Iron deficiency is frequent among athletes. All types of iron deficiency may affect physical performance and should be treated. The main mechanisms by which sport leads to iron deficiency are increased iron demand, elevated iron loss and blockage of iron absorption due to hepcidin bursts. As a baseline set of blood tests, haemoglobin, haematocrit, mean cellular volume, mean cellular haemoglobin and serum ferritin levels help monitor iron deficiency. In healthy male and female athletes >15 years, ferritin values <15 mcg are equivalent to empty, values from 15 to 30 mcg/l to low iron stores. Therefore a cut-off of 30 mcg/l is appropriate. For children aged from 6-12 years and younger adolescents from 12-15 years, cut-offs of 15 and 20 mcg/l, respectively, are recommended. As an exception in adult elite sports, a ferritin value of 50 mcg/l should be attained in athletes prior to altitude training, as iron demands in these situations are increased. Treatment of iron deficiency consists of nutritional counselling, oral iron supplementation or, in specific cases, by intravenous injection. Athletes with repeatedly low ferritin values benefit from intermittent oral substitution. It is important to follow up the athletes on an individual basis, repeating the baseline blood tests listed above twice a year. A long-term daily oral iron intake or i.v. supplementation in the presence of normal or even high ferritin values does not make sense and may be harmful.

Iron deficiency is the most widespread and frequent nutritional disorder in the world. It affects a high proportion of children and women in developing countries and is also significantly prevalent in the industrialised world, with a clear predominance in adolescents and menstruating females. Iron is essential for optimal cognitive function and physical performance, not only as a binding site of oxygen but also as a critical constituent of many enzymes. Therefore iron deficiency at all its levels - nonanaemic iron deficiency, iron deficiency with microcytosis or hypochromia and iron deficiency anaemia - should be treated. In the presence of normal stores, however, preventative iron administration is inefficient, has side effects and seems to be harmful. In symptomatic patients with fatigue or in a population at risk for iron deficiency (adolescence, heavy or prolonged menstruation, high performance sport, vegetarian or vegan diet, eating disorder, underweight), a baseline set of blood tests including haemoglobin concentration, haematocrit, mean cellular volume, mean cellular haemoglobin, percentage of hypochromic erythrocytes and serum ferritin levels are important to monitor iron deficiency. To avoid false negative results (high ferritin levels in spite of iron deficiency), an acute phase reaction should be excluded by history and measurement of C-reactive protein. An algorithm leads through this diagnostic process and the decision making for a possible treatment. For healthy males and females aged >15 years, a ferritin cut-off of 30 µg/l is appropriate. For children from 6-12 years and younger adolescents from 12-15 years, cut-offs of 15 and 20 µg/l, respectively, are recommended. As a first step in treatment, counselling and oral iron therapy are usually combined. Integrating haem and free iron regularly into the diet, looking for enhancers and avoiding inhibitors of iron uptake is beneficial. In order to prevent reduced compliance, mainly as a result of gastrointestinal side effects of oral treatment, the use of preparations with reasonable but not excessive elemental iron content (28-50 mg) seems appropriate. Only in exceptional cases will an intravenous injection be necessary (e.g., concomitant disease needing urgent treatment, repeated failure of first-step therapy).To measure the success of treatment, the basic blood tests should be repeated after 8 to 10 weeks. Patients with repeatedly low ferritin will benefit from intermittent oral substitution to preserve iron stores and from long term follow-up, with the basic blood tests repeated every 6 or 12 months to monitor iron stores. Long-term daily oral or intravenous iron supplementation in the presence of normal or even high ferritin values is, however, not recommended and is potentially harmful.

Findings about the relation between musculoskeletal injuries and training patterns in orienteering athletes are sparse. Therefore, the musculoskeletal injuries and training patterns of 31 Swiss elite orienteering athletes aged 18-19 years were analyzed in a retrospective study. Individual training diaries and medical records were used to assess training data and injury history, respectively. Group comparisons and a multiple linear regression (MLR) were performed for statistical analysis. The junior elite orienteering athletes performed 7.38 ± 2.00 training sessions weekly, with a total duration of 455.75 ± 98.22 minutes. An injury incidence rate (IIR) of 2.18 ± 2.13 injuries per 1000 hours of training was observed. The lower extremity was affected in 93% of all injuries, and the knee (33%) was the most commonly injured location. The MLR revealed that gender and six training variables explained 60% of the variance in the injury severity index in this study. Supported by the low IIR in the observed age group, the training protocol of the junior elite orienteering athletes was generally adequate. In comparison to elite track, marathon, and orienteering athletes, the junior elite athletes performed less high-intensity interval training (HIIT). However, more frequent HIIT seems to be a protective factor against injuries.

Laboratory analyses in sports medicine are relevant for three reasons: 1. In actively exercising individuals laboratory analysis are one of the central elements in the diagnosis of diseases and overreaching. 2. Regularly done laboratory analysis in competitive athletes with high load of training and competition may help to detect certain deficiencies early on. 3. Physical activity in general and competitive exercise training specifically do change certain routine laboratory parameters significantly although not reflecting pathological changes. These so-called preanalytic variations should be taken into consideration while interpreting laboratory data in medical emergency and routine diagnostics. This article intends to help the physician to interprete laboratory data of actively exercising sportsmen.

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