2805-3260 kcal/day. Leisure EE significantly (p less than 0.0001) affected energy and nutrient intakes. Energy, riboflavin and calcium intakes were also higher in heavy subjects (P = 0.0006-0.03). The estimated percentage of subjects with deficient dietary intakes, calculated from probability analyses, was 0-6, depending on group and nutrient. Erythrocyte transketolase activation coefficient (E-TKAC) was highest in controls (1.17 +/- 0.0008; p = 0.001). Serum magnesium was highest (p = 0.01) in ModEE athletes (0.85 +/- 0.006 mmol/L). No intergroup differences were found for plasma ascorbic acid, serum zinc or serum ferritin concentration, whereas blood hemoglobin was lowest (p less than 0.001) in HighEE athletes (149 +/- 0.5 g/L). Ten percent of the control subjects had E-TKAC greater than 1.24. Percentage of other values outside reference range was 0-4, depending on group and indicator. Since lowered blood hemoglobin concentration can be explained by hemodilution, we conclude that sports training did not have a negative effect on biochemical indices of thiamin, vitamin C, magnesium, iron, or zinc status in Finnish male athletes.
To measure the resting metabolic rate (RMR) of a group of endurance-trained male and female athletes and to compare it with values predicted using published equations.
RMR was measured twice: 1 week apart for the men and approximately 1 month apart for the women. RMR was predicted using equations of Harris and Benedict, Owen et al, Mifflin et al, and Cunningham.
Subjects were 37 trained endurance athletes (24 men, 13 women) who had participated in studies previously completed in our laboratory.
The primary outcome measure was the comparison of predicted RMR with measured RMR. An exploratory procedure for the determination of predictive variables in these athletes was also performed.
The Root Mean Squared Prediction Error method was used to compare predicted RMR with measured RMR. The maximum R2 procedure method was used to determine the best possible combination of four variables that explained the largest amount of variance in RMR.
The Cunningham equation was found to predict measured RMR most accurately (within 158 kcal/d for men and 103 kcal/d for women). Fat-free mass was the best predictor of RMR in men, whereas energy intake was the best predictor in women.
The Cunningham equation provides an accurate estimate of RMR when determining energy needs of highly active people. Equations specific to athletes need to be developed. Factors in addition to body weight, height, and age should be investigated as possible predictor variables in athletes.
We studied serum transferrin and ferritin concentrations in relation to individual body growth, stage of puberty, blood hemoglobin, and red blood cell iron (RBCI) in 60 prepubertal or early pubertal boys at 3-mo intervals for 18 mo. One-third of the boys had increased serum transferrin concentrations and almost all had decreased ferritin concentrations during the followup. No change in mean transferrin was observed but the individual 18-mo increments in transferrin correlated positively with the increments in hemoglobin (r = 0.55, P < 0.001) and in estimated RBCI (r = 0.31, P = 0.02). Serum transferrin remained stable at different genital stages, but ferritin was lower in the pubertal than in the prepubertal boys. Transferrin concentrations at 18 mo correlated positively with the preceding weight velocities. The rise in transferrin did not lead to an increase in iron-deficiency anemia. In contrast, transferrin rose in boys whose hemoglobin increased. In pubertal boys with relatively ample iron status, serum transferrin may be an indicator of increased availability of iron for erythropoiesis. The declining ferritin concentration indicates that part of the extra iron is mobilized through redistribution from stores to red blood cell mass and is generally associated with greatly increasing absorption. Thus, the pubertal changes in transferrin and ferritin are not necessarily indications of iron deficiency.
The aim of the present study was to evaluate the influence of menstruation, method of contraception, and iron supplementation on iron status in young Danish women, and to assess whether iron deficiency could be predicted from the pattern of menstruation. Iron status was examined by measuring serum (S-) ferritin and hemoglobin (Hb) in 268 randomly selected, healthy, menstruating, nonpregnant Danish women aged 18–30 years. Iron deficiency (S-ferritin <16 μg/l) was observed in 9.7% of the women, iron deficiency anemia (S-ferritin <13 μg/l and Hb <121 g/l) in 2.2%. Iron supplementation, predominantly as vitamin-mineral tablets containing 14–20 mg of ferrous iron was used by 35.1%. The median serum ferritin was similar in non-iron users and in iron users, whereas the prevalence of iron deficiency was 12.6% in nonusers vs. 4.3% in users, the prevalence of iron deficiency anemia 3.4% in nonusers vs. 0% in users (p=0.17) In non-iron-supplemented women, S-ferritin levels were inversely correlated with the duration of menstrual bleeding (r
s=–0.25, p<0.001) and with the women's assessment of the intensity of menstrual bleeding (r
s=–0.27, p<0.001), whereas no such correlations were found in iron-supplemented women. The results demonstrate that even moderate daily doses of ferrous iron can influence iron status in women with small iron stores. Women using hormonal contraceptives had menstrual bleeding of significantly shorter duration than those using intrauterine devices (IUD) or other methods. There was a high prevalence of small and absent body iron stores in young women, suggesting that preventive measures should be focused on those women whose menstruation lasts 5 days or longer, who have menstrual bleeding of strong intensity, who use an IUD without gestagen, and who are blood donors.
