Exercise and the immune response

Exercise may improve lung immunity after surgical stress: Evidence from a nephrectomy model via a bioinformatic analysis

Exercise offers numerous benefits to cancer patients and plays an essential role in postsurgical cancer rehabilitation. However, there is a lack of research examining the effects of exercise after the surgical stress of nephrectomy. To address this gap, we created an animal model that simulated patients who had undergone nephrectomy with or without an exercise intervention. Next, we performed a bioinformatic analysis based on the data generated by the RNA sequencing of the lung tissue sample. An overrepresentation analysis was conducted using two genome databases (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes [KEGG]). A KEGG analysis of the exercise-treated nephrectomy mice revealed enrichment in immune-related pathways, particularly in the NF-κB and B cell-related pathways. The expression of CD79A and IGHD, which are responsible for B cell differentiation and proliferation, was upregulated in the nephrectomy mice. Differential gene expression was categorized as significantly upregulated or downregulated according to nephrectomy and exercise groups. Notably, we identified several gene expression reversals in the nephrectomy groups with exercise that were not found in the nephrectomy without exercise or control groups. Our preliminary results potentially reveal a genetic landscape for the underlying mechanisms of the effects of exercise on our nephrectomy model.

Monitoring training, performance, biomarkers, and psychological state throughout a competitive season: a case study of a triathlete

INTRODUCTION

Ironman triathletes undergo high workloads during competition preparation which can result in nonfunctional overreaching or overtraining syndrome if not matched with adequate recovery.

PURPOSE

The purpose of this case study was to observe changes in physiological and psychological status over the course of a competitive season in a free-living triathlete.

METHODS

The subject was a 41-year-old triathlete competing in three 113.1-km events. Over the course of a 40-week period, the participant arrived at the laboratory every 4 weeks and underwent body composition testing via air displacement plethysmography, a blood draw for analysis of various biomarkers, and a treadmill-based lactate threshold test. Workload during training and competitions was monitored via a wearable heart rate-monitoring device.

RESULTS

Throughout the season, training volume remained high (12.5 ± 3.4 h/week) and body mass and fat-free mass (FFM) continuously decreased, while biomarkers including cortisol, testosterone, and markers of immunological status exhibited minor changes. Laboratory performance remained relatively consistent, while competition performance continually improved. Following the completion of the competitive period, training volume decreased, FFM remained below baseline levels, free cortisol increased, and both free and total testosterone decreased.

CONCLUSIONS

Workload and recovery seem to have been properly managed throughout the season, evidenced by minimal fluctuations in endocrine and immunological markers. The reason for changes observed in testosterone, cortisol, and body composition following the last competition is unclear, though it may be attributed to changes in stressors and recovery practices outside of training. It is recommended that athletes follow a structured plan during the transition period into the offseason to ensure recovery of physiological state and to set up a productive offseason.

Non-coding RNAs in exercise immunology: A systematic review

Regular physical exercise has been recognized as a potent modulator of immune function, with its effects including enhanced immune surveillance, reduced inflammation, and improved overall health. While strong evidence exists that physical exercise affects the specific expression and activity of non-coding RNAs (ncRNAs) also involved in immune system regulation, heterogeneity in individual study designs and analyzed exercise protocols exists, and a condensed list of functional, exercise-dependent ncRNAs with known targets in the immune system is missing from the literature. A systematic review and qualitative analysis was used to identify and categorize ncRNAs participating in immune modulation by physical exercise. Two combined approaches were used: (a) a systematic literature search for "ncRNA and exercise immunology", (b) and a database search for microRNAs (miRNAs) (miRTarBase and DIANA-Tarbase v8) aligned with known target genes in the immune system based on the Reactome database, combined with a systematic literature search for "ncRNA and exercise". Literature searches were based on PubMed, Web of Science, and SPORTDiscus; and miRNA databases were filtered for targets validated by in vitro experimental data. Studies were eligible if they reported on exercise-based interventions in healthy humans. After duplicate removal, 95 studies were included reporting on 164 miRNAs, which were used for the qualitative synthesis. Six studies reporting on long-noncoding RNAs (lncRNAs) or circular RNAs were also identified. Results were analyzed using ordering tables that included exercise modality (endurance/resistance exercise), acute or chronic interventions, as well as the consistency in reported change between studies. Evaluation criteria were defined as "validated" with 100% of ≥3 independent studies showing identical direction of regulation, "plausible" (≥80%), or "suggestive" (≥70%). For resistance exercise, upregulation of miR-206 was validated while downregulation of miR-133a appeared plausible. For endurance exercise, 15 miRNAs were categorized as validated, with 12 miRNAs being consistently elevated and 3 miRNAs being downregulated, most of them after acute exercise training. In conclusion, our approach provides evidence that miRNAs play a major role in exercise-induced effects on the innate and adaptive immune system by targeting different pathways affecting immune cell distribution, function, and trafficking as well as production of (anti-)inflammatory cytokines. miRNAs miR-15, miR-29c, miR-30a, miR-142/3, miR-181a, and miR-338 emerged as key players in mediating the immunomodulatory effects of exercise predominantly after acute bouts of endurance exercise.

The health benefit of physical exercise on COVID-19 pandemic: Evidence from mainland China

Objectives

Our study aims to investigate the health benefit of regular physical exercise participation on a series of COVID-19 outcomes including COVID-19 morbidity, mortality, and cure rate.

Methods

Prefecture-level panel data related to physical exercise and the COVID-19 pandemic in China were collected from January 1 to March 17, 2020, (N = 21379). Multiple linear regression was conducted, and the ordinary least squares technique was used to estimate the coefficient.

Results

It was shown that regular sports participation significantly negatively affected COVID-19 morbidity (estimate = -1.1061, p<0.01) and mortality (estimate = -0.3836, p<0.01), and positively affected cure rate (estimate = 0.0448, p<0.01), implying that engaging in physical exercise regularly does have a significant positive effect on COVID-19 outcomes. Then, we explored the heterogeneity of the effect of physical exercise on areas with different risk levels and it was revealed that the effect of physical exercise was more pronounced in high-risk areas in terms of morbidity (estimate = -1.8776, p<0.01 in high-risk areas; estimate = -0.0037, p<0.01 in low-risk areas), mortality (estimate = -0.3982, p<0.01 in high-risk areas; estimate = -0.3492, p<0.01 in low-risk areas), and cure rate (estimate = 0.0807, p<0.01 in high-risk areas; 0.0193 = -0.0037, p<0.05 in low-risk areas).

Conclusions

Our results suggest that regularly engaging in physical exercise before the pandemic has positive health effects, especially in the case of a more severe epidemic. Therefore, we urge readers to actively engage in physical exercise so that we can reduce the risks in the event of a pandemic.

