Immune system adaptation in elite athletes

Retrospective study of COVID-19 experiences in elite multinational aquatic athletes

This study assessed the experiences of elite aquatic athletes with coronavirus disease 2019 (COVID-19) during the first World Championship conducted without social distancing and an isolation "bubble". An online questionnaire was completed by 812 athletes (22.7 ± 5.9 years, 467 females) to provide data on demographics, sports activity, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rates, symptoms, reinfection, vaccination status, and psychological aspects. The answers revealed that 49.4% of athletes had experienced SARS-CoV-2 infection. The infection rates varied significantly across different aquatic sports, with open water swimmers having the lowest (28%) and water polo players (67%) and artistic swimmers (61%) having the highest infection rates (p < 0.0001). The majority reported mild (51%) or moderate (27%) symptoms, while 16% remained asymptomatic. Reinfection occurred in 13%, and 10% of initial infections led to long COVID, with fatigue (65%) and shortness of breath (48%) being the most common long-term symptoms. Significantly, 92% of athletes received at least two vaccine doses and reported a positive vaccination experience (median score of 8 out of 10 for each shot). Mood changes and subjective performance drops significantly correlated with the overall experience scores (rho: 0.617, p < 0.0001, and rho: 0.466, p < 0.0001, respectively). In conclusion, most athletes experienced a benign disease course despite a relatively high infection rate. This study provides valuable insights into the COVID-19 experiences of elite aquatic athletes. The findings emphasize the importance of vaccination initiatives, monitoring psychological well-being and the need to fortify athletes' resilience in the face of future health challenges.

Exercise-induced increase in M2 macrophages accelerates wound healing in young mice

Moderate-intensity exercise performed during wound healing has been reported to decrease inflammatory cytokines and chemokines and accelerate wound healing. However, its effect on macrophage phenotype and the mechanism by which exercise accelerates wound healing remain unclear. The purpose of this study was to investigate the effect of exercise on macrophage phenotype during wound healing and to clarify the relationship between angiogenesis and wound healing. 12-week-old male C57BL/6J mice were divided into sedentary (n = 6) and exercise groups (n = 6). The exercise group performed moderate-intensity treadmill running exercise (9.0 m/min, 60 min) for 10 days. Double immunofluorescence analysis was performed using F4/80+ inducible nitric oxide synthase (iNOS)+ for M1 macrophages, F4/80+ transforming growth factor-beta (TGF-β)1+ for M2 macrophages, and CD31+ alpha smooth muscle actin (α-SMA)+ for angiogenesis. The exercise group showed significantly accelerated wound healing compared with the sedentary group. From early wound healing onward, exercise significantly inhibited M1 macrophage infiltration and increased M2 macrophage count. Exercise also significantly increased angiogenesis. Furthermore, the M2 macrophage phenotype was significantly correlated with angiogenesis in the exercise group, indicating that M2 macrophages and angiogenesis are related to accelerated wound healing. These findings suggest that moderate-intensity exercise increases TGF-β1 derived from M2 macrophages, which may be associated with enhanced angiogenesis and wound healing in young mice.

Characterization of Meningitis and Meningoencephalitis in the Israeli Defense Forces From 2004 to 2015: A Population-Based Study

Background

Meningitis and meningoencephalitis (MME) are potential medical emergencies. Mandatory reporting of all MME cases in the Israel Defense Force (IDF) allows accurate characterization of MME incidence and course. In the present study, we described the epidemiology of MME in soldiers.

Methods

Medical charts of 860,000 combat and non-combat soldiers serving during the years 2004–2015, accounting for 2,256,060 patient years, were retrospectively evaluated. The diagnosis of MME was based on signs of meningeal irritation and a count of > 5 white blood cells (WBC) in the cerebrospinal fluid (CSF). Data on the diagnosis of bacterial or aseptic MME, significant sequelae, and associated mortality were collected.

Results

Approximately 273 cases of MME were diagnosed. Overall, MME incidence was 12.1/100,000 patient-years. Bacterial and viral pathogens were identified in 31/273 (11.4%) and 52/273 (19%) cases, respectively. Combat soldiers had higher incidence of bacterial meningitis [14/40 (35%) vs. 31/212 (14.6%); p = 0.002] and meningoencephalitis [13/40 (32.5%) vs. 33/212 (15.6%); p = 0.023] compared to non-combat soldiers. Their clinical presentation was more severe, including confusion [10/40 (25%) vs. 22/212 (10.4%); p = 0.018], focal neurological deficits [12/40 (30%) vs. 11/212 (5.2%); p < 0.0001], and status epilepticus [3/40 (7.5%) vs. 0/212 (0.0%); p < 0.01]. Mortality among combat soldiers was higher [5/40 (15%) vs. 1/212 (0.5%); p < 0.001]. N. meningitidis was the most frequently isolated bacteria, despite universal preventative vaccination.

Conclusion

The incidence of bacterial MME in the IDF is higher than in the civilian population. Combat soldiers present with higher incidence of meningoencephalitis and bacterial meningitis.

Supply of Antioxidants vs. Recruit Firefighters' Cellular Immune Status: A Randomized Double-Blinded Placebo-Controlled Parallel-Group Trial

Background: Physical exercise can affect the immune system. We studied the effect of antioxidants on hematological and immune biomarkers after heavy training. Methods: 24 well-trained and well-fed male firefighters were randomly divided into supplemented and placebo groups, and tested for immunology-related variables using venous blood samples in the fasting state, pre- (M1) and post- (M2) five weeks of daily micronutrient supplementation (15 mg of beta-carotene, 200 mg of vitamin C, 136 mg of vitamin E, 200 μg of selenium, 15 mg of zinc, 100 mg of magnesium). Total leukocytes and a differential count for five populations were determined using standard procedures (MAXM—Beckman Coulter Diagnostics; Brea, CA, USA). Lymphocyte subsets were determined through immunophenotyping. Results: Although all values were within the normal range for healthy adults and athletes in the supplemented group (SG), mean CD3+CD8+, CD8+ and CD16+CD56+ decreased (p < 0.05; small to moderate effects), while mean CD4+, CD19+ and CD4+/CD8+ increased (p < 0.05; small effects) after five-weeks. Regarding the placebo group (PG), higher total leukocyte count (p < 0.05; trivial effect) and natural killer cells percentage (CD16+CD56+; p < 0.05; moderate effect) were observed when comparing M1 and M2. Conclusions: Antioxidants supplementation did not alter well-fed male firefighters recruit firefighters’ immune cell response during the five-week physical training program.

The effect of exercise on cytokines: implications for musculoskeletal health: a narrative review

The physiological effects of physical exercise are ubiquitously reported as beneficial to the cardiovascular and musculoskeletal systems. Exercise is widely promoted by medical professionals to aid both physical and emotional wellbeing; however, mechanisms through which this is achieved are less well understood. Despite numerous beneficial attributes, certain types of exercise can inflict significant significant physiological stress. Several studies document a key relationship between exercise and immune activation. Activation of the innate immune system occurs in response to exercise and it is proposed this is largely mediated by cytokine signalling. Cytokines are typically classified according to their inflammatory properties and evidence has shown that cytokines expressed in response to exercise are diverse and may act to propagate, modulate or mitigate inflammation in musculoskeletal health. The review summarizes the existing literature on the relationship between exercise and the immune system with emphasis on how exercise-induced cytokine expression modulates inflammation and the immune response.

