Cytokine changes after a marathon race

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.

Exercise-induced immunodepression in endurance athletes and nutritional intervention with carbohydrate, protein and fat-what is possible, what is not?

Heavily exercising endurance athletes experience extreme physiologic stress, which is associated with temporary immunodepression and higher risk of infection, particularly upper respiratory tract infections (URTI). The aim of this review is to provide a critical up-to-date review of existing evidence on the immunomodulatory potential of selected macronutrients and to evaluate their efficacy. The results of 66 placebo-controlled and/or crossover trials were compared and analysed. Among macronutrients, the most effective approach to maintain immune function in athletes is to consume ≥6% carbohydrate during prolonged exercise. Because inadequate nutrition affects almost all aspects of the immune system, a well-balanced diet is also important. Evidence of beneficial effects from other macronutrients is scarce and results are often inconsistent. Using a single nutrient may not be as effective as a mixture of several nutritional supplements. Due to limited research evidence, with the exception of carbohydrate, no explicit recommendations to reduce post-exercise URTI symptoms with single macronutrients can be derived.

SELDI-TOF-MS Serum Profiling Reveals Predictors of Cardiac MRI Changes in Marathon Runners

Purpose. To utilize proteomics to discover proteins associated with significant cardiac magnetic resonance imaging (MRI) changes in marathon runners. Methods. Serum from 25 runners was analyzed by surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Proteomic profiles were compared in serum samples obtained prior to the race, at the finish line and within 7 hours after race to identify dynamic proteins correlated with cardiac MRI changes. Results. 693 protein/peptide clusters were identified using two ProteinChip surface chemistries and, of these, 116 were significantly different between the three time points. We identified 7 different patterns of protein expression change within the runners and 5 prerace protein peaks, 16 finish-line protein levels, and 15 postrace proteins which were correlated with significant postrace cardiac MRI changes. Conclusions. This study has identified baseline levels of proteins which may be predictive of risk of significant cardiac damage following a marathon race. Preliminary identification of the significant proteins suggested the involvement of cytokines and other proteins involved in stress and inflammatory response.

Expression pattern of the transforming growth factor β signaling genes in human peripheral blood mononuclear cells after exercise-inflammatory aspects

OBJECTIVE

The present study has focused on the identification of differences between the expression pattern of TGF-β signaling pathway genes in athletes after exercise.

MATERIALS AND METHODS

The study group consisted of three healthy cyclists, which were collected pre-exercise, immediately postexercise, and after 15 min of recovery. The analysis of the expression profile of genes related to the TGF-β signal transduction pathway was performed in peripheral blood mononuclear cells using HG-U133A oligonucleotide microarrays.

RESULTS

A significant differential gene expression was recorded for RUNX3, TGFBR3, MLC1, and GRB2.

CONCLUSIONS

The effect of physical exercise on immune response may be essential for human health. Moreover, alterations of TGF-β signaling can be involved in the process of adaptation of human organism to physical exertion.

Lipid transfer to HDL is higher in marathon runners than in sedentary subjects, but is acutely inhibited during the run

Although exercise increases HDL-cholesterol, exercise-induced changes in HDL metabolism have been little explored. Lipid transfer to HDL is essential for HDL's role in reverse cholesterol transport. We investigated the effects of acute exhaustive exercise on lipid transfer to HDL. We compared plasma lipid, apolipoprotein and cytokine levels and in vitro transfer of four lipids from a radioactively labeled lipid donor nanoemulsion to HDL in sedentary individuals (n = 28) and in marathon runners (n = 14) at baseline, immediately after and 72 h after a marathon. While HDL-cholesterol concentrations and apo A1 levels were higher in marathon runners, LDL-cholesterol, apo B and triacylglycerol levels were similar in both groups. Transfers of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.2 (4.5-6), p = 0.001], phospholipids [21.7 (20.4-22.2) vs. 8.2 (7.7-8.9), p = 0.0001] and triacylglycerol [3.7 (3.1-4) vs. 1.3 (0.8-1.7), p = 0.0001] were higher in marathon runners, but esterified-cholesterol transfer was similar. Immediately after the marathon, LDL- and HDL-cholesterol concentrations and apo A1 levels were unchanged, but apo B and triacylglycerol levels increased. Lipid transfer of non-esterified cholesterol [6.8 (5.7-7.2) vs. 5.8 (4.9-6.6), p = 0.0001], phospholipids [21.7 (20.4-22.2) vs. 19.1 (18.6-19.3), p = 0.0001], esterified-cholesterol [3.2 (2.2-3.8) vs. 2.3 (2-2.9), p = 0.02] and triacylglycerol [3.7 (3.1-4) vs. 2.6 (2.1-2.8), p = 0.0001] to HDL were all reduced immediately after the marathon but returned to baseline 72 h later. Running a marathon increased IL-6 and TNF-α levels, but after 72 h these values returned to baseline. Lipid transfer, except esterified-cholesterol transfer, was higher in marathon runners than in sedentary individuals, but the marathon itself acutely inhibited lipid transfer. In light of these novel observations, further study is required to clarify how these metabolic changes can influence HDL composition and anti-atherogenic function.

Effect of time of day and partial sleep deprivation on plasma concentrations of IL-6 during a short-term maximal performance

The present study was designed to evaluate the effect of time of day and partial sleep deprivation (PSD) on short-term maximal performance and level of interleukin-6 (IL-6) in trained subjects. In a randomized order, 12 football players were asked to perform a 30-s Wingate test during which we measured the peak (PP) and mean (MP) powers. Measurements were performed at 0800 and 1800 hours, after two nocturnal regimens: (1) a reference normal sleep night (RN) and (2) 4 h of PSD caused by an early awakening. Plasma IL-6 concentrations were measured before (P1), immediately after (P2), and 60 min after the exercise (P3). PP and MP improved significantly from the morning to the afternoon after RN (P < 0.05) and from the afternoon to the morning after PSD (P < 0.05). Compared to RN, PP and MP were not affected by PSD the following morning. However, there was a significant decrease in PP and MP (P < 0.001) after the PSD at 1800 hours. In all conditions, IL-6 and resting core temperature were significantly higher (P < 0.05) in the afternoon than in the morning. In all sessions, IL-6 levels increased significantly from P1 to P2 (P < 0.01) and remained elevated in the afternoon during the recovery period after PSD (P < 0.05). However, no significant difference was observed in IL-6 between P1 and P3 during RN and PSD at 0800 hours. In conclusion, a short-term high-intensity exercise may increase the IL-6 concentrations in the morning and the afternoon. Moreover, IL-6 remained elevated during the recovery period in the afternoon after the PSD at the end of the night.

Exertional heat stroke

The increasing popularity of mass participation endurance events necessitates that on-site medical teams be well versed in the management of both common and life-threatening conditions. Exertional heat stroke is one such condition, which if left untreated can be fatal.

Clinical implications of exercise immunology

Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation, an underlying factor in multiple chronic diseases. The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein, total blood leukocytes, interleukin-6, and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease, certain types of cancer, type 2 diabetes, sarcopenia, and dementia. Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper respiratory tract infection (URTI). During each bout of moderate exercise, an enhanced recirculation of immunoglobulins, neutrophils, and natural killer cells occurs that persists for up to 3-h post-exercise. This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens. As moderate exercise continues on a near-daily basis for 12–15 weeks, the number of symptoms days with URTI is decreased 25%–50% compared to randomized sedentary controls. Epidemiologic and animal studies support this inverse relationship between URTI risk and increased physical activity.

Effect of Ultra-marathon (308 km) Race on Bone Metabolism and Cartilage Damage Biomarkers

Objective

To evaluate the potential effects of a 308-km ultra-marathon on bone and cartilage biomarkers.

