The haematological, biochemical and immunological profile of athletes suffering from the overtraining syndrome

L-glutamine protects against enterohemorrhagic Escherichia coli infection by inhibiting bacterial virulence and enhancing host defense concurrently

IMPORTANCE

The type 3 secretion system (T3SS) was obtained in many Gram-negative bacterial pathogens, and it is crucial for their pathogenesis. Environmental signals were found to be involved in the expression regulation of T3SS, which was vital for successful bacterial infection in the host. Here, we discovered that L-glutamine (Gln), the most abundant amino acid in the human body, could repress enterohemorrhagic Escherichia coli (EHEC) T3SS expression via nitrogen metabolism and therefore had potential as an antivirulence agent. Our in vitro and in vivo evidence demonstrated that Gln could decline EHEC infection by attenuating bacterial virulence and enhancing host defense simultaneously. We repurpose Gln as a potential treatment for EHEC infection accordingly.

Glutamine deficiency shifts the asthmatic state toward neutrophilic airway inflammation

Background

The administration of L‐glutamine (Gln) suppresses allergic airway inflammation via the rapid upregulation of MAPK phosphatase (MKP)‐1, which functions as a negative regulator of inflammation by deactivating p38 and JNK mitogen‐activated protein kinases (MAPKs). However, the role of endogenous Gln remains to be elucidated. Therefore, we investigated the mechanism by which endogenous Gln regulates MKP‐1 induction and allergic airway inflammation in an ovalbumin‐based murine asthma model.

Methods

We depleted endogenous Gln levels using L‐γ‐glutamyl‐p‐nitroanilide (GPNA), an inhibitor of the Gln transporter ASCT2 and glutamine synthetase small interfering siRNA. Lentivirus expressing MKP‐1 was injected to achieve overexpression of MKP‐1. Asthmatic phenotypes were assessed using our previously developed ovalbumin‐based murine model, which is suitable for examining sequential asthmatic events, including neutrophil infiltration. Gln levels were analyzed using a Gln assay kit.

Results

GPNA or glutamine synthetase siRNA successfully depleted endogenous Gln levels. Importantly, homeostatic MKP‐1 induction did not occur at all, which resulted in prolonged p38 MAPK and cytosolic phospholipase A₂ (cPLA₂) phosphorylation in Gln‐deficient mice. Gln deficiency augmented all examined asthmatic reactions, but it exhibited a strong bias toward increasing the neutrophil count, which was not observed in MKP‐1‐overexpressing lungs. This neutrophilia was inhibited by a cPLA₂ inhibitor and a leukotriene B4 inhibitor but not by dexamethasone.

Conclusion

Gln deficiency leads to the impairment of MKP‐1 induction and activation of p38 MAPK and cPLA₂, resulting in the augmentation of neutrophilic, more so than eosinophilic, airway inflammation.

Physical Fitness and Inflammatory Response to the Training Load of Wheelchair Rugby Players

The aim of the study was the evaluation of the hormonal response of wheelchair rugby participants under the half-year training cycle. The study sample included 11 members of the Polish national wheelchair rugby team with spinal cord injury at the cervical level, ranging in age from 21 to 41 years, body weight (72.2 ± 11.53 kg), and body height (182.3 ± 6.11 cm). The disabled individuals with spinal cord injury subjected to the study constitute a homogeneous group in terms of age, body height, weight, and injury level. The study was carried out at the beginning and at the end of a 6-month training period. In the first and second examination, measurements of the peak oxygen uptake (peakVO₂) and blood biochemical analysis were performed (Lactate dehydrogenase (LDH) activity and concentration of creatinine (Cr), total testosterone (TT), free testosterone (FT), and cortisol (C)). A significant change was observed in the concentration of C in the Wheelchair Rugby players’ blood between two research periods (p < 0.05 (ES:0.76)) and a correlation between the post-training change in FT/C concentration and the change in Cr concentration (r = −0.6014, p < 0.05). The 6-month training period did not result in overloads within the group of players. However, due to the significant loss of the capacity of the spinal cord injury (SCI) and the possibility of a life-threatening trend, the anabolic/catabolic status of the players should be monitored using blood biochemical indices.

Association Between Changes in Serum and Skeletal Muscle Metabolomics Profile With Maximum Power Output Gains in Response to Different Aerobic Training Programs: The Times Study

Purpose: High heterogeneity of the response of cardiorespiratory fitness (CRF) to standardized exercise doses has been reported in different training programs, but the associated mechanisms are not widely known. This study investigated whether changes in the metabolic profile and pathways in blood serum and the skeletal muscle are associated with the inter-individual variability of CRF responses to 8-wk of continuous endurance training (ET) or high-intensity interval training (HIIT).

Methods: Eighty men, young and sedentary, were randomized into three groups, of which 70 completed 8 wk of intervention (> 90% of sessions): ET, HIIT, or control. Blood and vastus lateralis muscle tissue samples, as well as the measurement of CRF [maximal power output (MPO)] were obtained before and after the intervention. Blood serum and skeletal muscle samples were analyzed by 600 MHz ¹H-NMR spectroscopy (metabolomics). Associations between the pretraining to post-training changes in the metabolic profile and MPO gains were explored via three analytical approaches: (1) correlation between pretraining to post-training changes in metabolites' concentration levels and MPO gains; (2) significant differences between low and high MPO responders; and (3) metabolite contribution to significantly altered pathways related to MPO gains. After, metabolites within these three levels of evidence were analyzed by multiple stepwise linear regression. The significance level was set at 1%.

Results: The metabolomics profile panel yielded 43 serum and 70 muscle metabolites. From the metabolites within the three levels of evidence (15 serum and 4 muscle metabolites for ET; 5 serum and 1 muscle metabolites for HIIT), the variance in MPO gains was explained: 77.4% by the intervention effects, 6.9, 2.3, 3.2, and 2.2% by changes in skeletal muscle pyruvate and valine, serum glutamine and creatine phosphate, respectively, in ET; and 80.9% by the intervention effects; 7.2, 2.2, and 1.2% by changes in skeletal muscle glycolate, serum creatine and creatine phosphate, respectively, in HIIT. The most changed and impacted pathways by these metabolites were: arginine and proline metabolism, glycine, serine and threonine metabolism, and glyoxylate and dicarboxylate metabolism for both ET and HIIT programs; and additional alanine, aspartate and glutamate metabolism, arginine biosynthesis, glycolysis/gluconeogenesis, and pyruvate metabolism for ET.

Conclusion: These results suggest that regulating the metabolism of amino acids and carbohydrates may be a potential mechanism for understanding the inter-individual variability of CRF in responses to ET and HIIT programs.

Diagnosing Overtraining Syndrome: A Scoping Review

Context:

Overtraining syndrome (OTS) is a condition characterized by a long-term performance decrement, which occurs after a persisting imbalance between training-related and nontraining-related load and recovery. Because of the lack of a gold standard diagnostic test, OTS remains a diagnosis of exclusion.

Objective:

To systematically review and map biomarkers and tools reported in the literature as potentially diagnostic for OTS.

Data Sources:

PubMed, Web of Science, and SPORTDiscus were searched from database inception to February 4, 2021, and results screened for eligibility. Backward and forward citation tracking on eligible records were used to complement results of database searching.

Study Selection:

Studies including athletes with a likely OTS diagnosis, as defined by the European College of Sport Science and the American College of Sports Medicine, and reporting at least 1 biomarker or tool potentially diagnostic for OTS were deemed eligible.

Study Design:

Scoping review following the guidelines of the Joanna Briggs Institute and PRISMA Extension for Scoping Reviews (PRISMA-ScR).

Level of Evidence:

Level 4.

Data Extraction:

Athletes’ population, criteria used to diagnose OTS, potentially diagnostic biomarkers and tools, as well as miscellaneous study characteristics were extracted.