Nutrition and Athlete Immune Health: New Perspectives on an Old Paradigm

Respiratory and gastrointestinal infections limit an athlete's availability to train and compete. To better understand how sick an athlete will become when they have an infection, a paradigm recently adopted from ecological immunology is presented that includes the concepts of immune resistance (the ability to destroy microbes) and immune tolerance (the ability to dampen defence yet control infection at a non-damaging level). This affords a new theoretical perspective on how nutrition may influence athlete immune health; paving the way for focused research efforts on tolerogenic nutritional supplements to reduce the infection burden in athletes. Looking through this new lens clarifies why nutritional supplements targeted at improving immune resistance in athletes show limited benefits: evidence supporting the old paradigm of immune suppression in athletes is lacking. Indeed, there is limited evidence that the dietary practices of athletes suppress immunity, e.g. low-energy availability and train- or sleep-low carbohydrate. It goes without saying, irrespective of the dietary preference (omnivorous, vegetarian), that athletes are recommended to follow a balanced diet to avoid a frank deficiency of a nutrient required for proper immune function. The new theoretical perspective provided sharpens the focus on tolerogenic nutritional supplements shown to reduce the infection burden in athletes, e.g. probiotics, vitamin C and vitamin D. Further research should demonstrate the benefits of candidate tolerogenic supplements to reduce infection in athletes; without blunting training adaptations and without side effects.

Whole body vibration elicits differential immune and metabolic responses in obese and normal weight individuals

Traditional aerobic exercise reduces the risk of developing chronic diseases by inducing immune, metabolic, and myokine responses. Following traditional exercise, both the magnitude and time-course of these beneficial responses are different between obese compared to normal weight individuals. Although obesity may affect the ability to engage in traditional exercise, whole body vibration (WBV) has emerged as a more tolerable form of exercise . The impact of WBV on immune, metabolic, and myokine responses as well as differences between normal weight and obese individuals, however, is unknown.

Purpose

To determine if WBV elicits differential magnitudes and time-courses of immune, metabolic, and myokine responses between obese and normal weight individuals.

Methods

21 participants [Obese (OB): n = 11, Age: 33 ± 4 y, percent body fat (%BF): 39.1 ± 2.4% & Normal weight (NW) n = 10, Age: 28 ± 8 y, %BF: 17.4 ± 2.1%] engaged in 10 cycles of WBV exercise [1 cycle = 1 min of vibration followed by 30 s of rest]. Blood samples were collected pre-WBV (PRE), immediately (POST), 3 h (3H), and 24 h (24H) post-WBV and analyzed for leukocytes, insulin, glucose, and myokines (IL-6, decorin, myostatin).

Results

The peak (3H) percent change in neutrophil counts (OB: 13.9 ± 17.4 vs. NW: 47.2 ± 6.2%Δ; p = 0.007) was different between groups. The percent change in neutrophil percentages was increased in NW (POST: -1.6 ± 2.0 vs. 3H: 13.0 ± 7.2%Δ, p = 0.019) but not OB (p > 0.05). HOMA β-cell function was increased at 24H (PRE: 83.4 ± 5.4 vs. 24H: 131.0 ± 14.1%; p = 0.013) in NW and was not altered in OB (p > 0.05). PRE IL-6 was greater in OB compared to NW (OB: 2.7 ± 0.6 vs. NW: 0.6 ± 0.1 pg/mL; p = 0.011); however, the percent change from PRE to peak (3H) was greater in NW (OB: 148.1 ± 47.9 vs. NW: 1277.9 ± 597.6 %Δ; p = 0.035). Creatine kinase, decorin, and myostatin were not significantly altered in either group (p > 0.05).

Conclusion

Taken together, these data suggest that acute whole body vibration elicits favorable immune, metabolic, and myokine responses and that these responses differ between obese and normal weight individuals.

An economical solution to record and control wheel-running for group-housed mice

BACKGROUND

The effects of exercise on brain function are widely known; however, there is a need for inexpensive, practical solutions for monitoring and metering the activity of multiple mice.

NEW METHOD

A contoured running wheel that has a built-in radio-frequency identification (RFID) receiver to monitor the activity of several mice in a single cage is presented. This system is scalable , the interface is easy to use, and the wheel can be dynamically locked so that each group-housed mouse receives a set exercise regimen.

RESULTS

We were able to reliably monitor three mice that were group-housed. We were able to reliably meter the amount of exercise performed by the mice using the servo-controlled lock.

COMPARISON WITH EXISTING METHODS

Current methods allow a wheel to be locked when a set distance is reached. However, an issue with this method is that the set distance includes the cumulative activity of all mice in the cage so one mouse could contribute a disproportionate amount to the total distance. Our solution ensures that the wheel is locked when an individual mouse reaches the target distance, but remains unlocked for individuals that have not reached the programmed distance.

CONCLUSIONS

The dynamic locking wheel (DynaLok) is designed to allow a researcher to provide individually designed exercise plans for multi-housed mice; therefore, users are able to house mice conventionally rather than in individual cages. DynaLok reduces animal housing costs, allows for new experimental exercise regimens to be developed, and is scalable and cost-effective.

No Evidence for Effect of Exercise on Transcriptome of NK Cells in Breast Cancer Patients Undergoing Adjuvant Therapy: Results From a Pilot Study

Background

Mobilization and activation of natural killer cells (NK cells) have been hypothesized to contribute to observed protective effects of exercise on cancer development and progression. Some evidence exists for acute effects of aerobic exercise on NK cell mobilization and function, i.e., alteration of the gene expression profile of NK cells. Yet, the chronic effects of exercise training, and effects of other modalities than endurance exercise are still understudied. Here, we investigated the chronic effects of a 12-week resistance exercise program on NK cell gene expression in breast cancer patients undergoing adjuvant chemo- or radiotherapy.

Methods

Breast cancer patients were randomly assigned to either a 12-week resistance exercise program or a relaxation control group concomitant to adjuvant therapy. In a subsample of 19 participants, RNA was extracted from magnet bead isolated NK cells and subsequently analyzed for differential gene expression using microarray Illumina HumanHT-12 v4 before and after the intervention.

Results

After chronic exercise intervention several genes showed higher differential expression compared to the control group. However, after correction for multiple testing, baseline-adjusted analyses of covariance indicated no significant differences between the intervention and the control group with regard to the gene expression profile.

Discussion

Our findings suggest that 12-week resistance-exercise did not alter the gene expression profile of NK cells in breast cancer patients undergoing adjuvant therapy on the long term. Further studies with larger sample sizes and specifically designed to investigate whether exercise-induced changes in NK cell function are attributed to acute effects are warranted.

Impact of Physical Exercise on Growth and Progression of Cancer in Rodents-A Systematic Review and Meta-Analysis

Background: Physical exercise is suspected to reduce cancer risk and mortality. So far, little is known about the underlying mechanisms. Although limited, murine models represent a promising attempt in order to gain knowledge in this field. Objective: A systematic review and meta-analysis examining various treatment protocols was conducted in order to determine the impact of exercise on tumor growth in rodents. Methods: PubMed, Google scholar and System for information on Gray literature in Europe were screened from inception to October 2017. Risk of bias within individual studies was assessed using the Office of Health Assessment and Translation risk of bias rating tool for human and animal trials. The effect of exercise on tumor growth over and above non-exercise control was pooled using random-effects model. Subgroup analyses were conducted to identify potential moderators. Results: The quality of the included 17 articles ranged between "probably low" and "high risk of bias." A significant reduction in tumor growth in exercising animals compared to controls was detected (Hedges' g = -0.40; 95% CI -0.66 to -0.14, p < 0.01) with between-study heterogeneity (τ² = 0.217, I ² = 70.28%, p < 0.001). The heterogeneity was partially explained by three moderators representing the in-between group differences of "maximum daily exercise" R ² = 33% (p < 0.01), "type of cancer administration" R ² = 28% (p < 0.05), and "training initiation" R ² = 27% (p < 0.05). Conclusion: This meta-analysis suggests that physical exercise leads to reduction of tumor size in rodents. Since "maximum daily exercise" was found to have at least modest impact on tumor growth, more clinical trials investigating dose-response relationships are needed.