There is still debate in the literature on whether or not endurance athletes tend to have low iron stores. In this article, we propose that endurance athletes really are at risk of becoming iron deficient due to an imbalance between absorption of dietary iron and exercise-induced iron loss. The purpose of this article is to present a critical review of the literature on iron supplementation in sport. The effect of iron deficiency on performance, its diagnosis and suggestions for treatment are also discussed. Studies of the nutritional status of athletes in various disciplines have shown that male, but not female, athletes clearly achieve the recommended dietary intake of iron (10 to 15 mg/day). This reflects the situation in the general population, with menstruating women being the main risk group for mild iron deficiency, even in developed countries. Whereas the benefit of iron supplementation in athletes with iron deficiency anaemia is well established, this is apparently not true for non-anaemic athletes who have exhausted iron stores alone (prelatent iron deficiency); most of the studies in the literature show no significant changes due to supplementation in the physical capacity of athletes with prelatent iron deficiency. However, the treatment protocols used in some of these studies do not meet the general recommendations for the optimal clinical management of iron deficiency, that is, with respect to adequate daily dosage, mode of administration and treatment period. For future studies, we recommend a prolonged treatment period (> or = 3 months) with standardised conditions of administration (use of a pharmaceutical iron preparation with known high bioavailability and a dosage of ferrous (Fe++) iron 100 mg/day, taken on an empty stomach). Currently, decisions regarding iron supplementation are best made on the basis of taking care of individual athletes. We believe that there are sufficient arguments to support controlled iron supplementation in all athletes with low serum ferritin levels. Firstly, the development of iron deficiency is prevented. Secondly, the nonspecific upregulation of intestinal metal ion absorption is reverted to normal, thus limiting the hyperabsorption of potentially toxic lead and cadmium even in individuals with mild iron deficiency.
The prevalence of iron deficiency anemia is likely to be higher in athletic populations and groups, especially in younger female athletes, than in healthy sedentary individuals. In anemic individuals, iron deficiency often not only decreases athletic performance but also impairs immune function and leads to other physiologic dysfunction. Although it is likely that dietary choices explain much of a negative iron balance, evidence also exists for increased rates of red cell iron and whole-body iron turnover. Other explanations of decreased absorption and increased sweat or urine losses are unlikely. The young female athlete may want to consider use of low-dose iron supplements under medical and dietary supervision to prevent a decline in iron status during training.
Much attention has focused on the nutrition and hematological profile of female athletes, especially gymnasts. The few studies on iron status of male adolescent athletes found a low incidence of iron deficiency. The present studies investigated the iron status of male and female gymnasts (G) and compared it with athletes of other sports. Subjects were 68 elite athletes (43 M, 25F) ages 12-18, of four sports: gymnasts (11M,12F), swimmers (11M,6F), tennis players (10M,4F), and table tennis players (11M,3F). All lived in the national center for gifted athletes, trained over 25 hr a week, ate in the same dining room, and shared a similar life style. Mean levels of hemoglobin (Hb), red blood cell indexes, serum ferritin, serum iron, and transferrin were measured in venous blood. There was no difference in mean Rb among gymnasts (G) and nongymnasts (NG). However Hb was less than 14g/dL in 45% of MG vs. only 25% in NG, and less than 13g/dL in 25% of premenarcheal FG vs. 15% in NG. Low transferrin saturation (<20%) was detected in 18% of MG and 25% of FG vs. 6% and 8% in male and female NG, respectively (p<.05). The percentage of males suffering from low ferritin level (<20 ng/ml) was twice as high in G (36%) vs. NG(19%), and about 30% in all females. In summary, iron stores were consistently lower in MG vs. NG. Adolescent athletes of both genders, G in particular, are prone to nonanemic iron deficiency, which might compromise their health and athletic performance.
