Does exercise increase the risk of upper respiratory tract infections?

Demystifying roles of exercise in immune response regulation against acute respiratory infections: A narrative review

The benefits of physical activity and exercise, especially those classified as moderate-to-vigorous activity (MVPA), have been well-established in preventing non-communicable diseases and mental health problems in healthy adults. However, the relationship between physical activity and exercise and the prevention and management of acute respiratory infection (ARI), a global high-burden disease, has been inconclusive. There have been debates and disagreements among scientific publications regarding the relationship between exercise and immune response against the causative agents of ARI. This narrative review aims to explore the theory that sufficiently explains the correlation between exercise, immune response, and ARI. The potential root causes of discrepancies come from research associated with the "open window" hypothesis. The studies have several limitations, and future improvements to address them are urgently needed in the study design, data collection, exercise intervention, subject recruitment, biomarkers for infection and inflammation, nutritional and metabolism status, and in addressing confounding variables. In conclusion, data support the clinical advantages of exercise have a regulatory contribution toward improving the immune response, which in turn potentially protects humans fromARI. However, the hypothesis related to its negative effect must be adopted cautiously.

It's Dead! Can Postbiotics Really Help Performance and Recovery? A Systematic Review

In recent years, postbiotics have increased in popularity, but the potential relevancy of postbiotics for augmenting exercise performance, recovery, and health is underexplored. A systematic literature search of Google Scholar and PubMed databases was performed with the main objective being to identify and summarize the current body of scientific literature on postbiotic supplementation and outcomes related to exercise performance and recovery. Inclusion criteria for this systematic review consisted of peer-reviewed, randomized, double-blind, and placebo-controlled trials, with a population including healthy men or women >18 years of age. Studies required the incorporation of a postbiotic supplementation regimen and an outcome linked to exercise. Search terms included paraprobiotics, Tyndallized probiotics, ghost biotics, heat-killed probiotics, inactivated probiotics, nonviable probiotics, exercise, exercise performance, and recovery. Only investigations written in English were considered. Nine peer-reviewed manuscripts and two published abstracts from conference proceedings were included and reviewed. Supplementation periods ranged from 13 days to 12 weeks. A total of 477 subjects participated in the studies (n = 16-105/study) with reported results spanning a variety of exercise outcomes including exercise performance, recovery of lost strength, body composition, perceptual fatigue and soreness, daily logs of physical conditions, changes in mood states, and biomarkers associated with muscle damage, inflammation, immune modulation, and oxidative stress. Early evidence has provided some indication that postbiotic supplementation may help to support mood, reduce fatigue, and increase the readiness of athletes across several weeks of exercise training. However, more research is needed to further understand how postbiotics may augment health, resiliency, performance, and recovery. Future investigations should include longer supplementation periods spanning a wider variety of competitive athletes and exercising populations.

Relationships of Total and Domain-Specific Moderate-to-Vigorous Physical Activity with All-Cause and Disease-Specific Mortality

PURPOSE

This study aimed to investigate the relationships of moderate-to-vigorous physical activity (MVPA) with all-cause and disease-specific mortality. We also investigated how the association between MVPA at leisure time (LT-MVPA) and health outcomes differs at different MVPA at work (WT-MVPA) levels.

METHODS

The 81,601 community-dwelling Japanese persons age 50-79 yr who responded to a questionnaire in 2000-2003 were followed until 2018. Cox proportional hazard model was used to examine the association of total MVPA with risks of all-cause, cancer, heart disease, stroke, and respiratory disease mortality. Then, we compared the mortality risk according to the tertile of LT-MVPA, stratified by the tertile of WT-MVPA.

RESULTS

During the 15.1 yr of average follow-up, 16,951 deaths were identified. Even total MVPA below the recommended volume (i.e., 0.1-1.49 MET·h·d -1 ) was associated with 11% to 24% reductions in all-cause (hazard ratio [HR], 0.89; 95% confidence interval [CI], 0.82-0.96) and heart disease mortality (HR, 0.76; 95% CI, 0.61-0.94), compared with no MVPA at all. The further reduced risks were seen in MVPA up to 10 MET·h·d -1 . The inverse association between LT-MVPA and mortality risks was more evident at lower WT-MVPA, which was also inversely associated with the risks.

CONCLUSIONS

Health benefits were observed at low levels of MVPA and up to 10 MET·h·d -1 , although the fine threshold for excessive MVPA was not clear. LT-MVPA had distinct health benefits especially for persons with lower WT-MVPA.

Effects of Ingesting Food Containing Heat-Killed Lactococcus lactis Strain Plasma on Fatigue and Immune-Related Indices after High Training Load: A Randomized, Double-Blind, Placebo-Controlled, and Parallel-Group Study

Lactococcus lactis strain Plasma (LC-Plasma) is a unique lactic acid bacterium that activates plasmacytoid dendritic cells (pDCs). We evaluated the effect of LC-Plasma on fatigue indices and dendritic cells activity in athletes after 14 days’ continuous exercise load. Thirty-seven participants were divided into two groups and consumed placebo (PL) or LC-Plasma capsules (containing 100 billion cells) daily for 14 days. Maturation markers on dendritic cells, blood parameters, physiological indices, and fatigue-related indices were recorded on days 1 and 15 (before and after exercise). Cumulative days of symptoms relating to physical conditions were also recorded during the continuous exercise period. We observed that CD86 as a maturation marker on pDCs was significantly higher and that cumulative days of fatigue were significantly fewer in the LC-Plasma group than in the Placebo group on day 15. We also conducted 2 h ergometer exercise on day 15 to evaluate fatigue. The results showed that autonomic fatigue parameters (LF/HF) were significantly lower in the LC-Plasma group. These results suggest that LC-Plasma supplementation alleviates fatigue accumulation and increases pDC activity caused by a continuous high training load.

Acute effects of concurrent muscle power and sport-specific endurance exercises on markers of immunological stress response and measures of muscular fitness in highly trained youth male athletes

PURPOSE

To examine the acute effects of concurrent muscle power and sport-specific endurance exercises order on immunological stress responses, muscular-fitness, and rating-of-perceived-exertion (RPE) in highly trained youth male judo athletes.

METHODS

Twenty male participants randomly performed two concurrent training (CT) sessions; power-endurance and endurance-power. Measures of immune response (e.g., white blood cells), muscular-fitness (i.e., counter-movement-jump [CMJ]), RPE, blood-lactate, and -glucose were taken at different time-point (i.e., pre, mid, post, and post6h).

RESULTS

There were significant time*order interactions for white blood cells, lymphocytes, granulocytes, granulocyte-lymphocyte-ratio, and systemic-inflammation-index. Power-endurance resulted in significantly larger pre-to-post increases in white blood cells and lymphocytes while endurance-power resulted in significantly larger pre-to-post increases in the granulocyte-lymphocyte-ratio and systemic-inflammation-index. Likewise, significantly larger pre-to-post6h white blood cells and granulocytes increases were observed following power-endurance compared to endurance-power. Moreover, there was a significant time*order interaction for blood-glucose and -lactate. Following endurance-power, blood-lactate and -glucose increased from pre-to-mid but not from pre-to-post. Meanwhile, in power-endurance blood-lactate and -glucose increased from pre-to-post but not from pre-to-mid. A significant time*order interaction was observed for CMJ-force with larger pre-to-post decreases in endurance-power compared to power-endurance. Further, CMJ-power showed larger pre-to-mid performance decreases following power-endurance, compared to endurance-power. Regarding RPE, significant time*order interactions were noted with larger pre-to-mid values following endurance-power and larger pre-to-post values following power-endurance.

CONCLUSION

CT induced acute and delayed order-dependent immune cell count alterations in highly trained youth male judo athletes. In general, power-endurance induced higher acute and delayed immunological stress responses compared to endurance-power. CMJ-force and RPE fluctuated during both CT sessions but went back to baseline 6 h post-exercise.

Antioxidant, anti-inflammatory and immunomodulatory effects of spirulina in exercise and sport: A systematic review

Arthrospira platensis, also known as spirulina, is currently one of the most well-known algae supplements, mainly due to its high content of bioactive compounds that may promote human health. Some authors have hypothesized that spirulina consumption could protect subjects from exercise-induced oxidative stress, accelerate recovery by reducing muscle damage, and stimulate the immune system. Based on this, the main goal of this review was to critically analyze the effects of spirulina on oxidative stress, immune system, inflammation and performance in athletes and people undergoing exercise interventions. Of the 981 articles found, 428 studies were considered eligible and 13 met the established criteria and were included in this systematic review. Most recently spirulina supplementation has demonstrated ergogenic potential during submaximal exercise, increasing oxygen uptake and improving exercise tolerance. Nevertheless, spirulina supplementation does not seem to enhance physical performance in power athletes. Considering that data supporting benefits to the immune system from spirulina supplementation is still lacking, overall evidence regarding the benefit of spirulina supplementation in healthy people engaged in physical exercise is scarce and not consistent. Currently, spirulina supplementation might be considered in athletes who do not meet the recommended dietary intake of antioxidants. Further high-quality research is needed to evaluate the effects of spirulina consumption on performance, the immune system and recovery in athletes and active people.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=262896], identifier [CRD42021262896].