Method

Venous blood samples were collected at pre-race, 100 km, 200 km, and 308 km checkpoints. The following markers of cartilage damage and bone metabolism were studied: osteocalcin (OC), osteoprotegerin (OPG), and calcium, phosphorous, and cartilage oligomeric matrix protein (COMP).

Results

Blood samples were taken from 20 male runners at four different checkpoints. Serum COMP was increased by 194.1% (130.7% at 100 km and 160.4% at 200 km). Serum OPG was significantly increased by 158.57% at 100 km and 114.1% at 200 km compared to the pre-race measures. OC was transiently suppressed at 200 km. Serum calcium and phosphorous concentrations decreased compared to the pre-race measures.

Conclusion

This study showed that the 308-km ultra-marathon induced several changes, including transient uncoupling of bone metabolism, increased bone resorption, suppressed bone formation, and bone turnover and had a major impact on cartilage structure.

Exercise induced bronchospasm in physically fit female students of Kerman University and their pulmonary function tests

INTRODUCTION

High prevalence of respiratory symptoms and bronchial hyper-responsiveness has been reported in professionals athletes, particularly in relation to climate and environment. However, the airway response to exercise in active population has been poorly investigated especially in women. The aim of this study was to examine pulmonary function test changes in physically fit female students of Kerman University.

METHODS

Sixty physically fit female students (19 ± 1.12 years old) were randomly selected out of 500 students. Each subject underwent the physical fitness test (Couper test) of the maximal distance running in 12 min. The exercise induced bronchospasm (EIB) symptoms including coughing, wheezing, chest tightness, dyspnea, previously diagnosed asthma and allergy, the use of anti-asthmatics medication and the family history of asthma were recorded using a questionnaire. Pulmonary function tests including; forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), peak expiratory flow (PEF), and maximal expiratory flow at 50% of the FVC (MEF(50)) were measured at rest (baseline), immediately, 5, and 15 min after an exercise test.

RESULT

The result of this study showed that the prevalence of the symptoms of EIB was 40.0%. There was not any significant difference in baseline PFT values between symptomatic and asymptomatic subjects. However, All PFT values of symptomatic subjects were significantly lower than asymptomatic immediately after exercise (p < 0.05 to p < 0.01). In addition, PFT values were significantly reduced in all times intervals for the symptomatic subjects (p < 0.05 to p < 0.01).

CONCLUSION

The results showed a high prevalence of respiratory symptoms and EIB in healthy female students.

Physiological and nutritional aspects of post-exercise recovery: specific recommendations for female athletes

Gender-based differences in the physiological response to exercise have been studied extensively for the last four decades, and yet the study of post-exercise, gender-specific recovery has only been developing in more recent years. This review of the literature aims to present the current state of knowledge in this field, focusing on some of the most pertinent aspects of physiological recovery in female athletes and how metabolic, thermoregulatory, or inflammation and repair processes may differ from those observed in male athletes. Scientific investigations on the effect of gender on substrate utilization during exercise have yielded conflicting results. Factors contributing to the lack of agreement between studies include differences in subject dietary or training status, exercise intensity or duration, as well as the variations in ovarian hormone concentrations between different menstrual cycle phases in female subjects, as all are known to affect substrate metabolism during sub-maximal exercise. If greater fatty acid mobilization occurs in females during prolonged exercise compared with males, the inverse is observed during the recovery phase. This could explain why, despite mobilizing lipids to a greater extent than males during exercise, females lose less fat mass than their male counterparts over the course of a physical training programme. Where nutritional strategies are concerned, no difference appears between males and females in their capacity to replenish glycogen stores; optimal timing for carbohydrate intake does not differ between genders, and athletes must consume carbohydrates as soon as possible after exercise in order to maximize glycogen store repletion. While lipid intake should be limited in the immediate post-exercise period in order to favour carbohydrate and protein intake, in the scope of the athlete's general diet, lipid intake should be maintained at an adequate level (30%). This is particularly important for females specializing in long-duration events. With protein balance, it has been shown that a negative nitrogen balance is more often observed in female athletes than in male athletes. It is therefore especially important to ensure that this remains the case during periods of caloric restriction, especially when working with female athletes showing a tendency to limit their caloric intake on a daily basis. In the post-exercise period, females display lower thermolytic capacities than males. Therefore, the use of cooling recovery methods following exercise, such as cold water immersion or the use of a cooling vest, appear particularly beneficial for female athletes. In addition, a greater decrease in arterial blood pressure is observed after exercise in females than in males. Given that the return to homeostasis after a brief intense exercise appears linked to maintaining good venous return, it is conceivable that female athletes would find a greater advantage to active recovery modes than males. This article reviews some of the major gender differences in the metabolic, inflammatory and thermoregulatory response to exercise and its subsequent recovery. Particular attention is given to the identification of which recovery strategies may be the most pertinent to the design of training programmes for athletic females, in order to optimize the physiological adaptations sought for improving performance and maintaining health.

Intense flight and endotoxin injection elicit similar effects on leukocyte distributions but dissimilar effects on plasma-based immunological indices in pigeons

Most birds rely on flight for survival. Yet as an energetically-taxing and physiologically-integrative process, flight has many repercussions. Studying pigeons (Columba livia) and employing physiological and immunological indices that are relevant to ecologists working with wild birds, we determined what, if any, acute immune-like responses result from bouts of intense, non-migratory flight. We compared the effects of flight with the effects of a simulated bacterial infection. We also investigated indices in terms of their post-flight changes within individuals and their relationship with flight speed among individuals. Compared to un-flown controls, flown birds exhibited significant elevations in numbers of heterophils relative to numbers of lymphocytes and significant reductions in numbers eosinophils and monocytes. Furthermore, within-individual changes in concentrations of an acute phase protein were greater in flown birds than in controls. However, none of the flight-affected indices showed any evidence of being related to flight speed. While some of the effects of flight were comparable to the effects of the simulated bacterial infection, other effects were observed only after one of these two physiological challenges. Our study suggests that flight by pigeons yields immune-like responses, and these responses have the potential to complicate the conclusions drawn by ecologists regarding immune function in free-living birds. Still, a better understanding of the repercussions of flight can help clarify the ties between the physiology of exercise and the disease ecology of migration and will ultimately assist in the broader goal of accounting for immunological variation within and among species.

Variance in the acute inflammatory response to prolonged cycling is linked to exercise intensity

This study investigated the influence of age, body composition, physical fitness, training volume and intensity, and underlying systemic inflammation on exercise-induced inflammation and innate immune function in a heterogeneous group of cyclists. Subjects included 31 male cyclists (mean ± standard deviation, age 38.8 ± 10.6 years, body fat 17.8%± 5.6%, VO(2max) 55.8 ± 8.4 mL kg(-1) min(-1)) who cycled for 1.75 h at 60% watts(max) followed by a 10-km time trial (18.3 ± 0.3 min). Blood samples were collected pre-, post-, and 1-h-postexercise, and analyzed for WBCs, 9 cytokines [interleukin (IL)-6, tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, interferon-γ, IL-1β, IL-2, IL-8, IL-10, and IL-12p70], and granulocyte and monocyte phagocytosis (GR-PHAG and MO-PHAG) and oxidative burst activity (GR-OBA and MO-OBA). Exercise-induced changes varied widely, with significant increases measured for 8 of 9 cytokines, GR-PHAG (mean change 99%) (95% confidence limits, 69%, 128%) and MO-PHAG (43%) (28%, 58%), and WBC (160%) (133%, 187%), and decreases for GR-OBA (-30%) (-43%,-16%) and MO-OBA (-23%) (-36%,-10%). Correlation and stepwise regression analysis revealed that changes in these variables were not related to age, body fat percentage, VO(2max), training volume, or pre-exercise C-reactive protein. Performance measures, specifically the average heart rate and rating of perceived exertion, were correlated with changes in several variables, including IL-8 (r=0.68 and 0.67, respectively, P<0.001) and IL-6 (r=0.51, P=0.004, and r=0.46, P=0.011, respectively). In summary, variance in exercise-induced inflammation and innate immunity in male cyclists in response to 2 h of endurance exercise is best explained by exercise intensity.