Chronic Aerobic Training at Different Volumes in the Modulation of Macrophage Function and in vivo Infection of BALB/c Mice by Leishmania major

Physical inactivity is one of the main causes of chronic diseases; however, strenuous exercise can induce immunosuppression. Several studies suggest that moderate amounts of exercise lead to a Th1 response, favoring the resolution of infections caused by intracellular microorganisms, while high volumes of exercise tend to direct the response to Th2, favoring infection by them. Leishmaniasis is a parasitic disease promoted by parasites of the Leishmania genus, with clinical manifestations that vary according to the species of the parasite and the immune response of the host. The experimental Leishmania major–BALB/C mouse model provides a good model for the resistance (Th1 response) or susceptibility (Th2 response) that determines the progression of this infection. The aim of this study was to evaluate the effect of aerobic training at different volumes on modulation of in vitro macrophage infection by L. major, as well as to assess the effect of high volume (HV) aerobic training on the development of L. major in vivo in BALB/c mice. Uninfected animals were submitted to various exercise volumes: none (SED), light (LV), moderate (MV), high (HV), very high (VHV), and tapering (TAP). The macrophages of these animals were infected by L. major and the LV and MV groups showed a decrease in the infection factor, while the VHV showed an increase in the infection factor, when treated with LPS. The cytokine concentration pattern measured in the supernatants of these macrophages suggested a predominant Th1 response profile in the LV and MV groups, while the Th2 profile predominated in the VHV and TAP groups. Groups of BALB/C mice infected with L. major were subjected to high volume (iHV) or non-periodized high volume (iNPHV) exercise or kept sedentary (iSED). The exercised animals suffered a significant increase in injuries caused by the parasites. The animals in the group submitted to high volume exercise (iHV) showed visceralization of the infection. These data strongly suggest that a very high volume of aerobic training increased the susceptibility of BALB/C mice to L. major infection, while moderate distribution of training loads promoted immunological balance, better controlling the infection by this parasite.

Potential Long-Term Health Problems Associated with Ultra-Endurance Running: A Narrative Review

It is well established that physical activity reduces all-cause mortality and can prolong life. Ultra-endurance running (UER) is an extreme sport that is becoming increasingly popular, and comprises running races above marathon distance, exceeding 6 h, and/or running fixed distances on multiple days. Serious acute adverse events are rare, but there is mounting evidence that UER may lead to long-term health problems. The purpose of this review is to present the current state of knowledge regarding the potential long-term health problems derived from UER, specifically potential maladaptation in key organ systems, including cardiovascular, respiratory, musculoskeletal, renal, immunological, gastrointestinal, neurological, and integumentary systems. Special consideration is given to youth, masters, and female athletes, all of whom may be more susceptible to certain long-term health issues. We present directions for future research into the pathophysiological mechanisms that underpin athlete susceptibility to long-term issues. Although all body systems can be affected by UER, one of the clearest effects of endurance exercise is on the cardiovascular system, including right ventricular dysfunction and potential increased risk of arrhythmias and hypertension. There is also evidence that rare cases of acute renal injury in UER could lead to progressive renal scarring and chronic kidney disease. There are limited data specific to female athletes, who may be at greater risk of certain UER-related health issues due to interactions between energy availability and sex-hormone concentrations. Indeed, failure to consider sex differences in the design of female-specific UER training programs may have a negative impact on athlete longevity. It is hoped that this review will inform risk stratification and stimulate further research about UER and the implications for long-term health.

Effect of Seasonal Variation during Annual Cyclist Training on Somatic Function, White Blood Cells Composition, Immunological System, Selected Hormones and Their Interaction with Irisin

The aim of this study was to evaluate somatic, hormonal and immunological changes during the macrocycle of cyclists (9 well-trained men, age 25.6 ± 5.2 years and body weight 72.4 ± 7.35 kg). During the training macrocycle, four exercise control tests were carried out, and biochemical markers were measured in the laboratory. Seasonal training changes did not significantly disturb resting somatic and functional parameters, physical capacity (VO2max), body weight, the number of leukocytes and selected hormones. The secretory system of the organism did not respond significantly to the exercise stress in the training process, even with the increasing share of anaerobic processes in the subsequent periods of the macrocycle. Irisin and other parameters globally did not correlate with training volume. Irisin showed a significant correlation only with cortisol in the first period and human growth hormone in the second, and it showed a weak correlation in the third period with body mass and BMI. The lack of interactions between irisin level and other variables practically excludes its use in monitoring cyclist training. Future research would be complemented by the assessment of stress and postexercise changes in the cyclists’ macrocycle and expanding the research group to other athletes, including women.

Obesity and aging: Molecular mechanisms and therapeutic approaches

The epidemic of obesity is a major challenge for health policymakers due to its far-reaching effects on population health and potentially overwhelming financial burden on healthcare systems. Obesity is associated with an increased risk of developing acute and chronic diseases, including hypertension, stroke, myocardial infarction, cardiovascular disease, diabetes, and cancer. Interestingly, the metabolic dysregulation associated with obesity is similar to that observed in normal aging, and substantial evidence suggests the potential of obesity to accelerate aging. Therefore, understanding the mechanism of fat tissue dysfunction in obesity could provide insights into the processes that contribute to the metabolic dysfunction associated with the aging process. Here, we review the molecular and cellular mechanisms underlying both obesity and aging, and how obesity and aging can predispose individuals to chronic health complications. The potential of lifestyle and pharmacological interventions to counter obesity and obesity-related pathologies, as well as aging, is also addressed.

Upper Respiratory Tract Infections in Sport and the Immune System Response. A Review

Simple Summary

This review aims at clarifying the relationships of heavy training with the upper respiratory tract infections (URTI), a topic which has reach the public awareness with the recent outbreaks of Covid 19. The URTIs are quite common in several sport activities among athletes who undergo heavy training. Causes of URTI are still poorly understood, because can be related with innate and genetic susceptibility and with several environmental factors connected with training load and nutrition. The time course of the inflammation process affecting URTI after training, has been also reviewed. After a survey of the possible physiological and psychological causes (stressors), including a survey of the main markers of inflammation currently found in scientific literature (mainly catecholamines), we provided evidence of the ingestion of carbohydrates, C, D, and E vitamins, probiotics and even certain fat, in reducing URTI in athletes. Possible countermeasures to URTI can be a correct nutrition, sleep hygiene, a proper organization of training loads, and the use of technique to reduce stress in professional athletes. There is a lack of studies investigating social factors (isolation) albeit with Covid 19 this gap has been partially fill. The results can be useful also for non-athletes.