A Case Series of SARS-CoV-2 Reinfection in Elite Athletes

OBJECTIVES

The actual frequency and the risk factors of SARS-CoV-2 reinfection is still a matter of intense scientific discussion. In this case series, we report three elite athletes who underwent COVID-19 reinfection with a short time frame.

CASE PRESENTATIONS

As a part of contact tracing, three speed skaters (22-, 24-, and 29-year-old males) were found to be SARS-CoV-2 positive by polymerase chain reaction (PCR) tests. Later on, only one of the athletes experienced mild symptoms, such as fatigue, loss of smell and taste and subfebrility, while the other two athletes were asymptomatic. Following the quarantine period, detailed return-to-play examinations, including laboratory testing, ECG, 24-h Holter monitoring, transthoracic echocardiography and cardiac magnetic resonance imaging, revealed no apparent abnormality; therefore, the athletes restarted training. After a median of 74 days, all three athletes presented with typical symptoms of COVID-19, such as fever, marked fatigue and headache. SARS-CoV-2 PCR tests were performed again, showing recurrent positivity. Repeated return-to-play assessments were initiated, finding no relevant abnormality. Athletes were also tested for SARS-CoV-2 anti-nucleoprotein antibody titers, showing only modest increases following the second infection.

CONCLUSIONS

We report a small cluster of elite athletes who underwent a PCR-proven SARS-CoV-2 reinfection. According to these findings, athletes may be considered as a high-risk group in terms of recurrent COVID-19.

Physical exercise, immune response, and susceptibility to infections-current knowledge and growing research areas

This review presents state-of-the-art knowledge and identifies knowledge gaps for future research in the area of exercise-associated modifications of infection susceptibility. Regular moderate-intensity exercise is believed to have beneficial effects on immune health through lowering inflammation intensity and reducing susceptibility to respiratory infections. However, strenuous exercise, as performed by professional athletes, may promote infection: in about half of athletes presenting respiratory symptoms, no causative pathogen can be identified. Acute bouts of exercise enhance the release of pro-inflammatory mediators, which may induce infection-like respiratory symptoms. Relatively few studies have assessed the influence of regularly repeated exercise on the immune response and systemic inflammation compared to the effects of acute exercise. Additionally, ambient and environmental conditions may modify the systemic inflammatory response and infection susceptibility, particularly in outdoor athletes. Both acute and chronic regular exercise influence humoral and cellular immune response mechanisms, resulting in decreased specific and non-specific response in competitive athletes. The most promising areas of further research in exercise immunology include detailed immunological characterization of infection-prone and infection-resistant athletes, examining the efficacy of nutritional and pharmaceutical interventions as countermeasures to infection symptoms, and determining the influence of various exercise loads on susceptibility to infections with respiratory viruses, including SARS-CoV-2. By establishing a uniform definition of an "elite athlete," it will be possible to make a comparable and straightforward interpretation of data from different studies and settings.

Effects of Probiotic Supplementation on Immune and Inflammatory Markers in Athletes: A Meta-Analysis of Randomized Clinical Trials

Background and Objectives: Probiotic supplementation can prevent and alleviate gastrointestinal and respiratory tract infections in healthy individuals. Markers released from the site of inflammation are involved in the response to infection or tissue injury. Therefore, we measured the pre-exercise and postexercise levels of inflammation-related markers-tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8, IL-10, interferon (IFN)-γ, salivary immunoglobulin A (IgA), IL-1β, IL-2, IL-4, and C-reactive protein (CRP)-in probiotic versus placebo groups to investigate the effects of probiotics on these markers in athletes. Probiotics contained multiple species (e.g., Bacillus subtilis, Bifidobacterium bifidum, etc.). Materials and Methods: We performed a systematic search for studies published until May 2022 and included nine randomized clinical trials. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline. Fixed-effects meta-analyses and sensitivity analyses were performed. Subgroup analyses were conducted on the basis of the period of probiotic intervention and timing of postassessment blood sampling. Results: The levels of IFN-γ and salivary IgA exhibited a significant positive change, whereas those of TNF-α and IL-10 demonstrated a negative change in the probiotic group. The subgroup analysis revealed that the probiotic group exhibited significant negative changes in TNF-α and IL-10 levels in the shorter intervention period. For the subgroup based on the timing of postassessment blood sampling, the subgroup whose blood sample collection was delayed to at least the next day of exercise exhibited significant negative changes in their TNF-α and IL-10 levels. The subgroups whose blood samples were collected immediately after exercise demonstrated negative changes in their TNF-α, IL-8, and IL-10 levels. Conclusions: Probiotic supplementation resulted in significant positive changes in the IFN-γ and salivary IgA levels and negative changes in the IL-10 and TNF-α levels. No significant changes in the IL-1β, IL-2, IL-4, IL-6, IL-8, or CRP levels were observed after probiotic use in athletes.

COVID-19 lockdown: Impairments of objective measurements of selected physical activity, cardiorespiratory and sleep parameters in trained fitness coaches

The COVID-19 outbreak resulted in the shutdown of athletic training facilities. Although the effects of these restrictions on daily activity and sleep patterns have been widely analyzed, the employed tools often lacked accuracy, and were based on subjective measures. This study assessed the effects of home confinement on objective physical activity (PA), physiological and sleep parameters in active individuals. Sixteen male elite fitness coaches (age: 29±3 years; height: 183±6 cm; body mass: 82±5 kg, body mass index: 24.7±1.8 kg/m²) participated in this retrospective study. One-way analysis of variance was conducted to analyze selected PA, physiological and sleep parameters collected by smartwatch (Garmin Fenix 6 pro, USA) data during four consecutive months [i.e., pre-confinement, 1^st and 2^nd months of confinement, and post-confinement, year 2020]. Ramadan intermittent fasting (RIF) month occurred during the 2^nd month of confinement. Compared to pre-confinement, significant changes were registered for almost all parameters during the 1^st and/or the 2^nd month of confinements (p<0.001), with (i) higher values for resting heart rate, sleep latency, and total, light and rapid eye movements sleep times (% change=7-523 %), and (ii) lower values for PA parameters, calories/day spent, average and highest respiratory rates, and deep sleep time during the home confinement period (% change=5-36 %). During the post-confinement month, all parameters regained pre-confinement values. In conclusion, home confinement-induced detraining negatively influenced the objective measurements of cardiorespiratory and sleep parameters among fitness coaches with a deeper effect during the 2^nd month of home confinement, possibly due to the effect of RIF.

Can the immunological system of the upper respiratory tract, improved by physical exercise, act as a first immunological barrier against SARS-CoV-2?

INTRODUCTION

The main route of transmission of SARS-CoV-2 is the upper respiratory tract via cell membranes, including angiotensin-converting enzyme 2 (ACE2) and transmembrane host-associated serine protease transmembrane serine protease 2 (TMPRSS2). Both enzymes present in the nasal epithelium are the first direct point of contact for SARS-CoV-2. In this sense, the mucosal immune mechanisms of the upper respiratory tract, including immunoglobulin A (IgA), could be enhanced by physical exercise and be the first defense mechanism against the transmission and infection of SARS-CoV-2.

AREAS COVERED

The authors reviewed recent biomedical literature available in databases related to the effects of exercise and training modalities on IgA concentration levels in the upper respiratory tract in different populations.

EXPERT OPINION

: According to the biomedical literature reviewed, physical exercise can decrease or improve the level of IgA concentrations. However, it is important to take into account factors such as training load, recovery during the exercise session and between training, as well as the exercise modality. Furthermore, the characteristics of the target population should be taken into account to maximize the adaptive immune response to adequately strengthen the upper respiratory tract and potentially be a barrier against SARS-CoV-2 infection.

Respiratory Viral Infections in Athletes: Many Unanswered Questions

Upper respiratory tract infections (“common cold”) are the most common acute illnesses in elite athletes. Numerous studies on exercise immunology have proposed that intense exercise may increase susceptibility to respiratory infections. Virological data to support that view are sparse, and several fundamental questions remain. Immunity to respiratory viral infections is highly complex, and there is a lack of evidence that minor short- or long-term alterations in immunity in elite athletes have clinical implications. The degree to which athletes are infected by respiratory viruses is unclear. During major sport events, athletes are at an increased risk of symptomatic infections caused by the same viruses as those in the general population. The symptoms are usually mild and self-limiting. It is anecdotally known that athletes commonly exercise and compete while having a respiratory viral infection; there are no virological studies to suggest that such activity would affect either the illness or the performance. The risk of myocarditis exists. Which simple mitigation procedures are crucial for effective control of seasonal respiratory viral infections is not known.