Divergent cytokine response following maximum progressive swimming in hot water

Exercise promotes transitory alterations in cytokine secretion, and these changes are affected by exercise duration and intensity. Considering that exercise responses also are affected by environmental factors, the goal of the present study was to investigate the effect of water temperature on the cytokine response to maximum swimming. Swiss mice performed a maximum progressive swimming exercise at 31 or 38°C, and plasma cytokine levels were evaluated immediately or 1, 6 or 24 h after exercise. The cytokine profile after swimming at 31°C was characterized by increased interleukin (IL)-6 and monocyte chemotactic protein-1 (MCP-1) levels, which peaked 1 h after exercise, suggesting an adequate inflammatory milieu to induce muscle regeneration. Transitory reductions in IL-10 and IL-12 levels also were observed after swimming at 31°C. The cytokine response to swimming was modified when the water temperature was increased to 38°C. Although exercise at 38°C also led to IL-6 secretion, the peak in IL-6 production occurred 6 h after exercise, and IL-6 levels were significantly lower than those observed after maximum swimming at 31°C (p = 0·030). Furthermore, MCP-1 levels were lower and tumour necrosis factor-α levels were higher immediately after swimming at 38°C, suggesting a dysregulated pro-inflammatory milieu. These alterations in the cytokine profile can be attributed in part to reduced exercise total work because exhaustion occurred sooner in mice swimming at 38°C than in those swimming at 31°C.

Obesity-associated insulin resistance in skeletal muscle: role of lipid accumulation and physical inactivity

An alarming increase in the prevalence of obesity, type 2 diabetes mellitus, and associated diseases can be observed world-wide during the past 20 years. In obesity, profound alterations in the secretion profile of adipokines and inflammatory markers as well as increased lipolysis occur, leading besides other events to elevated levels of free fatty acids, which in turn are distributed to nonadipose tissue such as skeletal muscle. While the amount of intramyocellular lipids can be used as a marker of insulin resistance in physical inactive individuals, these neutral triglycerides themselves are not thought to be harmful. However, they provide a source for the generation of harmful lipid metabolites such as diacylglycerol and ceramide, which are implicated in insulin resistance by perturbing insulin signaling pathways. In this review, we will discuss the role of lipid metabolites in insulin resistance and potential mechanism involved in accumulation of intramyocellular lipids. Furthermore, we will highlight the key role of PGC-1α, which is a master regulator of mitochondrial biogenesis and coordinates the activation of genes involved in oxidative energy production as well as genes involved in fiber type transformation. Finally, the role of exercise in stimulating PGC-1α activity and expression as well as the release of contraction-induced myokines is discussed.

Modulation of dendritic cells and toll-like receptors by marathon running

The focus of this study was to assess exercise-induced alterations of circulating dendritic cell (DC) subpopulations and toll-like receptor (TLR) expression after marathon running. Blood sampling was performed in 15 obese non-elite (ONE), 16 lean non-elite (LNE) and 16 lean elite (LE) marathon runners pre- and post-marathon as well as 24 h after the race. Circulating DC-fractions were measured by flow-cytometry analyzing myeloid DCs (BDCA-1+) and plasmacytoid DCs (BDCA-2+). We further analyzed the (TLR) -2/-4/-7 in peripheral blood mononuclear cells (rt-PCR/Western Blot) and the cytokines CRP, IL-6, IL-10, TNF-α and oxLDL by ELISA. After the marathon, BDCA-1 increased significantly in all groups [LE (pre/post): 0.35/0.47%; LNE: 0.26/0.50% and ONE: 0.30/0.49%; all p < 0.05]. In contrast, we found a significant decrease for BDCA-2 directly after the marathon (LE: 0.09/0.01%; LNE: 0.12/0.03% and ONE: 0.10/0.02%; all p < 0.05). Levels of TLR-7 mRNA decreased in all groups post-marathon (LE 44%, LNE 67% and ONE 52%; all p < 0.01), with a consecutive protein reduction (LE 31%, LNE 52%, ONE 42%; all p < 0.05) 24 h later. IL-6 and IL-10 levels increased immediately after the run, whereas increases of TNF-α and CRP-levels were seen after 24 h. oxLDL levels remained unchanged post-marathon. In our study population, we did not find any relevant differences regarding training level or body weight. Prolonged endurance exercise induces both pro- and anti-inflammatory cytokines. Anti-inflammatory cytokines, such as IL-10, may help to prevent excessive oxidative stress. Marathon running is associated with alterations of DC subsets and TLR-expression independent of training level or body weight. Myeloid and plasmacytoid DCs are differently affected by the excessive physical stress. Immunomodulatory mechanisms seem to play a key role in the response and adaptation to acute excessive exercise.

Effects of interventions on oxidative stress and inflammation of cardiovascular diseases

Excessive oxidative stress and low-grade chronic inflammation are major pathophysiological factors contributing to the development of cardiovascular diseases (CVD) such as hypertension, diabetes and atherosclerosis. Accumulating evidence suggests that a compromised anti-oxidant system can lead to excessive oxidative stress in cardiovascular related organs, resulting in cell damage and death. In addition, increased circulating levels of pro-inflammatory cytokines, such as tumor necrosis factor α, interleukin-6 and C-reactive protein, are closely related to morbidity and mortality of cardiovascular complications. Emerging evidence suggests that interventions including nutrition, pharmacology and exercise may activate expression of cellular anti-oxidant systems via the nuclear factor erythroid 2-related factor 2-Kelch-like ECH-associated protein 1 signaling pathway and play a role in preventing inflammatory processes in CVD. The focus of the present review is to summarize recent evidence showing the role of these anti-oxidant and anti-inflammatory interventions in cardiovascular disease. We believe that these findings may prompt new effective pathogenesis-oriented interventions, based on the exercise-induced protection from disease in the cardiovascular system, aimed at targeting oxidant stress and inflammation.

Cytokine responses to carbohydrate ingestion during recovery from exercise-induced muscle injury

We investigated the effect of carbohydrate ingestion after maximal lengthening contractions of the knee extensors on circulating concentrations of myocellular proteins and cytokines, and cytokine mRNA expression in muscle. Using a cross-over design, 10 healthy males completed 5 sets of 10 lengthening (eccentric) contractions (unilateral leg press) at 120% 1 repetition-maximum. Subjects were randomized to consume a carbohydrate drink (15% weight per volume; 3 g/kg BM) for 3 h after exercise using one leg, or a placebo drink after exercise using the contralateral leg on another day. Blood samples (10 mL) were collected before exercise and after 0, 30, 60, 90, 120, 150, and 180 min of recovery. Muscle biopsies (vastus lateralis) were collected before exercise and after 3 h of recovery. Following carbohydrate ingestion, serum concentrations of glucose (30-90 min and at 150 min) and insulin (30-180 min) increased (P < 0.05) above pre-exercise values. Serum myoglobin concentration increased ( approximately 250%; P < 0.05) after both trials. In contrast, serum cytokine concentrations were unchanged throughout recovery in both trials. Muscle mRNA expression for IL-8 (6.4-fold), MCP-1 (4.7-fold), and IL-6 (7.3-fold) increased substantially after carbohydrate ingestion. TNF-alpha mRNA expression did not change after either trial. Carbohydrate ingestion during early recovery from exercise-induced muscle injury may promote proinflammatory reactions within skeletal muscle.