Exercising the hepatobiliary-gut axis. The impact of physical activity performance

BACKGROUND

Physical inactivity puts the populations at risk of several health problems, while regular physical activity brings beneficial effects on cardiovascular disease, mortality and other health outcomes, including obesity, glycaemic control and insulin resistance. The hepatobiliary tract is greatly involved in several metabolic aspects which include digestion and absorption of nutrients in concert with intestinal motility, bile acid secretion and flow across the enterohepatic circulation and intestinal microbiota. Several metabolic abnormalities, including nonalcoholic fatty liver as well as cholesterol cholelithiasis, represent two conditions explained by changes of the aforementioned pathways.

MATERIALS AND METHODS

This review defines different training modalities and discusses the effects of physical activity in two metabolic disorders, that is nonalcoholic fatty liver disease (NAFLD) and cholelithiasis. Emphasis is given to pathogenic mechanisms involving intestinal bile acids, microbiota and inflammatory status.

RESULTS

A full definition of physical activity includes the knowledge of aerobic and endurance exercise, metabolic equivalent tasks, duration, frequency and intensity, beneficial and harmful effects. Physical activity influences the hepatobiliary-gut axis at different levels and brings benefits to fat distribution, liver fat and gallbladder disease while interacting with bile acids as signalling molecules, intestinal microbiota and inflammatory changes in the body.

CONCLUSIONS

Several beneficial effects of physical activity are anticipated on metabolic disorders linking liver steatosis, gallstone disease, gut motility, enterohepatic circulation of signalling bile acids in relation to intestinal microbiota and inflammatory changes.

Immune cell response to strenuous resistive breathing: comparison with whole body exercise and the effects of antioxidants

Background/hypothesis

Whole body exercise (WBE) changes lymphocyte subset percentages in peripheral blood. Resistive breathing, a hallmark of diseases of airway obstruction, is a form of exercise for the inspiratory muscles. Strenuous muscle contractions induce oxidative stress that may mediate immune alterations following exercise. We hypothesized that inspiratory resistive breathing (IRB) alters peripheral blood lymphocyte subsets and that oxidative stress mediates lymphocyte subpopulation alterations following both WBE and IRB.

Patients and methods

Six healthy nonathletes performed two WBE and two IRB sessions for 45 minutes at 70% of VO₂ maximum and 70% of maximum inspiratory pressure (Pi_max), respectively, before and after the administration of antioxidants (vitamins E, A, and C for 75 days, allopurinol for 30 days, and N-acetylcysteine for 3 days). Blood was drawn at baseline, at the end of each session, and 2 hours into recovery. Lymphocyte subsets were determined by flow cytometry.

Results

Before antioxidant supplementation at both WBE end and IRB end, the natural killer cell percentage increased, the T helper cell (CD3+ CD4+) percentage was reduced, and the CD4/CD8 ratio was depressed, a response which was abolished by antioxidants only after IRB. Furthermore, at IRB end, antioxidants promoted CD8+ CD38+ and blunted cytotoxic T-cell percentage increase. CD8+ CD45RA+ cell percentage changes were blunted after antioxidant supplementation in both WBE and IRB.

Conclusion

We conclude that IRB produces (as WBE) changes in peripheral blood lymphocyte subsets and that oxidative stress is a major stimulus predominantly for IRB-induced lymphocyte subset alterations.

Exercise-Induced Vasculitis: A Review with Illustrated Cases

Although exercise-induced vasculitis (EIV) is usually misdiagnosed, it is not uncommon. Occurring mostly after prolonged exercise, especially in hot weather, EIV is an isolated cutaneous vasculitis with stereotypical presentation. This article reviews the clinical characteristics, treatments, and outcomes of EIV based on the published literature. We report 99 patients who developed EIV after walking, dancing, swimming, or hiking especially during hot weather, including the records of 16 patients with EIV treated at our hospital from 2007 to 2015. Erythematous or purpuric plaques arise on the lower legs, without the involvement of compression socks or stockings. Symptoms include itch, pain, and a burning sensation. EIV is an isolated cutaneous vasculitis. Lesions resolve spontaneously after 10 days. When triggering conditions persist, relapses are frequent (77.5 %). Histopathology demonstrates leukocytoclastic vasculitis in 95 % of cases with C3 or immunoglobulin M deposits in 88 and 46 % of cases, respectively. Blood investigations are negative. EIV appears to be a consequence of venous stasis induced by an acute failure of the muscle pump of the calf and thermoregulation decompensation. Both appear after prolonged and unusual exercise in hot weather. Treatment is not codified; topical corticosteroids may reduce symptoms and wearing light clothes might limit lesion occurrence.

DESEMPENHO DE INDIVÍDUOS COM DERMOPIGMENTAÇÃO SUBMETIDOS À PRÁTICA DE EXERCÍCIO FÍSICO

RESUMO Introdução: A duração e a intensidade dos exercícios provocam diferentes alterações no sistema imunológico, dentre elas a diminuição das respostas imunes, acarretando queda no desempenho físico. Sabe-se também que a dermopigmentação pode colaborar com tais alterações no comportamento deste sistema. Objetivo: Avaliar os efeitos da dermopigmentação sobre o desempenho no exercício físico. Método: Neste ensaio clínico participaram 12 sujeitos, dentre eles seis com dermopigmentação, idade (anos), peso (Kg), estatura (cm) e gordura corporal (%) de 16,5 ± 1,16; 68,10 ± 6,83; 176,29 ± 7,71; 11,49 ± 0,58 respectivamente, divididos em dois grupos, sendo submetidos a teste de esforço máximo com intensidade progressiva em esteira ergométrica para determinação do consumo máximo de oxigênio (VO2máx), limiares anaeróbios (LAns) e economia de corrida (EC 14km/h %), sendo realizadas coletas de lactato pré e 5 minutos pós-teste. Os dados foram tratados por "teste t" para variáveis independentes, tendo como nível de significância adotado α < 0,05. Resultados: Foram observadas diferenças significativas entre os grupos em relação à concentração sanguínea de lactato (CSL) pré-teste (4,6 ± 0,11 e 3,23 ± 0,88 para dermopigmentados e não dermopigmentados, respectivamente; p < 0,05) e 5 minutos pós-teste (5,65 ± 0,49 e 13,13 ± 2,20 para dermopigmentados e não dermopigmentados, respectivamente; p < 0,05). O tempo de teste também foi significativamente superior para o grupo não dermopigmentado em comparação ao grupo com dermopigmentação (8 min 47 seg ± 0,08 e 7 min 39 seg ± 0,03 respectivamente; p < 0,05), bem como análise do WURSS-21 (3,33 ± 3,14 e 2,00 ± 1,09, respectivamente; p > 0,05). Em relação às demais variáveis dependentes (VO2máx, segundo limiar anaeróbio e economia de corrida) não foram encontradas diferenças estatisticamente significativas. Conclusão: A dermopigmentação produziu rendimento inferior no teste de esforço máximo, influenciando o desempenho no exercício físico.