Results:

The search yielded 5561 results, of which 39 met the eligibility criteria. Three diagnostic scores, namely the EROS-CLINICAL, EROS-SIMPLIFIED, and EROS-COMPLETE scores (EROS = Endocrine and Metabolic Responses on Overtraining Syndrome study), were identified. Additionally, basal hormone, neurotransmitter and other metabolite levels, hormonal responses to stimuli, psychological questionnaires, exercise tests, heart rate variability, electroencephalography, immunological and redox parameters, muscle structure, and body composition were reported as potentially diagnostic for OTS.

Conclusion:

Specific hormones, neurotransmitters, and metabolites, as well as psychological, electrocardiographic, electroencephalographic, and immunological patterns were identified as potentially diagnostic for OTS, reflecting its multisystemic nature. As exemplified by the EROS scores, combinations of these variables may be required to diagnose OTS. These scores must now be validated in larger samples and within female athletes.

Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities

The symptom similarities between training-overload (with or without an Overtraining Syndrome (OTS) diagnosis) and Relative Energy Deficiency in Sport (RED-S) are significant, with both initiating from a hypothalamic-pituitary origin, that can be influenced by low carbohydrate (CHO) and energy availability (EA). In this narrative review we wish to showcase that many of the negative outcomes of training-overload (with, or without an OTS diagnosis) may be primarily due to misdiagnosed under-fueling, or RED-S, via low EA and/or low CHO availability. Accordingly, we undertook an analysis of training-overload/OTS type studies that have also collected and analyzed for energy intake (EI), CHO, exercise energy expenditure (EEE) and/or EA. Eighteen of the 21 studies (86%) that met our criteria showed indications of an EA decrease or difference between two cohorts within a given study (n = 14 studies) or CHO availability decrease (n = 4 studies) during the training-overload/OTS period, resulting in both training-overload/OTS and RED-S symptom outcomes compared to control conditions. Furthermore, we demonstrate significantly similar symptom overlaps across much of the OTS (n = 57 studies) and RED-S/Female Athlete Triad (n = 88 studies) literature. It is important to note that the prevention of under-recovery is multi-factorial, but many aspects are based around EA and CHO availability. Herein we have demonstrated that OTS and RED-S have many shared pathways, symptoms, and diagnostic complexities. Substantial attention is required to increase the knowledge and awareness of RED-S, and to enhance the diagnostic accuracy of both OTS and RED-S, to allow clinicians to more accurately exclude LEA/RED-S from OTS diagnoses.

Urinary Catecholamines as Markers in Overtraining Syndrome

In this study, potential urinary markers that show the presence of overtraining syndrome (OTS) were investigated. After a hard training period without an optimal recovery, OTS could appear in athletes. This syndrome could result in a decreasing of performance, a state of chronic fatigue and a not well-being state. The search for markers that demonstrate the presence of OTS could prevent the physiological and psychological health of the athletes, improving the performance.In this chapter, we will analyze some studies that have examined biochemical, physiological, and immunological markers of overtraining in urine and the variation of the catecholamines in a situation of stressed training.

Effects of military training on plasma amino acid concentrations and their associations with overreaching

IMPACT STATEMENT

The diagnosis of overtraining syndrome and overreaching poses a great challenge. Military training aims at improving the physical performance of the conscripts, but an excessive training load could also lead to overreaching. This study of Finnish conscripts provides new insights into the pathophysiology of overreaching and overtraining through amino acids concentrations. In addition to confirming the possible use of plasma glutamine/glutamate concentration to indicate and predict overreaching, we made a novel finding, i.e. low alanine and arginine concentrations might have a role in performance decrement and fatigue related to overreaching. Moreover, this study is the first to show the possible association between amino acids with putative neuronal properties and overreaching. Thus, the present findings might help to detect and prevent overreaching and offer a reliable diagnostic approach. In order to avoid overreaching, military training should be planned more periodically and individually, especially during the first four weeks of military service.

Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition

Glutamine is a conditionally essential amino acid widely used in sports nutrition, especially because of its immunomodulatory role. Notwithstanding, glutamine plays several other biological functions, such as cell proliferation, energy production, glycogenesis, ammonia buffering, maintenance of the acid-base balance, among others. Thus, this amino acid began to be investigated in sports nutrition beyond its effect on the immune system, attributing to glutamine various properties, such as an anti-fatigue role. Considering that the ergogenic potential of this amino acid is still not completely known, this review aimed to address the main properties by which glutamine could delay fatigue, as well as the effects of glutamine supplementation, alone or associated with other nutrients, on fatigue markers and performance in the context of physical exercise. PubMed database was selected to examine the literature, using the keywords combination “glutamine” and “fatigue”. Fifty-five studies met the inclusion criteria and were evaluated in this integrative literature review. Most of the studies evaluated observed that glutamine supplementation improved some fatigue markers, such as increased glycogen synthesis and reduced ammonia accumulation, but this intervention did not increase physical performance. Thus, despite improving some fatigue parameters, glutamine supplementation seems to have limited effects on performance.

Performance and altitude: Ways that nutrition can help

High altitudes are a challenge for human physiology and for sports enthusiasts. Several reasons lead to deterioration in performance at high altitudes. Hypoxia owing to high altitude causes a breakdown of homeostasis with imbalance in several physiological systems, including the immune system. The reduction in mucosal immunity and inflammation and the predominance of the humoral immune response causes a condition of immunosuppression and an increased likelihood of infection. In addition, it is known that worsening of the immune response is associated with reduced performance. On the other hand, immunonutrition plays an important role in modulating the effects of physical exercise on the immune system. However, to our knowledge, few studies have evaluated the effect of nutrition on the immune system after exercise in hypoxia. Although the association between exercise and hypoxia has been shown to be more severe for the body owing to the sum of stressful agents, supplementation with carbohydrates and glutamine seems to play a relevant role in mitigating immunosuppressive effects. These findings, although limited by the fact that they are the result of very few studies, shed light on a relevant theme for sports physiology and nutrition and suggest that both supplements may be useful for athletes, visitors, and workers in high-altitude regions. The aim of this review was to discuss the effects of high-altitude hypoxia on the human body from the point of view of exercise immunology because it is known that transient immunosuppression after strenuous exercise and competition should be followed by reduction in training overload and worse performance.

Beneficial Autophagic Activities, Mitochondrial Function, and Metabolic Phenotype Adaptations Promoted by High-Intensity Interval Training in a Rat Model

The effects of high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) on basal autophagy and mitochondrial function in cardiac and skeletal muscle and plasma metabolic phenotypes have not been clearly characterized. Here, we investigated how 10-weeks HIIT and MICT differentially modify basal autophagy and mitochondrial markers in cardiac and skeletal muscle and conducted an untargeted metabolomics study with proton nuclear magnetic resonance (¹H NMR) spectroscopy and multivariate statistical analysis of plasma metabolic phenotypes. Male Sprague–Dawley rats were separated into three groups: sedentary control (SED), MICT, and HIIT. Rats underwent evaluation of exercise performance, including exercise tolerance and grip strength, and blood lactate levels were measured immediately after an incremental exercise test. Plasma samples were analyzed by ¹H NMR. The expression of autophagy and mitochondrial markers and autophagic flux (LC3II/LC3-I ratio) in cardiac, rectus femoris, and soleus muscle were analyzed by western blotting. Time to exhaustion and grip strength increased significantly following HIIT compared with that in both SED and MICT groups. Compared with those in the SED group, blood lactate level, and the expression of SDH, COX-IV, and SIRT3 significantly increased in rectus femoris and soleus muscle of both HIIT and MICT groups. Meanwhile, SDH and COX-IV content of cardiac muscle and COX-IV and SIRT3 content of rectus femoris and soleus muscle increased significantly following HIIT compared with that following MICT. The expression of LC3-II, ATG-3, and Beclin-1 and LC3II/LC3-I ratio were significantly increased only in soleus and cardiac muscle following HIIT. These data indicate that HIIT was more effective for improving physical performance and facilitating cardiac and skeletal muscle adaptations that increase mitochondrial function and basal autophagic activities. Moreover, ¹H NMR spectroscopy and multivariate statistical analysis identified 11 metabolites in plasma, among which fine significantly and similarly changed after both HIIT and MICT, while BCAAs isoleucine, leucine, and valine and glutamine were changed only after HIIT. Together, these data indicate distinct differences in specific metabolites and autophagy and mitochondrial markers following HIIT vs. MICT and highlight the value of metabolomic analysis in providing more detailed insight into the metabolic adaptations to exercise training.