Abstract

Immunity is the consequence of a complex interaction between organs and the environment. It is mediated the interaction of several genes, receptors, molecules, hormones, cytokines, antibodies, antigens, and inflammatory mediators which in turn relate and influence the psychological health. The immune system response of heavily trained athletes resembles an even more complex conditions being theorized to follow a J or S shape dynamics at times. High training loads modify the immune response elevating the biological markers of immunity and the body susceptibility to infections. Heavy training and/or training in a cold environment increase the athletes’ risk to develop Upper Respiratory Tract Infections (URTIs). Therefore, athletes, who are considered healthier than the normal population, are in fact more prone to infections of the respiratory tract, due to lowering of the immune system in the time frames subsequent heavy training sessions. In this revision we will review the behavioral intervention, including nutritional approaches, useful to minimize the “open window” effect on infection and how to cope with stressors and boost the immune system in athletes.

Women in sports: the applicability of common national reference intervals for inflammatory and coagulation biomarkers (HemSter Study)

Introduction

Intensive physical activity causes functional and metabolic changes in the athlete’s organism. The study aimed to verify the common national available reference intervals (RIs) for common inflammatory and screening coagulation tests in a population of healthy young female athletes.

Materials and methods

One hundred and twenty-one female athletes (age range: 16–34), from various sports disciplines (water polo, handball, volleyball, football, basketball), were included in the study. All participants completed the international physical activity short-form questionnaire. Blood samples were collected between 8–10 am, after an overnight fast, before any physical activity. Reference intervals were determined according to Clinical & Laboratory Standards Institute EP28-A3C Guidelines.

Results

Calculated RIs for white blood cell count (WBC), prothrombin time (PT), and activated partial thromboplastin time (APTT) ratio were in accordance with the common national RIs. Calculated RI for C-reactive protein (CRP) was lower (< 2.9 mg/L) than the proposed cut-off for a healthy population (< 5.0 mg/L). Reference interval for fibrinogen was higher (1.9–4.4 g/L), than the available RIs (1.8–3.5 g/L). D-dimer cut-off value was set at 852 µg/L fibrinogen equivalent units (FEU), higher than the proposed 500 µg/L FEU for venous thromboembolism (VTE) exclusion.

Conclusions

The applicability of the available RIs for WBC count, PT, and APTT-ratio was confirmed. However, RIs for CRP and fibrinogen differed significantly than the available common national RIs for the healthy non-athletes’ population. A higher cut-off for D-dimers should be extensively verified before implementation for VTE diagnosis exclusion in a group of healthy young female athletes.

COVID-19 AND ITS EFFECT ON OLYMPIC SPORT: THE IMPORTANCE OF STUDYING SOCIAL ISOLATION AND THE HARM IT CAUSES, IN ORDER TO MINIMIZE IT

ABSTRACT In March 2020, the World Health Organization (WHO) declared the disease caused by the SARS-CoV2 virus, known as COVID-19, to be a pandemic. The sporting world, too, is suffering from the global effects of this disease, with the postponement or cancellation of competitions, including the 2020 Tokyo Olympic Games. As a proposal for containing the disease, social isolation was declared. Despite the importance of this measure, it was harmful for Olympic athletes, as they had to stay away from their training site and trainers, as well as their interdisciplinary teams. It is therefore important to study this harm caused, in order to minimize it. In general, it is believed that regular physical activity is associated with improved immune system functioning. The lack of training can therefore have significant consequences for the performance and health of the Olympic athlete. From the athlete's point of view, the impaired immune system, due to the reduced frequency of physical exercise, leaves them more vulnerable to contracting or developing infections or other diseases. The risk of harm due to the decreased performance of preventive works is also evident in this population. The reductions in training load and intensity can cause changes in the athlete's body composition and affect various aspects of cardiorespiratory fitness, as well as reducing strength levels and muscle potency. In relation to the athlete's mental health, two aspects are particularly challenging: isolation and uncertainty. Based on the possible harm caused by social isolation, the need is seen for a specific and joint work, in an attempt to minimize it. This work addresses the following topics: (I) context: transmission, symptoms, diagnosis, treatment, discharge criteria, isolation and post-pandemic consequences; (II) harm and proposals: nutritional, physiological, biomechanical and psychological. Level of evidence II; Review Article.

Profile of gamma-delta (γδ) T lymphocytes in the peripheral blood of crossbreed dogs during stages of life and implication in aging

Background

Data on gamma-delta (γδ) T lymphocytes in the peripheral blood of dogs are scant, related only to healthy pure breed dogs and limited to a restricted age range. The aim of the study was to investigate the modulation of the γδ T lymphocyte (TCRγδ+) subpopulation in peripheral blood of crossbreed healthy dogs according to five identified stages of life: Puppy, Junior, Adult, Mature, Senior and to determine its implication in aging.

A rigorous method of recruitment was used to minimize the influence of internal or external pressure on the immune response. Twenty-three intact female and twenty-four intact male dogs were enrolled. Blood samples were collected and immunophenotyping of peripheral blood T lymphocytes and γδ T cell subpopulations was performed.

Results

The percentage of γδ T cells in peripheral blood lymphocytes was comparable with the value of 2.5% published by Faldyna and co-workers (2001), despite the percentage reported was investigated in less arranged age range groups and coming from four different dog pure breeds, whereas our data were recorded on wider age range groups and coming from crossbreed dogs. Therefore, the γδ T cell percentage (2.5%) is consistent and points out that such value is breed-independent. Statistical analysis highlighted differences in both percentage and absolute γδ T cells according to the stage of life. γδ T cells decreased significantly in the peripheral blood of elder dogs (Senior group) in comparison with previous stages of life (Puppy, Junior, and Adult groups). Differences in γδ T cells are significant and they are reported, for the first time, related to dog aging.

Conclusions

The study confirms dogs to be among the animals with a low TCRγδ+ cell profile. A decrease of the TCRγδ+ subpopulation percentage was observed in elder dogs. TCRγδ+ cells of group S were different from those of groups P, J, and A. The differences are reported for the first time in dog aging. Identifying the stage of life when the decrease of γδ T lymphocytes starts can be useful for providing a rationale for drafting a wellness plan trial to support thymus immune functions and mitigate its functional exhaustion.

Medical recommendations for home-confined footballers' training during the COVID-19 pandemic: from evidence to practical application

In early 2020, the world is facing a global emergency called COVID-19. Many professional footballers around the world are home confined. The maintenance of physical capacity is a fundamental requirement for the athlete, so the training sessions must be adapted to this unique situation. Specific recommendations must be followed concerning the type of training, its intensity, the precautions that have to be followed to avoid the possibility of contagion, and the restrictions in accordance with the presence of any symptoms.

This article analyses the available scientific evidence in order to recommend a practical approach.

