Immune nutrition and exercise: Narrative review and practical recommendations

L-Tryptophan-Rich Diet Alleviates High-Intensity-Exercise-Induced Liver Dysfunction via the Metabolite Indole-3-Acetic Acid and AhR Activation

High-intensity exercise (HIE) induces liver dysfunction and is detrimental to exercise performance. The underlying mechanism and preventive strategy urgently need to be explored. We increased the amount of tryptophan appropriately in the diet and explored the effect of an L-tryptophan-rich diet on the alleviation of HIE-induced liver dysfunction and the underlying mechanism. In this work, by establishing a C57BL/6 mouse model of high-intensity swimming exercise, the results demonstrated an L-tryptophan-rich diet significantly attenuated HIE-induced liver dysfunction, which was associated with increased levels of the tryptophan metabolite indole-3-acetic acid (IAA). Furthermore, IAA indeed exerted a protective effect against HIE-induced liver dysfunction in vivo and LPS-induced hepatocyte dysfunction in vitro. In conclusion, an L-tryptophan-rich diet may be a promising strategy to prevent HIE-induced liver dysfunction and metabolic disturbance via the metabolite indole-3-acetic acid and AhR activation.

Nutrition for optimising immune function and recovery from injury in sports

The immune system, sports injuries, physical activity and clinical sports nutrition are closely linked. Inadequate nutrition and intense stress in athletes increase the risk of immune dysfunction, injury and disease, while injury reduces the positive effects of physical activity, creating a vicious cycle affecting health and performance. Nutritional support is key to reducing the risk of injury, speeding up recovery and shortening rehabilitation. The intake of energy, protein, carbohydrates, fats and micronutrients should be adapted to the needs following injury. Quality nutrition is preferred over the use of dietary supplements, which are limited to cases of identified deficiencies (e.g. vitamin D or iron deficiencies). Health professionals with knowledge of clinical nutrition have a key role to play in injury prevention, treatment and rehabilitation, and nutritional interventions are an indispensable part of a holistic approach to athletes' health.

The Variability of the Salivary Antimicrobial Peptide Profile: Impact of Lifestyle

Saliva is crucial in maintaining oral health; its composition reflects the body's physiological and diseased state. Among salivary components, antimicrobial peptides (AMPs) stand out for their broad antimicrobial activities and role in modulating the oral microbiota and innate immune response. Local and systemic diseases can affect the levels of AMPs in saliva, making them attractive biomarkers. However, the large variability in their concentrations hampers their use in diagnostics. Knowledge of the various factors influencing the profile of salivary AMPs is essential for their use as biomarkers. Here, we examine how lifestyle factors such as physical activity, dietary supplementation, tobacco smoking, and psychological stress impact salivary AMP levels. By understanding these sources of variability, we can take a step forward in using AMPs for diagnostics and prognostics and develop new tailored and preventative approaches.

Repeated mouth rinsing of coffee improves the specific-endurance performance and jump performance of young male futsal players

BACKGROUND

Mouth-rinsing with ergogenic solutions such as carbohydrate and caffeinated drinks has been considered among athletes as a practical nutritional strategy. Therefore, this study aimed to determine the effect of repeated coffee mouth-rinsing (CMR) doses on specific performances of futsal players.

METHOD

Twenty-four male futsal players randomly participated in this randomized, double-blind, and crossover design study. During the intervention, participants were randomly placed in four different conditions including 1. low-dose CMR (LDC, n = 6, ~60 mg caffeine); 2. high-dose CMR (HDC, n = 6, ~125 mg caffeine); 3. decaffeinated CMR (PLA, n = 6, ~10 mg caffeine); and 4. no CMR (CON, n = 6). Vertical jump height was measured at baseline, baseline after CMR (baseline-CMR), immediately after the intermittent futsal endurance test (FIET) (IA-FIET), 5 min after the FIET (5"A-FIET) and 10 min after the FIET (10"A-FIET). Perceived fatigue was also measured by visual analogue scale (VAS) at baseline, IA-FIET, 5"A-FIET, and 10"A-FIET. CMR was also performed at baseline, during FIET (Repeated between levels), and 10'A-FIET. The collected data were analyzed (with SPSS software) by one- and two-way repeated measure ANOVA and Bonferroni post hoc test at P < 0.05 level.