An attempt to induce an immunomodulatory effect in rowers with spirulina extract

Background

The aim of this study was to analyze the response of selected components of the immune system in rowers to maximal physical exercise, and to verify if this response can be modulated by supplementation with spirulina (cyanobacterium Spirulina platensis).

Method

The double-blind study included 19 members of the Polish Rowing Team. The subjects were randomly assigned to the supplemented group (n = 10), receiving 1500 mg of spirulina extract for 6 weeks, or to the placebo group (n = 9). The participants performed a 2000-m test on a rowing ergometer at the beginning (1st examination) and at the end of the supplementation period (2nd examination). Blood samples were obtained from the antecubital vein prior to each exercise test, 1 min after completing the test, and after a 24-h recovery period. Subpopulations of T regulatory lymphocytes (Tregs) [CD4+/CD25+/CD127-], cytotoxic lymphocytes (CTLs) [CD8+/TCRαβ+], natural killer (NK) cells [CD3-/CD16+/CD56+] and TCRδγ-positive (Tδγ) cells were determined by means of flow cytometry.

Results

On the 2nd examination, athletes from the supplemented group showed neither a post-exercise increase in Treg count nor a post-recovery decrease in Tδγ cell count (both observed in the placebo group), and presented with significantly lower values of Treg/CTL prior to and after the exercise. During the same examination, rowers from the placebo group showed a significant post-recovery increase in Treg/(NK + Tδγ + CTL) ratio, which was absent in the supplemented group.

Conclusion

The results of this study imply that supplementation with spirulina extract may protect athletes against a deficit in immune function (especially, anti-infectious function) associated with strenuous exercise, and may cause a beneficial shift in "overtraining threshold" preventing a radical deterioration of immunity.

Recovery of the immune system after exercise

The notion that prolonged, intense exercise causes an "open window" of immunodepression during recovery after exercise is well accepted. Repeated exercise bouts or intensified training without sufficient recovery may increase the risk of illness. However, except for salivary IgA, clear and consistent markers of this immunodepression remain elusive. Exercise increases circulating neutrophil and monocyte counts and reduces circulating lymphocyte count during recovery. This lymphopenia results from preferential egress of lymphocyte subtypes with potent effector functions [e.g., natural killer (NK) cells, γδ T cells, and CD8⁺ T cells]. These lymphocytes most likely translocate to peripheral sites of potential antigen encounter (e.g., lungs and gut). This redeployment of effector lymphocytes is an integral part of the physiological stress response to exercise. Current knowledge about changes in immune function during recovery from exercise is derived from assessment at the cell population level of isolated cells ex vivo or in blood. This assessment can be biased by large changes in the distribution of immune cells between blood and peripheral tissues during and after exercise. Some evidence suggests that reduced immune cell function in vitro may coincide with changes in vivo and rates of illness after exercise, but more work is required to substantiate this notion. Among the various nutritional strategies and physical therapies that athletes use to recover from exercise, carbohydrate supplementation is the most effective for minimizing immune disturbances during exercise recovery. Sleep is an important aspect of recovery, but more research is needed to determine how sleep disruption influences the immune system of athletes.

Biological, Hormonal, and Psychological Parameters in Professional Soccer Players Throughout a Competitive Season

We examined changes in the haematological, metabolic, immunological, hormonal, and psychological fields using selected variables in 20 professional soccer players, over the course of a competitive season. The team performance was assessed by computing the winning percentage. A symptom checklist was used to assess the severity of upper respiratory tract infections. A high-intensity training programme induced a significant increase in cortisol and uric acid concentrations. Despite lower glutamine concentrations than the normal range throughout the study, infection occurred only in two of the soccer players. Moreover, the levels of immunological factors IgA, IgG, and IgM, and the haematological parameters were unaltered. Subsequent decreased performance coincided with changes in specific mood states of the team. Our results show some alterations on the metabolic, hormonal, and psychological variables over the five fields studied, suggesting that combined psychological and physiological changes during training are of primary interest to monitor the training stress in relation to performance in team sport.

Impact of intensified training and carbohydrate supplementation on immunity and markers of overreaching in highly trained cyclists

Purpose

To determine effects of intensified training (IT) and carbohydrate supplementation on overreaching and immunity.

Methods

In a randomized, double-blind, crossover design, 13 male cyclists (age 25 ± 6 years, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}O_{2\hbox{max} }$$\end{document}V˙O2max 72 ± 5 ml/kg/min) completed two 8-day periods of IT. On one occasion, participants ingested 2 % carbohydrate (L-CHO) beverages before, during and after training sessions. On the second occasion, 6 % carbohydrate (H-CHO) solutions were ingested before, during and after training, with the addition of 20 g of protein in the post-exercise beverage. Blood samples were collected before and immediately after incremental exercise to fatigue on days 1 and 9.

Results

In both trials, IT resulted in decreased peak power (375 ± 37 vs. 391 ± 37 W, P < 0.001), maximal heart rate (179 ± 8 vs. 190 ± 10 bpm, P < 0.001) and haematocrit (39 ± 2 vs. 42 ± 2 %, P < 0.001), and increased plasma volume (P < 0.001). Resting plasma cortisol increased while plasma ACTH decreased following IT (P < 0.05), with no between-trial differences. Following IT, antigen-stimulated whole blood culture production of IL-1α was higher in L-CHO than H-CHO (0.70 (95 % CI 0.52–0.95) pg/ml versus 0.33 (0.24–0.45) pg/ml, P < 0.01), as was production of IL-1β (9.3 (95 % CI 7–10.4) pg/ml versus 6.0 (5.0–7.8) pg/ml, P < 0.05). Circulating total leukocytes (P < 0.05) and neutrophils (P < 0.01) at rest increased following IT, as did neutrophil:lymphocyte ratio and percentage CD4+ lymphocytes (P < 0.05), with no between-trial differences.

Conclusion

IT resulted in symptoms consistent with overreaching, although immunological changes were modest. Higher carbohydrate intake was not able to alleviate physiological/immunological disturbances.

Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting.

Carbohydrate and glutamine supplementation modulates the Th1/Th2 balance after exercise performed at a simulated altitude of 4500 m

OBJECTIVE

The aim of this study was to evaluate the effect of carbohydrate or glutamine supplementation, or a combination of the two, on the immune system and inflammatory parameters after exercise in simulated hypoxic conditions at 4500 m.

METHODS

Nine men underwent three sessions of exercise at 70% VO2peak until exhaustion as follows: 1) hypoxia with a placebo; 2) hypoxia with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after; and 3) hypoxia after 6 d of glutamine supplementation (20 g/d) and supplementation with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after. All procedures were randomized and double blind. Blood was collected at rest, immediately before exercise, after the completion of exercise, and 2 h after recovery. Glutamine, cortisol, cytokines, glucose, heat shock protein-70, and erythropoietin were measured in serum, and the cytokine production from lymphocytes was measured.

RESULTS

Erythropoietin and interleukin (IL)-6 increased after exercise in the hypoxia group compared with baseline. IL-6 was higher in the hypoxia group than pre-exercise after exercise and after 2 h recovery. Cortisol did not change, whereas glucose was elevated post-exercise in the three groups compared with baseline and pre-exercise. Glutamine increased in the hypoxia + carbohydrate + glutamine group after exercise compared with baseline. Heat shock protein-70 increased post-exercise compared with baseline and pre-exercise and after recovery compared with pre-exercise, in the hypoxia + carbohydrate group. No difference was observed in IL-2 and IL-6 production from lymphocytes. IL-4 was reduced in the supplemented groups.