Effects of competition on acute phase proteins and lymphocyte subpopulations - oxidative stress markers in eventing horses

The aim of the study was to evaluate markers of the acute phase response (APR) in eventing horses by measuring acute phase proteins (APP) (haptoglobin, Hp, and serum amyloid A, SAA), lysozyme, protein adducts such as pentosidine-like adducts (PENT), malondialdehyde adducts (MDA), hydroxynonenal adducts (HNE) and total advanced glycation/glycoxidation end products (AGEs), complete blood count and lymphocyte subpopulations (CD4+, CD8+ and CD21+) both at rest and at the end of an eventing competition. Blood samples were collected from eight Warmblood horses (medium age 10 ± 3) during an official national 2-day event competition at rest (R) and 10 min after the arrival of the cross-country test on the second day. Exercise caused a significant increase in red blood cell number, haemoglobin, packed cell volume, neutrophils, white blood cell and lymphocyte number; however, these values remained within the normal range. The CD4+ and CD8+ cells significantly increased, whereas the CD21+ lymphocytes decreased; a significant increase in serum SAA, lysozyme and protein carbonyl derivates was also observed. Two-day event causes significant changes in APR markers such as lysozyme, protein carbonyl derivates (HNE, AGEs, PENT) and lymphocyte subpopulations. The data support the hypothesis that 2-day event may alter significantly APR markers. Limitations of the study were the relatively small sample size and sampling time conditioned by the official regulations of the event. Therefore, further studies are needed to investigate the time required for recovery to basal values in order to define the possible effects on the immune function of the athlete horse.

Moderate Intensity Training Impact on the Inflammatory Status and Glycemic Profiles in NOD Mice

The nonobese diabetic (NOD) mouse represents a well-established experimental model analogous to human type 1 diabetes mellitus (T1D) as it is characterized by progressive autoimmune destruction of pancreatic β-cells. Experiments were designed to investigate the impact of moderate-intensity training on T1D immunomodulation and inflammation. Under a chronic exercise regime, NOD mice were trained on a treadmill for 12 weeks (12 m/min for 30 min, 5 d/wk) while age-matched, control animals were left untrained. Prior to and upon completion of the training period, fed plasma glucose and immunological soluble factors were monitored. Both groups showed deteriorated glycemic profiles throughout the study although trained mice tended to be more compensated than controls after 10 weeks of training. An exercise-induced weight loss was detected in the trained mice with respect to the controls from week 6. After 12 weeks, IL-6 and MIP-1β were decreased in the trained animals compared to their baseline values and versus controls, although not significantly. Morphometric analysis of pancreata revealed the presence of larger infiltrates along with decreased α-cells areas in the control mice compared to trained mice. Exercise may exert positive immunomodulation of systemic functions with respect to both T1D and inflammation, but only in a stringent therapeutic window.

Exhaustive exercise modifies different gene expression profiles and pathways in LPS-stimulated and un-stimulated whole blood cultures

Exhaustive exercise can interfere with immunity, causing transient immunosuppression and infections/inflammation in athletes. We used microarray technology to analyze the gene expression profiles of whole blood in short time (1h) LPS-stimulated and un-stimulated cultures drawn before, 30min after, 3h after and 24h after a half-marathon run. Four male and 4 female athletes participated. Exercise induced differential expression of genes known to be involved in innate immunity/inflammatory response, metabolic response, DNA methylation, apoptosis and regulation of brain function. Several genes with prominent anti-inflammatory function were up-regulated in un-stimulated cultures, including ARG-1, SOCS3, DUSP-1, ORMs, IRAK3, and GJB6. Some of these genes were also strongly up-regulated in LPS-stimulated cultures (ARG-1, ORM2, and GJB6). Some genes were strongly up-regulated through exercise in LPS-stimulated cultures, but not in un-stimulated cultures (TNIP3, PLAU, and HIVEP1). There was also a row of genes, which were strongly down-regulated by exercise in LPS-stimulated cultures, notably IFN-β1 and CXCL10. Exercise also significantly changed the expression of genes (OLIG2, TMEM106B) which are known to be related to brain function and expression of which has never been documented in peripheral blood. In summary, exhaustive exercise, in addition to modifying gene expression in un-stimulated cells, could also interfere with the early gene expression response to endotoxin. There was an anti-inflammatory bias of gene regulation by exercise, including genes involved in the negative regulation of TLRs signalling. The results of the present study demonstrate that some potentially important effects of exercise can only be detected in relation to pathogen stimulation.

Physiological and leukocyte subset responses to exercise and cold exposure in cold-acclimatized skaters

We investigated physiological responses and changes in circulating immune cells following exercise in cold and thermoneutral conditions. Participants were short track skaters (n=9) who were acclimatized to cold conditions, and inline skaters (n=10) who were not acclimatized. All skaters were young, and skating at a recreational level three days per week for at least one year. Using a cross-over design, study variables were measured during 60 min of submaximal cycling (65% V.O₂max) in cold (ambient temperature: 5±1°C, relative humidity: 41±9%) and thermoneutral conditions (ambient temperature: 21±1°C, relative humidity: 35±5%). Heart rate, blood lactate and tympanic temperature were measured at rest, during exercise and recovery. Plasma cortisol, calprotectin and circulating blood cell numbers were measured before and after 60 min of cold or thermoneutral conditions, and during recovery from exercise. Heart rate was lower in both groups during exercise in cold versus thermoneutral conditions (P<0.05). The increase in total leukocytes during recovery was primarily due to an increase in neutrophils in both groups. The cold-acclimatized group activated neutrophils after exercise in cold exposure, whereas the non-acclimatized group activated lymphocyte and cortisol after exercise in cold exposure. Lymphocyte subsets significantly changed in both groups over time during recovery as compared to rest. Immediately after exercise in both groups, CD16+ and CD69+ cells were elevated compared to rest or before exercise in both conditions. Acclimatization to exercise in the cold does not appear to influence exercise-induced immune changes in cold conditions, with the possible exception of neutrophils, lymphocytes and cortisol concentration.