RESULTS

The findings of the present study illustrated that the perceived fatigue in IA-FIET increased significantly compared to the baseline which was accompanied by a significant decrease in 5"A-FIET and 10"A-FIET compared to IA-FIET (P < 0.05), and no significant difference was observed between conditions in the baseline, IA-FIET, 5"A-FIET, and 10"A-FIET (P > 0.05). However, HDC and LDC rose significantly the distance covered in FIET compared to CON and PLA (P < 0.05). In addition, HDC increased the FIET performance more than LDC (P < 0.05). Although there was no difference between any of the conditions at baseline (P > 0.05), baseline-CMR increased significantly the vertical jump height (P < 0.05). At IA-FIET, vertical jump height decreased to baseline levels in CMR conditions but increased in 5"A-FIET, which remained constant until 10"A-FIET (P < 0.05). In addition, vertical jump height in HDC and LDC conditions was significantly higher than CON in IA-FIET, 5"A-FIET, and 10"A-FIET.

CONCLUSION

This study showed that repeated CMR with low and high doses is a useful strategy to improve specific futsal performance. However, higher dose CMR appears to have more profound effects on performance improvement than lower doses.

Physical activity and immunity in obese older adults: A systematic bibliographic analysis

Extensive research has been conducted on the roles of physical activity in immune functioning. However, reviews on the effect of physical activity on immune function among obese older adults are scarce. This study aimed to map the trend and development of the key terms and prominent sources to identify potential research opportunities through a systematic bibliographic analysis. A systematic search was conducted in the Scopus database on the following query: (sport∗ OR "physical activity" OR exercise) AND (elderly OR "older adult∗" OR aging) AND (immun∗) AND (obes∗) AND NOT (animal), in March 2023. Publication timing and citation were descriptively analyzed, followed by the bibliographic coupling and the term co-occurrence analyses for generating network and overlay visualization mapping using the VOSviewers software. The search resulted in 426 articles dating back from 1991 to the present and were dominated by authors from Western countries. Three thematic clusters of this research area were generated, covering (1) the impact of physical activity or inactivity on health, (2) physical activity assessments and the use of association and cross-sectional study as the primary type of research, and (3) the physical activity impacts at the population level. For future research, more intervention studies are needed to understand how exercise affects immune response in older obese adults and to explore optimal duration, type, and intensity of the exercise, using a multi-omics approach. Studies in non-Western populations and systematic reviews are recommended to complement this bibliographic analysis.

The Use of Some Polyphenols in the Modulation of Muscle Damage and Inflammation Induced by Physical Exercise: A Review

Food bioactive compounds (FBC) comprise a vast class of substances, including polyphenols, with different chemical structures, and they exert physiological effects on individuals who consume them, such as antioxidant and anti-inflammatory action. The primary food sources of the compounds are fruits, vegetables, wines, teas, seasonings, and spices, and there are still no daily recommendations for their intake. Depending on the intensity and volume, physical exercise can stimulate oxidative stress and muscle inflammation to generate muscle recovery. However, little is known about the role that polyphenols may have in the process of injury, inflammation, and muscle regeneration. This review aimed to relate the effects of supplementation with mentation with some polyphenols in oxidative stress and post-exercise inflammatory markers. The consulted papers suggest that supplementation with 74 to 900 mg of cocoa, 250 to 1000 mg of green tea extract for around 4 weeks, and 90 mg for up to 5 days of curcumin can attenuate cell damage and inflammation of stress markers of oxidative stress during and after exercise. However, regarding anthocyanins, quercetins, and resveratrol, the results are conflicting. Based on these findings, the new reflection that was made is the possible impact of supplementation associating several FBCs simultaneously. Finally, the benefits discussed here do not consider the existing divergences in the literature. Some contradictions are inherent in the few studies carried out so far. Methodological limitations, such as supplementation time, doses used, forms of supplementation, different exercise protocols, and collection times, create barriers to knowledge consolidation and must be overcome.