CONCLUSION

Carbohydrate or glutamine supplementation shifts the T helper (Th)1/Th2 balance toward Th1 responses after exercise at a simulated altitude of 4500 m. The nutritional strategies increased in IL-6, suggesting an important anti-inflammatory effect.

A proteomic study of plasma protein changes under extreme physical stress

The Spartathlon race (brisk walking a distance of 246km in less than 36h) was employed as a model of severe physical stress to investigate proteomic alterations in the plasma of athletes at the start (Athens) and finish (Sparta) of the race, as well as 48h after the race (Post). The athletes' plasma was analyzed by 2D gel electrophoresis (2-DE) and the differentially expressed proteins were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS). The ProteoSeek™ Albumin/IgG removal kit and the ProteoMiner™ enrichment kit were utilized to detect medium- and low-abundance proteins, whose expression may be masked due to high-abundance proteins. Our results were confirmed by Western blot and biochemical analyses. Overall fifty-two proteins were differentially expressed between the starting point, the finishing line and two days after the end of the race. Of these, thirty proteins were involved in inflammation, while the rest concerned anti-oxidation, anti-coagulation and iron and vitamin D transport. These results indicate that prolonged physical stress affects circulating stress-related proteins, which might be employed as biomarkers of stress-related diseases.

BIOLOGICAL SIGNIFICANCE

The current study employed the Spartathlon, as a model of prolonged endurance exercise, to identify and isolate putative biomarkers of inflammation under extreme physical stress conditions. These protein quantitative variations may pave the way to exploration and understanding of stress-related physiological processes, the stress response itself and diseases whose onset appears to be linked to stress.

Prevention, diagnosis, and treatment of the overtraining syndrome: joint consensus statement of the European College of Sport Science and the American College of Sports Medicine

Successful training not only must involve overload but also must avoid the combination of excessive overload plus inadequate recovery. Athletes can experience short-term performance decrement without severe psychological or lasting other negative symptoms. This functional overreaching will eventually lead to an improvement in performance after recovery. When athletes do not sufficiently respect the balance between training and recovery, nonfunctional overreaching (NFOR) can occur. The distinction between NFOR and overtraining syndrome (OTS) is very difficult and will depend on the clinical outcome and exclusion diagnosis. The athlete will often show the same clinical, hormonal, and other signs and symptoms. A keyword in the recognition of OTS might be "prolonged maladaptation" not only of the athlete but also of several biological, neurochemical, and hormonal regulation mechanisms. It is generally thought that symptoms of OTS, such as fatigue, performance decline, and mood disturbances, are more severe than those of NFOR. However, there is no scientific evidence to either confirm or refute this suggestion. One approach to understanding the etiology of OTS involves the exclusion of organic diseases or infections and factors such as dietary caloric restriction (negative energy balance) and insufficient carbohydrate and/or protein intake, iron deficiency, magnesium deficiency, allergies, and others together with identification of initiating events or triggers. In this article, we provide the recent status of possible markers for the detection of OTS. Currently, several markers (hormones, performance tests, psychological tests, and biochemical and immune markers) are used, but none of them meet all the criteria to make their use generally accepted.

Female distance runners show a different response to post-workout consumption of wheat gluten hydrolysate compared to their male counterparts

Wheat gluten hydrolysate (WGH) is rich in glutamyl residue; glutamine is considered a conditionally essential amino acid under physical stress. WGH has been reported to suppress post-exercise rises in serum creatine kinase in male distance runners. This study aimed to reproduce the effects in female distance runners under similar conditions. The study was conducted in a double-blinded crossover manner. Six female collegiate distance runners ingested WGH or a placebo after a 2-h run at an intensity estimated as 60-70% of their maximum oxygen uptake. Blood was sampled before, immediately after, and at 10 and 24 h after the run. Unlike those in male runners, serum creatine kinase (CK) increased slightly, with a peak at 10 h after the run, while plasma glutamine kept declining. The anti-inflammatory effect of WGH was not evident since the post-exercise elevation of CK was ambiguous. Plasma glutamine concentrations also showed a different kinetics from that in men.

Development and characterization of an overtraining animal model

PURPOSE

Development of an endurance training-overtraining protocol for Wistar rats that includes increased workload and is characterized by analyses of performance and biomarkers.

METHODS

The running protocol lasted 11 wk: 8 wk of daily exercise sessions followed by 3 wk of increasing training frequency (two, three, and four times), with decreasing recovery time between sessions (4, 3, and 2 h) to cause an imbalance between overload and recovery. The performance tests were made before training (T1) and after the 4th (T2), 8th (T3), 9th (T4), 10th (T5), and 11th (T6) training weeks. All rats showed significantly increased performance at T4, at which time eight rats, termed the trained group (Tr), were sacrificed for blood and muscle assays. After T6, two groups were distinguishable by differences in the slope (alpha) of a line fitted to the individual performances at T4, T5, and T6: nonfunctional overreaching (NFOR; alpha < -15.05 kg x m) and functional overreaching (FOR; alpha >or= -15.05 kg x m).

RESULTS

Data were presented as mean +/- SD. FOR maintained the performance at T6 similar to Tr at T4 (530.6 +/- 85.3 and 487.5 +/- 61.4 kg x m, respectively). The FOR and the Tr groups showed higher muscle citrate synthase activity (approximately 40%) and plasma glutamine/glutamate ratio (Gm/Ga; 4.5 +/- 1.7 and 4.5 +/- 0.9, respectively) than the sedentary control (CO) group (2.8 +/- 0.5). The NFOR group lost the performance acquired at T4 (407.3 +/- 88.2 kg x m) after T6 (280.5 +/- 93.1 kg x m) and exhibited sustained leukocytosis. NFOR's Gm/Ga (3.1 +/- 0.2) and muscle citrate synthase activity were similar to CO values.

CONCLUSIONS

The decline in performance in the NFOR group could be related to the decrease in muscle oxidative capacity. We observed a trend in the Gm/Ga and leukocytosis that is similar to what has been sometimes observed in overtrained humans. This controlled training-overtraining animal model may be useful for seeking causative mechanisms of performance decline.

Effect of exercise on glutamine synthesis and transport in skeletal muscle from rats

1. Reductions in plasma glutamine are observed after prolonged exercise. Three hypotheses can explain such a decrease: (i) high demand by the liver and kidney; (ii) impaired release from muscles; and (iii) decreased synthesis in skeletal muscle. The present study investigated the effects of exercise on glutamine synthesis and transport in rat skeletal muscle. 2. Rats were divided into three groups: (i) sedentary (SED; n = 12); (ii) rats killed 1 h after the last exercise bout (EX-1; n = 15); and (iii) rats killed 24 h after the last exercise bout (EX-24; n = 15). Rats in the trained groups swam 1 h/day, 5 days/week for 6 weeks with a load equivalent to 5.5% of their bodyweight. 3. Plasma glutamine and insulin were lower and corticosterone was higher in EX-1 compared with SED rats (P < 0.05 and P < 0.01, respectively). Twenty-four hours after exercise (EX-24), plasma glutamine was restored to levels seen in SED rats, whereas insulin levels were higher (P < 0.001) and corticosterone levels were lower (P < 0.01) than in EX-1. In the soleus, ammonia levels were lower in EX-1 than in SED rats (P < 0.001). After 24 h, glutamine, glutamate and ammonia levels were lower in EX-24 than in SED and EX-1 rats (P < 0.001). Soleus glutamine synthetase (GS) activity was increased in EX-1 and was decreased in EX-24 compared with SED rats (both P < 0.001). 4. The decrease in plasma glutamine concentration in EX-1 is not mediated by GS or glutamine transport in skeletal muscle. However, 24 h after exercise, lower GS may contribute to the decrease in glutamine concentration in muscle.