Elite athletes on regular training show more pronounced induction of vaccine-specific T-cells and antibodies after tetravalent influenza vaccination than controls

Compliance of elite athletes with vaccination recommendations is low mainly based on concerns about side-effects and perceived poor vaccine efficacy due to continued physical training. We therefore employed seasonal influenza vaccination to investigate the effect of regular physical training on vaccine-induced cellular and humoral immunity in elite athletes and controls. Lymphocyte subpopulations and vaccine-specific T-cells were quantified and functionally characterized from 45 athletes and 25 controls before, and 1, 2 and 26 weeks after vaccination. Moreover, influenza-specific antibodies and their neutralizing function were quantified. Both groups showed a significant increase in vaccine-reactive CD4 T-cell levels which peaked one week after vaccination (p < 0.0001). The increase was significantly more pronounced in athletes (4.1-fold) compared to controls (2.3-fold; p = 0.0007). The cytokine profile changed from multifunctional T-cells co-producing IFNγ, IL-2 and TNFα to cells with restricted cytokine expression. This change in functionality was associated with a significant increase in CTLA-4 expression (p < 0.0001), which again was more pronounced in athletes. Likewise, the increase in neutralizing antibodies was stronger in athletes (p = 0.004 for H1N1; p = 0.032 for H3N2). In conclusion, both groups mounted a strong vaccine-specific cellular and humoral immunity after standard vaccination. The more pronounced increase in specific T-cells and neutralizing antibodies indicates that high frequency and intensity of training enhance vaccine-responses in elite athletes.

Immunomodulation From Moderate Exercise Promotes Control of Experimental Cutaneous Leishmaniasis

Physical exercise has been described as an important tool in the prevention and treatment of numerous diseases as it promotes a range of responses and adaptations in several biological systems, including the immune system. Studies on the effect of exercise on the immune system could play a critical role in improving public health. Current literature suggests that moderate intensity exercise can modulate the Th1/Th2 dichotomy directing the immune system to a Th1 cellular immune response, which favors the resolution of infections caused by intracellular microorganisms. Leishmaniasis is a group of diseases presenting a wide spectrum of clinical manifestations that range from self-limiting lesions to visceral injuries whose severity can lead to death. The etiological agents responsible for this group of diseases are protozoa of the genus Leishmania. Infections by the parasite Leishmania major in mice (Balb/c) provide a prototype model for the polarization of CD4+ T cell responses of both Th1 (resistance) or Th2 (susceptibility), which determines the progression of infections. The aim of this study was to evaluate the effect of exercise on the development of L. major experimental infections by scanning the pattern of immune response caused by exercise. Groups of Balb/c mice infected with L. major were divided into groups that preformed a physical exercise of swimming three times a week or were sedentary along with treatment or not with the reference drug, meglumine antimoniate. Animals in groups submitted to physical exercise did not appear to develop lesions and presented a significantly lower parasite load independent of drug treatment. They also showed a positive delayed hypersensitivity response to a specific Leishmania antigen compared to control animals. The IFN-γ/IL-4 and IFN-γ/IL10 ratios in trained animals were clearly tilted to a Th1 response in lymph node cells. These data suggest that moderate intensity exercise is able to modulate the Th1 response that provides a protective effect against the development of leishmanial lesions.

Exercise, Immunity, and Illness

It is generally accepted that moderate amounts of exercise improve immune system functions and hence reduce the risk of infection whereas athletes engaged in regular prolonged and/or intensive training have a higher than “normal” incidence of minor infections, especially of the upper respiratory tract (URT, e.g., common cold and influenza). This is likely related to regular acute (and possibly chronic) periods of exercise-induced changes in immune function. URT infections can compromise performance directly if suffered shortly before or during competition or indirectly if suffered at other times via effects on training and/or physiological adaptations. This chapter covers the effects of exercise (acute and chronic), both positive and negative, on immune function and consequent infection risk, and considers the current state-of-the-art for monitoring and assessing this in athletes.

Respiratory Infections

Respiratory infections are the most frequent cause of athletes’ visits in medical practices. Simultaneously, contradictory beliefs are generally held regarding influence of repeated exercise on immunity reflected in susceptibility to infections. Many tend to claim that exercise weakens the immunity and renders regular exercisers more prone to develop airway infections. On the other hand, voices are heard in favor of the possible beneficial influence of regular exercise on immune system efficiency. This chapter focuses on the associations of various kinds of exercise with respiratory infection susceptibility. Influence of exercise, in particular associated with competitive performance, on selected innate and acquired immune response mechanisms is also addressed.

Anthropometric characteristics of top-class Olympic race walkers

BACKGROUND

Typical training programmes in elite race walkers involve high training volumes at low and moderate intensities, which have been reported to induce functional and structural adaptations at an anthropometric level. Since anthropometrical variables are closely related to movement efficiency and performance in endurance events, the aim of this study was to describe the anthropometric profile of world-class race walkers.

METHODS

Twenty-nine world-class race walkers (21 men and 8 women) participated in this study. Anthropometric characteristics, including height, body mass, eight skinfolds, five girths and four bone breadths were measured. Body composition, somatotype, somatotype dispersion mean, somatotype attitudinal mean and height to weight ratio, as well as skinfolds extremity to trunk ratio were also calculated.

RESULTS

Mean height, body mass and body mass index were 177.1±7.1 cm, 66.4±5.8 kg, and 21.2±1.3 kg·m2 for men and 165.6±4.5 cm, 53.6±3.7 kg, and 19.6±1.6 kg· m2 for women, respectively. Women presented greater body fat content (6.7±0.6 vs. 12.2±0.8%; very large effect), less muscle mass (65.6±4.6 vs. 61.6±2.6 kg; large effect), and were more endomorphic (large effect) than men. Men specialists in 20-km showed greater muscle mass (66.7±4.9 vs. 64.4±4.3 kg; moderate effect), and slightly higher skinfolds, girths, body fat content and were more mesomorphic than 50-km specialists (moderate effect).

CONCLUSIONS

The present study expands the limited knowledge on the anthropometric characteristics and somatotype elements of elite top-class race walkers. The characterisation of the morphology of elite race walkers provides coaches a reference values to control the training development of the race walker, as well as providing reference values to improve talent identification.

Circulating miRNAs as Putative Biomarkers of Exercise Adaptation in Endurance Horses

Endurance exercise induces metabolic adaptations and has recently been reported associated with the modulation of a particular class of small noncoding RNAs, microRNAs, that act as post-transcriptional regulators of gene expression. Released into body fluids, they termed circulating miRNAs, and they have been recognized as more effective and accurate biomarkers than classical serum markers. This study examined serum profile of miRNAs through massive parallel sequencing in response to prolonged endurance exercise in samples obtained from four competitive Arabian horses before and 2 h after the end of competition. MicroRNA identification, differential gene expression (DGE) analysis and a protein-protein interaction (PPI) network showing significantly enriched pathways of target gene clusters, were assessed and explored. Our results show modulation of more than 100 miRNAs probably arising from tissues involved in exercise responses and indicating the modulation of correlated processes as muscle remodeling, immune and inflammatory responses. Circulating miRNA high-throughput sequencing is a promising approach for sports medicine for the discovery of putative biomarkers for predicting risks related to prolonged activity and monitoring metabolic adaptations.