Fatigue and plasma cytokine concentrations at rest and during exercise in patients with sarcoidosis

BACKGROUND

Patients with sarcoidosis exhibit exercise intolerance-related fatigue and increased levels of circulating proinflammatory cytokines at rest. Exercise may result in increased plasma cytokine levels (PCLs) in healthy adults, but such a relationship has not been studied in sarcoidosis patients.

OBJECTIVES

To assess relationship of fatigue in sarcoidosis with PCLs at rest and with cardiopulmonary exercise testing (CPET).

METHODS

We assessed lung function, CPET data, multidimensional fatigue inventory, plasma tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) concentrations before, immediately after, and 4-6 h following CPET in 22 sarcoidosis patients (13 receiving immunomodulatory drugs) and 22 controls.

RESULTS

Patients exhibited greater fatigue, reduced cardiorespiratory function, higher Medical Research Council (MRC) scores and higher plasma TNF-α concentrations than controls at all times. Plasma IL-1β levels did not differ between cohorts. Patients exhibited a 28% increase (statistically not significant) in TNF-α level immediately post exercise. Plasma IL-β concentrations did not change among cohorts. Treated patients exhibited higher MRC and physical fatigue scores and lower breathing reserve, but no differences in cardiorespiratory function or PCLs compared to untreated patients. In treated patients, pre-exercise plasma IL-1β correlated with physical fatigue, reduced motivation and total fatigue; TNF-α levels only correlated with general fatigue score.

CONCLUSION

Treated sarcoidosis patients exhibit a relation between physical fatigue, reduced motivation and total fatigue and pre-exercise plasma IL-1β concentrations. Acute exercise does not increase PCLs. Whether the reduced MRC score and physical fatigue in treated patients is related to the therapy or to the underlying inflammatory process is difficult to determine.

Physical activity, immunity and infection

During the last few decades, scientific evidence has confirmed a wide range of health benefits related to regular physical activity. How physical activity affects the immune function and infection risk is, however, still under debate. Commonly, intensive exercise suppresses the activity and levels of several immune cells, while other immune functions may be stimulated by moderate physical activity. With this knowledge, the understanding of the relationship between different levels of physical activity on the immune function has been raised as a potential tool to protect health not only in athletes but also in the general population; the mechanisms that translate a physically active lifestyle into good health continue to be investigated. Reviewing the literature, although several outcomes (i.e. the mechanisms by which different levels and duration of physical activity programmes affect numerous cell types and responses) remain unclear, given that the additional benefits encompass healthy habits including exercise, the use of physical activity programmes may result in improved health of elderly populations. Moderate physical activity or moderate-regulated training may enhance the immune function mainly in less fit subjects or sedentary population and the pre-event fitness status also seems to be an important individual factor regarding this relationship. Although adequate nutrition and regular physical activity habits may synergistically improve health, clinical trials in athletes using nutritional supplements to counteract the immune suppression have been inconclusive so far.Further research is necessary to find out to what extent physical activity training can exert an effect on the immune function.

Circuit resistance training in sedentary women: body composition and serum cytokine levels

Exercise can generate alterations in body composition and modulate the immune system. The objective of this study was to verify whether a circuit resistance training (CRT) protocol can increase lean body mass (LM), and reduce fat body mass (FM) and the percent of FM (%FM) of sedentary women, without inducing inflammatory responses, indicated by serum cytokine levels. The initial hypothesis was that CRT would improve body composition, without changing serum cytokine levels. The study consisted of 14 healthy, sedentary women, aged 33–45 years (mean ± SD, 40.23 ± 3.98 years), with a normal body mass index. They participated in 3 sessions per week of CRT, which included 2 rounds in 9 stations with 1 set of 8–12 repetition maximum at each station, for 10 weeks. During the 10-week CRT period, participants maintained their pretraining nutritional standard. Body composition was analysed with dual-energy X-ray absorptiometry both pre- and post-training. Blood samples were collected after 96 h of rest pre- and post-training, and 5 min, 24 h, and 48 h after the second and last training sessions to measure serum cytokine levels by flow cytometry. The nutritional standard was accompanied throughout the study period with 24-h dietary recall. Increases in LM (35.937 ± 4.926 to 39.130 ± 4.950 kg) and decreases in FM (21.911 ± 8.150 to 17.824 ± 4.235 kg) and %FM (37.10 ± 10.84 to 31.19 ± 6.06), without concurrent changes in serum cytokine levels, and in the nutritional standard (α = 0.05). The proposed CRT improved body composition and did not induce any changes in serum cytokine levels characteristic of the inflammatory response in women.

Variable number of tandem repeat polymorphisms of the interleukin-1 receptor antagonist gene IL-1RN: a novel association with the athlete status

BACKGROUND

The interleukin-1 (IL-1) family of cytokines is involved in the inflammatory and repair reactions of skeletal muscle during and after exercise. Specifically, plasma levels of the IL-1 receptor antagonist (IL-1ra) increase dramatically after intense exercise, and accumulating evidence points to an effect of genetic polymorphisms on athletic phenotypes. Therefore, the IL-1 family cytokine genes are plausible candidate genes for athleticism. We explored whether IL-1 polymorphisms are associated with athlete status in European subjects.

METHODS

Genomic DNA was obtained from 205 (53 professional and 152 competitive non-professional) Italian athletes and 458 non-athlete controls. Two diallelic polymorphisms in the IL-1beta gene (IL-1B) at -511 and +3954 positions, and a variable number tandem repeats (VNTR) in intron 2 of the IL-1ra gene (IL-1RN) were assessed.

RESULTS

We found a 2-fold higher frequency of the IL-1RN 1/2 genotype in athletes compared to non-athlete controls (OR = 1.93, 95% CI = 1.37-2.74, 41.0% vs. 26.4%), and a lower frequency of the 1/1 genotype (OR = 0.55, 95% CI = 0.40-0.77, 43.9% vs. 58.5%). Frequency of the IL-1RN 2/2 genotype did not differ between groups. No significant differences between athletes and controls were found for either -511 or +3954 IL-1B polymorphisms. However, the haplotype (-511)C-(+3954)T-(VNTR)2 was 3-fold more frequent in athletes than in non-athletes (OR = 3.02, 95% CI = 1.16-7.87). Interestingly, the IL-1RN 1/2 genotype was more frequent in professional than in non-professional athletes (OR = 1.92, 95% CI = 1.02-3.61, 52.8% vs. 36.8%).

CONCLUSIONS

Our study found that variants at the IL-1ra gene associate with athletic status. This confirms the crucial role that cytokine IL-1ra plays in human physical exercise. The VNTR IL-1RN polymorphism may have implications for muscle health, performance, and/or recovery capacities. Further studies are needed to assess these specific issues. As VNTR IL-1RN polymorphism is implicated in several disease conditions, athlete status may constitute a confounding variable that will need to be accounted for when examining associations of this polymorphism with disease risk.

High-intensity interval training attenuates the exercise-induced increase in plasma IL-6 in response to acute exercise

This aims of this study were to investigate the effects of carbohydrate availability during endurance training on the plasma interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α response to a subsequent acute bout of high-intensity interval exercise. Three groups of recreationally active males performed 6 weeks of high-intensity interval running. Groups 1 (LOW+GLU) and 2 (LOW+PLA) trained twice per day, 2 days per week, and consumed a 6.4% glucose or placebo solution, respectively, before every second training session and at regular intervals throughout exercise. Group 3 (NORM) trained once per day, 4 days per week, and consumed no beverage during training. Each group performed 50 min of high-intensity interval running at the same absolute workloads before and after training. Muscle glycogen utilization in the gastrocnemius muscle during acute exercise was reduced (p < 0.05) in all groups following training, although this was not affected by training condition. Plasma IL-6 concentration increased (p < 0.05) after acute exercise in all groups before and after training. Furthermore, the magnitude of increase was reduced (p < 0.05) following training. This training-induced attenuation in plasma IL-6 increase was similar among groups. Plasma IL-8 concentration increased (p < 0.05) after acute exercise in all groups, although the magnitude of increase was not affected (p > 0.05) by training. Acute exercise did not increase (p > 0.05) plasma TNF-α when undertaken before or after training. Data demonstrate that the exercise-induced increase in plasma IL-6 concentration in response to customary exercise is attenuated by previous exercise training, and that this attenuation appears to occur independent of carbohydrate availability during training.