Nutritional ergogenic aids and exercise performance

The use of nutritional supplements in sport is widespread and few serious athletes do not, at some stage in their career, succumb to the temptation to experiment with one or more nutritional supplements. Nutritional ergogenic aids are aimed primarily at enhancing performance (either by affecting energy metabolism or by an effect on the central nervous system), at increasing lean body mass or muscle mass by stimulation of protein synthesis and at reducing body fat content. Although not strictly ergogenic (i.e. capable of enhancing work performance), supplements aimed at increasing resistance to infection and improving general health are seen by athletes as important in reducing the interruptions to training that minor illness and infection can cause. Creatine is perhaps the most widely used supplement in sport at the moment. Supplementation can increase muscle creatine phosphate levels and, although not all published studies show positive results, there is much evidence that performance of short-term high-intensity exercise can be improved by supplementation. Ingestion of large doses of bicarbonate can enhance performance of exercise where metabolic acidosis may be a limiting factor, but there is a significant risk of adverse gastrointestinal side effects. Caffeine can also improve performance, in part by a stimulation of fatty acid mobilization and sparing of the body's limited carbohydrate stores, but also via direct effects on muscle and possibly by central nervous system effects on the perception of effort and fatigue. Carnitine plays an essential role in fatty acid oxidation in muscle but, although supplements are used by athletes, there is no good evidence of a beneficial effect of supplementation. None of these products contravenes the International Olympic Committee regulations on doping in sports, although caffeine is not permitted above a urine concentration of 12 mg/l. Supplementation is particularly prevalent among strength and power athletes, where an increase in muscle mass can benefit performance. Protein supplements have not been shown to be effective except in those rare cases where the dietary protein intake is otherwise inadequate. Individual amino acids, especially ornithine, arginine and glutamine, are also commonly used, but their benefit is not supported by documented evidence. Cr and hydroxymethylbutyrate are also used by strength athletes, but again there are no well-controlled studies to provide evidence of a beneficial effect. Athletes use a wide variety of supplements aimed at improving or maintaining general health and vitamin and mineral supplementation is widespread. There is a theoretical basis, and limited evidence, to support the use of antioxidant vitamins and glutamine during periods of intensive training, but further evidence is required before the use of these supplements can be recommended.

Plasma Glutamine Changes After High-Intensity Exercise in Elite Male Swimmers

The aim of this study was to establish the pattern and time course of plasma glutamine recovery after acute, high-intensity exercise in well-trained swimmers. In Study 1, elite male swimmers (n=8) performed 15 x 100 m swimming intervals (ITS) at 70% and 95% of maximal 100m freestyle time. Resting plasma glutaminle levels were determined on a nonexercise control day (0% ITS). Venous blood samples were obtained prior to, immediately afte;, and 30, 60, 120, and 150 mini postexercise. In Study 2, the 95% ITS was repeated in elite male swuimmers (n=8), while control subjects (n=8) did not exercise, to test for any diurnal variation in plasma glutamine levels. Venous blood samples were obtained prior to and 2, 4, 6, and 8 h postexercise. In Study 1, no change was observed in plasma glutamine following the 0% (control) and 70% ITS, but following the 95% ITS glutamine decreased significantly (p < 0.01) over the recovery period. In Study 2, plasma glutamine again decreased over the recovery period in the swimmers, but no changes were observed in the controls. It was concluded that intensive swim traininlg results in postexercise decreases in plasma glutamine levels. Because glutamine has been suggested as a marker of overtraining, a need to measure glutaminle at standard times within training programs is indicated.

Psychomotor speed: possibly a new marker for overtraining syndrome

Overtraining syndrome (OTS) is a major threat for performance and health in athletes. OTS is caused by high levels of (sport-specific) stress in combination with too little regeneration, which causes performance decrements, fatigue and possibly other symptoms. Although there is general consensus about the causes and consequences, many different terminologies have been used interchangeably. The consequences of overreaching and overtraining are divided into three categories: (i) functional overreaching (FO); (ii) non-functional overreaching (NFO); and (iii) OTS. In FO, performance decrements and fatigue are reversed within a pre-planned recovery period. FO has no negative consequences for the athlete in the long term; it might even have positive consequences. When performance does not improve and feelings of fatigue do not disappear after the recovery period, overreaching has not been functional and is thus called NFO. OTS only applies to the most severe cases. NFO and OTS could be prevented using early markers, which should be objective, not manipulable, applicable in training practice, not too demanding, affordable and should be based on a sound theoretical framework. No such markers exist up to today. It is proposed that psychomotor speed might be such a marker. OTS shows similarities with chronic fatigue syndrome and with major depression (MD). Through two meta-analyses, it is shown that psychomotor slowness is consistently present in both syndromes. This leads to the hypothesis that psychomotor speed is also reduced in athletes with OTS. Parallels between commonly used models for NFO and OTS and a threshold theory support the idea that psychomotor speed is impaired in athletes with NFO or OTS and could also be used as an early marker to prevent NFO and/or OTS.

Monitoring for overreaching in rugby league players

The aim of this study was to identify indicators of non-functional overreaching (NFOR) in team sport athletes undertaking intensive training loads. Eighteen semi-professional rugby league players were randomly assigned into two pair matched groups. One group completed 6 weeks of normal training (NT) whilst the other group was deliberately overreached through intensified training (IT). Both groups then completed the same 7-day stepwise training load reduction taper. Multistage fitness test (MSFT) performance, VO2 (max), peak aerobic running velocity (V (max)), maximal heart rate, vertical jump, 10-s cycle sprint performance and body mass were measured pre- and post-training period and following the taper. Hormonal, haematological and immunological parameters were also measured pre-training and following weeks 2, 4 and 6 of training and post-taper. MANOVA for repeated measures with contrast analysis indicated that MSFT performance and VO2 (max) were significantly reduced in the IT group over time and condition, indicating that a state of overreaching was attained. However, the only biochemical measure that was significantly different between the IT and NT group was the glutamine to glutamate (Gln/Glu) ratio even though testosterone, testosterone to cortisol (T/C) ratio, plasma glutamate, and CK activity were significantly changed after training in both groups. Positive endurance and power performance changes were observed post-taper in the IT group confirming NFOR. These changes were associated with increases in the T/C ratio and the Gln/Glu ratio and decreases in plasma glutamate and CK activity. These results indicate that although there was no single reliable biochemical marker of NFOR in these athletes, the Gln/Glu ratio and MSFT test may be useful measures for monitoring responses to IT in team sport athletes.

Effects of acute exhaustive physical exercise upon glutamine metabolism of lymphocytes from trained rats

Transitory immunosupression is reported after intense exercise, especially after an increase in training overload and in overtraining. The influence of intense exercise on plasma hormones and glutamine concentration may contribute to this effect. However, the effect of such exercise-induced changes upon lymphocyte and glutamine metabolism is not known. We compared glutamine metabolism in lymphocytes in sedentary (SED) and trained rats. Rats from the moderate group (MOD) swam for 6 weeks, 1 h/day, in water at 32+/-1 degrees C, with a load of 5.5% body weight attached to the tail. Animals from the exhaustive group (EXT) trained like MOD, with training increasing to 3 times 1 h a day during the last week, with 150 min rest between each bout. Animals were killed immediately after the last training bout. We observed reduced concentrations of plasma glucose (p<0.05), glutamine (p<0.05), glutamate (p<0.05) in EXT compared to SED. In MOD, decreases in glutamine (p<0.05) were observed. Analyzing lymphocyte metabolism, we observed an increase in lactate production and glutamine consumption (p<0.05) in MOD (p<0.05) compared to SED and a decrease in glutamine consumption (p<0.05) and aspartate production in EXT. An increase in the proliferative response of lymphocytes in MOD and EXT was also observed when stimulated by ConA and LPS similarly to SED. Acute exercise promoted decreased glutamine plasma concentration and changes in glutamine metabolism that did not impair lymphocyte proliferation in exhaustive trained rats.