Evaluation of Supplement Use in Sport Climbers at Different Climbing Levels

The lack of specific recommendations on the use of supplements for sport climbers may be the reason for their misuse by athletes of this discipline. This study aimed to evaluate choices of dietary supplementation, the reasons for taking them, and the source of information on supplementation among sport climbers at different levels. In addition, how climbers subjectively evaluated the impact of their diets in supporting selected aspects of climbing training was evaluated. We enrolled 110 regular sport climbers (40 women and 70 men) from Wroclaw, Poland, who completed a validated questionnaire, assessing their use of dietary supplements, attitudes towards the influence of diet on sports performance, and climbing level. Their anthropometric measurements were also collected. Participants regarded diet as an important element of sports performance. Sport climbers indicated the Internet to be the main source of information on supplements. Health maintenance and improvement of recovery were the most frequently chosen reasons for taking dietary supplements. The most common supplements were isolated protein, vitamin C, vitamin D, magnesium, and amino acid blends. However, participants rarely used supplements suggested as beneficial for sport climbing performance. Therefore, developing recommendations for supplementation in sport climbing and promoting this should be an elementary part of the preparation for climbing training.

Dihydromyricetin Attenuates High-Intensity Exercise-Induced Intestinal Barrier Dysfunction Associated with the Modulation of the Phenotype of Intestinal Intraepithelial Lymphocytes

BACKGROUND

Exercise-induced gastrointestinal syndrome (GIS) has symptoms commonly induced by strenuous sports. The study aimed to determine the effect of dihydromyricetin (DHM) administration on high-intensity exercise (HIE)-induced intestinal barrier dysfunction and the underlying mechanism involved with intestinal intraepithelial lymphocytes (IELs).

METHODS

The HIE model was established with male C57BL/6 mice using a motorized treadmill for 2 weeks, and DHM was given once a day by oral gavage. After being sacrificed, the small intestines of the mice were removed immediately.

RESULTS

We found that DHM administration significantly suppressed HIE-induced intestinal inflammation, improved intestinal barrier integrity, and inhibited a HIE-induced increase in the number of IELs and the frequency of CD8αα⁺ IELs. Meanwhile, several markers associated with the activation, gut homing and immune functions of CD8αα⁺ IELs were regulated by DHM. Mechanistically, luciferase reporter assay and molecular docking assay showed DHM could activate the aryl hydrocarbon receptor (AhR).

CONCLUSIONS

These data indicate that DHM exerts a preventive effect against HIE-induced intestinal barrier dysfunction, which is associated with the modulation of the quantity and phenotype of IELs in the small intestine. The findings provide a foundation to identify novel preventive strategies based on DHM supplementation for HIE-induced GIS.

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].

International Olympic Committee (IOC) consensus statement on acute respiratory illness in athletes part 1: acute respiratory infections

Acute illnesses affecting the respiratory tract are common and form a significant component of the work of Sport and Exercise Medicine (SEM) clinicians. Acute respiratory illness (ARill) can broadly be classified as non-infective ARill and acute respiratory infections (ARinf). The aim of this consensus is to provide the SEM clinician with an overview and practical clinical approach to ARinf in athletes. The International Olympic Committee (IOC) Medical and Scientific Commission appointed an international consensus group to review ARill (non-infective ARill and ARinf) in athletes. Six subgroups of the IOC Consensus group were initially established to review the following key areas of ARill in athletes: (1) epidemiology/risk factors for ARill, (2) ARinf, (3) non-infective ARill including ARill due to environmental exposure, (4) acute asthma and related conditions, (5) effects of ARill on exercise/sports performance, medical complications/return-to-sport and (6) acute nasal/vocal cord dysfunction presenting as ARill. Several systematic and narrative reviews were conducted by IOC consensus subgroups, and these then formed the basis of sections in the consensus documents. Drafting and internal review of sections were allocated to 'core' members of the consensus group, and an advanced draft of the consensus document was discussed during a meeting of the main consensus core group in Lausanne, Switzerland on 11 to 12 October 2021. Final edits were completed after the meeting. This consensus document (part 1) focusses on ARinf, which accounts for the majority of ARill in athletes. The first section of this consensus proposes a set of definitions and classifications of ARinf in athletes to standardise future data collection and reporting. The remainder of the consensus paper examines a wide range of clinical considerations related to ARinf in athletes: epidemiology, risk factors, pathology/pathophysiology, clinical presentation and diagnosis, management, prevention, medical considerations, risks of infection during exercise, effects of infection on exercise/sports performance and return-to-sport guidelines.