Immunological and growth mediator response to cross-country training in adolescent females

BACKGROUND

Exercise affects growth and development through a complex interaction between the endocrine, immune, and nervous systems. To date very little is known about how these systems respond to exercise in children or adolescents. Moreover, there are few studies that have examined growth factors, pro-inflammatory cytokines, and peripheral blood mononuclear cell responses to 'real-life' or field exercise solely in girls.

AIM

To determine the acute exercise-induced alterations in the growth hormone (GH)-insulinlike growth factor-I (IGF-I) axis, inflammatory cytokines, and certain aspects of immune function (white blood cell [WBC] subpopulations and their associated adhesion molecules) in a group of adolescent girls following a typical cross country practice.

METHODS

Eight, healthy, postpubertal, high school females, 15-18 years old, performed a single, typical, one hour cross-country practice session. Blood was sampled before and after the session.

RESULTS

Following exercise, lactate increased by 364 +/- 67% (p < 0.001). Significant increases were noted in circulating IL-6 (p < 0.023), TNF-alpha (p < 0.027), IL-1beta (p < 0.047) and IL-1ra (p < 0.002), as well as a substantial increase in GH (p < 0.007). The exercise led to significant increases in all WBC subpopulations and platelets. The most significant changes were observed for natural killer cells (p < 0.0005). The exercise significantly influenced adhesion molecules (such as CD62L, CD54).

CONCLUSIONS

These data demonstrate that an intense exercise bout in adolescent females leads to profound increases in inflammatory cytokines, with substantial changes in WBC and adhesion molecules. The role of these frequent, almost-daily perturbations on growth, development and immunity has yet to be determined.

Glucose ingestion during endurance training in men attenuates expression of myokine receptor

Glucose ingestion during exercise attenuates the release of the myokine interleukin-6 (IL-6) from working skeletal muscle, which results in a diminished increase in plasma IL-6. Interleukin-6 receptor alpha (IL-6Ralpha) expression in skeletal muscle is induced by acute exercise, mediated in part by an increased IL-6 concentration in the bloodstream. We hypothesized that endurance training would increase the density of IL-6Ralpha in skeletal muscle and that glucose ingestion would attenuate the effect. Nine subjects performed 10 weeks of one-legged knee-extensor training. They trained one leg (Glc-leg) while ingesting a glucose solution (Glc) and ingested a placebo (Plc) while training the other leg (Plc-leg). Endurance training increased peak power by 14% and reduced the exercise-induced gene expression of IL-6 and IL-6Ralpha in skeletal muscle and IL-6 plasma concentration. The IL-6Ralpha density increased to a lesser extent in the Glc-leg, suggesting that glucose ingestion attenuates the effect of training on IL-6Ralpha by blunting the IL-6 response. We conclude that glucose ingestion during endurance training attenuates the increase in IL-6Ralpha density.

Influência da suplementação de carboidrato na função imune de judocas durante o treinamento

O objetivo deste trabalho foi investigar os efeitos da suplementação de carboidrato, durante uma sessão de treino, sobre a função imune de atletas de judô. Dezesseis judocas do sexo masculino foram submetidos a duas sessões de treinamento de 120 minutos cada, com três dias de intervalo entre elas. Na primeira sessão, oito judocas, separados de forma aleatória, foram suplementados (3mL/kg peso corporal) com solução carboidratada (grupo CHO) e os demais, com solução placebo (grupo PLA), de forma duplo-cega. Na segunda sessão os tratamentos foram invertidos. O número de leucócitos, linfócitos, monócitos, eosinófilos, neutrófilos, os níveis de cortisol e as concentrações de glicose e lactato foram medidos em repouso (Pré-E), imediatamente após (Pós-E) e uma hora após o término da sessão de treino (1h pós-E). Os resultados mostraram que a glicemia aumentou (p < 0,05) durante a sessão de treino no grupo CHO e reduziu-se (p < 0,05) no grupo PLA. O cortisol aumentou (p < 0,05) durante a sessão de treino, independente do tipo de solução consumida, bem como durante a recuperação no grupo PLA. O consumo de CHO resultou em menor (p < 0,05) leucocitose, quando comparado com o PLA, nos períodos Pós-E e 1h Pós-E. A elevação da concentração de lactato sangüíneo decorrente do exercício correlacionou-se positivamente com o aumento dos leucócitos (r = 0,86, p < 0,001) nos dois grupos. Concluiu-se que a ingestão de bebida carboidratada por atletas de judô durante uma sessão de treino resultou em menor perturbação da contagem total de leucócitos e suas subclasses: linfócitos, monócitos, eosinófilos e neutrófilos. Esses resultados sugerem proteção à saúde imunológica de judocas fomentada por essa estratégia nutricional.

Circulating progenitor cells decrease immediately after marathon race in advanced-age marathon runners

INTRODUCTION

Exercise is thought to stimulate the release of hematopoietic and endothelial progenitor cells (EPC) from the bone marrow. Little is known about the influence of strenuous exercise on the content of circulating progenitor cells. The aim of this study was to investigate the influence of a marathon race on the amount of circulating progenitor cells immediately after the race in advanced-aged runners.

METHODS

Sixty-eight healthy marathon runners (age: 57+/-6 years) were included in this study. Blood cell counts were evaluated by standard methods, and circulating progenitor cells before and immediately after the race were quantified by fluorescence-activated cell sorter (FACS). Vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) was quantified by enzyme-linked immunosorbent assay.

RESULTS

A marathon race led to a significant increase in white blood cell count (5283+/-155 vs. 13706+/-373 cells/mul; P<0.001). Fluorescence-activated cell sorter analysis revealed a significant decrease of CD34 cells (1829+/-115 vs. 1175+/-75 cells/ml blood; P<0.0001), CD117 cells (2478+/-245 vs. 2193+/-85 cells/ml blood; P<0.05), and CD133 cells (3505+/-286 vs. 2239+/-163 cells/ml blood; P<0.001). No significant change was observed for EPCs defined as CD34/VEGF-R2 cells (117+/-8 vs. 128+/-9 cells/ml blood; P=0.33). With respect to VEGF a significant downregulation was evident directly after the race (48.9+/-8.0 vs. 34.0+/-7.5 pg/ml; P<0.05), whereas no change was obvious in EGF levels.

CONCLUSION

The results of our study suggest that finishing a marathon race will lead to an inflammatory response and downregulation of circulating hematopoietic stem cells. With respect to EPCs no change is observed, which may be because of a greater differentiation of the remaining CD34 cells towards EPCs.

Does exercise increase the risk of upper respiratory tract infections?

INTRODUCTION OR BACKGROUND

Heavy exercise induces marked immunodepression, which is multifactorial in origin. Evidence showing clinical significance of this immunodepression is scarce.

SOURCES OF DATA

We assessed in a systematic manner whether physical activity or intensity of exercise increase susceptibility to upper respiratory tract infections (URTI). A literature search was performed using the keywords 'upper respiratory tract infections', 'athletes', 'exercise' and 'physical activity'. We considered all studies reporting of the effect of exercise, physical activity, sport and training on susceptibility to URTI. A total of 162 publications were identified and 30 studies were eligible (4 descriptive, 18 observational and 8 interventional). The 30 studies included 8595 athletes (5471 runners, 2803 swimmers) and 1798 non-athletes.