Physical exercise therapy for autoimmune neuroinflammation: Application of knowledge from animal models to patient care

Physical exercise (PE) impacts various autoimmune diseases. Accordingly, clinical trials demonstrated the safety of PE in multiple sclerosis (MS) patients and indicated beneficial outcomes. There is also an increasing body of research on the beneficial effects of exercise on experimental autoimmune encephalomyelitis (EAE), the animal model of MS, and various mechanisms underlying these effects were suggested. However, despite the documented favorable impact of PE on our health, we still lack a thorough understanding of its effects on autoimmune neuroinflammation and specific guidelines of PE therapy for MS patients are lacking. To that end, current findings on the impact of PE on autoimmune neuroinflammation, both in human MS and animal models are reviewed. The concept of personalized PE therapy for autoimmune neuroinflammation is discussed, and future research for providing biological rationale for clinical trials to pave the road for precise PE therapy in MS patients is described.

Medical Diagnoses in a University Athlete Training Room Clinic

INTRODUCTION

Approximately 560 000 student-athletes participate in university athletic programs every year. These athletes develop a variety of medical injuries and illnesses during their time at the university. There is currently a paucity of data with regarding medical encounters in a dedicated university athlete training room clinic.

OBJECTIVE

This study aims to provide data regarding medical diagnoses from a university athlete training room clinic.

STUDY DESIGN

Descriptive epidemiology study.

SETTING

University athlete training room clinic.

PATIENTS

University athletes.

METHODS

The electronic medical record for a year-round, athlete-only training room clinic at a private US university was reviewed. Athlete age, sex, sport, date of medical encounter, and encounter diagnoses across 5 calendar years were recorded; medical diagnoses were then manually stratified into diagnostic categories and subgroups.

RESULTS

A total of 1258 university athletes were evaluated during 5303 medical encounters. Approximately two-thirds of athletes were evaluated one or more times per year. Average number of encounters per athlete per year was 2.2 (0.6-3.8, 95% confidence interval). The football team accounted for the greatest number of encounters (15.2% of total encounters). The most common medical diagnosis category was otorhinolaryngology (30.6% of total diagnoses). The most common diagnosis subgroup was upper respiratory infection (14.8% of total diagnoses).

CONCLUSIONS

Approximately two-thirds of athletes were evaluated annually with an average of 2 encounters per athlete per year. Upper respiratory infection represented the most common individual diagnosis. The results reported in this study may be useful in directing future care and research of university athletes.

Moderate Intensity Aerobic Exercise Potential Favorable Effect Against COVID-19: The Role of Renin-Angiotensin System and Immunomodulatory Effects

The coronavirus disease (COVID-19) pandemic is caused by a novel coronavirus (CoV) named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As the angiotensin converting enzyme 2 (ACE2) is the cellular receptor of SARS-CoV-2, it has a strong interaction with the renin angiotensin system (RAS). Experimental studies have shown that the higher levels of ACE2 or increasing ACE2/ACE1 ratio improve COVID-19 outcomes through lowering inflammation and death. Aerobic moderate intensity physical exercise fights off infections by two mechanisms, the inhibition of ACE/Ang II/AT1-R pathway and the stimulation of ACE2/Ang-(1-7)/MasR axis. Exercise can also activate the anti-inflammatory response so that it can be a potential therapeutic strategy against COVID-19. Here, we summarize and focus the relation among COVID-19, RAS, and immune system and describe the potential effect of aerobic moderate intensity physical exercise against CoV as a useful complementary tool for providing immune protection against SARS-CoV-2 virus infection, which is a novel intervention that requires further investigation.

Effect of Moderate Intensity Exercise on Infection Rates in Individuals with Primary Immunodeficiency Disease: A Preliminary Pilot Randomized Investigation

PURPOSE

Individuals with a diagnosis of primary immunodeficiency disease (PID) have poorer health-related quality of life (HRQoL) compared with healthy individuals. Regular moderate exercise enhances immune function and wellbeing. Whether exercise at recommended levels for the general population is tolerated by individuals diagnosed with PID, without adverse effects, is unknown and warrants investigation.

METHODS

A prospective randomized preliminary pilot investigation with individuals diagnosed with PID was undertaken; participants were assigned to either an exercise (n = 18) or control group (n = 16). The exercise group completed an eight-week, semi-customized, home-based, moderate intensity exercise program, while the control group engaged in routine activities. Participants completed recall surveys assessing infection rates and non-routine medical care over 8 weeks prior to the eight-week intervention.

RESULTS

Given recruitment issues, the study was underpowered. Thus, as expected, no difference between groups was observed.

CONCLUSION

This preliminary pilot investigation provides the foundation for a large scale, appropriately powered, randomized controlled trial to investigate the effect of moderate exercise on infection rates and non-routine medical care for individuals with PID. Recommendations are made to strengthen the methodology of future investigations on the effects of exercise on the immune function and quality of life for individuals diagnosed with PID.

Effects of Regular Physical Activity on the Immune System, Vaccination and Risk of Community-Acquired Infectious Disease in the General Population: Systematic Review and Meta-Analysis

Background

Regular physical activity is the prime modality for the prevention of numerous non-communicable diseases and has also been advocated for resilience against COVID-19 and other infectious diseases. However, there is currently no systematic and quantitative evidence synthesis of the association between physical activity and the strength of the immune system.

Objective

To examine the association between habitual physical activity and (1) the risk of community-acquired infectious disease, (2) laboratory‐assessed immune parameters, and (3) immune response to vaccination.

Methods

We conducted a systemic review and meta-analysis according to PRISMA guidelines. We searched seven databases (MEDLINE, Embase, Cochrane CENTRAL, Web of Science, CINAHL, PsycINFO, and SportDiscus) up to April 2020 for randomised controlled trials and prospective observational studies were included if they compared groups of adults with different levels of physical activity and reported immune system cell count, the concentration of antibody, risk of clinically diagnosed infections, risk of hospitalisation and mortality due to infectious disease. Studies involving elite athletes were excluded. The quality of the selected studies was critically examined following the Cochrane guidelines using ROB2 and ROBINS_E. Data were pooled using an inverse variance random-effects model.

Results

Higher level of habitual physical activity is associated with a 31% risk reduction (hazard ratio 0.69, 95% CI 0.61–0.78, 6 studies, N = 557,487 individuals) of community-acquired infectious disease and 37% risk reduction (hazard ratio 0.64, 95% CI 0.59–0.70, 4 studies, N = 422,813 individuals) of infectious disease mortality. Physical activity interventions resulted in increased CD4 cell counts (32 cells/µL, 95% CI 7–56 cells/µL, 24 studies, N = 1112 individuals) and salivary immunoglobulin IgA concentration (standardised mean difference 0.756, 95% CI 0.146–1.365, 7 studies, N = 435 individuals) and decreased neutrophil counts (704 cells/µL, 95% CI 68–1340, 6 studies, N = 704 individuals) compared to controls. Antibody concentration after vaccination is higher with an adjunct physical activity programme (standardised mean difference 0.142, 95% CI 0.021–0.262, 6 studies, N = 497 individuals).

Conclusion

Regular, moderate to vigorous physical activity is associated with reduced risk of community-acquired infectious diseases and infectious disease mortality, enhances the first line of defence of the immune system, and increases the potency of vaccination.

Protocol registration

The original protocol was prospectively registered with PROSPERO (CRD42020178825).

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01466-1.

Effects of probiotic supplementation on respiratory infection and immune function in athletes: systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The aim of this study was to evaluate the effectiveness of probiotic supplementation on upper tract respiratory infection and inflammatory markers in elite athletes.

DATA SOURCES

We identified sources by searching the PubMed, EBSCO host, Scopus, and Web of Science databases using the following search terms: "probiotic" OR "probiotics" AND "exercise" OR "sport" OR "athletes" AND "URTI" OR "respiratory infection" OR "upper respiratory tract infections" OR "inflammation" OR "inflammatory OR "cytokines".

STUDY SELECTION

We screened the title and abstracts of 2498 articles using our inclusion critieria. A total of 14 articles were selected for further analysis.

DATA EXTRACTION

Data from the included studies were extracted by 2 independent reviewers. These data included the study design, participant characteristics, inclusion and exclusion, intervention characteristics, outcome measures, and the main results of the study.

DATA SYNTHESIS

The meta-analysis did not show any significant effect of probiotic supplementation on the number of days of illness or the mean number and duration of URTI episodes, but there was a significant effect of probiotic supplementation on total symptom severity score (-0.65, 95% CI: -1.05; -0.25, p = 0.02). Lower levels of IL-6 (-2.52 pg/ml, 95% CI: -4.12, -0.51, p = 0.001) and TNF-α (-2.31 pg/ml, 95% CI: -4.12, -0.51, p = 0.008) were also reported after supplementation.