Dihydromyricetin-Encapsulated Liposomes Inhibit Exhaustive Exercise-Induced Liver Inflammation by Orchestrating M1/M2 Macrophage Polarization

Exhaustive exercise (EE) induced hepatic inflammatory injury has been well reported. Dihydromyricetin (DHM) has shown anti-inflammatory bioactivity and hepatoprotective effects but is limited by poor bioavailability. Here, high-bioavailability DHM-encapsulated liposomes were synthesized and explored for their therapeutic potential and regulatory mechanisms in a hepatic inflammatory injury model. The animal model was established by swimming-to-exhaustive exercise in C57BL/6 mice, and the anti-inflammatory effects were detected after administration of DHM or DHM liposome. NIR fluorescence imaging was used to assess the potential of liver targeting. The DHM liposome-induced macrophage polarization was measured by flow cytometry ex vivo. The anti-inflammatory mechanism of DHM was studied in cell line RAW264.7 in vitro. Liposome encapsulation enhanced DHM bioavailability, and DHM liposome could alleviate liver inflammation more effectively. Moreover, DHM liposome targeted hepatic macrophages and polarized macrophages into an anti-inflammatory phenotype. The SIRT3/HIF-1α signaling pathway could be the major mechanism of DHM motivated macrophage polarization. Our study indicates that DHM liposomes can alleviate liver inflammation induced by EE through sustained releasing and hepatic targeting. It is a promising option to achieve the high bioavailability of DHM. Also, this study provides new insights into the regional immune effect of DHM against inflammation.

Bioactive compounds, nutritional profile and health benefits of colostrum: a review

Bovine colostrum is defined as first milk by milching animals responsible for providing the innate immunity to the neonatal and possess many immunoglobulins for preventing the calf from diseases. Colostrum consist of many bioactive compounds like proteins, enzymes, growth factors, immunoglobulins and nucleotides that provides several benefits to human health. Numerous clinical and pre-clinical studies have demonstrated the therapeutic benefits of the bovine colostrum. This review focusses on bioactive compounds, their health benefits, potential of colostrum for developing several health foods and prevention of respiratory and gastrointestinal tract disorders. Processing can also be done to extend shelf-life and extraction of bioactive constituents either as encapsulated or as extracts. The products derived from bovine colostrum are high-end supplements possessing high nutraceutical value.

Effects of Long-Term Supplementation of Bovine Colostrum on the Immune System in Young Female Basketball Players. Randomized Trial

An intensive physical exercise program could lead to a decrease in immune system function. Effects of long-term supplementation of bovine colostrum on the response of immune function on physical exercise test in athletes were examined. Twenty-seven elite female basketball players (age 16–19) were randomly assigned to either an experimental group or a control group. Eventually, n = 11 athletes completed intervention in the experimental group (3.2 g bovine colostrum orally twice a day for 24 weeks), while n = 9 athletes in the control group were given a placebo. Before the supplementation, after 3 and 6 months, subjects performed the physical exercise stress test. Before, just after, and 3 h after physical exercise testing, blood was drawn and immune system indicators were examined. Plasma interleukin (IL)-1alpha, IL-2, IL-10, IL-13, tumor necrosis factor (TNF) alpha, creatine kinase (CK MM), immunoglobulin G (IgG), insulin-like growth factor 1 (IGF1), and WBC, lymphocyte (LYM), monocyte (MON), and granulocyte (GRA) were measured. A statistically significant change in IL-10 in response to the exercise program during the supplementation period in both groups was observed (p = 0.01). However, the results of the rest of the comparisons were statistically insignificant (p > 0.05). Contrary to our initial hypothesis, there were no significant effects of bovine supplementation on the dynamics of immune system function indicators.