Effects of Traumeel (Tr14) on recovery and inflammatory immune response after repeated bouts of exercise: a double-blind RCT

PURPOSE

The purpose of this double-blind, randomized, placebo-controlled clinical trial was to investigate the effects of the natural combination medicine Traumeel (Tr14) consisting of 14 diluted biological and mineral components on the inflammatory immune response and recovery up to 72 h after repetitive bouts of bicycle tests.

METHODS

Antigen-stimulated IL-1ra and IL-6 were defined as primary outcome measures. Moreover, various immunological and serum muscle damage markers were investigated. The evaluation was performed using the score of the area under the curve with respect to increase (AUC_i) for 24 and 72 h after the second exercise test (EX2).

RESULTS

The Tr14 group indicated a lower decrease of lymphocytes by tendency (p = 0.06) and a lower activation of lymphocyte activation markers (CD62L absolute: p = 0.04; CD69: p = 0.01 and CD69 absolute: p = 0.05) in the period 24 h after EX2. In addition, the Tr14 group indicated a higher expression of antigen-stimulated CCL3 (p = 0.01), CCL4 (p = 0.07) and serum CCL2 (p = 0.05) in the period 24 h after EX2. There was a tendentially lower decrease of monocytes (p = 0.09) and a lower expression of antigen-stimulated MMP-3 (p = 0.01) in the Tr14 group in the period 72 h after EX2. However, antigen-stimulated IL-1ra and IL-6 showed no group differences.

CONCLUSION

In line with the previous results, it was shown that Tr14 attenuates the adaptive immune response partially. Furthermore, the results indicate that Tr14 is able to stimulate the innate immune system via an increased production of pro-inflammatory chemokines. It is speculated that the higher expression of chemokines might play a role in the regeneration and recovery after exercise.

Leg Power As an Indicator of Risk of Injury or Illness in Police Recruits

Tactical trainees, like those entering the police force, are required to undergo vigorous training as part of their occupational preparation. This training has the potential to cause injuries. In addition, the physical training, communal living and pressures of tactical training are known to induce immune suppression and have the potential to increase the risk of illness. The aim of this study was to investigate the relationship between leg power, as measured by a vertical jump (VJ), and rates of reported injuries and illnesses during police recruit training. Retrospective data from recruits (n = 1021) undergoing basic police recruit training at an Australian Police Force College was collected. Recruits completed a VJ assessment at the commencement of their second state of training. Formally reported illness and injuries were collected 12 weeks later, following completion of training. Correlations between VJ height and rates of reported illness and injury were low (r = −0.16 and −0.09, respectively) but significant (p < 0.005), with VJ height accounting for 2.6% and 0.8% of the variance in illness and injury rates, respectively. In terms of relative risks, recruits with the lowest recorded VJ heights were more than three times as likely as those with highest VJ heights to suffer injury and/or illness. Police recruits with lower VJ height are at a significantly greater risk of suffering an injury or illness during police basic recruit training.

Effects of carbohydrate ingestion on acute leukocyte, cortisol, and interleukin-6 response in high-intensity long-distance running

The purpose of this study was to investigate the effect of ingestion of fluids with different carbohydrate concentrations (0, 1.5, and 7%) on the acute immune stress responses after high-intensity long-distance running. Continuous 18- to 20-km run was performed at 75% of maximal oxygen uptake with carbohydrate supplementation (CHO7%, 7% carbohydrate solution) and low-carbohydrate supplementation (lowCHO1.5%, 1.5% carbohydrate solution) in a randomized, double-blind, placebo (PLA) controlled design. Seven recreational runners (4 men and 3 women) completed all 3 trials. Blood was collected at baseline (PRE) and immediately after the run (POST). The running task induced significant (p ≤ 0.05) increases in leukocyte (white blood cells), neutrophil, and interleukin-6 (IL-6) counts in every trial. There was a significant (p ≤ 0.05) increase in cortisol with PLA and lowCHO1.5% but not with CHO7%. Increase in total leukocyte and neutrophil concentration was significantly lower with CHO7% compared with PLA (p ≤ 0.05). Postexercise IL-6 levels were significantly elevated when compared with baseline in all conditions (p ≤ 0.05). Interleukin-6 (IL-6) concentrations did not differ significantly between trials. LowCHO1.5% sport drink did not significantly differ from PLA in measured variables, which indicated that the amount and rate of carbohydrate ingestion (15 g, 10 g·h) in low-carbohydrate sport drink was not enough to significantly protect from the stress induced by high-intensity long-distance running, whereas the ingestion of CHO7% (45 g·h) blunted the significant cortisol response and significantly decreased the leukocyte response.

Physical activity and environmental influences on adrenal fatigue of Saudi adults: biochemical analysis and questionnaire survey

[Purpose] This research work was performed to examine whether different levels of physical activity and environmental and social factors are associated with changes in adrenal hormones as markers of adrenal fatigue in Saudi adult volunteers. [Subjects and Methods] A total of 160 Saudi adults aged 15-22 years were included in this study. The adrenal fatigue score, sociodemographic attributes, and the level of physical activity were evaluated via pre-validated internet-based questionnaire surveys. Adrenal hormones such as ACTH and cortisol were measured using immunoassay techniques. [Results] Significant increases in the levels of ACTH and cortisol biomarkers were found in the participants with moderate to severe fatigue scores, poor environmental factors, and low physical activity. However, in physically active participants, significant decreases in ACTH and cortisol levels were found with remarkable improvement in adrenal fatigue status. The decrement in adrenal hormonal levels positively correlated (r= 0.976) with the improvement in adrenal fatigue status in the physically active participants. [Conclusion] Our results suggest that the level of physical activity and environmental and social factors differentially influence the adrenal fatigue status via changes in the levels of adrenal hormones. Also, ACTH and cortisol biomarkers may be useful as markers measuring the severity of adrenal fatigue.

Dano muscular e perfil imunológico no triatlo ironman Brasil

INTRODUÇÃO: O triatlo Ironman se caracteriza por ser uma atividade de longa duração em que alterações orgânicas agudas estão presentes. OBJETIVO: verificar a ocorrência de dano muscular e sua relação com o perfil imunológico em triatletas do Ironman - Brasil. MÉTODOS: A amostra de sangue foi obtida de 21 atletas em três momentos: dois dias antes da prova (pré), imediatamente após a prova (pós) e seis dias após a prova (seis dias pós), em que foram analisadas de forma isolada as variáveis creatinoquinase (CK), os leucócitos totais, linfócitos, subtipos de linfócitos CD4+ e CD8+, e relação CD4+/CD8+ e a correlação da CK como marcador de dano muscular, com as demais variáveis. RESULTADOS: As diferenças significativas foram observadas nos leucócitos pré (média: 6.242,9 mm³; DP: 1.233,3) e pós (média: 18.398,1 mm³; DP: 3.904,0; p < 0,0001); pós (média: 18.398,1 mm³; DP: 3.904,0) e seis dias pós (média: 6.396,4 mm³; DP: 1.299,8; p < 0,0001); CK pré (média: 173,2 U/l; DP: 103,7) e pós (média: 2.339,4 U/l; DP: 1.729,0; p < 0,0001), CK pré (média: 173,2 U/l; DP: 103,7) e seis dias pós (média: 368,1 U/l; DP: 274,4; p < 0,0053); CK pós (média: 2.339,4 U/l; DP: 1.729,0) e seis dias pós (média: 368,1 U/l; DP: 274,4; p < 0,0003); CD4+/CD8+ pré (média: 1,9; DP: 0,8) e seis dias pós (média: 2,4; DP: 1,1: p < 0,00032). CONCLUSÃO: Houve dano muscular no período pós-prova imediato e melhora do perfil imunológico após o sexto dia.