We provide an updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure. It was developed to enhance the comparability of results across studies using self-reports of PA. The Compendium coding scheme links a five-digit code that describes physical activities by major headings (e.g., occupation, transportation, etc.) and specific activities within each major heading with its intensity, defined as the ratio of work metabolic rate to a standard resting metabolic rate (MET). Energy expenditure in MET-minutes, MET-hours, kcal, or kcal per kilogram body weight can be estimated for specific activities by type or MET intensity. Additions to the Compendium were obtained from studies describing daily PA patterns of adults and studies measuring the energy cost of specific physical activities in field settings. The updated version includes two new major headings of volunteer and religious activities, extends the number of specific activities from 477 to 605, and provides updated MET intensity levels for selected activities.
Soluble transferrin receptor (sTfr) is a new marker of iron status and erythropoietic activity. It has been included in multivariable blood testing models for the detection of performance enhancing erythropoietin misuse in sport.
To evaluate the effect of different types and volumes of physical activity on sTfr concentration, variables of iron status (ferritin, transferrin, iron, and protein), and haematological indices.
Thirty nine subjects were divided into three groups: 1, untrained (n = 12); 2, moderately trained (n = 14); 3, highly trained (n = 13, seven men, six women). Groups 1 and 2 carried out two exercise tests: an incremental running test until exhaustion (test A) and a 45 minute constant speed running test at 70% VO(2)MAX (test B). Group 3 performed three days (women) or four days (men) of prolonged aerobic cycling exercise. The above variables together with haemoglobin and packed cell volume were analysed in venous blood samples before and after exercise. Changes in blood and plasma volume were estimated.
sTfr levels were slightly increased in trained and untrained subjects immediately after test A. Test B and aerobic exercise had no significant effect on sTfr. Ferritin levels were increased after the laboratory tests for trained and untrained subjects and after prolonged aerobic exercise in male cyclists. Transferrin was increased significantly in trained and untrained subjects after both laboratory tests, but remained unchanged after prolonged exercise. Plasma and blood volumes were decreased after the laboratory tests but increased after aerobic exercise. No differences in the variables were observed between trained and untrained subjects with respect to response to exercise.
The changes in sTfr and the variables of iron status can be mainly attributed to exercise induced changes in volume. Taking these limitations into account, sTfr can be recommended as a marker of iron deficiency in athletes.
Low reporting of food intake is an acknowledged problem in dietary assessments; however, differences in food intake relative to reporting status are poorly understood. This study examined the relation of a measure of dietary reporting status with the nature of food intake reported by adults in the third National Health and Nutrition Examination Survey.
Subjects were 6948 women and 6452 men, 20 years of age or older, with a complete and reliable 24-hour dietary recall. The ratio of reported energy intake to estimated basal energy expenditure (EI/BEE) was computed as a measure of dietary reporting status. The independent relation of EI/BEE ratio with 1) the amount, number, and energy density of nutrient-dense and low-nutrient-dense foods, 2) the number of reported eating occasions, 3) macro- and micronutrient intake and 4) serum concentrations of folate, ascorbate and carotenoids were examined using gender-specific multiple regression models.
The EI/BEE ratio related positively with the amount, number and energy density of both nutrient-dense and low-nutrient-dense foods, and grams of alcoholic beverages. The EI/BEE ratio was an independent negative predictor of serum folate, ascorbate and alpha-carotene concentrations confirming the underreporting of food sources of these nutrients. The relative odds of reporting < or = 30% of energy as fat or < 10% of energy as saturated fat decreased with ratio of EI/BEE; however, the odds of reporting all five food groups or meeting the recommended intake of selected micronutrients increased with EI/BEE.
The quantity and the quality of food intake reported in the 24-hour recall in NHANES III differed in relation to the ratio of EI/BEE.