Serum immunoglobulin concentrations in horses racing a multiday endurance event

Chronic exercise can alter immune function. The objective of this study was to determine the effect of training and racing on serum immunoglobulin fractions (sIg) in horses participating in a multiday endurance event. Blood was obtained from 54 horses the day before a multiday race event with distance categories of 40 km (n=10) or 80 km (n=44) per day; from all available horses after completing each day; and once from 15 sedentary control horses. sIgGa, IgGb, sIgG(T), sIgA, and sIgM concentrations were measured via equine-specific ELISA, and data were analysed via repeated measures ANOVA (P<0.05, mean ± standard error). Ten horses completed 40 km once, and 44, 18 and 9 horses completed one, two and three 80 km days, respectively. Distance category and number of days raced had no effect on any immunoglobulin subtype. For horses in the 80 km category, sIgA before racing (1.97±0.14 mg/dl) was similar to controls (1.48±0.19) and after one, two or three days of racing (1.98±0.13, 1.80±0.15 and 1.76±0.26, respectively). Similarly, sIgM before racing (1.02±0.05 mg/dl) was not different to controls (1.08±0.12) and after one, two or three days of racing (1.03±0.06, 0.91±0.08 and 0.89±0.11). Similar findings were observed for sIgG(T) and sIgGa. For horses in the 40 km category, immunoglobulin subtype concentrations did not differ from before to after one day of racing, or from control horses, with the exception that sIgGb before racing (7.00±0.57), similarly to horses racing 80 km days (7.65±0.41), was significantly higher than in sedentary horses (5.71±0.54 mg/dl). This study identified higher sIgGb concentrations in trained endurance horses compared to sedentary horses, perhaps reflecting immune stimulation from disease exposure or more frequent vaccination.

Effects of training on resting peripheral blood and BAL-derived leucocyte function in horses

In this study, the effects of prolonged, high intensity training on aspects of peripheral blood and bronchoalveolar lavage (BAL)-derived leucocyte function were evaluated in 8 horses. All horses undertook a 7 week endurance training programme, followed by 5 weeks of high intensity training (HIT). Thereafter, horses were divided into control (C) and overtraining (OT) groups. The frequency and intensity of training were increased more substantially for horses in the OT group. Training was terminated in week 32 when horses in the OT group demonstrated a significant performance reduction. Peripheral blood and BAL samples were collected from 4 horses in C and OT groups in training weeks 7, 11, 14, 18, 22, 28 and 32. Flow cytometric techniques were used to assess phagocytosis by peripheral blood neutrophils and pulmonary alveolar macrophages (PAM), and oxidative burst activity of neutrophils, PAM, peripheral blood and BAL-derived lymphocytes. Peripheral blood neutrophil phagocytosis (internalisation) increased during the initial HIT period and decreased from week 16 when the training workload was increased for both groups. The oxidative burst activity of peripheral blood neutrophils and lymphocytes similarly increased and then decreased in response to training. The oxidative burst activity of PAM was reduced towards the end of the overtraining phase of the programme. Pulmonary alveolar macrophage phagocytosis and oxidative burst activity of BAL-derived lymphocytes demonstrated no change throughout the course of the study. There was no difference in results obtained from C or OT group horses, suggesting that protracted HIT, rather than overtraining, was associated with impaired cell function. The detrimental effects observed in peripheral blood neitrophil and PAM function may indicate impaired nonspecific immunity which may adversely affect the health and performance of horses undergoing protracted periods of intense training.

Immunological pattern alteration in shoe, hide, and leather industry workers exposed to hexavalent chromium

OBJECTIVE

The aim of this work was to assess the effects of hexavalent chromium [Cr(VI)] on shoe, leather, and hide industry workers, based on the assumption that Cr(VI) can behave as an environmental immunological "stressor."

METHODS

The immunological patterns of 84 male subjects were studied in relation to Cr(VI) hematic and urinary levels. Cr(VI) was measured through atomic absorption. Lymphocyte subsets, mitogen-mediated lymphocyte-proliferation, cytokine levels, and natural killer (NK) cytotoxic activity were also assayed.

RESULTS

The urinary levels of the total amount of Cr(VI) were significantly higher in a subgroup of exposed subjects (group B) than in the control or in the lower exposed (group A). In group B, Cr(VI) caused a decrease in the density of glucocorticoid receptors (GR) on peripheral blood mononuclear cells (PBMC) and a increase of IL-6. Cr(VI) did not modify NK-mediated cytotoxicity, the plasmatic levels of inflammatory cytokines and related soluble receptors, and prostaglandin levels, while it tended to increase lymphocyte sensitivity to mitogens and the production of immunomodulant cytokines (IFN-gamma, IL-4, and IL-2). The experimental addition of Cr(VI) to the in vitro lymphocyte culture determined a significant inhibition of phagocytosis percentage, index, and killing percentage. These effects were neutralized by exogenous IFN-gamma.

CONCLUSION

Cr(VI) could represent an environmental immunological stressor whose effects can be evaluated through laboratory surveys. The lymphocyte mitogen-induced proliferation, GR receptor on PBMC, and IL-6 plasma levels may represent a discriminating element between Cr(VI)-induced stress and other kinds of stress.

Differential Response of Lymphocytes and Neutrophils to High Intensity Physical Activity and to Vitamin C Diet Supplementation

We have determined the effects of chronic vitamin C intake on neutrophil and lymphocyte antioxidant defences during the acute phase immune response induced by intense exercise. Blood samples were taken from 16 voluntary athletes in basal conditions, both immediately after and 1 h after a duathlon competition. Sportsmen's nutrient intakes were determined before the competition. After determining the basal plasmatic ascorbate levels, the results were analysed taking into account the vitamin C intake and their plasmatic levels. Two groups were constituted, the vitamin C supplemented group and the control group, with the dietary vitamin C intake as the only statistical difference between groups. The duathlon competition induced a significant neutrophilia, which was higher in the supplemented group. Lymphocyte antioxidant enzyme activities increased after the competition, with a higher increase in SOD activity in the control group than in the supplemented one. The competition decreased neutrophil antioxidant enzyme activities and neutrophil ascorbate concentration. The decrease in the SOD activity in the supplemented group was higher than in the control group. Finally, the duathlon competition increased the expression of MAC-1 neutrophil adhesion molecule in the supplemented group. High vitamin C intake influenced the response of neutrophils and lymphocytes to oxidative stress induced by exercise, increasing the neutrophil activation.

Acute effects of soccer training on white blood cell count in elite female players

PURPOSE

To investigate the acute changes in leukocyte number and cortisol after a single bout of soccer training.

METHODS

Ten elite female national-team soccer players and 8 nonathletes participated in the study. The duration of the exercise was 2 h, and it was performed at an intensity of 75% of maximal heart rate (HRmax). Blood samples were taken before, immediately after, and 4 h after a soccer training session to determine total white blood cells; the subsets of neutrophils, lymphocytes, monocytes, eosinophils, and basophils; and cortisol. At the same time, blood samples were obtained from nonathletes who refrained from exercise.

RESULTS

Data analysis indicated a significant increase in total white blood cells in the athletes postexercise (P < .001). The leukocytosis was still evident after 4 h of recovery (78% higher than the preexercise values), and there was a significant difference between athletes and nonathletes (P < .001). This leukocytosis was primarily caused by neutrophilia-there were no significant differences in lymphocytes after the end of exercise or between the 2 groups (P > 0.05). In addition, there was a statistically significant difference in cortisol concentration between athletes and nonathletes after the exercise (P < .001).

CONCLUSION

These findings revealed that the single bout of soccer training at an intensity of 75% of HRmax induced leukocytosis without affecting the lymphocyte count in elite female athletes and probably the effectiveness of cellular components of adaptive immunity. Coaches should provide adequate time (>4 h) until the next exercise session.