Differences in plasma cytokine levels between elite kayakers and nonathletes

Regular moderate exercise has been shown to have anti-inflammatory effects that help prevent several chronic diseases. However, the effects of chronic training an elite athletes have not been the focus of much research. This study aimed to determine whether there were differences in cytokine levels (IL-1β, IL-1ra, IL-6, IL-10, IL-18, IFN-γ, and TNF-α) in circulating peripheral blood (PB) between elite kayakers and nonathletes. Subjects were 13 elite male kayakers, aged 20.0 ± 3 years, with average body mass of 75.0 ± 7.9 kg and 177.3 ± 7.1 cm height and with a VO_2max of 58.3 ± 7.8 mL·kg⁻¹·min⁻¹. The nonathletes were 7 men, aged 18.2 ± 1.1 years, body mass of 81.3 ± 13.8 kg, and 171.9 ± 4.5 cm height. Blood samples were collected after six weeks of offtraining and before the start of a new training season. PB leukocyte populations were determined by flow cytometry. Cytokine levels were quantified by ELISA. When nonathletes were compared with the kayakers, the latter exhibited lower plasma concentrations of IL-1β, IL-18, and IFN-γ as well as a lower concentration of IL-1ra. Positive correlations between IL-18 and B cells in the athletes were also found. These results seem to reinforce the anti-inflammatory role of regular training.

Changes in lymphocyte and neutrophil function induced by a marathon race

The aim of this study was to investigate the changes in lymphocyte and neutrophil selected functions before and after a marathon race. Fifteen professional athletes were recruited, and the following parameters were measured: plasma concentrations of IL-1ra, IL-6, IL-8, IL-10, TNF-α and C-reactive protein (CRP); neutrophil phagocytic capacity; cytokine production by neutrophils and lymphocytes and signs of neutrophil and lymphocyte death. The marathon race had no effect on CRP levels, but plasma concentrations of IL-6 and IL-1ra were increased. Although no effect was observed on the production of IL-6, IL1-ra, TNF-α, IL-1β and IL-8 by unstimulated or stimulated neutrophils, a decrease in neutrophil phagocytic activity was observed immediately following the marathon. A high percentage of neutrophils undergoing apoptosis was observed due to the intense training regimen, whereas the percentages of apoptotic neutrophils were reduced after the race. The production of IL-2, TNF-α, IL-1β and IL-10 by lymphocytes was decreased by 50%-80%, and the percentage of apoptotic and necrotic lymphocytes was increased by 42% and fourfold, respectively, as a result of the race. In conclusion, the increase in plasma levels of IL-6, IL-8, IL-1ra and IL-10 after the race was not due to the production of the cytokines by neutrophils or lymphocytes. In fact, the marathon led to a decrease in lymphocyte and neutrophil function, and the diminished function was more pronounced in lymphocytes, indicating an impairment in acquired immunity.

Passing the anaerobic threshold is associated with substantial changes in the gene expression profile in white blood cells

High and moderate intensity endurance exercise alters gene expression in human white blood cells (WBCs), but the understanding of how this effect occurs is limited. To increase our knowledge of the nature of this process, we investigated the effects of passing the anaerobic threshold (AnT) on the gene expression profile in WBCs of athletes. Nineteen highly trained skiers participated in a treadmill test with an incremental step protocol until exhaustion (ramp test to exhaustion, RTE). The average total time to exhaustion was 14:40 min and time after AnT was 4:50 min. Two weeks later, seven of these skiers participated in a moderate treadmill test (MT) at 80% peak O(2) uptake for 30 min, which was slightly below their AnTs. Blood samples were obtained before and immediately after both tests. RTE was associated with substantially greater leukocytosis and acidosis than MT. Gene expression in WBCs was measured using whole genome microarray expression analysis before and immediately after each test. A total of 310 upregulated genes were found after RTE, and 69 genes after MT of which 64 were identical to RTE. Both tests influenced a variety of known gene pathways related to inflammation, stress response, signal transduction and apoptosis. A large group of differentially expressed previously unknown small nucleolar RNA and small Cajal body RNA was found. In conclusion, a 15-min test to exhaustion was associated with substantially greater changes of gene expression than a 30-min test just below the AnT.

Cytokine production by monocytes, neutrophils, and dendritic cells is hampered by long-term intensive training in elite swimmers

Elite level athletes seem to be prone to illness especially during heavy training phases. The aim of this study was to investigate the influence of long term intensive training on the functional features of innate immune cells from high competitive level swimmers, particularly the production of inflammatory mediators and the possible relationship with upper respiratory symptoms (URS) occurrence. A group of 18 swimmers and 11 healthy non athletes was studied. Peripheral blood samples were collected from athletes after 36 h of resting recovery from exercise at four times during the training season and at three times from non athletes. Samples were incubated in the presence or absence of LPS and IFN-γ and the frequency of cytokine-producing cells and the amount produced per cell were evaluated by flow cytometry. In addition, plasma cortisol levels were measured and URS recorded through daily logs. The athletes, but not the controls, showed a decrease in the number of monocytes, neutrophils, and dendritic cell (DC) subsets and in the amount of IL-1β, IL-6, IL-12, TNF-α, and MIP-1β produced after stimulation, over the training season. Differences were most noticeable between the first and second blood collections (initial increase in training volume). Athlete's cortisol plasma levels partially correlated with training intensity and could help explain the reduced in vitro cell response to stimulation. Our results support the idea that long-term intensive training may affect the function of innate immune cells, reducing their capacity to respond to acute challenges, possibly contributing to an elevated risk of infection.

Pleuran (β-glucan from Pleurotus ostreatus) supplementation, cellular immune response and respiratory tract infections in athletes

Prolonged and exhausting physical activity causes numerous changes in immunity and sometimes transient increases the risk of upper respiratory tract infections (URTIs). Nutritional supplements as countermeasures to exercise-induced changes have increasingly been studied in the last decade. One of the most promising nutritional supplements is β-glucan, a well-known immunomodulator with positive effects on the function of immunocompetent cells. In this double blind, placebo-controlled study, we investigated the effect of pleuran, an insoluble β-(1,3/1,6) glucan from mushroom Pleurotus ostreatus, on selected cellular immune responses and incidence of URTI symptoms in athletes. Fifty athletes were randomized to pleuran or placebo group, taking pleuran (commercial name Imunoglukan(®)) or placebo supplements during 3 months. Venous whole blood was collected before and after 3 months of supplementation and additionally 3 months after supplementation period was completed. Incidence of URTI symptoms together with characterization of changes in phagocytosis and natural killer (NK) cell count was monitored during the study. We found that pleuran significantly reduced the incidence of URTI symptoms and increased the number of circulating NK cells. In addition, the phagocytosis process remained stable in pleuran group during the study in contrast to placebo group where significant reduction of phagocytosis was observed. These findings indicate that pleuran may serve as an effective nutritional supplement for athletes under heavy physical training. Additional research is needed to determine the mechanisms of pleuran function.