Oxidative stress : relationship with exercise and training

Free radicals are reactive compounds that are naturally produced in the human body. They can exert positive effects (e.g. on the immune system) or negative effects (e.g. lipids, proteins or DNA oxidation). To limit these harmful effects, an organism requires complex protection - the antioxidant system. This system consists of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase) and non-enzymatic antioxidants (e.g. vitamin E [tocopherol], vitamin A [retinol], vitamin C [ascorbic acid], glutathione and uric acid). An imbalance between free radical production and antioxidant defence leads to an oxidative stress state, which may be involved in aging processes and even in some pathology (e.g. cancer and Parkinson's disease). Physical exercise also increases oxidative stress and causes disruptions of the homeostasis. Training can have positive or negative effects on oxidative stress depending on training load, training specificity and the basal level of training. Moreover, oxidative stress seems to be involved in muscular fatigue and may lead to overtraining.

Plasma glutamine responses to high-intensity exercise before and after endurance training

Glutamine responses to strenuous interval exercise were examined before and after 6 weeks of endurance training. Glutamine measures were obtained before and after the interval exercise sessions and training in untrained males assigned to training (T; n = 10) or control (C; n = 10) groups. Before training, C and T group glutamine progressively decreased (p < 0.05) by 18% and 16%, respectively, by 150-min postinterval exercise. Over the training period C group glutamine did not change, while T group values increased (p < 0.05) by 14%. After training, glutamine again decreased (p < 0.05) by similar percentages (C = 16% and T = 15%) by 150-min postinterval exercise, but the T group recorded higher (p < 0.05) resting and postexercise glutamine concentrations than the C group. Training induced increases in glutamine may prevent the decline in glutamine levels following strenuous exercise falling below a threshold where immune function might be acutely compromised.

Effects of visual occlusion and fatigue on motor performance in water

The purpose of this study was to test the effects of visual occlusion and fatigue on the motor performance of vertical skills in synchronized swimming. Experienced synchronized swimmers (n = 12) were randomly assigned to either an exercise or nonexercise (control) activity group. Subjective ratings of fatigue were obtained from the swimmers who then each performed four vertical skills under alternating conditions of vision and visual occlusion before and after either a swimming (designed to induce fatigue) or nonphysical activity. A main effect of activity (p < .03) was found for two measures of performance accuracy (lateral and anterior total distance traveled) but not for lateral and anterior maximum deviation from vertical, indicating that fatigue played a role in executing the skills. The data also indicate that the maintenance of a stationary position is a skill of greater difficulty than maintaining a true vertical. In contrast with previous research findings on synchronized swimmers, a significant effect of vision in all conditions was found, with performance decrements in the conditions of visual occlusion showing that vision provided important sensory input for the swimmers.

Does overtraining exist? An analysis of overreaching and overtraining research

Athletes experience minor fatigue and acute reductions in performance as a consequence of the normal training process. When the balance between training stress and recovery is disproportionate, it is thought that overreaching and possibly overtraining may develop. However, the majority of research that has been conducted in this area has investigated overreached and not overtrained athletes. Overreaching occurs as a result of intensified training and is often considered a normal outcome for elite athletes due to the relatively short time needed for recovery (approximately 2 weeks) and the possibility of a supercompensatory effect. As the time needed to recover from the overtraining syndrome is considered to be much longer (months to years), it may not be appropriate to compare the two states. It is presently not possible to discern acute fatigue and decreased performance experienced from isolated training sessions, from the states of overreaching and overtraining. This is partially the result of a lack of diagnostic tools, variability of results of research studies, a lack of well controlled studies and individual responses to training.The general lack of research in the area in combination with very few well controlled investigations means that it is very difficult to gain insight into the incidence, markers and possible causes of overtraining. There is currently no evidence aside from anecdotal information to suggest that overreaching precedes overtraining and that symptoms of overtraining are more severe than overreaching. It is indeed possible that the two states show different defining characteristics and the overtraining continuum may be an oversimplification. Critical analysis of relevant research suggests that overreaching and overtraining investigations should be interpreted with caution before recommendations for markers of overreaching and overtraining can be proposed. Systematically controlled and monitored studies are needed to determine if overtraining is distinguishable from overreaching, what the best indicators of these states are and the underlying mechanisms that cause fatigue and performance decrements. The available scientific and anecdotal evidence supports the existence of the overtraining syndrome; however, more research is required to state with certainty that the syndrome exists.

Dietary supplements

For the athlete training hard, nutritional supplements are often seen as promoting adaptations to training, allowing more consistent and intensive training by promoting recovery between training sessions, reducing interruptions to training because of illness or injury, and enhancing competitive performance. Surveys show that the prevalence of supplement use is widespread among sportsmen and women, but the use of few of these products is supported by a sound research base and some may even be harmful to the athlete. Special sports foods, including energy bars and sports drinks, have a real role to play, and some protein supplements and meal replacements may also be useful in some circumstances. Where there is a demonstrated deficiency of an essential nutrient, an increased intake from food or from supplementation may help, but many athletes ignore the need for caution in supplement use and take supplements in doses that are not necessary or may even be harmful. Some supplements do offer the prospect of improved performance; these include creatine, caffeine, bicarbonate and, perhaps, a very few others. There is no evidence that prohormones such as androstenedione are effective in enhancing muscle mass or strength, and these prohormones may result in negative health consequences, as well as positive drug tests. Contamination of supplements that may cause an athlete to fail a doping test is widespread.

Chronic glutamine supplementation increases nasal but not salivary IgA during 9 days of interval training

Oral glutamine supplementation during and after exercise abolishes exercise-induced decreases in plasma glutamine concentration but does not affect secretory IgA (sIgA) salivary output. Whether chronic glutamine supplementation during high-intensity interval training influences salivary and nasal sIgA concentration is unknown. The purpose of this study was examine the effects of chronic glutamine supplementation on sIgA during intense running training. Runners (n = 13, body mass 69.9 +/- 2.8 kg, peak whole body oxygen uptake 55.5 +/- 2 ml.kg(-1).min(-1), age 29.1 +/- 2.8 yr) participated in twice-daily interval training for 9-9.5 days, followed by recovery (5-7 days). Oral glutamine supplement (0.1 g/kg) or placebo was given four times daily for the first 14 days. After an overnight fast, venous blood, nasal washes, and stimulated saliva were collected at baseline (T1), midtraining (T2), posttraining (T3), and after recovery (T4). Mood states were assessed by using Profile of Mood States (POMS) inventories. We found that glutamine concentration in resting subjects decreased from T1 to T4 (P < 0.05) and was not altered by supplementation. Salivary IgA concentration and output were unchanged by training or supplementation. Mean nasal IgA across the study period was greater in runners receiving glutamine (264.7 +/- 35.0 microg/mg protein) vs. placebo (172.4 +/- 33.7 microg/mg protein; P < 0.05). POMS analyses indicated that vigor was lower at T3 vs. T1 (P < 0.05) and fatigue was higher at T2 vs. T1 and T4 (P < 0.05). We conclude that chronic glutamine supplementation during interval training results in higher nasal IgA than placebo but does not affect salivary IgA concentration or output.

Biochemical aspects of overtraining in endurance sports : the metabolism alteration process syndrome

Recent studies have shown that endurance overtraining could result from successive and cumulative alterations in metabolism, which become chronic during training. The onset of this process is a biochemical alteration in carbohydrate (saccharide) metabolism. During endurance exercises, the amount of saccharide chains from two blood glycoproteins (alpha(2)-macroglobulin and alpha(1)-acid glycoprotein) was found to have decreased, i.e. concentrations of these proteins remained unchanged but their quality changed. These saccharide chains were probably used for burning liver glycogen stores during exercise. This step was followed by alterations in lipid metabolism. The most relevant aspect of this step was that the mean chain length of blood fatty acids decreased, i.e. the same amount of fatty acids were found within the blood, but overtrained individuals presented shorter fatty acids than well-trained individuals. This suggests that alterations appeared in the liver synthesis of long-chain fatty acids or that higher peroxidation of blood lipoparticles occurred. For the final step of this overtraining process, it was found that these dysfunctions in carbohydrate/lipid metabolism led to the higher use of amino acids, which probably resulted from protein catabolism. The evolution of three protein concentrations (alpha(1)-acid glycoprotein, alpha(2)-macroglobulin and IgG(3)) correlated with this amino acid concentration increase, suggesting a specific catabolism of these proteins. At this time only, overtraining was clinically diagnosed through conventional symptoms. Therefore, this process described successive alterations in exercise metabolism that shifted from the main energetic stores of exercise (carbohydrates and lipids) towards molecular pools (proteins) normally not substantially used for the energetic supply of skeletal muscles. Now, a general biochemical model of the overtraining process may be proposed which includes most of the previously identified metabolic hypotheses.