Antioxidant endogenous defense in a human model of physical stress

The present work has used controlled conditions to study how physical activity and stress affect oxidant and anti-oxidant systems in a human model. Stress test consisting of one hour exercise at a cycloergometer with intensity over the 75% of the maximal cardiac frequency was followed by non-significant changes of malonyldialdehyde, assayed as a marker of lipid peroxidation, and by an increase of erythrocyte catalase and plasma and erythrocyte glutathione peroxidase after the test. These findings suggest that antioxidant response is broadly versatile and adaptable, and that physical activity may prevent extended cellular damage with consequent flogosis. Hence, controlled physical exercise may contribute to protect target organs, including cardiovascular systems, against oxidative stress.

Effect of acute maximal exercise on lymphocyte subgroups in type 1 diabetes

The essential therapy of diabetes mellitus includes medical nutrition therapy (MNT), exercise and medical therapy. Exercise, besides its metabolic effects, has positive influence on the immune system, but some forms of exercise may cause trauma for muscle and skeletal systems, they may also support negative effects on the immune system. Nineteen type 1 diabetic patients (mean age 22.1 +/- 2.8 yrs), followed by Diabetes Outpatient Clinic and twenty age matched male control subjects were included into the study, to demonstrate the effects of maximal, acute exercise on the immune system. The exercise test was performed according to Bruce protocol on treadmill. In diabetic subjects, increased CD19 and CD23 expressions were observed before exercise. In both groups (diabetic/control) CD3, CD4 expressions and CD4/CD8 ratio were decreased following the exercise, however expression of natural killer (NK) cells increased. Compared to type 1 diabetic patients healthy subjects had longer acute exercise that caused the increased level of CD8 expression, however type 1 diabetic patients did not show any difference. These results indicate that submaximal aerobic exercise might be recommended for type 1 diabetics without any complications because of its positive reflection on metabolic control and no negative effects on the immune system.

Elevated plasma interleukin-6 levels in trained male triathletes following an acute period of intense interval training

The aim of the present study was to investigate possible changes in the plasma IL-6 levels, subjective reporting of sources and symptoms of stress and the innate immune system in response to an acute period of intensified run training in highly trained endurance athletes. Eight healthy endurance trained male subjects (mean +/- SD age 23 +/- 2 years, VO(2max) 64.8 +/- 2.6 ml kg(-1) min(-1), mass 77.1 +/- 2.9 kg) completed the study which took place over a 4 week period. In weeks 2 and 3, in addition to their normal endurance training, subjects completed interval-training run sessions on three successive days. Saliva and venous blood samples were taken at the end of each week. Blood samples were analysed for leukocyte counts; neutrophil function; plasma IL-6; creatine kinase activity; and cortisol. Symptoms and sources of stress were assessed by questionnaire. Plasma IL-6 and creatine kinase activity were elevated following intensified training. Neutrophil function was reduced but total leukocyte and neutrophil counts, plasma cortisol and salivary IgA remained unchanged. There was a worsening in symptoms of stress despite there being no significant change in the sources of stress during intensified training. In conclusion, an acute period of intensified training can induce a suppression of the innate immune system and a chronic elevation in IL-6. This was associated with an increase in fatigue and generalised malaise which lends support to the recent cytokine theories of unexplained, underperformance syndrome.

Exercising in Environmental Extremes

Athletes, military personnel, fire fighters, mountaineers and astronauts may be required to perform in environmental extremes (e.g. heat, cold, high altitude and microgravity). Exercising in hot versus thermoneutral conditions (where core temperature is > or = 1 degrees C higher in hot conditions) augments circulating stress hormones, catecholamines and cytokines with associated increases in circulating leukocytes. Studies that have clamped the rise in core temperature during exercise (by exercising in cool water) demonstrate a large contribution of the rise in core temperature in the leukocytosis and cytokinaemia of exercise. However, with the exception of lowered stimulated lymphocyte responses after exercise in the heat, and in exertional heat illness patients (core temperature > 40 degrees C), recent laboratory studies show a limited effect of exercise in the heat on neutrophil function, monocyte function, natural killer cell activity and mucosal immunity. Therefore, most of the available evidence does not support the contention that exercising in the heat poses a greater threat to immune function (vs thermoneutral conditions). From a critical standpoint, due to ethical committee restrictions, most laboratory studies have evoked modest core temperature responses (< 39 degrees C). Given that core temperature during exercise in the field often exceeds levels associated with fever and hyperthermia (approximately 39.5 degrees C) field studies may provide an opportunity to determine the effects of severe heat stress on immunity. Field studies may also provide insight into the possible involvement of immune modulation in the aetiology of exertional heat stroke (core temperature > 40.6 degrees C) and identify the effects of acclimatisation on neuroendocrine and immune responses to exercise-heat stress. Laboratory studies can provide useful information by, for example, applying the thermal clamp model to examine the involvement of the rise in core temperature in the functional immune modifications associated with prolonged exercise. Studies investigating the effects of cold, high altitude and microgravity on immunity and infection incidence are often hindered by extraneous stressors (e.g. isolation). Nevertheless, the available evidence does not support the popular belief that short- or long-term cold exposure, with or without exercise, suppresses immunity and increases infection incidence. In fact, controlled laboratory studies indicate immuno-stimulatory effects of cold exposure. Although some evidence shows that ascent to high altitude increases infection incidence, clear conclusions are difficult to make because of some overlap with the symptoms of acute mountain sickness. Studies have reported suppressed cell-mediated immunity in mountaineers at high altitude and in astronauts after re-entering the normal gravity environment; however, the impact of this finding on resistance to infection remains unclear.

Golfer's vasculitis

A number of patients presented with an erythematous, purpuric rash occurring on the legs in association with playing golf and also after prolonged walks or hikes. Many patients believed that it was an allergic reaction to grasses or insecticides and had sometimes undergone extensive allergy testing. We collected reports of 17 such cases from dermatologists in the state of Victoria, Australia. Patients were interviewed by phone and asked to submit photographs of the rash if possible. Of these, the eruption developed in 15 after playing 18 holes of golf and in three following prolonged hikes. The rash would usually develop over the summer months under hot conditions. Most patients were over 50 years of age when the tendency to develop the eruption began. Biopsies of the rash in the active phase showed leukocytoclastic vasculitis. Patch testing and investigations for potential underlying causes for vasculitis were negative or unremarkable. It would seem that this is a common but poorly documented condition. The clinical presentation and histology would support the conclusion that it represents a leukocytoclastic vasculitis induced by prolonged exercise under hot conditions. The findings would suggest that it occurs in healthy people and extensive investigation with blood tests or allergy testing is inappropriate. We believe the condition should be termed 'golfer's vasculitis', as golf appears to be the most common precipitating event and such a term would enable the condition to become more widely recognized.

Study of hematological and biochemical parameters in runners completing a standard marathon

OBJECTIVE

To study hematological and biochemical parameters prospectively in runners completing a standard 42.2-km marathon run. To determine the incidence of hyponatremia in runners, and whether consumption of nonsteroidal anti-inflammatory medications (NSAIDs) was associated with alterations in serum biochemical parameters.

DESIGN

Observational cohort study.

SETTING

City of Christchurch (New Zealand) Marathon, June 2002.