Expression of KIR2DL3 and KIR2DS2 natural killer receptors in exercise

The mechanisms of early activation of natural killers were studied in volunteers of different athletic qualification. The initial levels of expression of KIR2DL2, PRF1, and GZMB genes regulating the functions of natural killer differ in athletes and untrained subjects. Moderate exercise stimulates transcription activities of these genes. In athletes, the expression increases more intensely than in controls. Stimulation of inhibitory (KIR2DL3) and activation (KIR2DS2) receptors was revealed. This indicated nonspecific stimulation of natural killers, probably mediated by an increase in serum concentration of heat shock protein with a molecular weight of 70 kDa.

Completing an ironman triathlon with pneumonia: a case report

Background

Athletes present a different category of the population. Trivial complaints may mask more serious illness, especially when the athlete is undergoing intensive training, and the function of his immune system may be sub-optimal.

Case Presentation

A triathlete presented a few days after completing an Ironman race, complaining of lethargy, pleuritic chest pain and loss of appetite. On examination he was afebrile, tachycardic and had decreased lower left lung air entry accompanied by crackling. A chest x-ray revealed left-sided basal pneumonia with a para-pneumonic effusion. Blood tests were unremarkable. The athlete was treated with oral antibiotics, and was advised to stop exercise completely for eight weeks. He made a full recovery and completed further Ironman races within a year.

Conclusion

The case highlights that clinicians treating elite endurance athletes must exclude severe infection, even when the clinical signs are few or absent. The reason is that if these athletes continue to train, serious complications could ensue due to their compromised resistance to infection.

The use of drugs and nutritional supplements in top-level track and field athletes

BACKGROUND

High use of medication and nutritional supplements has been reported in several sports.

PURPOSE

To document the use of prescribed medication and nutritional supplements in female and male junior, youth, and adult track and field athletes depending on their sports discipline.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Analysis of 3 887 doping control forms undertaken during 12 International Association of Athletics Federations World Championships and 1 out-of-competitions season in track and field.

RESULTS

There were 6 523 nutritional supplements (1.7 per athlete) and 3 237 medications (0.8 per athlete) reported. Nonsteroidal anti-inflammatory drugs (NSAIDs; 0.27 per athlete, n = 884), respiratory drugs (0.21 per athlete, n = 682), and alternative analgesics (0.13, n = 423) were used most frequently. Medication use increased with age (0.33 to 0.87 per athlete) and decreased with increasing duration of the event (from sprints to endurance events; 1.0 to 0.63 per athlete). African and Asian track and field athletes reported using significantly fewer supplements (0.85 vs 1.93 per athlete) and medications (0.41 vs 0.96 per athlete) than athletes from other continents. The final ranking in the championships was unrelated to the quantity of reported medications or supplements taken. Compared with middle-distance and long-distance runners, athletes in power and sprint disciplines reported using more NSAIDs, creatine, and amino acids, and fewer antimicrobial agents.

CONCLUSION

The use of NSAIDs in track and field is less than that reported for team-sport events. However, nutritional supplements are used more than twice as often as they are in soccer and other multisport events; this inadvertently increases the risk of positive results of doping tests.

CLINICAL RELEVANCE

It is essential that an evidence-based approach to the prescribing of medication and nutritional supplements is adopted to protect the athletes' health and prevent them from testing positive in doping controls.

Imunoglobulina A salivar (IgA-s) e exercício: relevância do controle em atletas e implicações metodológicas

O objetivo do presente estudo é realizar uma análise e discussão dos principais achados envolvendo o comportamento da imunoglobulina A salivar (IgA-s) em relação ao estímulo do exercício e evidenciar a importância de seu controle em atletas. O exercício físico é um importante modulador das características do sistema imune, sobretudo do comportamento da IgA-s, componente fundamental na proteção de infecções do trato respiratório superior (ITRS). No entanto, a relação direta entre baixas concentrações de IgA-s e ITRS precisa de mais evidências para ser confirmada. As concentrações de IgA-s durante e logo após um exercício intenso diminuem, deixando o indivíduo mais suscetível à infecção, porém, atletas envolvidos em atividades extenuantes não são clinicamente imunodeficientes, comparados com indivíduos sedentários. Essas modificações são transitórias, com retorno aos valores normais após aproximadamente 48 horas de repouso. A razão dessas alterações não é clara, mas se apresenta multifatorial: elevação de hormônios estressores; fatores nutricionais; ação de espécies reativas de oxigênio; e estresse psicológico. Apesar do efeito transitório das alterações provocadas nos elementos do sistema imune frente ao exercício, observa-se diferença na variabilidade da IgA-s em populações com diferentes níveis de condicionamento. Diferenças metodológicas - como o protocolo de exercício, o método de coleta, armazenamento e manipulação da saliva, a forma de expressão da IgA-s, o nível de hidratação, o controle da dieta, a sazonalidade do período de competição, a aclimatação entre outros fatores - devem ser levadas em consideração para comparação entre os estudos. Além disso, ajudam a explicar, em parte, os resultados adversos envolvendo exercício moderado e os intermitentes, em que se encontram aumento, redução e até ausência de alteração nos níveis de IgA-s. Investigações de elementos inovadores, como os toll-like receptors, e o avanço tecnológico podem colaborar para aumentar as evidências sobre o tema.

The Pro- and Anti-Inflammatory Cytokine Response to Exercise in Adolescent Swimmers

OBJECTIVE

Whether or not individuals with allergy and asthma experience different patterns of change in the balance of both pro- and anti-inflammatory mediators with acute exercise is not known. We hypothesized that adolescent swimmers with a clinical diagnosis of respiratory allergy would have an exaggerated proinflammatory response to laboratory exercise relative to a no-allergy comparison group.

METHODS

Adolescent swimmers (17 with clinical symptoms of respiratory allergy (CSRA) and 17 in comparison group) completed the American Thoracic Society (ATS) exercise challenge on cycle ergometer. Blood was collected at baseline and immediately post-exercise. All study tests were conducted at the Institute for Clinical Translational Science at the University of California, Irvine. Circulating cytokines, growth factors, and adhesion molecules were measured using ELISAs including transforming growth factor-β1 (TGF-β1), tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), IL-6, IL-10, P-selectin, and immunoglobulin E (IgE).

RESULTS

There was a trend toward higher resting levels of TNF-α in the CSRA group (P = 0.076). Exercise induced a significant increase in P-selectin and TGF-β1 in both groups. TNF-α increased significantly (17%) in the comparison group (pre = 0.6, post = 0.7 pg/mL), but not in the CSRA group. IL-6 increased significantly in the CSRA group (pre = 0.7, post = 0.8 pg/mL), but not in the comparison group. Circulating levels of IL-4 and IL-10 were not altered immediately post-exercise in either group.

