Iron deficiency in sports - definition, influence on performance and therapy.

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.

Muscle-Derived IL-6 Is Not Regulated by IL-1 during Exercise. A Double Blind, Placebo-Controlled, Randomized Crossover Study.

UNLABELLED: Exercise increases muscle derived Interleukin­6 (IL­6) leading to insulin secretion via glucagon-like peptide­1. IL­1 antagonism improves glycemia and decreases systemic inflammation including IL­6 in patients with type 2 diabetes. However, it is not known whether physiological, exercise-induced muscle-derived IL­6 is also regulated by the IL­1 system. Therefore we conducted a double blind, crossover study in 17 healthy male subjects randomized to receive either the IL­1 receptor antagonist IL-1Ra (anakinra) or placebo prior to an acute treadmill exercise. Muscle activity led to a 2­3 fold increase in serum IL­6 concentrations but anakinra had no effect on this exercise-induced IL­6. Furthermore, the IL­1 responsive inflammatory markers CRP, cortisol and MCP­1 remained largely unaffected by exercise and anakinra. We conclude that the beneficial effect of muscle-induced IL­6 is not meaningfully affected by IL­1 antagonism. TRIAL REGISTRATION: ClinicalTrials.gov NCT01771445.

[Laboratory analyses in sports medicine]. / Laboranalysen in der Sportmedizin.

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.

Acute effects of interval versus continuous endurance training on pulse wave reflection in healthy young men.

AIM: Our aim was to investigate the acute and 24-hour (h) effects of high-intensity interval training (HIIT) and moderate continuous training (MCT) on arterial pulse wave reflection, an established marker of arterial stiffness and cardiovascular risk. METHODS: In a randomized cross-over design, 21 young healthy male participants performed a HIIT or a MCT on separate visits. Before and 5 (t5), 20 (t20), 35 (t35), and 50 (t50) minutes after the acute exercise bouts, the crude augmentation index (AIx) and the AIx at a set heart rate (AIx@75) were analysed by applanation tonometry. Starting 1 h post-exercise, both indices were captured over 24-h with an oscillometric monitoring device. RESULTS: AIx did not change significantly after MCT but declined progressively after HIIT, reaching significantly lower values compared to MCT at t35 (P = 0.045) and t50 (P = 0.008). AIx@75 increased after both acute exercise types but was higher after HIIT at t5 (P < 0.001), t20 (P < 0.001) and t35 (P = 0.009) compared to MCT. The 24-h follow-up revealed a significant decline in AIx@75 after HIIT (P = 0.007) but not after MCT (P = 0.813). CONCLUSIONS: Exercise intensity affects pulse wave reflection, with different time courses for AIx and AIx@75 post-exercise. Although initially higher after HIIT, AIx@75 declines in the 24-h recovery period indicating more favourable effects on pulse wave reflection compared to MCT. This may result in substantial positive chronic training effects on arterial stiffness in health and cardiovascular disease.

Aerobic, resistance and combined exercise training on arterial stiffness in normotensive and hypertensive adults: A review.

Exercise training has different effects on arterial stiffness according to training modalities. The optimal exercise modality for improvement of arterial function in normotensive and hypertensive individuals has not been well established. In this review, we aim to evaluate the effects of aerobic, resistance and combined aerobic and resistance training on arterial stiffness in individuals with and without hypertension. We systematically searched the Pubmed and Web of Science database from 1985 until December 2013 for relevant randomised controlled trials (RCTs). The data were extracted by one investigator and checked by a second investigator. The training effects on arterial stiffness were estimated using weighted mean differences of the relative changes (%) with 95% confidence intervals (CIs). We finally reviewed the results from 17 RCTs. The available evidence indicates that aerobic exercise tends to have a beneficial effect on arterial stiffness in normotensive and hypertensive patients, but does not affect arterial stiffness in patients with isolated systolic hypertension. Resistance exercise has differing effects on arterial stiffness depending on type and intensity. Vigorous resistance training is associated with an increase in arterial stiffness. There seem to be no unfavourable effects on arterial stiffness if the training is of low intensity, in a slow eccentric manner or with lower limb in healthy individuals. Combined training has neutral or even a beneficial effect on arterial stiffness. In conclusion, our review shows that exercise training has varying effects on arterial stiffness depending on the exercise modalities.