'Lyme disease': ancient engine of an unrecognized borreliosis pandemic?

Unexpectedly we have found large numbers of chronically ill Borrelia burgdorferi PCR- and seropositive patients in Houston, Texas, a zoonotically 'non-endemic' area. In order to understand this finding prior to sufficient data availability, we chose to examine critically currently accepted but troublesome 'Lyme disease' concepts. Our method was to analyze each foundation 'Lyme disease' premise within the context of available medical and veterinary literature, then to reconstruct the disease model consistent with the preponderance of that data. We find the present conceptualization of the illness seriously truncated, with a high likelihood of two distinct but connected forms of human B. burgdorferi infection. The yet-unrecognized form appears to have a broader clinical presentation, wider geographic distribution, and vastly greater prevalence. We conclude that 'Lyme disease' currently acknowledges only its zoonosis arm and is a limited conceptualization of a far more pervasive and unrecognized infection state that must be considered a global epidemic.

Biochemical aspects of overtraining in endurance sports: a review

Top-level performances in endurance sports require several years of hard training loads. A major objective of this endurance training is to reach the most elevated metabolic adaptations the athlete will be able to support. As a consequence, overtraining is a recurrent problem that highly-trained athletes may experience during their career. Many studies have revealed that overtraining could be highlighted by various biochemical markers but a principal discrepancy in the diagnosis of overtraining stems from the fact that none of these markers may be considered as universal. In endurance sports, the metabolic aspects of training fatigue appear to be the most relevant parameters that may characterise overtraining when recovery is not sufficient, or when dietary habits do not allow an optimal replenishment of substrate stores. From the skeletal muscle functions to the overall energetic substrate availability during exercise, six metabolic schemes have been studied in relation to overtraining, each one related to a central parameter, i.e. carbohydrates, branched-chain amino acids, glutamine, polyunsaturated fatty acids, leptin, and proteins. We summarise the current knowledge on these metabolic hypotheses regarding the occurrence of overtraining in endurance sports.

Diagnosis of overtraining: what tools do we have?

The multitude of publications regarding overtraining syndrome (OTS or 'staleness') or the short-term 'over-reaching' and the severity of consequences for the athlete are in sharp contrast with the limited availability of valid diagnostic tools. Ergometric tests may reveal a decrement in sport-specific performance if they are maximal tests until exhaustion. Overtrained athletes usually present an impaired anaerobic lactacid performance and a reduced time-to-exhaustion in standardised high-intensity endurance exercise accompanied by a small decrease in the maximum heart rate. Lactate levels are also slightly lowered during submaximal performance and this results in a slightly increased anaerobic threshold. A reduced respiratory exchange ratio during exercise still deserves further investigation. A deterioration of the mood state and typical subjective complaints ('heavy legs', sleep disorders) represent sensitive markers, however, they may be manipulated. Although measurements at rest of selected blood markers such as urea, uric acid, ammonia, enzymes (creatine kinase activity) or hormones including the ratio between (free) serum testosterone and cortisol, may serve to reveal circumstances which, for the long term, impair the exercise performance, they are not useful in the diagnosis of established OTS. The nocturnal urinary catecholamine excretion and the decrease in the maximum exercise-induced rise in pituitary hormones, especially adrenocorticotropic hormone and growth hormone, and, to a lesser degree, in cortisol and free plasma catecholamines, often provide interesting diagnostic information, but hormone measurements are less suitable in practical application. From a critical review of the existing overtraining research it must be concluded that there has been little improvement in recent years in the tools available for the diagnosis of OTS.

[Clinical diagnosis of overtraining using blood tests: current knowledge]

PURPOSE

Overtraining results from an imbalance between training load-induced fatigue and organism's recovery abilities. Its etiology is complex and to date there is no useful clinical diagnostic tool. The purpose of this review is to discuss the blood chemistry parameters potentially useful for diagnosing overtraining in athletes.

CURRENT KNOWLEDGE AND KEY POINTS

Chronic alterations of the myocyte structure may cause high plasma concentration increases of myoglobin, troponin I and creatine kinase enzyme, resulting in chemical and/or mechanical aggression. Monitoring reactive oxygen species' activity appears to be a good tool for evaluation of the metabolic stress level experienced by skeletal muscles. In energetic metabolism, a succession of chronic glycogen depletions might change the use of amino acids and lipids, inducing transient but severe hypoglycemia during exercise. A higher oxidation of circulating glutamine might cause immunosuppression (lower reactivity to inflammations and cellular traumatisms), inhibiting alarm signals during acute training. A higher branched-chain amino acid oxidation might favor free tryptophan's entry into the cerebral area, enhancing serotonin synthesis. As a consequence, asthenia and a loss of sensitivity to muscular and tendon traumatism might appear. Exercise anemia might also be a worsening factor of the physiological situation of the tired athlete, inducing predisposition to overtraining by the lower inflammation reactivity of depleted hepatic and muscular proteins.

FUTURE PROSPECTS AND PROJECTS

Early diagnosis of overtraining diagnosis may be established only from a battery of analyses, which should include the whole of the potential parameters. These remain unpredictable and do not allow systematic determination of new cases. Only a longitudinal study of the physiological situation appears to allow the necessary conditions for detecting overtraining in the early stages of its process for each subject.

Special feature for the Olympics: effects of exercise on the immune system: overtraining effects on immunity and performance in athletes

Overtraining is a process of excessive exercise training in high-performance athletes that may lead to overtraining syndrome. Overtraining syndrome is a neuroendocrine disorder characterized by poor performance in competition, inability to maintain training loads, persistent fatigue, reduced catecholamine excretion, frequent illness, disturbed sleep and alterations in mood state. Although high-performance athletes are generally not clinically immune deficient, there is evidence that several immune parameters are suppressed during prolonged periods of intense exercise training. These include decreases in neutrophil function, serum and salivary immunoglobulin concentrations and natural killer cell number and possibly cytotoxic activity in peripheral blood. Moreover, the incidence of symptoms of upper respiratory tract infection increases during periods of endurance training. However, all of these changes appear to result from prolonged periods of intense exercise training, rather than from the effects of overtraining syndrome itself. At present, there is no single objective marker to identify overtraining syndrome. It is best identified by a combination of markers, such as decreases in urinary norepinephrine output, maximal heart rate and blood lactate levels, impaired sport performance and work output at 110% of individual anaerobic threshold, and daily self-analysis by the athlete (e.g. high fatigue and stress ratings). The mechanisms underlying overtraining syndrome have not been clearly identified, but are likely to involve autonomic dysfunction and possibly increased cytokine production resulting from the physical stress of intense daily training with inadequate recovery.

FT-IR spectroscopy utilization to sportsmen fatigability evaluation and control

PURPOSE

A longitudinal biological study of 20 elite rowers was performed using capillary blood (serum) FT-IR spectra to evaluate their training load adaptations and fatigue.

METHODS

Difference spectra (rest serum spectra subtracted to exercise serum spectra) were used to evaluate subjects' metabolic response to exercise. Spectra classifications were used for serum contents differentiation on the basis of biomolecular absorption.

RESULTS

For two subjects, several metabolic differentiations were observed. These started with sugars metabolism on the fifth training week, followed successively by lipid metabolism and protein metabolism, when overtraining was clinically diagnosed. Several weeks further into the training program, the same onset of metabolic differentiations was observed for eight other subjects. When differentiations reached lipid metabolism, they were asked to reduce their training loads. Unlike the overtrained subjects, a rapid recovery was observed (3 vs 22 wk) and metabolism alterations disappeared.