CONCLUSIONS

A short bout of intense exercise increased inflammatory growth factors and adhesion molecules, namely TGF-β1 and P-selectin, both of which are known to be involved in allergic airway diseases. Differences in resting IL-6 and TNF-α and exercise alterations in these cytokines may also contribute to allergic disease in adolescent elite swimmers.

Circulating T-regulatory cells, exercise and the elite adolescent swimmer

Brief high intensity exercise induces peripheral leukocytosis possibly leading to a higher incidence of allergic symptoms in athletes undergoing excessive training. We studied the exercise-induced alternation of circulating Tregs and FoxP3+ Tregs due to acute intense swim exercise in elite swimmers (n = 22, 12 males, age = 15.4 yrs). Twelve had prior or current rhinitis or asthma and 10 had no current or prior allergy or asthma. Circulating Tregs increased significantly (p < .001) following exercise (pre = 133 +/- 11.2, post = 196 +/- 17.6) as did FoxP3+ cells (pre = 44, post = 64 cells/microl). Increases in Tregs and FoxP3+ Tregs occurred to the same extent in both groups of adolescent swimmers.

Effects of L-citrulline oral supplementation on polymorphonuclear neutrophils oxidative burst and nitric oxide production after exercise

Seventeen volunteer male professional cyclists were randomly assigned to control or supplemented (6 g L-citrulline-malate) groups and participated in a cycling stage. Blood samples were taken in basal conditions, after the race and 3 h post-race. Citrulline supplementation significantly increased plasma concentration of both arginine and citrulline after the stage only in the supplemented group. Polymorphonuclear neutrophils (PMNs) from controls responded to exercise with a progressive decrease in ROS production. Supplemented PMNs significantly increased ROS production after exercise compared to basal values and diminished to values lower than basal at recovery. PMN nitrite concentration was significantly higher after exercise and recovery only in the supplemented group. Markers of oxidative damage-CK, LDH, malondialdehyde-and DNA damage remained unchanged in both groups. In conclusion, oral L-citrulline administration previous to a cycling stage increases plasma arginine availability for NO synthesis and PMNs priming for oxidative burst without oxidative damage.

The level of physical activity affects adrenal and cardiovascular reactivity to psychosocial stress

Physical activity plays a key role in the control of neuroendocrine, autonomic, and behavioral responses to physical and psychosocial stress. However, little is known about how the level of physical activity modulates stress responsiveness. Here, we test whether different levels of physical activity are associated with different adrenal, cardiovascular, and psychological responses to psychosocial stress. In addition, competitiveness is assessed as a personality trait that possibly modulates the relationship between physical activity and stress reactivity. Eighteen elite sportsmen, 50 amateur sportsmen, and 24 untrained men were exposed to a standardized psychosocial laboratory stressor (Trier Social Stress Test). Repeated measures of salivary free cortisol, heart rate, and psychological responses to psychosocial stress were compared among the 3 study groups. Elite sportsmen exhibited significantly lower cortisol, heart rate, and state anxiety responses compared with untrained subjects. Amateur sportsmen showed a dissociation between sympathetic and hypothalamic-pituitary-adrenal responsiveness to stress, with significantly reduced heart rate responses but no difference in cortisol responses compared with untrained men. Different levels of competitiveness among groups did not mediate stress reactivity. Our results are in line with previous studies indicating reduced reactivity of the autonomic nervous system to psychosocial stress in trained individuals. More importantly, these findings imply a differential effect of the level of physical activity on different stress-related neurophysiological systems in response to psychosocial stress.

Dosing and efficacy of glutamine supplementation in human exercise and sport training

Some athletes can have high intakes of l-glutamine because of their high energy and protein intakes and also because they consume protein supplements, protein hydrolysates, and free amino acids. Prolonged exercise and periods of heavy training are associated with a decrease in the plasma glutamine concentration and this has been suggested to be a potential cause of the exercise-induced immune impairment and increased susceptibility to infection in athletes. However, several recent glutamine feeding intervention studies indicate that although the plasma glutamine concentration can be kept constant during and after prolonged strenuous exercise, the glutamine supplementation does not prevent the postexercise changes in several aspects of immune function. Although glutamine is essential for lymphocyte proliferation, the plasma glutamine concentration does not fall sufficiently low after exercise to compromise the rate of proliferation. Acute intakes of glutamine of approximately 20-30 g seem to be without ill effect in healthy adult humans and no harm was reported in 1 study in which athletes consumed 28 g glutamine every day for 14 d. Doses of up to 0.65 g/kg body mass of glutamine (in solution or as a suspension) have been reported to be tolerated by patients and did not result in abnormal plasma ammonia levels. However, the suggested reasons for taking glutamine supplements (support for immune system, increased glycogen synthesis, anticatabolic effect) have received little support from well-controlled scientific studies in healthy, well-nourished humans.

Ecologic immunology of avian influenza (H5N1) in migratory birds

Studies do not support the claim that migratory birds can spread highly pathogenic avian influenza (H5N1) over long distances.

The claim that migratory birds are responsible for the long-distance spread of highly pathogenic avian influenza viruses of subtype H5N1 rests on the assumption that infected wild birds can remain asymptomatic and migrate long distances unhampered. We critically assess this claim from the perspective of ecologic immunology, a research field that analyzes immune function in an ecologic, physiologic, and evolutionary context. Long-distance migration is one of the most demanding activities in the animal world. We show that several studies demonstrate that such prolonged, intense exercise leads to immunosuppression and that migratory performance is negatively affected by infections. These findings make it unlikely that wild birds can spread the virus along established long-distance migration pathways. However, infected, symptomatic wild birds may act as vectors over shorter distances, as appears to have occurred in Europe in early 2006.

Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise

PURPOSE

To investigate the effects of quercetin supplementation on incidence of upper respiratory tract infections (URTI) and exercise-induced changes in immune function.

METHODS

Trained male cyclists (N=40) were randomized to quercetin (N=20) or placebo (N=20) groups and, under double-blind procedures, received 3 wk quercetin (1000 mg.d(-1)) or placebo before, during, and for 2 wk after a 3-d period in which subjects cycled for 3 h.d(-1) at approximately 57% Wmax. Blood and saliva samples were collected before and after each of the three exercise sessions and assayed for natural killer cell activity (NKCA), PHA-stimulated lymphocyte proliferation (PHA-LP), polymorphonuclear oxidative-burst activity (POBA), and salivary IgA output (sIgA).

RESULTS

Pre- to postexercise changes in NKCA, PHA-LP, POBA, and sIgA did not differ significantly between quercetin and placebo groups. URTI incidence during the 2-wk postexercise period differed significantly between groups (quercetin=1/20 vs placebo=9/20, Kaplan-Meier analysis statistic=8.31, P=0.004).

CONCLUSION

Quercetin versus placebo ingestion did not alter exercise-induced changes in several measures of immune function, but it significantly reduced URTI incidence in cyclists during the 2-wk period after intensified exercise.