CONCLUSIONS

This meta-analysis provides evidence that probiotic supplementation, especially among professional athletes, is an effective way to decrease the total URTI symptom severity score. Additionally, probiotic supplementation may decrease TNF-α and IL-6 levels. There is a need for more studies with larger groups to better estimate this effect. It is necessary to determine the best timing, duration, composition and dose of such supplementation.

Second Wave of COVID-19 Global Pandemic and Athletes' Confinement: Recommendations to Better Manage and Optimize the Modified Lifestyle

Coronavirus 2019 (COVID-19) is an infectious viral disease that has spread globally, resulting in the ongoing pandemic. Currently, there is no vaccine or specific treatment for COVID-19. Preventive measures to reduce the chances of contagion consist mainly of confinement, avoiding crowded places, social distancing, masks, and applying strict personal hygiene as recommended by the World Health Organization (WHO). After the first wave of infection in many countries, the potential effects of relaxing containment and physical distancing control measures suggest that as a result of these measures, a second wave of COVID-19 appears probable in these countries. In sport, the period of self-isolation, and quarantine, for COVID-19 affects the physical preparation of athletes as well as their mental health and quality of life to an even greater extent (i.e., nutrition, sleep, healthy lifestyle), and thus, relevant and practical recommendations are needed to help alleviate these physical and mental health concerns. Our review aims to summarize the physiological and psychological effects of detraining associated with athletes' confinement during the proposed second wave of COVID-19. This article also proposes answers to questions that concern the advantages and disadvantages of different types of social media platforms, the importance of nutrition, and the effects of sleep disturbance on the health and modified lifestyle of athletes during this worldwide pandemic. Thus, this review provides some general guidelines to better manage their modified lifestyle and optimally maintain their physical and mental fitness with respect to measures taken during this restrictive proposed second wave of the COVID-19 confinement period.

Enhancing innate immunity against virus in times of COVID-19: Trying to untangle facts from fictions

Introduction

In light of the current COVID-19 pandemic, during which the world is confronted with a new, highly contagious virus that suppresses innate immunity as one of its initial virulence mechanisms, thus escaping from first-line human defense mechanisms, enhancing innate immunity seems a good preventive strategy.

Methods

Without the intention to write an official systematic review, but more to give an overview of possible strategies, in this review article we discuss several interventions that might stimulate innate immunity and thus our defense against (viral) respiratory tract infections. Some of these interventions can also stimulate the adaptive T- and B-cell responses, but our main focus is on the innate part of immunity. We divide the reviewed interventions into: 1) lifestyle related (exercise, >7 h sleep, forest walking, meditation/mindfulness, vitamin supplementation); 2) Non-specific immune stimulants (letting fever advance, bacterial vaccines, probiotics, dialyzable leukocyte extract, pidotimod), and 3) specific vaccines with heterologous effect (BCG vaccine, mumps-measles-rubeola vaccine, etc).

Results

For each of these interventions we briefly comment on their definition, possible mechanisms and evidence of clinical efficacy or lack of it, especially focusing on respiratory tract infections, viral infections, and eventually a reduced mortality in severe respiratory infections in the intensive care unit. At the end, a summary table demonstrates the best trials supporting (or not) clinical evidence.

Conclusion

Several interventions have some degree of evidence for enhancing the innate immune response and thus conveying possible benefit, but specific trials in COVID-19 should be conducted to support solid recommendations.

Follow-up of Acute Respiratory Disorders in Cyclists Competing in the 100th Giro d'Italia

Acute respiratory disorder is a common sub-clinical condition affecting elite cyclists. Monitoring the perturbations of the immunological cells in the respiratory tract, indicative of a likely proinflammatory state, during an International Cycling Union world tour is a challenging task. The aim of this study was to follow up on the sign and symptoms of upper way respiratory infections with or without asthma, using non-invasive methods, during a 21-day race (100° Giro d'Italia, 2017). Nine male elite cyclists of the Bahrain Merida Team were evaluated before the training season and daily during the race. Clinical history, skin prick and spirometric test, acute respiratory symptoms were measured using validated questionnaires, and values of fraction of exhaled nitric oxide were collected longitudinally. Four of the 9 athletes had allergies with/or consistent abnormal spirometric curves before the race. During the race, 5 athletes had a fraction of exhaled nitric oxide values >20 ppb which correlated with respiratory symptoms collected through questionnaires. These were related to the environmental characteristics of the places travelled through in the race. The athletes with a predisposition to chronic respiratory inflammation in the pre-competitive season were more likely to develop acute respiratory symptoms during the race.

Urinary Biomarkers: Diagnostic Tools for Monitoring Athletes' Health Status

Acute or intense exercise is sometimes related to infections of the urinary tract. It can also lead to incorrect hydration as well as incorrect glomerular filtration due to the presence of high-molecular-weight proteins that cause damage to the kidneys. In this context, our study lays the foundations for the use of a urine test in a team of twelve male basketball players as a means of monitoring numerous biochemical parameters, including pH, specific weight, color, appearance, presence of bacterial cells, presence of squamous cells, leukocytes, erythrocytes, proteins, glucose, ketones, bilirubin, hemoglobin, nitrite, and leukocyte esterase, to prevent and/or treat the onset of pathologies, prescribe personalized treatments for each athlete, and monitor the athletes’ health status.

Athlete's Passport: Prevention of Infections, Inflammations, Injuries and Cardiovascular Diseases

Laboratory medicine in sports medicine is taking on an ever-greater role in the assessment and monitoring of an athlete's health condition. The acute or intense exercise practiced by elite athletes can lead to the appearance of infections, inflammations, muscle injuries or cardiovascular disorders, whose diagnosis is not always rapid and efficient, as there is no continuous monitoring of the athlete. The absence of such monitoring can have serious consequences in terms of recovery of the professional athlete. These imbalances can induce metabolic adaptations which translate into alterations of specific parameters in terms of concentration and activity. The aim of this study was to follow the variation of specific biochemical biomarkers in a basketball team participating to the maximum championship during different phases of the agonistic season. The evaluation of serum biomarkers can help doctors to safeguard the athlete's health and sports trainers to adapt workouts, thus avoiding the appearance of diseases and injuries that in some cases can be underestimated by becoming irreversible ailments that do not allow the athlete to return to a healthy state. This information can be useful to create athlete biologic passports.

Prospective long-term follow-up analysis of the cardiovascular system in marathon runners: study design of the Pro-MagIC study

Introduction

Prolonged strenuous exercise training may result in structural, functional and electrical cardiac remodelling, as well as vascular and myocardial injuries. However, the extent to which high-volume, intense exercise is associated with arrhythmias, myocardial fibrosis, coronary heart disease and pathological alterations of the vasculature remains unknown. In addition, there is no clear consensus on the clinical significance of these exercise-induced changes. Previous studies typically used cross-sectional designs and examined exercise-induced cardiovascular changes in small cohorts of athletes for up to 3–7 days of recovery. Long-term longitudinal studies investigating cardiovascular changes induced by prolonged strenuous exercise in large cohorts of athletes are needed to improve scientific understanding in this area.

Methods and analysis

In this prospective observational monocenter study, 277 participants of the Beer, Marathon, Genetics, Inflammation and the Cardiovascular System (Be-MaGIC) study (ClinicalTrials.gov: NCT00933218) will be invited to participate in this 10-year follow-up study. A minimum target sample size of 130 participants will be included in the study. Participating athletes will be examined via the following: anthropometry, resting electrocardiography and echocardiography, blood sampling, retinal vessel diameters, carotid sonography and cardiopulmonary exercise testing, including exercise electrocardiography.

Discussion

This longitudinal study will provide comprehensive data on physiological changes in the cardiovascular system and the development of pathologies after a 10-year period of prolonged and strenuous endurance exercise. Since the participants will have engaged in a wide range of training loads and competitive race events, this study will provide useful risk factor determinants and training load cut-off values. The primary endpoint is the association between the exercise-induced increase in cardiac troponin during the Munich marathon 2009 and the decline in right ventricular ejection fraction over the next 10 years.

Trial registration number

NCT04166903.

HNP-1 and HBD-1 as Biomarkers for the Immune Systems of Elite Basketball Athletes

Acute or strenuous exercise is sometimes related to upper respiratory tract infections in athletes. Practicing intense and regular exercise can lead to incorrect activation of the immune system, causing athletes to be excluded from training programs and competitions. Defensins are small antimicrobial peptides that are part of the innate immune system and dynamically involved in several biological activities. In this study, we highlight the role of human defensins in competitive basketball athletes. In particular, we consider the behavior of alpha- and beta-defensins together with white blood cells in a cohort of players. Moreover, we focus our attention on cortisol, a physiological indicator of stress, and testosterone, both of which are human hormones involved in muscle metabolism. The free-testosterone/cortisol ratio is considered to be an indicator of overtraining among athletes. This paper provides an up-to-date information of the role of human defensins as self-defense molecules during a continuous stressor such as long-term exercise, and it recognizes them as potential markers of infection.