CONCLUSION

The fatigability limit in sportsmen seemed to be situated at a certain level of metabolic stress, beyond which a rapid overtraining process recover was no longer possible.

Chronic exercise training effects on immune function

PURPOSE

This paper reviews the recent literature on the chronic effects of exercise training on immune function in humans. There is a general perception by athletes and other physically active individuals that regular moderate activity enhances, whereas intense exercise suppresses, resistance to minor illnesses such as upper respiratory tract infection (URTI). This perception is supported by epidemiological data in endurance athletes and limited data from intervention studies using moderate exercise in previously untrained individuals. The apparently high incidence of URTI among endurance athletes has prompted interest the relationship between chronic exercise training and immune function. Whereas immune cell number is generally normal during intense exercise training, recent evidence suggests that prolonged periods of intense training may lead to slight impairment in immune parameters such as neutrophil function, serum and mucosal immunoglobulin levels, plasma glutamine concentration, and possibly natural killer cell cytotoxic activity. In contrast. moderate exercise training has either no effect on, or may stimulate, these immune parameters.

CONCLUSION

Whereas athletes are not clinically immune deficient, it is possible that the combined effects of small changes in several immune parameters may compromise resistance to minor illnesses such as URTI. Strategies to prevent URTI in athletes include avoiding overtraining, providing adequate rest and recovery during the training cycle and after competition, limiting exposure to sources of infection, ensuring adequate nutrition, and possibly vitamin C supplementation. It is uncertain at present whether moderate exercise training is helpful in preventing infectious illness among the wider population.

Changes in glutamine and glutamate concentrations for tracking training tolerance

PURPOSE

The purpose was to monitor high-performance athletes throughout training macrocycles and competitions and examine the changes in plasma glutamine (Gm) and glutamate (Ga) concentrations in order to develop a model of tolerance to training.

METHODS

Plasma glutamine and glutamate concentrations of 52 National team athletes (31 male and 21 female) divided into male and female groups of speed skating, swimming, and cross-country skiing were measured in an early season rested condition to determine highest Gm and lowest Ga concentrations and over 2-4 macrocycles, which included heavy training to establish lowest Gm and highest Ga concentrations.

RESULTS

In the rested condition, there were no differences within and between the male and female groups, excluding five athletes (OTA) who became overtrained in heavy training. The mean (+/-SD) Gm concentration was 585 +/- 54 micromol x L(-1), Ga concentration 101 +/- 16 micromol x L(-1), and Gm/Ga ratio 5.88 +/- 0.84 micromol x L(-1). The OTA had a significantly higher Ga concentration of 128 +/- 16 micromol x L(-1) and lower Gm/Ga ratio of 4.43 +/- 0.49 micromol x L(-1) than all the other groups. In heavy training, there was a significant decrease (P < 0.05) in Gm concentration to 522 +/- 53 micromol x L(-1), significant increase in Ga concentration to 128 +/- 19 micromol x L(-1) and significant decrease in Gm/Ga ratio to 4.15 +/- 0.57 micromol x L(-1). The OTA Gm concentration of 488 +/- 31 micromol x L(-1) was significant lower than only the male speed skating and swimming groups. However, the Ga concentration of 171 +/- 17 micromol x L(-1) and Gm/Ga ratio of 2.88 +/- 0.27 micromol x L(-1) were significantly higher and lower respectively than all other groups.

CONCLUSIONS

Based on the changes in Gm and Ga concentration under different training conditions, we propose an athlete tolerance to training model where glutamine concentration reflects tolerance to volume of work and glutamate concentration reflects tolerance to high intensity training. We suggest that the Gm/Ga ratio may globally represent overall tolerance to training.

Cytokine hypothesis of overtraining: a physiological adaptation to excessive stress?

Overtraining syndrome (OTS) is a condition wherein an athlete is training excessively, yet performance deteriorates. This is usually accompanied by mood/behavior changes and a variety of biochemical and physiological alterations. Presently, there is no global hypothesis to account for OTS. The present paper will attempt to provide a unifying paradigm that will integrate previous research under the rubric of the cytokine hypothesis of overtraining. It is argued that high volume/intensity training, with insufficient rest, will produce muscle and/or skeletal and/or joint trauma. Circulating monocytes are then activated by injury-related cytokines, and in turn produce large quantities of proinflammatory IL-1beta, and/or IL-6, and/or TNF-alpha, producing systemic inflammation. Elevated circulating cytokines then co-ordinate the whole-body response by: a) communicating with the CNS and inducing a set of behaviors referred to as "sickness" behavior, which involves mood and behavior changes that support resolution of systemic inflammation: b) adjusting liver function, to support the up-regulation of gluconeogenesis, as well as de novo synthesis of acute phase proteins, and a concomitant hypercatabolic state; and c) impacting on immune function. Theoretically, OTS is viewed as the third stage of Selye's general adaptation syndrome, with the focus being on recovery/survival, and not adaptation, and is deemed to be "protective," occurring in response to excessive physical/physiological stress. Recommendations are made for potential markers of OTS, based on a systemic inflammatory condition.

Nutritional aspects of immunosuppression in athletes

The literature suggests that a heavy schedule of training and competition leads to immunosuppression in athletes, placing them at a greater risk of opportunistic infection. There are many factors which influence exercise-induced immunosuppression, and nutrition undoubtedly plays a critical role. Misinterpretation of published data and misleading media reports have lead many athletes to adopt an unbalanced dietary regimen in the belief that it holds the key to improved performance. Some sports have strict weight categories, whilst in others low body fat levels are considered to be necessary for optimal performance or seen as an aesthetic advantage. This leads some athletes to consume a diet extremely low in carbohydrate content which, whilst causing rapid weight loss, may have undesirable results which include placing the athlete at risk from several nutrient deficiencies. Complete avoidance of foods high in animal fat reduces the intake of protein and several fat-soluble vitamins. On the other hand, diets with a very high carbohydrate content are usually achieved at the expense of protein. In addition, anecdotal and media reports have often promoted the supposed performance benefits of certain vitamins and minerals, yet most athletes do not realise that micronutrient supplementation is only beneficial when correcting a deficiency, and to date there is little scientific evidence to substantiate claims that micronutrients act as an ergogenic aid. Moreover, excessive intakes of micronutrients can be toxic. Deficiencies or excesses of various dietary components can have a substantial impact on immune function and may further exacerbate the immunosuppression associated with heavy training loads. This review examines the role of nutrition in exercise-induced immunosuppression and the effect of both excessive and insufficient nutrient intake on immunocompetence. As much of the present literature concerning nutrition and immune function is based on studies with sedentary participants, the need for future research which directly investigates the relationship between exercise, training, immunity and nutrition is highlighted.

Physiological and psychometric variables for monitoring recovery during tapering for major competition

PURPOSE

This study attempted to identify variables that are useful in monitoring recovery during tapering.

METHODS

Changes in physiological variables, tethered swimming force, mood states, and self-ratings of well-being were measured in 10 elite swimmers from before to after 2 wk of tapering for national championships. Physiological measures included resting heart rate (HR); blood pressure (BP); blood lactate concentration; red blood cell, white blood cell, and differential counts; and plasma cortisol, free testosterone, and catecholamine concentrations. Measures taken after 100-m maximal and 200-m standardized submaximal swims included HR, BP, and blood lactate concentration.

RESULTS

Step-down regression analysis showed that changes in plasma norepinephrine concentration, heart rate after maximal effort swimming and confusion as measured by the Profile of Mood States (POMS) predicted the change in swimming time with tapering (r2 = 0.98); the change in plasma norepinephrine concentration predicted the change in swim time with tapering (r2 = 0.82) by itself.

CONCLUSION

These data suggest that recovery after intense training can be monitored during tapering and that an accurate prediction of performance changes may be possible if the changes in a range of physiological and psychological variables are measured.