PARTICIPANTS

One hundred fifty-five of the 296 athletes entered in the 2002 City of Christchurch Marathon were enrolled in the study.

MAIN OUTCOME MEASURES

Athletes were weighed at race registration and immediately after the race. Blood was drawn postrace for measurement of serum sodium, potassium, creatinine, and urea concentrations and for hematological analysis (hemoglobin concentration, hematocrit, leukocyte distribution).

RESULTS

Complete data sets including prerace and postrace weights, and postrace hematological and biochemical analyses were collected on 134 marathon finishers. Postrace serum sodium concentrations were directly related to changes in body weight (P < 0.0001). There were no cases of biochemical or symptomatic hyponatremia. Thirteen percent of runners had taken an NSAID in the 24 hours prior to the race. Mean values for serum creatinine (P = 0.03) and serum potassium (P = 0.007) concentrations were significantly higher in runners who had taken an NSAID. No athlete who had taken an NSAID had a postrace serum creatinine concentration less than 0.09 mmol/L. Ninety-eight percent of runners had a postrace leukocytosis (mean white cell count, 18.97 b/L), of which the major component was a raised neutrophil count (mean neutrophil count, 15.69 b/L).

CONCLUSIONS

This study found no cases of hyponatremia in runners completing a standard distance marathon. This finding relates to a marathon run under ideal conditions (minimal climatic stress) and in which there were fewer aid stations (every 5 km) than is common in North American marathons (every 1.6 km). Also, aggressive hydration practices were not promoted. Consumption of NSAIDs in the 24 hours prior to distance running was associated with altered renal function.

Photoperiod influences the effects of exercise and food restriction on an antigen-specific immune response in Siberian hamsters

Environmental conditions influence the onset and severity of illness and infection and may compromise survival. Energetically challenging conditions during winter may directly induce death through hypothermia, starvation, or shock. The ability to forecast and prepare for the arrival of challenging conditions associated with winter (e.g. low temperatures, decreased food) likely confers survival advantages. Siberian hamsters (Phodopus sungorus) stop reproduction and reduce body mass (approximately 25%) during short, winter-like day lengths, resulting in energetic savings. Hamsters also increase circulating glucocorticoids and lymphocytes (e.g. T cells, NK cells), and exhibit enhanced antigen-specific delayed-type-hypersensitivity (DTH) responses in the skin during short days (SDs). We tested the hypothesis that Siberian hamsters use SD lengths to signal the onset of winter to mediate the energetic trade-offs among body mass, reproductive function, and immune function. Long-day (LD; 16 h light, 8 h dark) and SD (8 h light, 16 h dark) hamsters were either food restricted (25%) or provided ad libitum (ad lib) food for 4 wk; half of all hamsters in each food condition had voluntary access to a running wheel, and half remained sedentary. SD hamsters enhanced DTH responses compared with LD hamsters under sedentary ad lib conditions. Exercise enhanced DTH in LD hamsters regardless of food intake. Furthermore, food-restriction did not significantly influence DTH in LD hamsters. In contrast, food-restriction suppressed DTH in SD hamsters regardless of activity condition, and exercise modestly enhanced DTH only in SD hamsters with ad lib access to food. In sum, moderate energetic deficiency suppressed DTH in SD (but not LD) hamsters, and this suggests that hamsters may have evolved to enhance immune responses during winter in preparation for increased metabolic stressors.

Glutamine supplementation in vitro and in vivo, in exercise and in immunodepression

In situations of stress, such as clinical trauma, starvation or prolonged, strenuous exercise, the concentration of glutamine in the blood is decreased, often substantially. In endurance athletes this decrease occurs concomitantly with relatively transient immunodepression. Glutamine is used as a fuel by some cells of the immune system. Provision of glutamine or a glutamine precursor, such as branched chain amino acids, has been seen to have a beneficial effect on gut function, on morbidity and mortality, and on some aspects of immune cell function in clinical studies. It has also been seen to decrease the self-reported incidence of illness in endurance athletes. So far, there is no firm evidence as to precisely which aspect of the immune system is affected by glutamine feeding during the transient immunodepression that occurs after prolonged, strenuous exercise. However, there is increasing evidence that neutrophils may be implicated. Other aspects of glutamine and glutamine supplementation are also addressed.

Changes in plasma level of human leukocyte elastase during leukocytosis from physical effort

Physical exercise is known to induce immunological changes, mainly leukocytosis and neutrophil activation. However, it is not known to what extent the leukocytosis, observed after exertion, is associated with an increase in plasma neutrophil elastase, an early marker of inflammatory response and neutrophil degranulation. In the present study changes in circulating leukocyte and neutrophil counts and human neutrophil elastase plasma levels were evaluated in volley-ball players before and after 2 h and 12 h prolonged training, during a competition season. For comparison, the same parameters were evaluated in untrained subjects before and after a jogging session. Basal white blood cell WBC, polymorpho nuclear PMN, and human polymorpho nuclear-elastase PMN-ELA values were within the normal healthy reference range and no significant differences were found between the two groups studied. Venous blood samples of nine volley-ball players showed a statistically significant increase in blood WBCs after 2 h exercise. This effect was paralleled by a statistically significant increase in PMN-ELA concentration compared to the values observed in the same individuals at rest. The exercise did not significantly change the basal correlation parameters between PMN level and PMN-ELA concentration. More pronounced WBC, PMN, and PMN-ELA increases were observed in the seven inactive subjects after 2 h jogging. There was no linear correlation between increased PMN counts and increased PMN-ELA concentrations in untrained subjects after exercise. The results show that not only the leukocyte count but also PMN-ELA plasma levels can be higher after physical effort. This has a practical significance as regards differential diagnosis demonstrating that determination of these two laboratory parameters can give abnormally high values even in the absence of an existing inflammatory process. Besides, lack of correlation between PMN count and PMN-ELA plasma levels in the untrained group suggest a state in which activation of the neutrophils is not connected with their number in peripheral blood.

Immunological changes after cancer treatment and participation in an exercise program

PURPOSE

The purpose of this investigation was to evaluate the impact of undertaking peripheral blood stem cell transplantation (PBST) on T-cell number and function, and to determine the role of a mixed type, moderate intensity exercise program in facilitating the recovery of T-cell number and function.

METHODS

Immunological measures of white blood cell, lymphocyte, CD3, CD4, and CD8 counts, and CD3 cell function were assessed pretransplant (PI), immediately posttransplant (PII), and 1 month (I1), 2 months (I2) and 3 months (PIII) posttransplant. After PII, 12 patients were divided equally into a control group (CG) or exercise intervention group (EG).

RESULTS

Lower total T-cell, helper T-cell, and suppressor T-cell counts (P< 0.01), as well as lower T-cell function (P< 0.01), when compared with normative data, were found at PI. More specifically, 88% of the group had CD3, CD4, and CD8 counts that were more than 40%, 20%, and 50% below normal at PI, respectively. Undertaking a PBST caused further adverse changes to the total leukocyte, lymphocyte, CD3, CD4 and CD8 count, and the helper/suppressor ratio. Although CD8 counts had returned to normal by PIII, CD3, CD4, and the CD4 /CD8 ratio remained significantly lower than normative data (P< 0.01), with 66%, 100%, and 100% of the subject group reporting counts and ratios, respectively, below the normal range.