Exercise versus no exercise for the occurrence, severity, and duration of acute respiratory infections

BACKGROUND

Acute respiratory infections (ARIs) last for less than 30 days and are the most common acute diseases affecting people. Exercise has been shown to improve health generally, but it is uncertain whether exercise may be effective in reducing the occurrence, severity, and duration of ARIs. This is an update of our review published in 2015.

OBJECTIVES

To evaluate the effectiveness of exercise for altering the occurrence, severity, or duration of acute respiratory infections.

SEARCH METHODS

We searched CENTRAL (2020, Issue 2), MEDLINE (1948 to March week 1, 2020), Embase (1974 to 05 March 2020), CINAHL (1981 to 05 March 2020), LILACS (1982 to 05 March 2020), SPORTDiscus (1985 to 05 March 2020), PEDro (searched 05 March 2020), OTseeker (searched 05 March 2020), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov (searched 05 March 2020).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs (method of allocation that is not truly random, e.g. based on date of birth, medical record number) of exercise for ARIs in the general population.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from the included trials using a standard form. One review author entered data, which a second review author checked. We contacted trial authors to request missing data. There were sufficient differences in the populations trialed and in the nature of the interventions to use the random-effects model (which makes fewer assumptions than the fixed-effect model) in the analysis.

MAIN RESULTS

We included three new trials for this update (473 participants) for a total of 14 trials involving 1377 adults, published between 1990 and 2018. Nine trials were conducted in the USA, and one each in Brazil, Canada, Portugal, Spain, and Turkey. Sample sizes ranged from 16 to 419 participants, aged from 18 to 85 years. The proportion of female participants ranged from 52% to 100%. Follow-up duration ranged from 1 to 36 weeks (median = 12 weeks). Moderate-intensity aerobic exercise (walking, bicycling, treadmill, or a combination) was evaluated in 11 trials, and was most commonly prescribed at least three times a week for 30 to 45 minutes. There was no difference between exercise and no exercise in the number of ARI episodes per person per year (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.77 to 1.30; 4 trials; 514 participants; low-certainty evidence); proportion of participants who experienced at least one ARI over the study period (RR 0.88, 95% CI 0.72 to 1.08; 5 trials; 520 participants; low-certainty evidence); and the number of symptom days per episode of illness (mean difference (MD) -0.44 day, 95% CI -2.33 to 1.46; 6 trials; 557 participants; low-certainty evidence). Exercise reduced the severity of ARI symptoms measured on the Wisconsin Upper Respiratory Symptom Survey (WURSS-24) (MD -103.57, 95% CI -198.28 to -8.87; 2 trials; 373 participants; moderate-certainty evidence) and the number of symptom days during follow-up period (MD -2.24 days, 95% CI -3.50 to -0.98; 4 trials; 483 participants; low-certainty evidence). Excercise did not have a significant effect on laboratory parameters (blood lymphocytes, salivary secretory immunoglobulin, and neutrophils), quality of life outcomes, cost-effectiveness, and exercise-related injuries. There was no difference in participant dropout between the intervention and control groups. Overall, the certainty of the evidence was low, downgraded mainly due to limitations in study design and implementation, imprecision, and inconsistency. Seven trials were funded by public agencies; five trials did not report funding; and two trials were funded by private companies.

AUTHORS' CONCLUSIONS

Exercise did not reduce the number of ARI episodes, proportion of participants experiencing at least one ARI during the study, or the number of symptom days per episode of illness. However, exercise reduced the severity of ARI symptoms (two studies) and the number of symptom days during the study follow-up period (four studies). Small study size, risk of bias, and heterogeneity in the populations studied contributed to the uncertainty of the findings. Larger trials that are designed to avoid risk of bias associated with participant selection, blinding of outcomes assessors, and with adequate reporting of all outcomes proposed for measurement in trials, would help to provide more robust evidence.

Mutual Interactions among Exercise, Sport Supplements and Microbiota

The adult gut microbiota contains trillions of microorganisms of thousands of different species. Only one third of gut microbiota are common to most people; the rest are specific and contribute to enhancing genetic variation. Gut microorganisms significantly affect host nutrition, metabolic function, immune system, and redox levels, and may be modulated by several environmental conditions, including physical activity and exercise. Microbiota also act like an endocrine organ and is sensitive to the homeostatic and physiological changes associated with training; in turn, exercise has been demonstrated to increase microbiota diversity, consequently improving the metabolic profile and immunological responses. On the other side, adaptation to exercise might be influenced by the individual gut microbiota that regulates the energetic balance and participates to the control of inflammatory, redox, and hydration status. Intense endurance exercise causes physiological and biochemical demands, and requires adequate measures to counteract oxidative stress, intestinal permeability, electrolyte imbalance, glycogen depletion, frequent upper respiratory tract infections, systemic inflammation and immune responses. Microbiota could be an important tool to improve overall general health, performance, and energy availability while controlling inflammation and redox levels in endurance athletes. The relationship among gut microbiota, general health, training adaptation and performance, along with a focus on sport supplements which are known to exert some influence on the microbiota, will be discussed.

Exercise intensity-dependent immunomodulatory effects on encephalomyelitis

Background

Exercise training (ET) has beneficial effects on multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). However, the intensity‐dependent effects of ET on the systemic immune system in EAE remain undefined.

Objective

(1) To compare the systemic immune modulatory effects of moderate versus high‐intensity ET protocols in protecting against development of EAE; (2) To investigate whether ET affects autoimmunity selectively, or causes general immunosuppression.

Methods

Healthy mice performed moderate or high‐intensity treadmill running programs. Proteolipid protein (PLP)‐induced transfer EAE was utilized to examine ET effects specifically on the systemic immune system. Lymph node (LN)‐T cells from trained versus sedentary donor mice were transferred to naïve recipients and EAE severity was assessed, by clinical assessment and histopathological analysis. LN‐T cells derived from donor trained versus sedentary PLP‐immunized mice were analyzed in vitro for proliferation assays by flow cytometry analysis and cytokine and chemokine receptor gene expression using real‐time PCR. T cell‐dependent immune responses of trained versus sedentary mice to the nonautoantigen ovalbumin and susceptibility to Escherichia coli‐induced acute peritonitis were examined.

Results

High‐intensity training in healthy donor mice induced significantly greater inhibition than moderate‐intensity training on proliferation and generation of encephalitogenic T cells in response to PLP‐immunization, and on EAE severity upon their transfer into recipient mice. High‐intensity training also inhibited LN‐T cell proliferation in response to ovalbumin immunization. E. coli bacterial counts and dissemination were not affected by training.

Interpretation

High‐intensity training induces superior effects in preventing autoimmunity in EAE, but does not alter immune responses to E. coli infection.

Outbreak of influenza A in a boarding school in South Africa, 2016

Introduction

We investigated an outbreak of influenza-like illness (ILI) at a boarding school in Eastern Cape Province, South Africa. We aimed to confirm the etiological agent, estimate attack rates and identify risk factors for illness.

Methods

We conducted a retrospective cohort study including senior school boarders (n=308). Students with ILI (cough and fever) were identified through school medical records. We also conducted a questionnaire-based cross-sectional study among senior students including boarders (n=107) and day students (n=45). We collected respiratory specimens for respiratory pathogen testing by real-time polymerase chain reaction from a subset of symptomatic students. We calculated attack rates of medically attended ILI (medILI) and identified factors associated with medILI using logistic regression. We calculated seasonal influenza vaccine effectiveness (VE) against medILI.

Results

Influenza A (H3N2) virus was detected in 61% (23/38) of specimens. Attack rate for medILI was 13% among boarders (39/308) in the cohort study and 20% in both day students (9/45) and boarders (21/107) in the cross-sectional study. Playing squash was associated with medILI (aOR 5.35, 95% confidence interval [95% CI]: 1.68-17.07). Of the boarders, 19% (57/308) were vaccinated before the outbreak. The adjusted VE against medILI was 18% (aOR 0.82, 95% CI 0.38-1.78). The outbreak led to cancellation of several events and the need for academic remedial sessions.

Conclusion

We confirmed an influenza A (H3N2) virus outbreak with a high attack rate. The outbreak affected academic and sports activities. Participation in sports and social gatherings while experiencing ILI should be discouraged to reduce viral transmission and impact on school activities.