Returning to Play after Prolonged Training Restrictions in Professional Collision Sports

The COVID-19 pandemic in 2020 has resulted in widespread training disruption in many sports. Some athletes have access to facilities and equipment, while others have limited or no access, severely limiting their training practices. A primary concern is that the maintenance of key physical qualities (e. g. strength, power, high-speed running ability, acceleration, deceleration and change of direction), game-specific contact skills (e. g. tackling) and decision-making ability, are challenged, impacting performance and injury risk on resumption of training and competition. In extended periods of reduced training, without targeted intervention, changes in body composition and function can be profound. However, there are strategies that can dramatically mitigate potential losses, including resistance training to failure with lighter loads, plyometric training, exposure to high-speed running to ensure appropriate hamstring conditioning, and nutritional intervention. Athletes may require psychological support given the challenges associated with isolation and a change in regular training routine. While training restrictions may result in a decrease in some physical and psychological qualities, athletes can return in a positive state following an enforced period of rest and recovery. On return to training, the focus should be on progression of all aspects of training, taking into account the status of individual athletes.

Strategies and Solutions to Return to Training for Teams and Elite Athletes After Lifting COVID-19 Restrictions

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Coldzyme® Mouth Spray reduces duration of upper respiratory tract infection symptoms in endurance athletes under free living conditions

Upper respiratory tract infection (URTI) can compromise athlete preparation and performance, so countermeasures are desirable. The aim of this study was to assess the effects of ColdZyme® Mouth Spray (ColdZyme) on self-reported upper respiratory tract infection in competitive endurance athletes under free-living conditions. One hundred and twenty-three endurance-trained, competitive athletes (recruited across 4 sites in England, UK) were randomised to control (no treatment, n = 61) or ColdZyme (n = 62) for a 3-month study period (between December 2017 and March 2018; or December 2018 and April 2019). They recorded daily training and illness symptoms (Jackson common cold questionnaire) during the study period. A total of 130 illness episodes were reported during the study with no difference in incidence between groups (episodes per person: 1.1 ± 0.9 Control, 1.0 ± 0.8 ColdZyme, P = 0.290). Episode duration was significantly shorter in ColdZyme compared to Control: Control 10.4 ± 8.5 days vs. ColdZyme 7.7 ± 4.0 days, P = 0.016). Further analysis to compare episodes with poor vs. good compliance with ColdZyme instructions for use (IFU) within the ColdZyme group showed a greater reduction in duration of URTI when compliance was good (9.3 ± 4.5 days in ColdZyme poor IFU compliance vs. 6.9 ± 3.5 days in ColdZyme good IFU compliance, P = 0.040). ColdZyme may be an effective countermeasure to reduce URTI duration, which was significantly lower (by 26-34%) in the ColdZyme treatment group (with no influence on incidence). This may have implications for athlete performance.

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.

Probiotics, prebiotics and synbiotics: useful for athletes and active individuals? A systematic review

The purpose of this review was to synthesise available knowledge on the main health effects associated with the use of probiotics, prebiotics and/or synbiotics in athletes and active individuals, including their effects on the immune system, oxidative stress, the gastrointestinal and respiratory symptoms, as well as other possible clinical outcomes. A systematic and comprehensive search in electronic databases, including Web of Science (WOS, Scielo), PubMed-MEDLINE, Biblioteca virtual de la Salud (LILACS, IBECS), EBSCO (Academic Search Complete CINAHL; SPORTDiscus) and Cochrane Library, focused on generic articles about probiotics, prebiotics and/or synbiotics and their functionality and effects on human health. The search process was completed using the keywords: ‘probiotics’, ‘prebiotics’, ‘synbiotics’, ‘athletes’ and ‘health’. The only exclusion criterion was experimental studies with animals. A total of 31 studies met the inclusion criteria and were included in the review. The vast majority were experimental studies about probiotics and health effects (n=28), while only a few demonstrated the results of consuming prebiotics and/or synbiotics (n=3) in athletes and active individuals. Although most of the studies reported positive health effects in athletes and active individuals, there is still no substantial scientific evidence to suggest that probiotics, prebiotics and synbiotics play an important role in improving an athlete´s performance. These studies are currently limited in number and quality, hence it is necessary to improve the selection of functional biomarkers and methodological approaches, as well as determining the specific nutritional supplement and exercise doses.