CONCLUSION

The PBST patients were immunocompromised before undertaking the transplant, and the transplant procedure imposed further adverse changes to the leukocyte and lymphocyte counts. The leukocyte and CD8 counts returned to normal within 3 months posttransplant; however, the other immunological parameters assessed demonstrated a delayed recovery. Although participation in the exercise program did not facilitate a faster immune cell recovery, neither did the exercise program hinder or delay recovery.

Cold exposure: human immune responses and intracellular cytokine expression

It is commonly believed that exposure to cold environmental temperatures depresses immune function and increases the risk for infection. This review paper will 1) present an overview of human physiological responses to cold exposure, 2) present the human studies examining the effects of cold exposure on immune responses, and 3) summarize recent experiments from our laboratories examining the effects of exercise and fatigue on immune responses during subsequent cold exposure. Based on the review of the literature, there is no support for the concept that cold exposure depresses immune function.

Recovery time affects immunoendocrine responses to a second bout of endurance exercise

The purpose of this study was to examine the effect of different durations of rest between two bouts of exercise on immunoendocrine responses during and after the second bout of exercise. Nine endurance athletes participated in three 25-h trials: 1) complete bed rest (REST), 2) two bouts of exercise separated by 3 h of rest (SHORT), and 3) two bouts of exercise separated by 6 h of rest (LONG). Each cycle ergometer exercise bout lasted 75 min at 75% of maximal O(2) uptake. We observed a more pronounced increase in epinephrine, norepinephrine, adrenocorticotropic hormone, and cortisol, but not in growth hormone, and a larger neutrophilia and lymphocytopenia in connection with the second bout of exercise in trial SHORT compared with trial LONG. Lymphocyte activation was unaltered by the difference in rest protocol. In conclusion, a second bout of exercise elicited more pronounced change in neuroendocrine factors and leukocyte counts when preceded by 3 h of rest as opposed to 6 h of rest after the first bout of exercise.

Exercise and hypoxia: effects on leukocytes and interleukin-6-shared mechanisms?

Stress-induced immunological reactions to exercise have stimulated much research into stress immunology and neuroimmunology. It has been suggested that exercise can be employed as a model of temporary immunosuppression, which occurs during physical stress, such as hypoxia. Acute exercise and acute hypoxia mediate in principle identical effects on circulating lymphocyte and neutrophil numbers. Thus, during exercise and hypoxia, lymphocytes are recruited to the blood. After the stress, the number of lymphocytes declines after the stress, whereas the neutrophil number continues to increase. When exercise is performed during hypoxia, the exercise-induced immune changes are pronounced. There is some evidence that the exercise- and hypoxia-induced changes in leukocyte subpopulations are mediated by neuroendocrinological factors such as catecholamines, growth hormone, and cortisol. In contrast, although exercise, as well as hypoxia, is associated with increased plasma levels of IL-6, the mechanisms are not likely to be the same. Thus, during exercise, contracting skeletal muscles are the main source of IL-6 production, whereas the source of IL-6 during hypoxia has not been demonstrated. The increased level of adrenaline contributes to the enormous increase in plasma IL-6 only to a minor degree during strenuous exercise. However, the only modest increase in IL-6 during hypoxia may be linked to hormonal changes, whereas the prolonged increase in IL-6 during chronic hypoxia is likely to be multifactorial.

Effect of dietary intake on immune function in athletes

Athletes are exposed to acute and chronic stress that may lead to suppression of the immune system and increased oxidative species generation. In addition, the tendency to consume fewer calories than expended and to avoid fats may further compromise the immune system and antioxidant mechanisms. The exercise stress is proportional to the intensity and duration of the exercise, relative to the maximal capacity of the athlete. Muscle glycogen depletion compromises exercise performance and it also increases the stress. Glycogen stores can be protected by increased fat oxidation (glycogen sparing). The diets of athletes should be balanced so that total caloric intake equals expenditure, and so that the carbohydrates and fats utilised in exercise are replenished. Many athletes do not meet these criteria and have compromised glycogen or fat stores, have deficits in essential fats, and do not take in sufficient micronutrients to support exercise performance, immune competence and antioxidant defence. Either overtraining or under nutrition may lead to an increased risk of infections. Exercise stress leads to a proportional increase in stress hormone levels and concomitant changes in several aspects of immunity, including the following: high cortisol; neutrophilia; lymphopenia; decreases in granulocyte oxidative burst, nasal mucociliary clearance, natural killer cell activity, lymphocyte proliferation, the delayed-type sensitivity response, the production of cytokines in response to mitogens, and nasal and salivary immunoglobulin A levels; blunted major histocompatibility complex II expression in macrophages; and increases in blood granulocyte and monocyte phagocytosis, and pro- and anti-inflammatory cytokines. In addition to providing fuel for exercise, glycolysis, glutaminlysis, fat oxidation and protein degradation participate in metabolism and synthesis of the immune components. Compromising, or overusing, any of these components may lead to immunosuppression. In some cases, supplementation with micronutrients may facilitate the immune system and compensate for deficits in essential nutrients. In summary, athletes should eat adequate calories and nutrients to balance expenditure of all nutrients. Dietary insufficiencies should be compensated for by supplementation with nutrients, with care not to over compensate. By following these rules, and regulating training to avoid overtraining, the immune system can be maintained to minimise the risk of upper respiratory tract infections.

Can glutamine modify the apparent immunodepression observed after prolonged, exhaustive exercise?

Glutamine is an important fuel for some cells of the immune system. In situations of stress, such as clinical trauma, starvation, or prolonged, strenuous exercise, the concentration of glutamine in blood is decreased, often substantially. In endurance athletes this decrease occurs concomitantly with relatively transient immunodepression. Provision of glutamine or a glutamine precursor has been found to decrease the incidence of illness in endurance athletes. To date, it has not been established precisely which aspect of the immune system is affected by glutamine feeding during the transient immunodepression that occurs after prolonged, strenuous exercise. However, there is increasing evidence that neutrophils may be implicated.

Leukocyte counts and lymphocyte responsiveness associated with repeated bouts of strenuous endurance exercise

This study compared leukocyte counts and lymphocyte responsiveness during and after a second bout of high-intensity endurance exercise on the same day with the response to a similar but single bout of exercise. Nine athletes participated in three 24-h trials: 1) rest in bed (Rest); 2) one bout of exercise (One); and 3) two bouts of exercise (Two). All bouts consisted of 75 min at approximately 75% of maximal O(2) uptake on a cycle ergometer. Lymphocytes in whole blood were stimulated with monoclonal antibodies against CD2 and assessed by flow cytometry for expression of the early activation molecule CD69. The second bout of exercise in the Two trial was associated with significantly increased concentrations of total leukocytes, neutrophils, lymphocytes, CD4(+), CD8(+), and CD56(+) cells and a significantly decreased percentage of CD56(+) cells expressing CD69 compared with a single bout. Additionally, there was a significantly decreased CD69 fluorescence in CD56(+) cells postexercise. These differences suggest a "carry-over" effect in the immune system from a first to a second bout of exercise on the same day.