Molecular Pathways Mediating Immunosuppression in Response to Prolonged Intensive Physical Training, Low-Energy Availability, and Intensive Weight Loss

Exercise and exercise-induced weight loss have a beneficial effect on overall health, including positive effects on molecular pathways associated with immune function, especially in overweight individuals. The main aim of our study was to assess how energy deprivation (i.e., “semi-starvation”) leading to substantial fat mass loss affects the immune system and immunosuppression in previously normal weight individuals. Thus, to address this hypothesis, we applied a high-throughput systems biology approach to better characterize potential key pathways associated with immune system modulation during intensive weight loss and subsequent weight regain. We examined 42 healthy female physique athletes (age 27.5 ± 4.0 years, body mass index 23.4 ± 1.7 kg/m²) volunteered into either a diet group (n = 25) or a control group (n = 17). For the diet group, the energy intake was reduced and exercise levels were increased to induce loss of fat mass that was subsequently regained during a recovery period. The control group was instructed to maintain their typical lifestyle, exercise levels, and energy intake at a constant level. For quantification of systems biology markers, fasting blood samples were drawn at three time points: baseline (PRE), at the end of the weight loss period (MID 21.1 ± 3.1 weeks after PRE), and at the end of the weight regain period (POST 18.4 ± 2.9 weeks after MID). In contrast to the control group, the diet group showed significant (false discovery rate <0.05) alteration of all measured immune function parameters—white blood cells (WBCs), immunoglobulin G glycome, leukocyte transcriptome, and cytokine profile. Integrative omics suggested effects on multiple levels of immune system as dysregulated hematopoiesis, suppressed immune cell proliferation, attenuated systemic inflammation, and loss of immune cell function by reduced antibody and chemokine secretion was implied after intense weight loss. During the weight regain period, the majority of the measured immune system parameters returned back to the baseline. In summary, this study elucidated a number of molecular pathways presumably explaining immunosuppression in individuals going through prolonged periods of intense training with low-energy availability. Our findings also reinforce the perception that the way in which weight loss is achieved (i.e., dietary restriction, exercise, or both) has a distinct effect on how the immune system is modulated.

Whey Protein Isolate Supplementation While Endurance Training Does Not Alter Cycling Performance or Immune Responses at Rest or After Exercise

This study examined whey protein isolate supplementation combined with endurance training on cycling performance, aerobic fitness and immune cell responses. Eighteen male cyclists were randomly assigned to either placebo (PLA) or whey protein supplementation (WS; 1.0 g·kg body mass⁻¹·d⁻¹ in addition to their dietary intake). Both groups completed the identical endurance training program, 4 days per week for 6 weeks. Blood samples were obtained at rest and after 5 and 60 min of recovery from a simulated 40 km cycling time trial (TT) and were repeated after training. Baseline dietary intake of protein prior to supplementation was 1.52 ± 0.45 and 1.46 ± 0.44 g·kg body mass⁻¹·d⁻¹ for the WS and PLA groups, respectively. There were similar improvements in TT performance (WS: 71.47 ± 12.17 to 64.38 ± 8.09 min; PLA: 72.33 ± 12.79 to 61.13 ± 8.97 min), and peak oxygen uptake (WS: 52.3 ± 6.1 to 56.1 ± 5.4 mL·kg⁻¹·min⁻¹; PLA: 50.0 ± 7.1 to 54.9 ± 5.1 mL·kg⁻¹·min⁻¹) after training in both groups. White blood cells (WBC) and neutrophil counts were elevated 5 min after the TT and further increased after 60 min (P < 0.05). The exercise-induced increase in WBC and neutrophil counts at 5 and 60 min after the TT were attenuated after training compared to before training (P < 0.05). Lymphocytes increased 5 min after the TT and decreased below rest after 60 min of recovery (P < 0.05). Following training lymphocytes were lower after 60 min of recovery compared to before training. There was no change in natural killer cell activity with exercise, training or between groups. It was concluded that whey protein isolate supplementation while endurance training did not differentially change cycling performance or the immune response at rest or after exercise. However, endurance training did alter performance, aerobic fitness and some post exercise immune cell counts.

Redox correlation in muscle lengthening and immune response in eccentric exercise

This study was designed to examine the potential involvement of reactive oxygen species in skeletal muscle dysfunction linked with stretching in a mouse model and to explore the effects of combined antioxidant intake on peripheral leukocyte apoptosis following eccentrically-biased downhill runs in human subjects. In the mouse model, diaphragmatic muscle was stretched by 30% of its optimal length, followed by 5-min contraction. Muscle function and extracellular reactive oxygen species release was measured ex vivo. In human models, participants performed two trials of downhill running either with or without antioxidant supplementation, followed by apoptotic assay of inflammatory cells in the blood. The results showed that stretch led to decreased muscle function and prominent ROS increase during muscle contraction. In human models, we observed an elevation in circulating leukocyte apoptosis 24-48 hours following acute downhill runs. However, there is an attenuated leukocyte apoptosis following the second bout of downhill run. Interestingly, the combination of ascorbic acid (vitamin C) and α-tocopherol (vitamin E) supplementation attenuated the decrease in B-cell lymphoma 2 (Bcl-2) at 24 hours following acute downhill running. These data collectively suggest that significant ROS formation can be induced by muscle-lengthening associated with eccentric exercise, which is accompanied by compromised muscle function. The combination of antioxidants supplementation appears to have a protective role via the attenuation of decrease in anti-apoptotic protein.

Upper Respiratory Symptoms, Gut Health and Mucosal Immunity in Athletes

Upper respiratory symptoms remain the most common illness in athletes. Upper respiratory symptoms during heavy training and competition may impair performance. Preventing illness is the primary reason for the use of supplements, such as probiotics and prebiotics, for maintaining or promoting gut health and immune function. While exercise-induced perturbations in the immune system may increase susceptibility to illness and infection, growing evidence indicates that upper respiratory symptoms are related to a breakdown in the homeostatic regulation of the mucosal immune system of the airways. Balancing protection of the respiratory tract with normal physiological functioning requires dynamic orchestration between a wide array of immune parameters. The intestinal microbiota regulates extra-intestinal immunity via the common mucosal immune system and new evidence implicates the microbiota of the nose, mouth and respiratory tract in upper respiratory symptoms. Omics’ approaches now facilitate comprehensive profiling at the molecular and proteomic levels to reveal new pathways and molecules of immune regulation. New targets may provide for personalised nutritional and training interventions to maintain athlete health.

Efficacy of heat-killed Lactococcus lactis JCM 5805 on immunity and fatigue during consecutive high intensity exercise in male athletes: a randomized, placebo-controlled, double-blinded trial

Background

Lactococcus lactis JCM 5805 (LC-Plasma) is a unique lactic acid bacteria (LAB) which activates plasmacytoid dendritic cells (pDC). We aimed to evaluate the effect of LC-Plasma on dendritic cell (DC) activity and subjective indices of upper respiratory tract infections (URTI) and fatigue in athletes under high intensity exercise.

Methods

We conducted a randomized, placebo-controlled, double-blinded trial. Fifty-one male subjects belonging to a university sports club were randomized into placebo (n = 25) and LC-Plasma (n = 26) groups. Individuals ingested placebo capsules containing cornstarch or LC-Plasma capsules containing 100 billion cells of heat-killed LC-Plasma per day for 13 days. During the intervention period, subjects performed high intensity exercise according to their sports club training regime. Blood and saliva sampling were obtained at days 1 and 14, and physical conditions were recorded in a diary. We investigated expression of maturation markers on DCs, muscle damage and stress markers and used student’s t test adjusted by Bonferoni’s method for multiple comparison between groups. These data were presented as mean ± SD. We also investigated cumulative days of symptoms regarding infections and fatigue and used Chi-square test for comparison between groups. These data were presented as cumulative number.

Results

CD86 as maturation marker on pDC was significantly increased in the LC-Plasma group at day 14 (Placebo: 296 ± 70 vs. LC-Plasma: 365 ± 115; Mean Fluorescent Intensity; p = 0.013). Cumulative days of URTI were significantly lower in the LC-Plasma group (Placebo: URTI positive 56, URTI negative 256 vs. LC-Plasma: URTI positive 39, URTI negative 299; days; p = 0.028) and symptoms like sneeze or running nose were significantly lower in the LC-Plasma group (Placebo: Symptom positive 52, Symptom negative 258, vs. LC-Plasma: Symptom positive 36, Symptom negative 301; days; p = 0.032). Moreover, the cumulative days of fatigue were significantly fewer in the LC-Plasma group (Placebo: Symptom positive 128, Symptom negative 182, vs. LC-Plasma: Symptom positive 110, Symptom negative 225; days; p = 0.032). Markers of muscle damage and stress markers were not significantly different between groups.

Conclusion

We consider that heat-killed LC-Plasma supplementation relieves morbidity and symptoms of URTI via activation of pDC and decreases fatigue accumulation during consecutive high intensity exercise in athletes. However, LC-Plasma ingestion did not affect markers of muscle damage and stress.

Trial registration

UMIN-CTR, UMIN000020372. Registered 28 December 2015.