Current initiatives to reduce the high prevalence of nutritional iron deficiency have highlighted the need for reliable epidemiologic methods to assess iron status. The present report describes a method for estimating body iron based on the ratio of the serum transferrin receptor to serum ferritin. Analysis showed a single normal distribution of body iron stores in US men aged 20 to 65 years (mean +/- 1 SD, 9.82 +/- 2.82 mg/kg). A single normal distribution was also observed in pregnant Jamaican women (mean +/- 1 SD, 0.09 +/- 4.48 mg/kg). Distribution analysis in US women aged 20 to 45 years indicated 2 populations; 93% of women had body iron stores averaging 5.5 +/- 3.35 mg/kg (mean +/- 1 SD), whereas the remaining 7% of women had a mean tissue iron deficit of 3.87 +/- 3.23 mg/kg. Calculations of body iron in trials of iron supplementation in Jamaica and iron fortification in Vietnam demonstrated that the method can be used to calculate absorption of the added iron. Quantitative estimates of body iron greatly enhance the evaluation of iron status and the sensitivity of iron intervention trials in populations in which inflammation is uncommon or has been excluded by laboratory screening. The method is useful clinically for monitoring iron status in those who are highly susceptible to iron deficiency.
The objective of the study was to evaluate the diagnostic efficiency of laboratory tests, including serum transferrin receptor (TfR) measurements, in the diagnosis of iron depletion. The patient population consisted of 129 consecutive anemic patients at the University Hospital of Turku who were given a bone marrow examination. Of these patients, 48 had iron deficiency anemia (IDA), 64 anemia of chronic disease (ACD), and 17 patients had depleted iron stores and an infectious or an inflammatory condition (COMBI). Depletion of iron stores was defined as a complete absence of stainable iron in the bone marrow examination. Serum TfR concentrations were elevated in the vast majority of the IDA and COMBI patients, while in the ACD patients, the levels were within the reference limits reported earlier for healthy subjects. TfR measurement thus provided a reliable diagnosis of iron deficiency anemia (AUCROC 0.98). Serum ferritin measurement also distinguished between IDA patients and ACD patients. However, the optimal decision limit for evaluation of ferritin measurements was considerably above the conventional lower reference limits, complicating the interpretation of this parameter. Calculation of the ratio TfR/log ferritin (TfR-F Index) is a way of combining TfR and ferritin results. This ratio provided an outstanding parameter for the identification of patients with depleted iron stores (AUCROC 1.00). In anemic patients, TfR measurement is a valuable noninvasive tool for the diagnosis of iron depletion, and offers an attractive alternative to more conventional laboratory tests in the detection of depleted iron stores.
The assessment of nutrition and activity in athletes requires accurate and precise methods. The aim of this study was to validate a protocol for parallel assessment of diet and exercise against doubly labelled water, 24-h urea excretion, and respiratory gas exchange. The participants were 14 male triathletes under normal training conditions. Energy intake and doubly labelled water were weakly associated with each other (r = 0.69, standard error of estimate [SEE] = 304 kcal x day(-1)). Protein intake was strongly correlated with 24-h urea (r = 0.89) but showed considerable individual variation (SEE = 0.34 g kg(-1) x day(-1)). Total energy expenditure based on recorded activities was highly correlated with doubly labelled water (r = 0.95, SEE = 195 kcal x day(-1)) but was proportionally biased. During running and cycling, estimated exercise energy expenditure was highly correlated with gas exchange (running: r = 0.89, SEE = 1.6 kcal x min(-1); cycling: r = 0.95, SEE = 1.4 kcal x min(-1)). High exercise energy expenditure was slightly underestimated during running. For nutrition data, variations appear too large for precise measurements in individual athletes, which is a common problem of dietary assessment methods. Despite the high correlations of total energy expenditure and exercise energy expenditure with reference methods, a correction for systematic errors is necessary for the valid estimation of energetic requirements in individual athletes.
Combat soldiers have a higher prevalence of anemia than age- and gender-matched civilians. This may be caused by hemodilution, which is typical among athletes, or by reduced body iron stores. The aim of this study was to investigate the incidence of iron-deficiency anemia in recruits to the Israel Defense Force after 6 months of training.
Blood was collected from recruits before training. After 6 months of follow-up, 153 paired blood samples were collected from the initial cohort. Total blood count and serum iron, transferrin, and ferritin were measured at both time points. Soluble transferrin receptor (sTfR) was measured in 119 of the paired samples and the sTfR/log ferritin ratio was calculated.
At recruitment, mean hemoglobin concentration was 14.7 +/- .9 g/dl. Iron-transferrin saturation was 34.1% +/- 13.6%, and mean ferritin concentration was 53.6 +/- 33.2 ng/ml. Anemia prevalence (Hb <14 g/dl) was 17.6%, and 14.9% of participants were iron-deficient (ferritin <22 mg/dl). At 6 months, 50.3% of the cohort was anemic, and 27.3% demonstrated iron-store depletion. Paired analysis showed an average reduction of .83 g/dl in hemoglobin (p < .001), and of 9.8 mg/dl in ferritin (p < .001). sTfR increased from 1.9 to 2.1 mg/dl (p < .003) among recruits who became anemic. Half of the recruits experienced mild anemia after 6 months of training. Iron store depletion was observed among 24.5% of the cohort after training, as opposed to 15% at recruitment. Overall, these changes were not accompanied by a significant increase in sTfR, but among the subset of anemic subjects, there was a slight increase in index value.
