Transitory hematologic effects of moderate exercise are not influenced by iron supplementation

The Role of Mineral and Trace Element Supplementation in Exercise and Athletic Performance: A Systematic Review

Minerals and trace elements (MTEs) are micronutrients involved in hundreds of biological processes. Deficiency in MTEs can negatively affect athletic performance. Approximately 50% of athletes have reported consuming some form of micronutrient supplement; however, there is limited data confirming their efficacy for improving performance. The aim of this study was to systematically review the role of MTEs in exercise and athletic performance. Six electronic databases and grey literature sources (MEDLINE; EMBASE; CINAHL and SportDISCUS; Web of Science and clinicaltrials.gov) were searched, in accordance with PRISMA guidelines. Results: 17,433 articles were identified and 130 experiments from 128 studies were included. Retrieved articles included Iron (n = 29), Calcium (n = 11), Magnesium, (n = 22), Phosphate (n = 17), Zinc (n = 9), Sodium (n = 15), Boron (n = 4), Selenium (n = 5), Chromium (n = 12) and multi-mineral articles (n = 5). No relevant articles were identified for Copper, Manganese, Iodine, Nickel, Fluoride or Cobalt. Only Iron and Magnesium included articles of sufficient quality to be assigned as 'strong'. Currently, there is little evidence to support the use of MTE supplementation to improve physiological markers of athletic performance, with the possible exception of Iron (in particular, biological situations) and Magnesium as these currently have the strongest quality evidence. Regardless, some MTEs may possess the potential to improve athletic performance, but more high quality research is required before support for these MTEs can be given. PROSPERO preregistered (CRD42018090502).

Nonorthopaedic problems in the aquatic athlete

This article discusses a number of medical conditions that are common to aquatic athletes. Exercise-induced asthma is particularly prevalent in swimmers because swimming is among the activities tolerated best by asthmatics. The healthcare professional frequently must evaluate and manage respiratory infections and infectious mononucleosis in swimmers, particularly in regard to the safe timing of return to training and competition. Dilutional sports pseudoanemia must be differentiated from the true anemias that are due mostly to iron-deficiency and intravascular hemolysis. Finally, the evaluation, management, and prevention of otitis externa, external auditory canal exostoses, and dermatologic disorders in swimmers are reviewed.

Dietary iron deficiency and sports anaemia

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.

Effect of an iron supplement on body iron status and aerobic capacity of young training women

Serum iron deficiency has a high incidence in female athletes. We investigated the effects of a daily oral iron supplement, (160 mg) administered during an intensive 7-week physical training programme, on body iron status, and the maximal aerobic capacity (VO2max) of 13 women (group A) compared to 15 who took a placebo (group B). The subjects were 19 years old. Blood samples were obtained before training began and on days 1, 7, 21 and 42 of training. They were analysed for packed cell volume (PVC) and for haemoglobin (Hb), 2,3-diphosphoglycerate (2,3-DPG), haptoglobin, iron and ferritin concentrations. The VO2max was measured on days 0, 21 and 42 of training. Following 21 days of training Hb, PCV and ferritin were significantly higher (P less than or equal to 0.01) in group A compared to group B. Over the training period Hb rose by 9.3% and 2.4% in groups A and B, respectively. At the end of training 66% of group B exhibited ferritin concentrations below 10 ng.ml-1, while none of group A had such low values. Mean VO2max of group A had increased by 7.5% following 21 days of training (P less than or equal to 0.01) and by 15.3% after 42 days. No appreciable increase in VO2max had occurred in group B by day 21 (significantly lower than VO2max of group A; P less than or equal to 0.05), however by day 42 it had increased by 14.3% (P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Serum iron and transferrin during an exhaustive session of interval training

Conflicting data have been reported on "sports anaemia" and anaemia during physical training. Most of these results are of studies at rest before or after training. The aim of this investigation was to further study the profiles of serum iron (Se Fe) and transferrin (Se Tr), in 14 physically trained men (28 +/- 6 years) during an exhaustive interval training session. The 45 min Square-Wave Endurance Exercise Test (SWEET) was performed on a cycle ergometer. To the SWEET base, established as a % of individual VO2max, a peak of 1 min at VO2max was added every 5 minutes. Arterial blood samples were taken at rest, during the SWEET at the 14th, 15th, 29th, 30th, 44th and 45th minutes, just before and after the peaks, and at the 15th min of recovery. Lactate, acidity [H+], PaCO2, PaO2, Haematocrit (Hct), Haemoglobin (Hb), Se Fe and Se Tr were measured. After the SWEET, weight loss was 0.89 +/- 0.15 kg. Lactate and serum iron rose progressively at the base levels and at the peaks, while PaCO2 and bicarbonate fell progressively. Hct, [Hb], serum transferrin and [H+] increased significantly at the 14th min of SWEET and thereafter no change was observed. At the 45th min with respect to the value at rest, Se Fe increased as much as +32%, Se Tr +13% and [Hb] +8%. Haemoconcentration could explain the changes in Se Tr but not the total significant increase in Se, Fe, which moreover is not explained by acidosis [H+].(ABSTRACT TRUNCATED AT 250 WORDS)

The Anemias of Athletes

In brief: Diagnosing anemia in athletes is complicated, because athletes normally have lower hemoglobin and serum ferritin concentrations than nonathletes. This dilutional pseudoanemia-a beneficial adaptation that enhances athletic performance-needs no treatment. Athletes can also develop true anemia from iron deficiency and/or footstrike hemolysis. True anemia can be treated with iron supplements and diet modification to increase absorbable iron; footstrike hemolysis can be minimized by paying attention to body weight, gait, shoes, and terrain. The widespread notion that depletion of iron stores without anemia limits performance is probably wrong, but even very mild iron deficiency anemia impairs maximal performance. The physician who recognizes and manages the diverse anemias of athletes performs a vital service.

Variations in iron status with fatigue modelled from training in female distance runners

A low hemoglobin level or even frank anemia is common among female endurance runners; controversy presently exists on the effectiveness of iron supplementation. In the past inadequate descriptions of training and too infrequent measurement of iron indices over a sufficiently long period, have made it difficult to establish any relationship between iron status and training upon which to base a rational iron therapy. In this study 5 young women distance runners age 18-25 years have been studied for 300 days. A numerical index was used to quantify the extent of an individual's daily training effort and a conceptual model of the effect of training allowed definition of the extent of consequent fatigue, to be calculated. Red blood cell number and hemoglobin concentration were measured regularly throughout, and during the last 200 days serum iron, ferritin, total iron binding capacity and percent transferrin saturation were also measured. It has been shown in most subjects that serum iron and transferrin saturation varied in phase with training and the fatigue index, throughout the period while serum ferritin varied out of phase. It is suggested that supplementing iron intake may be of little use during heavy training and concomitant high fatigue because transferrin saturation is also very high at this time and ineffective in promoting absorption of dietary iron.

Red cell 2,3-DPG, ATP, and mean cell volume in highly trained athletes. Effect of long-term submaximal exercise

20 male elite long distance runners were compared to a control group of blood donors to determine the effect of training on red blood cells. The acute effects of exercise on red cells were investigated in 11 of the runners following a race of 15-30 km. The runners had elevated resting values of red cell 2,3-DPG (P less than 0.05) and mean cell volume (P less than 0.01); blood Hb and ATP were not different from concentrations in the control group. The red cell status of the athletes may be explained by an increased proportion of young erythrocytes in runners. No statistically significant changes in red cell 2,3-DPG, ATP, mean cell volume or blood Hb were found post exercise.