AREAS OF AGREEMENT

Moderate activity may enhance immune function, whereas prolonged, high-intensity exercise temporarily impairs the immune competence. Athletes, when compared with lesser active individuals, experience higher rate of URTI after training and competitions. In non-athletes, increasing physical activity is associated with a decreased risk of URTI.

AREAS OF CONTROVERSY

The relationship between exercise and URTI is affected by poorly known individual determinants such as genetic factors, fitness, nutritional status or atopy. Elite athletes may have a decreased susceptibility to URTI.

GROWING POINTS AND AREAS TIMELY FOR DEVELOPING RESEARCH

The dose-response relationship between immunodepression and risk for URTI during the weeks following heavy exercise. What are the clinically relevant methods to assess exercise-induced immunodepression? Is down-regulation of immunity after intense exercise a protective response to limit inflammation? Is there a role for nutritional or pharmaceutical interventions to reduce risk of URTI?

The effect of a pre-exercise carbohydrate meal on immune responses to an endurance performance run

This study examined the effect of a pre-exercise meal with different glycaemic index (GI) and glycaemic load (GL) on immune responses to an endurance performance run. Eight men completed a preloaded 1 h run at 70 % VO2maxon a level treadmill followed by a 10 km performance run on three occasions. In each trial, one of the three prescribed isoenergetic meals, i.e. high GI and high GL (H-H), high GI and low GL (H-L), or low GI and low GL (L-L) was consumed by the subjects 2 h before exercise. Carbohydrate intake (% of energy intake), GI, and GL were 65 %, 79·5, and 82·4 for H-H; 36 %, 78·5, and 44·1 for H-L; 65 %, 40·2, and 42·1 for L-L, respectively. The running time for the three trials was approximately 112 min at 70 % VO2maxfor the first hour and 76 % VO2maxfor the last 52 min. Consumption of pre-exercise high-carbohydrate meals (H-H and L-L) resulted in less perturbation of the circulating numbers of leucocytes, neutrophils and T lymphocyte subsets, and in decreased elevation of the plasma IL-6 concentrations immediately after exercise and during the 2 h recovery period compared with the H-L trial. These responses were accompanied by an attenuated increase in plasma IL-10 concentrations at the the end of the 2 h recovery period. The amount of carbohydrate consumed in the pre-exercise meal may be the most important influencing factor rather than the type of carbohydrate in modifying the immunoendocrine response to prolonged exercise.

Muscle as an endocrine organ: focus on muscle-derived interleukin-6

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. However, the first identified and most studied myokine is the gp130 receptor cytokine interleukin-6 (IL-6). IL-6 was discovered as a myokine because of the observation that it increases up to 100-fold in the circulation during physical exercise. Identification of IL-6 production by skeletal muscle during physical activity generated renewed interest in the metabolic role of IL-6 because it created a paradox. On one hand, IL-6 is markedly produced and released in the postexercise period when insulin action is enhanced but, on the other hand, IL-6 has been associated with obesity and reduced insulin action. This review focuses on the myokine IL-6, its regulation by exercise, its signaling pathways in skeletal muscle, and its role in metabolism in both health and disease.

Immunonutrition support for athletes

Multiple components of the immune systems in athletes exhibit transient dysfunction after prolonged, heavy exertion. During this "open window" of impaired immunity, pathogens may gain a foothold, increasing infection risk. Nutritional supplements have been studied as countermeasures to exercise-induced immune changes and infection risk. This review focuses on findings from recent exercise-based studies with macro- and micronutrient supplements, and "advanced" immunonutrition supplements including beta-glucan, curcumin, and quercetin. Results from these studies indicate that immunonutrition supplements have the potential to lessen the magnitude of exercise-induced perturbations in immune function and to reduce the risk of upper respiratory tract infections.

Heat stroke and cytokines

Heat stroke is a life-threatening illness that affects all segments of society, including the young, aged, sick, and healthy. The recent high death toll in France (Dorozynski, 2003) and the death of high-profile athletes has increased public awareness of the adverse effects of heat injury. However, the etiology of the long-term consequences of this syndrome remains poorly understood such that preventive/treatment strategies are needed to mitigate its debilitating effects. Cytokines are important modulators of the acute phase response (APR) to stress, infection, and inflammation. Current data implicating cytokines in heat stroke responses are mainly from correlation studies showing elevated plasma levels in heat stroke patients and experimental animal models. Correlation data fall far short of revealing the mechanisms of cytokine actions such that additional research to determine the role of these endogenous substances in the heat stroke syndrome is required. Furthermore, cytokine determinations have occurred mainly at end-stage heat stroke, such that the role of these substances in progression and long-term recovery is poorly understood. Despite several studies implicating cytokines in heat stroke pathophysiology, few studies have examined the protective effect(s) of cytokine antagonism on the morbidity and mortality of heat stroke. This is particularly surprising since heat stroke responses resemble those observed in the endotoxemic syndrome, for which a role for endogenous cytokines has been strongly implicated. The implication of cytokines as mediators of endotoxemia and the presence of circulating endotoxin in heat stroke patients suggests that much knowledge can be gained from applying our current understanding of endotoxemic pathophysiology to the study of heat stroke. Heat shock proteins (HSPs) are highly conserved proteins that function as molecular chaperones for denatured proteins and reciprocally modulate cytokine production in response to stressful stimuli. HSPs have been shown repeatedly to confer protection in heat stroke and injury models. Interactions between HSPs and cytokines have received considerable attention in the literature within the last decade such that a complex pathway of interactions between cytokines, HSPs, and endotoxin is thought to be occurring in vivo in the orchestration of the APR to heat injury. These data suggest that much of the pathophysiologic changes observed with heat stroke are not a consequence of heat exposure, per se, but are representative of interactions among these three (and presumably additional) components of the innate immune response. This chapter will provide an overview of current knowledge regarding cytokine, HSP, and endotoxin interactions in heat stroke pathophysiology. Insight is provided into the potential therapeutic benefit of cytokine neutralization for mitigation of heat stroke morbidity and mortality based on our current understanding of their role in this syndrome.

The biological roles of exercise-induced cytokines: IL-6, IL-8, and IL-15

Skeletal muscle fibers express several cytokines, including interleukin (IL)-6, IL-8, and IL-15. Solid evidence exists that muscular IL-6 and IL-8 are regulated by muscle contractions, at both the mRNA and the protein levels. IL-6 increases insulin-stimulated glucose disposal and fatty acid oxidation in humans in vivo. Both IL-6 and IL-8 are released from working skeletal muscle, but because IL-6 contributes to the systemic circulation only a small transient net release of IL-8 is found from working muscle, suggesting that IL-8 may exert its effects locally in the muscle. IL-15 is a recently discovered growth factor, which is highly expressed in skeletal muscle. Interestingly, although IL-15 has been demonstrated as having anabolic effects on skeletal muscle in vitro and in vivo, it seems to play a role in reducing adipose tissue mass, and a role for IL-15 in muscle-fat cross-talk has been hypothesized. In conclusion, muscle-derived cytokines appear to have important roles in metabolism, and exercise plays a role in orchestrating the interplay between cytokines and metabolism.