Immune nutrition and exercise: Narrative review and practical recommendations

Evidence suggests that periods of heavy intense training can result in impaired immune cell function, and whether this leaves elite athletes at greater risk of infections and upper respiratory symptoms (URS) is still debated. There is some evidence that episodes of URS do cluster around important periods of competition and intense periods of training. Since reducing URS, primarily from an infectious origin, may have implications for performance, a large amount of research has focused on nutritional strategies to improve immune function at rest and in response to exercise. Although there is some convincing evidence that meeting requirements of high intakes in carbohydrate and protein and avoiding deficiencies in nutrients such as vitamin D and antioxidants is integral for optimal immune health, well-powered randomised controlled trials reporting improvements in URS beyond such intakes are lacking. Consequently, there is a need to first understand whether the nutritional practices adopted by elite athletes increases their risk of URS. Second, promising evidence in support of efficacy and mechanisms of immune-enhancing nutritional supplements (probiotics, bovine colostrum) on URS needs to be followed up with more randomised controlled trials in elite athletes with sufficient participant numbers and rigorous procedures with clinically relevant outcome measures of immunity.

Prevalence of Inadequate Immunity to Measles, Mumps, Rubella, and Varicella in MLB and NBA Athletes

BACKGROUND

Multiple outbreaks of vaccine-preventable viral diseases have occurred in professional sports in recent years. Currently, there is no established protocol for vaccination or immunity screening for professional athletes.

HYPOTHESIS

There are significant differences in the prevalence of inadequate immunity dependent on age, sport, country of birth, and participation in collegiate sports.

STUDY DESIGN

Cross-sectional cohort study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A sample of Major League Baseball (MLB) and National Basketball Association (NBA) players were screened for serologic evidence of immunity to measles, mumps, rubella, and varicella prior to the 2015 and 2016 seasons. The results were designated as adequate (immune) or inadequate (equivocal or nonimmune) based on laboratory criteria. Comparison with an age-matched control group was performed using data from the National Health and Nutrition Examination Survey (NHANES).

RESULTS

A total of 98 athletes (62 MLB, 36 NBA) were screened. The prevalence of inadequate immunity for any virus was 35.5% in MLB players and 33.3% in NBA players. There was a significantly greater risk of inadequate immunity to rubella (risk ratio, 6.38; P < 0.01) and varicella (risk ratio, 4.21; P < 0.01) in athletes compared with the age-matched NHANES population. Our analysis did not reveal differences in rates of immunity based on sport, country of birth (US born vs international), or participation in college athletics. There was a lower rate of inadequate immunity to varicella with increasing age (odds ratio, 0.72; P = 0.05).

CONCLUSION

One-third of athletes studied had inadequate immunity to 1 of the 4 viruses tested. Younger players had a significantly greater risk of inadequate immunity to varicella. Birth outside the US and lack of participation in college athletics were not found to influence immunity rates.

CLINICAL RELEVANCE

These results can inform the development of future screening programs to prevent outbreaks of viral infections in professional athletes.

SIgA and Upper Respiratory Syndrome During a College Cross Country Season

We examined the changes in salivary immunoglobulin A (SIgA) and the incidence of upper respiratory syndrome (URS) throughout a college cross-country season as well as the acute effect of a VO _2max test on SIgA. Subjects were 22 cross country athletes (XC) (20.7±0.3 years) and 23 matched controls (C) (20.4±0.2 years). Saliva samples were collected pre and post VO2max and at four training time points (August – November). Weekly logs indicating S&S of URS from which a total symptom score (TSS) was calculated were collected. There was a significant decrease in SIgA F(1,43)=10.742, p<0.001 and the secretion rate of SIgA F(1,43)=15.617, p<0.001 for XC at time points two through four. XC was also significantly lower than controls in those two variables across those time points. The secretion rate of SIgA and URS were negatively correlated at time point four R2=0.443, F(4,22)=26.9, p=0.001. There was a significant acute post exercise decrease in the secretion rate of SIgA, pre (M=21.44, SEM=3.95) and post (M=14.5, SEM=3.0), t(1,21)=2.185, p=0.039. Prolonged training resulted in decreased mucosal SIgA.

Leisure-Time Physical Activity and the Risk of Suspected Bacterial Infections

INTRODUCTION

The risk of upper respiratory tract viral infections is reduced with increased physical activity, but little information is available regarding bacterial infections. We examined the relationship between leisure-time physical activity and suspected bacterial infections.

METHODS

Information on leisure-time physical activity was obtained from the 2007 and 2010 North Denmark Region Health Surveys of 18,874 Danes and linked to data from nationwide administrative registries. Suspected bacterial infections were determined based on filled prescriptions for antibiotics. Adjusted estimates were calculated using logistic regression models.

RESULTS

During a 1-yr follow-up, 5368 participants filled at least one antibiotic prescription. There was a statistically significant difference between physical activity level and filling any antibiotic prescriptions among women (P = 0.003) but not among men (P = 0.191). Logistic regression analysis showed that compared with sedentary behavior, all levels of leisure-time physical activities lowered the likelihood of filling an antibiotic prescription. However, after multivariable adjustments, only estimates of low physical activity were significant (odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.82; 0.99). Multivariable adjusted subgroup analyses of suspected cystitis showed a decreased likelihood of engaging in low (OR = 0.79, 95% CI = 0.65-0.95) and moderate (OR = 0.68, 95% CI = 0.54-0.87) physical activity.

CONCLUSION

Low leisure-time physical activity is associated with a statistically significant 10% lower risk of suspected bacterial infections during a 1-yr follow-up compared with sedentary behavior. Further, low and moderate levels of physical activity were associated with the statistically significant reduction of suspected cystitis. No reduction in suspected respiratory tract infections was statistically significant and associated with physical activity compared with sedentary behavior.

Pertussis outbreak in Polish shooters with adverse event analysis

In addition to different injuries, infections are the most common reason for giving up training altogether or reducing its volume and intensity, as well as a lack of opportunities to participate in sports competitions. Nowadays, a slow but constant re-emergence of pertussis, especially among teenagers and young adults, including athletes, can be observed. This paper describes an outbreak of pertussis among professional Polish shooters, focusing on the transmission of Bordetella pertussis infection between members of the national team, its influence on performance capacity and adverse event analysis. From 9 June, 2015 to 31 July, 2015, a total of 4 confirmed and suspected cases of pertussis were reported among members of the Polish Sport Shooting National Team, their relatives and acquaintances. Pertussis significantly decreased exercise performance of the first athlete, a 35-year-old woman, interrupted her training, and finally resulted in failure to win a medal or quota place. Pertussis also significantly decreased performance of the second athlete, a 25-year-old shooter. The other cases emerged in their families. Whooping cough is a real threat to athletes and should be prevented. Preventive measures include appropriate immunization, constant medical supervision, as well as early isolation, diagnostic tests and treatment of all infected sport team members. Regular administration of booster doses of the acellular pertussis vaccine (Tdpa) every 5 years seems reasonable.

Bewegung und Erkrankungen des Immunsystems

Die Effektivität von körperlicher Aktivität in der Primär- als auch Sekundär- und Tertiärprävention ist hinlänglich bekannt. Das Immunsystem spielt eine entscheidende Rolle bei einer Vielzahl von Erkrankungen, da es durch seine Botenfunktion (z. B. durch Zytokine) in einer Vielzahl der Regulationsprozesse mit involviert ist. So kommt es durch moderat-intensive körperliche Aktivität zu einer Stärkung des Immunsystems mit konsekutiv verminderter Infektanfälligkeit sowie eher anti-inflammatorischen Effekten, wohingegen langandauernde und höher intensive Belastungen zu einer Schwächung der Abwehrfunktion sowie einem pro-inflammatorischen Effekt führen. Somit stellt eine adäquat dosierte körperliche Aktivität eine erfolgversprechende Therapieoption bei Erkrankungen des infektiologischen Formenkreises sowie des Immunsystems dar.

Lymphocyte Redox Imbalance and Reduced Proliferation after a Single Session of High Intensity Interval Exercise

This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young healthy men underwent a HIIT session on a cycloergometer, consisting of eight bouts of 1 min at 90-100% of peak power, with 75 seconds of active recovery at 30 W between bouts. Venous blood was collected before, immediately after, and 30 minutes after the HIIT session. In response to Staphylococcus aureus superantigen B (SEB) stimulation, lymphocyte proliferation decreased and the IL-2 concentration increased after the HIIT session. However, the HIIT session had no effect on lymphocyte proliferation or IL-2 response to phytohemagglutinin stimulation. The HIIT session also induced lymphocyte redox imbalance, characterized by an increase in the concentration of thiobarbituric acid reactive substances and a decrease in the activity of the antioxidant enzyme catalase. Lymphocyte viability was not affected by the HIIT session. The frequencies of CD25+ and CD69+ T helper and B lymphocytes in response to superantigen stimulation were lower after exercise, suggesting that superantigen-induced lymphocyte activation was reduced by HIIT. However, HIIT also led to a reduction in the frequency of CD4+ and CD19+ cells, so the frequencies of CD25+ and CD69+ cells within the CD4 and CD19 cell populations were not affected by HIIT. These data indicate that the reduced lymphocyte proliferation observed after HIIT is not due to reduced early lymphocyte activation by superantigen. Our findings show that an acute HIIT session promotes lymphocyte redox imbalance and reduces lymphocyte proliferation in response to superantigenic, but not to mitogenic stimulation. This observation cannot be explained by alteration of the early lymphocyte activation response to superantigen. The manner in which lymphocyte function modulation by an acute HIIT session can affect individual immunity and susceptibility to infection is important and requires further investigation.