In half of the cases, new-onset anemia was attributable to iron deficiency, and in the remainder, to hemodilution.
Little is known about the prevalence and motives of supplement use among elite young athletes who compete on national and international levels. Therefore, the current survey was performed to assess information regarding the past and present use of dietary supplements among 164 elite young athletes (16.6 +/- 3.0 years of age). A 5-page questionnaire was designed to assess their past and present (last 4 weeks) use of vitamins, minerals, carbohydrate, protein, and fat supplements; sport drinks; and other ergogenic aids. Furthermore, information about motives, sources of advice, supplement sources, and supplement contamination was assessed. Eighty percent of all athletes reported using at least 1 supplement, and the prevalence of use was significantly higher in older athletes (p < .05). Among supplement users, minerals, vitamins, sport drinks, energy drinks, and carbohydrates were most frequently consumed. Only a minority of the athletes declared that they used protein/amino acids, creatine, or other ergogenic aids. Major motives for supplement use were health related, whereas performance enhancement and recommendations by others were less frequently reported. Supplements were mainly obtained from parents or by athletes themselves and were mostly purchased in pharmacies, supermarkets, and health-food stores. Among all athletes, only 36% were aware of the problem of supplement contamination. The survey shows that supplement use is common and widespread among German elite young athletes. This stands in strong contrast to recommendations by leading sport organizations against supplement use by underage athletes.
Low serum ferritin concentrations are commonly found in female athletes. By studying the effects of an 8-week iron or placebo supplementation in 31 female athletes (aged 17-31 years), with an initial serum ferritin concentration less than or equal to 25 micrograms/l and blood hemoglobin 120 g/l, we investigated whether low serum ferritin values hinder aerobic performance. Serum ferritin concentration increased from 14 (25th and 75th percentile: 11, 21) to 26 (18, 36) micrograms/l in the iron-supplemented group, but remained at a low 11 (9, 17) micrograms/l in the placebo group (group difference after supplementation: p = 0.001). Before supplementation, blood hemoglobin concentration was not different in the two groups. After supplementation, however, the concentration in the iron group was 139 (135, 144) g/l and 128 (126, 134) g/l in the placebo group (group difference: p = 0.001). Iron supplementation did not affect blood lactate concentration or VO2max during an incremental ergometer test. Hence, aerobic performance was not impaired in nonanemic female athletes with serum ferritin 25 micrograms/l.
Differences in body composition have often been examined in conjunction with measurements of energy expenditure in men and women. Numerous studies during the past decade examined the relationship between resting energy expenditure (REE) and the components of a two-compartment model of composition, namely the fat-free mass (FFM) and the fat mass (FM). A synthetic review of these studies confirms a primary correlation between REE and FFM in adults over a broad range of body weights. A generalized prediction equation is proposed as REE = 370 +/- 21.6 x FFM. This equation explains 65-90% of the variation in REE. Several studies suggest, further, that FFM predicts total daily energy expenditure (TDEE) equally well. An independent contribution by FM to the prediction of either REE or TDEE is not supported for the general population, perhaps reflecting the relative constancy of the absolute FM in nonobese individuals. In the subset of obese women, FM may be a significant predictor.
Previous studies have indicated a high prevalence of nonanemic iron deficiency in female high school aged endurance athletes. It is not clear, however, whether these adolescents are at more risk for iron depletion than their nonathletic peers. We have previously reported declining serum ferritin levels in response to running but not swimming training in competitive adolescents. In this study we compared these findings with serum ferritin levels and hematologic parameters in a group of nonathletic females from the same community. Mean serum ferritin levels were not significantly different among the groups. A greater percentage of the swimmers and runners had ferritin levels less than 12 ng/ml at the beginning of the season (46.7 and 40%, respectively, compared to 26.7% in the nonathletes), but the differences were not statistically significant. These findings suggest that the high prevalence of hypoferritinemia at the beginning of a competitive season in female high school athletes is similar to that of nonathletes. Other studies have indicated, however, that some sports, particularly running, increase the incidence of iron depletion with training.