Consumo alimentar de atletas: reflexões sobre recomendações nutricionais, hábitos alimentares e métodos para avaliação do gasto e consumo energéticos

O objetivo do artigo foi efetuar revisão sobre o consumo alimentar de atletas, enfatizando recomendações nutricionais, adequações dietéticas, comportamento alimentar e limitações dos métodos na avaliação dietética e estimativa do gasto energético nesta população. Foram analisados 30 artigos, publicados no período de 1984-2004, selecionados em bases eletrônicas de dados. O critério de inclusão dos artigos foi a abordagem sobre aspectos nutricionais relacionados ao exercício, recomendações de energia e nutrientes, bem como consumo alimentar de atletas. As recomendações de energia, macronutrientes e hidratação para atletas já estão bem determinadas, porém, pouco se conhece sobre as necessidades de vitaminas e minerais. Contudo, existe um consenso de que as necessidades de micronutrientes para a maioria desses indivíduos podem ser atendidas por uma dieta variada e equilibrada. Por outro lado, estudos indicam que a inadequação de energia e nutrientes ainda predomina em vários grupos atléticos, revelando a necessidade da reeducação nutricional. Diversos fatores inerentes à modalidade esportiva, tais como os esquemas de treinamento e as exigências relativas à imagem corporal, podem influenciar os hábitos alimentares do atleta. Portanto, a compreensão das relações entre o padrão de alimentação de atletas e os diversos fatores relacionados ao esporte são aspectos fundamentais para o estabelecimento de orientações nutricionais. A ocorrência de erros sistemáticos em pesquisas com atletas que empregam métodos que utilizam o auto-relato, ressalta a importância do rigor metodológico na aplicação desses instrumentos.

The influence of antioxidant supplementation on markers of inflammation and the relationship to oxidative stress after exercise

Interest in the relationship between inflammation and oxidative stress has increased dramatically in recent years, not only within the clinical setting but also in the fields of exercise biochemistry and immunology. Inflammation and oxidative stress share a common role in the etiology of a variety of chronic diseases. During exercise, inflammation and oxidative stress are linked via muscle metabolism and muscle damage. Because oxidative stress and inflammation have traditionally been associated with fatigue and impaired recovery from exercise, research has focused on nutritional strategies aimed at reducing these effects. In this review, we have evaluated the findings of studies involving antioxidant supplementation on alterations in markers of inflammation (e.g., cytokines, C-reactive protein and cortisol). This review focuses predominantly on the role of reactive oxygen and nitrogen species generated from muscle metabolism and muscle damage during exercise and on the modulatory effects of antioxidant supplements. Furthermore, we have analyzed the influence of factors such as the dose, timing, supplementation period and bioavailability of antioxidant nutrients.

Gene expression profiling in blood cells of endurance horses completing competition or disqualified due to metabolic disorder

REASONS FOR PERFORMING STUDY

Genomics using cDNA microarrays could provide useful information about physiological adaptations and metabolic disorders in endurance horses.

OBJECTIVES

In order to show that genes are modulated in leucocytes in relationship with performance and clinical status of the horses, gene expression in leucocytes, haematological and biochemical parameters were compared between successful and disqualified endurance horses.

METHODS

Blood samples were collected at rest (TO) and just after a 140-160 km endurance race (T1) in 2 groups of horses: 10 continuing successful (S) and 10 disqualified horses stopped at a vet-gate for metabolic disorders (D). Total RNA was extracted from the blood cells (leucocytes), checked for purity, amplified and hybridised using mouse cDNA microarrays including 15,264 unique genes. Differential gene expressions were studied by hybridisation of each sample T1 vs. a control sample collected at TO (pool of 20 sound horses).

RESULTS

Some significant differences were observed in the haematology and biochemistry of the 2 groups (S vs. D). In Group D, rhadomyolysis was confirmed with CK 13,124 u/l and AST 1242 u/l. The list of 726 (including 603 annotated genes) significant genes was filtered according to a high P-value cut-off (P<0.00001). Among them, 130 were upregulated (expression ratio>1.5) and 288 were down-regulated (<1/1.5). Analysis of variance revealed 62 genes differentially expressed (P<0.05) in Groups D and S. The expression levels of 28 and 50 genes were significantly correlated (r>0.75) with CK and AST level in Group D, respectively. The gene ontology classification showed that more genes were up-regulated in S than in the D. More genes were down-regulated in the disqualified horses.

CONCLUSIONS

Long exercise induced many significant gene modulations in leucocytes. Some genes were expressed in relationship with the clinical phenotype observed in Group D: rhabdomyolysis and haemolysis.

POTENTIAL RELEVANCE

Some of these genes could be candidates to explain poor performance or pathologies. Further association studies with a greater number of genes should be conducted.

Role of myokines in exercise and metabolism

During the past 20 yr, it has been well documented that exercise has a profound effect on the immune system. With the discovery that exercise provokes an increase in a number of cytokines, a possible link between skeletal muscle contractile activity and immune changes was established. For most of the last century, researchers sought a link between muscle contraction and humoral changes in the form of an "exercise factor," which could mediate some of the exercise-induced metabolic changes in other organs such as the liver and the adipose tissue. We suggest that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert either paracrine or endocrine effects should be classified as "myokines." Since the discovery of interleukin (IL)-6 release from contracting skeletal muscle, evidence has accumulated that supports an effect of IL-6 on metabolism. We suggested that muscle-derived IL-6 fulfils the criteria of an exercise factor and that such classes of cytokines should be named "myokines." Interestingly, recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. Thus skeletal muscle has the capacity to express several myokines. To date the list includes IL-6, IL-8, and IL-15, and contractile activity plays a role in regulating the expression of these cytokines in skeletal muscle. The present review focuses on muscle-derived cytokines, their regulation by exercise, and their possible roles in metabolism and skeletal muscle function and it discusses which cytokines should be classified as true myokines.

Biomarkers of muscle and cartilage damage and inflammation during a 200 km run

Ultra-marathon running is frequently associated with muscle fibre damage. However, ultra-marathon related information is scarce. The present study evaluated muscle and cartilage biomarkers, and cytokine secretion during a 200 km running event. Venous blood samples from 54 trained male ultra-marathon runners (mean +/- SD, 45.7 +/- 5.1 years). Plasma creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate, glucose, high-sensitivity C-reactive protein (Hs-CRP), interleukin-6 (IL-6), TNF- proportional, variant and serum cartilage oligomeric matrix protein (COMP) content were determined before, midway and immediately after the race. CPK increased 90-fold (19-fold at 100 km) from pre-race value and LDH increased 3.7-fold (2.2-fold at 100 km). AST increased 15-fold (5-fold at 100 km) and ALT increased 3.9-fold (2-fold at 100 km). Blood lactate and glucose levels did not change significantly. Hs-CRP increased 23-fold (3-fold at 100 km) and IL-6 increased 121-fold at 100 km, and then remained stable up to 200 km, whereas TNF- proportional, variant did not change significantly. Serum COMP increased 3-fold (1.3-fold at 100 km). Post-run CPK was correlated with LDH (r = 0.62, P < 0.001), Hs-CRP (r = 0.45, P < 0.001), ALT (r = 0.89, P < 0.001), AST (r = 0.97, P < 0.001), and IL-6 (r = 0.61, P < 0.001). The present study demonstrated that blood biomarkers related to muscle and cartilage damage and inflammation were increased during a 200 km run and that this was particularly marked during the second half of the event. Ultra-marathon running clearly has a major impact on muscle and cartilage structures.

Influence of carbohydrate on immune function following 2 h cycling

The influence of carbohydrate compared with placebo ingestion on changes in immune cell counts and functions following 2 h intensive cycling was studied in 12 trained cyclists who functioned as their own controls. The subjects performed two tests 2 weeks apart where they cycled for 2 h at approximately 64% Watts(max) while receiving 4 mL x kg(-1) x 15 min(-1) carbohydrate (6%) (Cho) or placebo (Pla) beverages. Blood samples were collected 30 min preexercise, and immediately and 1 h postexercise. The samples were assayed for plasma cortisol and epinephrine, blood leukocyte subset counts, PHA-induced lymphocyte proliferation, and natural killer cell activity (NKCA). Compared with Pla ingestion, Cho attenuated exercise-induced changes in plasma cortisol, blood neutrophil, and monocyte counts, but not in total blood lymphocyte, T cell, and NK cell counts, PHA-induced lymphocyte proliferation, and NKCA. Thus despite a strong attenuating influence of carbohydrate ingestion on exercise-induced changes in plasma cortisol and blood neutrophil and monocyte counts, other immune measures related to lymphocyte subset counts, and function were unaffected.