CD56(dim)CD16(high) and CD56(bright)CD16(-) cell percentages associated with maximum knee extensor strength and incidence of death in elderly

Physical fitness is an indicator of systemic well-being in humans. Little is known about the role of physical fitness for maintaining systemic health in the elderly. Here, we study elderly subjects to determine the relationships between physical fitness and CD56 and CD16 surface NK cell markers on peripheral blood lymphocytes, as well as to analyze the relationship between the surface markers and incidence of death. We selected 253 independent elderly subjects (122 female; 131 male) who were 79–80 years old. Subjects having a higher proportion of CD56^dimCD16^high within CD56⁺CD16⁺ cells, or ration of CD56^dimCD16^high and CD56^dimCD16⁻ cells had a significant positive correlation with maximum bilateral knee extensor strength/weight (kg) (r = 0.425; P < 0.0001 or r = 0.323; P < 0.0001). In contrast, an increased proportion of CD56^brightCD16⁻ cells within lymphocyte significantly negatively correlated with the maximum bilateral knee extensor strength/weight (kg) (r = −0.290; P = 0.0004); and these subjects had a significantly lower mortality during the 5 years following measurement of death. Therefore, we found that a synergistic effect of the right and left leg muscle strength was associated with proportion of matured NK and NKT cells and induced a low proportion of CD56^brightCD16⁻ cells within lymphocyte. Moreover, the low proportion of CD56^brightCD16⁻ cells was associated with incidence of death. In conclusion, measurements of physical fitness, the proportion of CD56^dimCD16^high within CD56⁺CD16⁺ cells, the ratio of CD56^dimCD56^high and CD56^dimCD16⁻ cells, and the proportion of CD56^brightC16⁻ cells in lymphocytes are important indicators to check elderly health.

Effect of Regular Exercise on Inflammation Induced by Drug-resistant Staphylococcus aureus 3089 in ICR mice

Obesity is often associated with irregular dietary habits and reduced physical activity. Regular exercise induces a metabolic response that includes increased expression of various cytokines, signaling proteins and hormones, and reduced adipocyte size. In this study, mice performed a swimming exercise for 10 min/day, 5 days/week for 3 weeks. We then investigated the effect of this exercise regimen on inflammation induced by infection with drug-resistant Staphylococcus aureus strain 3089 (DRSA). In humans, DRSA causes dermatitis and pneumonitis. Similarly, DRSA induced inflammatory pneumonitis in both no-exercise (No-EX) and swim-trained (SW-EX) ICR mice. Regular exercise increased levels of the pro-inflammatory cytokines TNF-α and IL-1β and nitric oxide in both serum and whole lung tissue in SW-EX, as compared to No-EX control mice. Moreover, levels of the antimicrobial peptide cathelicidin were significantly increased in visceral adipose tissue and whole lung tissue in the SW-EX group, and this was accompanied by a reduction in the size of visceral adipocytes. In addition, levels of the inflammation marker peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) were not increased in the lung tissue of SW-EX mice. These findings suggest that in these model mice, regular exercise strengthens immune system responses, potentially preventing or mitigating infectious disease.

Training Effects on Immune Function in Judoists

BACKGROUND

It has been reported that high intensity long term training in elite athletes may increase risk of immune function.

OBJECTIVES

This study is to examine training effects on immunoglobulin and changes of physiological stress and physical fitness level induced by increased cold stress during 12-week winter off-season training in elite Judoists.

PATIENTS AND METHODS

Twenty-nine male participants (20 ± 1 years) were assigned to only Judo training (CG, n = 9), resistance training combined with Judo training (RJ, n = 10), and interval training combined with Judo training (IJ, n = 10). Blood samples collected at rest, immediately after all-out exercise, and 30-minute recovery period were analyzed for testing IgA, IgG, and IgM, albumin and catecholamine levels.

RESULTS

VO2max and anaerobic mean power in IJ (P < 0.05) and anaerobic power in RJ (P < 0.05) were significantly increased after 12-week training compared to CG. There was no significant interaction effect (group × period) in albumin after 12-week training; however, there was a significant interaction effect (group × period) in epinephrine after 12-week training (F (4, 52) = 3.216, P = 0.002) and immediately after all-out exercise and at 30-minute recovery (F (2, 26) = 14.564, P = 0.008). There was significantly higher changes in epinephrine of RJ compared to IJ at 30-minute recovery (P = 0.045). There was a significant interaction effect (group × period) in norepinephrine after 12-week training (F (4, 52) = 8.141, P < 0.0001), at rest and immediately after all-out exercise (F (2, 26) = 9.570, P = 0.001), and immediately after all-out exercise and at 30-minute recovery (F (2, 26) = 8.862, P = 0.001).

CONCLUSIONS

Winter off-season training of IJ increased physical fitness level as well as physical stress induced by overtraining. Along with increased physical stress, all groups showed reduced trend of IgA; however, there was no group difference based on different training methods.

The role of sports and exercise in allergic disease: drawbacks and benefits

Although training and exercise have several benefits, overdoing it might not necessarily be a good thing. For instance, elite athletes have an increased risk for asthma and allergy. Several mechanisms can be implicated for this risk, which include the interplay between environmental training factors and athlete's personal risk factors, such as genetic susceptibility, neurogenic-mediated inflammation, and epithelial sensitivity. However, an overwhelming amount of scientific evidence shows the positive effects of sports as part of a healthy lifestyle. Training reduces breathlessness and asthma symptoms and attenuates Th2-mediated inflammatory responses. Taken together, the benefits far outweigh the potential hazards of training. An easily administered therapeutic healthy lifestyle intervention, which could be used alongside current treatment, must be developed.

Effect of an intense period of competition on race performance and self-reported illness in elite cross-country skiers

The aim of this study was to determine whether participating in a cross-country skiing stage race (Tour de Ski; TDS) affects subsequent illness incidence, training, and race performance. Self-reported training and illness data from 44 male and female elite cross-country skiers were included. In total, 127 years of data were collected (2-3 seasons per athlete). Illness incidence, training load, and performance in international competitions were calculated for athletes who did and did not participate in TDS. Forty-eight percent of athletes reported becoming ill during or in the days immediately after taking part in TDS vs 16% of athletes who did not participate. In both groups, illness incidence was somewhat lower for female athletes. For male athletes, race performance was significantly worse for 6 weeks following TDS vs 6 weeks before TDS. Furthermore, while female athletes who participated in TDS performed relatively better than controls in Olympics/World Championships, male athletes who participated in TDS typically performed worse in subsequent major championships. Participating in TDS appears to result in ∼ 3-fold increase in risk of illness in this period. Male athletes appear more prone to illness and also see a drop in race performance following TDS, possibly linked to differences in training load before and after the event.

Therapeutic exercise attenuates neutrophilic lung injury and skeletal muscle wasting

Early mobilization of critically ill patients with the acute respiratory distress syndrome (ARDS) has emerged as a therapeutic strategy that improves patient outcomes, such as the duration of mechanical ventilation and muscle strength. Despite the apparent efficacy of early mobility programs, their use in clinical practice is limited outside of specialized centers and clinical trials. To evaluate the mechanisms underlying mobility therapy, we exercised acute lung injury (ALI) mice for 2 days after the instillation of lipopolysaccharides into their lungs. We found that a short duration of moderate intensity exercise in ALI mice attenuated muscle ring finger 1 (MuRF1)-mediated atrophy of the limb and respiratory muscles and improved limb muscle force generation. Exercise also limited the influx of neutrophils into the alveolar space through modulation of a coordinated systemic neutrophil chemokine response. Granulocyte colony-stimulating factor (G-CSF) concentrations were systemically reduced by exercise in ALI mice, and in vivo blockade of the G-CSF receptor recapitulated the lung exercise phenotype in ALI mice. Additionally, plasma G-CSF concentrations in humans with acute respiratory failure (ARF) undergoing early mobility therapy showed greater decrements over time compared to control ARF patients. Together, these data provide a mechanism whereby early mobility therapy attenuates muscle wasting and limits ongoing alveolar neutrophilia through modulation of systemic neutrophil chemokines in lung-injured mice and humans.