Diurnal variation of arterial stiffness in healthy individuals of different ages and patients with heart disease.

BACKGROUND: Arterial stiffness can be measured using various non-invasive methods. It is not well established whether it is necessary to standardize the time of the day when performing these measurements. The aim of the present study is to examine the effect of daytime on arterial stiffness in individuals with and without heart disease. METHODS: We investigated the diurnal variation of cardio-ankle vascular index (CAVI) and carotid femoral pulse wave velocity (cfPWV). CAVI and cfPWV were measured in 70 participants (23 healthy young individuals [HY], 22 healthy elderly individuals [HE], 25 patients with heart disease [HD]) at 09:00, 13:00 and 17:00 h. RESULTS: There was a significant diurnal variation in CAVI with the highest values at 09:00 h in both univariate and multivariate analysis. After adjusting for age, sex and MAP (mean arterial pressure), CAVI maintained a significant highest values at 09:00 h, which was 4% higher than at 13:00 h (p = 0.022) and 5% higher than at 17:00 h (p = 0.002). However, a lack of diurnal variation was found in cfPWV in multivariate analysis in our study population. CONCLUSION: Our findings suggest that it does not appear mandatory to measure cfPWV at the same time of day. However, standardizing the time of day for CAVI is important in routine clinical practice and longitudinal studies.

Balance and gait performance after maximal and submaximal endurance exercise in seniors: is there a higher fall-risk?

Impaired balance and gait performance increase fall-risk in seniors. Acute effects of different exercise bouts on gait and balance were not yet addressed. Therefore, 19 healthy seniors (10 women, 9 men, age: 64.6 ± 3.2 years) were examined on 3 days. After exhaustive treadmill testing, participants randomly completed a 2-km treadmill walking test (76 ± 8 % VO(2max)) and a resting control condition. Standing balance performance (SBALP) was assessed by single limb-eyes opened (SLEO) and double limb-eyes closed (DLEC) stance. Gait parameters were collected at comfortable walking velocity. A condition × time interaction of center of pressure path length (COP(path)) was observed for both balance tasks (p < 0.001). Small (Cohen's d = 0.42, p = 0.05) and large (d = 1.04, p < 0.001) COP(path) increases were found after 2-km and maximal exercise during DLEC. Regarding SLEO, slightly increased COP(path) occurred after 2-km walking (d = 0.29, p = 0.65) and large increases after exhaustive exercise (d = 1.24, p < 0.001). No significant differences were found for gait parameters. Alterations of SBALP after exhaustive exercise might lead to higher fall-risk in seniors. Balance changes upon 2-km testing might be of minor relevance. Gait is not affected during single task walking at given velocities.

Recommendations for aerobic endurance training based on subjective ratings of perceived exertion in healthy seniors.

The study investigated physiological responses during 2-km walking at a certain intensity of a previously performed maximal exercise test where moderate perceived exertion was reported. Twenty seniors were examined by an incremental walking treadmill test to obtain maximal oxygen uptake (VO2max). A submaximal 2-km walking test was applied 1 wk later. The corresponding moderate perceived exertion (4 on the CR-10 scale) during the VO2max test was applied to the 2-km treadmill test. Moderate exertion (mean rating of perceived exertion [RPE]: 4 ± 1) led to 76% ± 8% of VO2max and 79% ± 6% of maximal heart rate. RPE values drifted with a significant time effect (p = .001, η(p) = .58) during the 2-km test from 3 ± 0.7 to 4.6 ± 0.8. Total energy expenditure (EE) was 3.3 ± 0.5 kcal/kg. No gender differences in ventilatory, heart-rate, or EE data occurred. Brisk walking at moderate RPE of 3-5 would lead to a beneficial physiological response during endurance training and a weekly EE of nearly 1,200 kcal when exercising 5 times/wk for 30 min.