Nutritional modulation of exercise-induced immunodepression in athletes: a systematic review and meta-analysis

BACKGROUND

Heavy exercise induces marked immunodepression that is multifactorial in origin. Nutrition can modulate normal immune function.

OBJECTIVE

To assess the efficacy of nutritional supplements in exercise-induced immunodepression in athletes.

DESIGN

Systematic review.

REVIEW METHODS

Randomised and/or controlled trials of athletes undertaking nutritional supplements to minimise the immunodepression after exercise were retrieved. The primary outcome measure was incidence of upper respiratory tract (URT) illness symptoms after exercise, and secondary outcomes included cortisol, cell counts, plasma cytokine concentration, cell proliferative response, oxidative burst, natural killer cell activity and immunoglobulins. When data were available for a pooled estimate of the effect of intervention, meta-analyses were conducted for direct comparisons.

RESULTS

Forty-five studies were included (1603 subjects). The studies were heterogeneous in terms of exercise interventions, selection of athletes, settings and outcomes. The overall methodological quality of most of the trials was poor. Twenty studies addressed carbohydrate supplementation, eight glutamine, 13 vitamin C and four others interventions. Three trials assessed the effect of intervention on prevention of URT infections. The pooled rate ratio for URT infections after vitamin C supplementation against placebo was 0.49 (0.34-0.71). Carbohydrate supplementation attenuated the increase in cortisol and neutrophils after exercise; vitamin C attenuated the decrease in lymphocytes after exercise. No other interventions had significant or consistent effect on any of the studied outcomes.

CONCLUSIONS

Although the prevention of URT infections by vitamin C was supported by two trials, further studies are needed. The available evidence failed to support a role for other nutritional supplements in preventing exercise-induced immune suppression. Larger trials with clinically relevant and uniform end points are necessary to clarify the role of these nutritional interventions.

Ibuprofen use, endotoxemia, inflammation, and plasma cytokines during ultramarathon competition

The primary purpose of this study was to measure the influence of ibuprofen use during the 160-km Western States Endurance Run on endotoxemia, inflammation, and plasma cytokines. Subjects included 29 ultramarathoners who consumed 600 and 1200 mg ibuprofen the day before and on race day, respectively, and 25 controls that competed in the race but avoided ibuprofen and all other medications. Blood and urine samples were collected the morning prior to and immediately following the race, and subjects recorded muscle soreness during the week following the race using a 10-point Likert scale (DOMS). Race time (25.8+/-.6 and 25.6+/-.8 h, respectively) and ratings of perceived exertion (RPE, 6-20 scale) (14.6+/-.4 and 14.5+/-.2, respectively) did not differ significantly between ibuprofen users and nonusers. Ibuprofen use compared to nonuse was linked to a smaller increase in urine creatinine (P=.038), higher plasma levels of lipopolysaccharide (group effect, P=.042), and greater increases (pre-to-post race) in serum C-reactive protein and plasma cytokine levels for interleukin (IL)-6, IL-10, IL-8, IL-1 ra, granulocyte colony-stimulating factor, monocyte chemotactic protein 1, and macrophage inflammatory protein 1 beta, but not tumor necrosis factor alpha. Post-race DOMS and serum creatine kinase levels did not differ significantly between ibuprofen users and nonusers (20,621+/-3565 and 13,886+/-3068 microcal/L, respectively, P=.163). In conclusion, ibuprofen use compared to nonuse by athletes competing in a 160-km race did not alter muscle damage or soreness, and was related to elevated indicators of endotoxemia and inflammation.

Do circulating leucocytes and lymphocyte subtypes increase in response to brief exercise in children with and without asthma?

BACKGROUND

Exercise can alter health in children in both beneficial (eg reduced long-term risk of atherosclerosis) and adverse (eg exercise-induced asthma) ways. The mechanisms linking exercise and health are not known, but may rest, partly, on the ability of exercise to increase circulating immune cells. Little is known about the effect of brief exercise, more reflective of naturally occurring patterns of physical activity in children, on immune cell responses.

OBJECTIVES

To determine whether (1) a 6-min bout of exercise can increase circulating inflammatory cells in healthy children and (2) the effect of brief exercise is greater in children with a history of asthma.

METHODS

Children with mild-moderate persistent asthma and age-matched controls (n = 14 in each group, mean age 13.6 years) performed a 6-min bout of cycle-ergometer exercise. Spirometry was performed at baseline and after exercise. Blood was drawn before and after exercise, leucocytes were quantified and key lymphocyte cell surface markers were assessed by flow cytometry.

RESULTS

Exercise decreased spirometry only in children with asthma, but increased (p<0.001) most types of leucocytes (eg lymphocytes (controls, mean (SD) 1210 (208) cells/microl; children with asthma, 1119 (147) cells/microl) and eosinophils (controls, 104 (22) cells/microl; children with asthma, 88 (20) cells/microl)) to the same degree in both groups. Similarly, exercise increased T helper cells (controls, 248 (60) cells/microl; children with asthma, 232 (53) cells/microl) and most other lymphocyte subtypes tested. By contrast, although basophils (16 (5) cells/microl) and CD4+ CD45RO+ RA+ lymphocytes (19 (4) cells/microl) increased in controls, no increase in these cell types was found in children with asthma.

CONCLUSIONS

Exercise increased many circulating inflammatory cells in both children with asthma and controls. Circulating inflammatory cells did increase in children with asthma, but not to a greater degree than in controls. In fact, basophils and T helper lymphocyte memory transition cells did not increase in children with asthma, whereas they did increase in controls. Even brief exercise in children and adolescents robustly mobilizes circulating immune cells.

Blood Leukocyte mRNA Expression for IL-10, IL-1Ra, and IL-8, but Not IL-6, Increases After Exercise

The primary purpose of this project was to study exercise-induced leukocyte cytokine mRNA expression. Changes in plasma cytokine levels and blood leukocyte mRNA expression for interleukin-6 (IL-6), IL-8, IL- 10, and IL-1 receptor antagonist (IL-1Ra) were measured in 12 athletes following 2 h of intensive cycling ( approximately 64% Watts(max)) while ingesting a carbohydrate or placebo beverage (randomized and double blinded). Blood samples were collected 30 min preexercise and immediately and 1 h postexercise. Carbohydate compared with placebo ingestion attenuated exercise-induced changes in plasma cortisol (8.8% vs. 62%, respectively), epinephrine (-9.2% vs. 138%), IL-6 (10-fold vs. 40-fold), IL-10 (8.9-fold vs. 26-fold, and IL-1Ra (2.1-fold vs. 5.6-fold). Significant time effects were measured for blood leukocyte IL-8 (2.4-fold increase 1 h postexercise), IL-10 (2.7-fold increase), IL-1Ra (2.2-fold increase), and IL-6 (0.8-fold decrease) mRNA content, with no significant differences between Cho and Pla test conditions. In summary, gene expression for IL-8, IL-10, and IL-1Ra, but not IL-6, is increased in blood leukocytes taken from athletes following 2 h of intensive cycling and is not influenced by carbohydrate compared with placebo ingestion. mRNA expression was high enough to indicate a substantial contribution of blood leukocytes to plasma levels of IL-8, IL-10, and IL-1Ra during prolonged exercise.