Effect of Probiotics Supplementations on Health Status of Athletes

Athletes are prone to several health complications, including upper respiratory tract infections, allergies, and gastrointestinal discomforts during practice and after the performance due to the intense exercise, travel, insufficient rest and restricted food consumption. Probiotics are well known as complementary therapeutic and health supplements for several diseases and disorders. Studies suggest that the intervention of probiotics improved the health status of elite athletes, but the results are not consistent in all the studies. The beneficial effect of probiotic supplementation profoundly relies on species or strain, dose, duration, form, and host physiology. The manuscript summarizes the effect of probiotic supplementation on health status of athletes. The literature was collected from PubMed, Scopus, Web of Science, and Google Scholar using the search term “probiotic and athletes”. As per the literature survey, probiotic supplementation improved the intestinal permeability, immune system, intestinal microbiota, inflammatory system, reduced the severity and incidence of respiratory tract infections, and duration of gastrointestinal symptoms. Several studies were conducted on Lactobacillus species and the outcomes were found to be species- or strain-specific. More studies are required to know the detailed mechanism behind the beneficial effect of probiotic intervention in athletes. Further studies are desired on formulation and optimization of probiotic supplements to develop generalized and personalized sports supplements to boost the overall health and enactment of elite athletes.

Tear Lactoferrin and Lysozyme as Clinically Relevant Biomarkers of Mucosal Immune Competence

Tears have attracted interest as a minimally-invasive biological fluid from which to assess biomarkers. Lactoferrin (Lf) and lysozyme (Lys) are abundant in the tear fluid and have antimicrobial properties. Since the eye is a portal for infection transmission, assessment of immune status at the ocular surface may be clinically relevant. Therefore, the aim of this series of studies was to investigate the tear fluid antimicrobial proteins (AMPs) Lf and Lys as biomarkers of mucosal immune status. To be considered biomarkers of interest, we would expect tear AMPs to respond to stressors known to perturb immunity but be robust to confounding variables, and to be lower in participants with heightened risk or incidence of illness. We investigated the relationship between tear AMPs and upper respiratory tract infection (URTI; study 1) as well as the response of tear AMPs to prolonged treadmill exercise (study 2) and dehydration (study 3). Study 1 was a prospective cohort study conducted during the common cold season whereas studies 2 and 3 used repeated-measures crossover designs. In study 1, tear Lys concentration (C) as well as tear AMP secretion rates (SRs) were lower in individuals who reported pathogen-confirmed URTI (n = 9) throughout the observation period than in healthy, pathogen-free controls (n = 17; Lys-C, P = 0.002, d = 0.85; Lys-SR, P < 0.001, d = 1.00; Lf-SR, P = 0.018, d = 0.66). Tear AMP secretion rates were also lower in contact lens wearers. In study 2, tear AMP SRs were 42-49% lower at 30 min-1 h post-exercise vs. pre-exercise (P < 0.001, d = 0.80-0.93). Finally, in study 3, tear AMPs were not influenced by dehydration, although tear AMP concentrations (but not secretion rates) displayed diurnal variation. We conclude that Lf and Lys have potential as biomarkers of mucosal immune competence; in particular, whether these markers are lower in infection-prone individuals warrants further investigation.

Keeping Athletes Healthy at the 2020 Tokyo Summer Games: Considerations and Illness Prevention Strategies

Keeping athletes healthy will be important for optimal athletic performance at the 2020 Tokyo Summer Olympic and Paralympic Games. Athletes will be exposed to several stressors during the preparatory and competition phases of the Summer Games that have the potential to depress immunity and increase illness risk. This mini-review provides an overview on effective and practical stressor-specific illness prevention strategies that can be implemented to maintain and protect the health of Olympic and Paralympic athletes.