Michael Gleeson

• BSc PhD
• Loughborough University

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising...

Periods of short-term intensified training (IT) are often used by athletes during training cycles over the season and undergoing phases of increased physical stress may impact upon the immune system. This study investigated the effects of a period of IT on free light chains (FLCs) in saliva - an emerging immune biomarker of oral inflammation - and...

In this consensus statement on immunonutrition and exercise, a panel of knowledgeable contributors from across the globe provides a consensus of updated science, including the background, the aspects for which a consensus actually exists, the controversies and, when possible, suggested directions for future research.

Altitude exposure can exaggerate the transient increase in markers of oxidative stress observed following acute exercise. However, these responses have not been monitored in endurance-trained cyclists at altitudes typically experienced whilst training. Endurance trained males (n=12; mean (±SD) age: 28 ± 4 years, V ̇O2max 63.7 ± 5.3 ml/kg/min) under...

Athletes participating in elite sports are exposed to high training loads and increasingly saturated competition calendars. Emerging evidence indicates that poor load management is a major risk factor for injury. The International Olympic Committee convened an expert group to review the scientific evidence for the relationship of load (defined broa...

The modern-day athlete participating in elite sports is exposed to high training loads and increasingly saturated competition calendar. Emerging evidence indicates that inappropriate load management is a significant risk factor for acute illness and the overtraining syndrome. The IOC convened an expert group to review the scientific evidence for th...

Aim To examine symptoms indicative of respiratory tract and gastrointestinal infections and determine risk factors for such symptoms in elite cross-country skiers. Methods Self-reported training and symptom data for 37 elite cross-country skiers from 2007 to 2015 were analysed using multilevel logistic regression equations with symptom incidence an...

Aims: To assess evidence of health and immune benefit by consumption of a Lactobacillus casei Shirota probiotic in highly physically active people. Methods: Single-centre, population-based, randomized, double-blind, placebo-controlled trial. Daily ingestion of probiotic (PRO) or placebo (PLA) for 20 weeks for n = 243 (126 PRO, 117 PLA) universit...

Purpose: To determine how immune markers are affected by acute hypoxic exercise at the same relative intensity. Methods: Twelve endurance-trained males (age: 28 ± 4 years, [Formula: see text]O2max: 63.7 ± 5.3 mL/kg/min) cycled for 75 min at 70 % of altitude-specific [Formula: see text]O2max, once in normoxia (N) and once in hypobaric hypoxia equ...

Aim: To examine symptoms indicative of respiratory tract and gastrointestinal infections and determine risk factors for such symptoms in elite cross-country skiers. Methods: Self-reported training and symptom data for 37 elite cross-country skiers from 2007 to 2015 were analysed using multilevel logistic regression equations with symptom inciden...

Purpose: To determine effects of intensified training (IT) and carbohydrate supplementation on overreaching and immunity. Methods: In a randomized, double-blind, crossover design, 13 male cyclists (age 25 ± 6 years, [Formula: see text] 72 ± 5 ml/kg/min) completed two 8-day periods of IT. On one occasion, participants ingested 2 % carbohydrate (L...

Background: Free light chains (FLCs) have a range of biological functions and may act as a broad marker of immunesuppression and activation and inflammation. Measurement of salivary FLCs may provide practical advantages in a range of clinical populations. The aim of the present study was to develop normal reference ranges of FLCs in saliva and ass...

Vitamin D is mainly obtained through sunlight ultraviolet-B (UVB) exposure of the skin, with a small amount typically coming from the diet. It is now clear that Vitamin D has important roles beyond its well-known effects on calcium and bone homeostasis. Immune cells express the Vitamin D receptor, including antigen presenting cells, T cells and B c...

Prolonged bouts of exercise and heavy training regimens are associated with depression of immune system functions which can increase the risk of picking up opportunistic infections such as the common cold and influenza. Some common sport nutrition practices including high carbohydrate diets and carbohydrate ingestion during exercise, training with...

The purpose of this study was to investigate the responses of salivary hormones and salivary secretory immunoglobulin A (SIgA) and anxiety in winners and losers during an international judo competition. Twenty-three trained, male, national-level judo athletes provided three saliva samples during a competition day: morning, in anticipation of compet...

Few studies have investigated the effects of exercise training on sleep physiology in well-trained athletes. We investigated changes in sleep markers, mood state and exercise performance in well-trained cyclists undergoing short-term intensified training and carbohydrate nutritional intervention. Thirteen highly-trained male cyclists (age: 25 ± 6y,...

This study examined the effects of postexercise chocolate milk (CM) or water (W) consumption during 5 days of intensive judo training with concomitant weight loss on salivary cortisol and testosterone, salivary secretory immunoglobulin A (SIgA), delayed-onset muscle soreness (DOMS), and judo-related performance. Twelve trained male judo athletes en...

Abstract Purpose Antimicrobial proteins (AMPs) in saliva including secretory immunoglobulin A (SIgA), lactoferrin (SLac) and lysozyme (SLys) are important in host defence against oral and respiratory infections. This study investigated the effects of hydration status on saliva AMP responses to endurance exercise. Methods Using a randomized design,...

Heavy training is associated with increased respiratory infection risk and antimicrobial proteins are important in defence against oral and respiratory tract infections. We examined the effect of 14 weeks of vitamin D3 supplementation (5000 IU/day) on the resting plasma cathelicidin concentration and the salivary secretion rates of secretory immuno...

Purpose: This study investigated the impact of intensified training (IT) and carbohydrate (CHO) supplementation on resting and exercise-induced oxidative stress. Methods: Male cyclists (n=13, mean ± SD: age 25 ± 6 years; VO2max 72 ± 5 ml/kg/min) undertook two 9-day periods of endurance-based IT. In a counterbalanced, crossover and double-blinded st...

This study examined the influence of 10-days intensified training on salivary cortisol and testosterone responses to 30-min, high-intensity cycling (55/80) in a group of male elite triathletes. Seven male elite triathletes (Age 19 ± 1 y; VO2max 67.6 ± 4.5 mL.kg-1.min-1) completed this study. Swim distances increased by 45%. Running and cycling trai...

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 p...

Aim: To determine whether participating in a cross-country skiing stage race (TDS) affects subsequent illness incidence, training and race performance. Methods: Self-reported training and illness data from 44 male and female elite cross-country skiers were included. In total, 125 years’ of data was collected (2-3 seasons per athlete). Illness incid...

Understanding psychological factors that affect immunity in sport might help to reduce infection risk in athletes. The present study examined within-person changes and individual differences in perceived coach control, intentions to drop out, and saliva secretory immunoglobulin A (SIgA). Thirty-two field hockey players completed questionnaires and...

Understanding psychological factors that affect immunity in sport might help to reduce infection risk in athletes. The present study examined within-person changes and individual differences in perceived coach control, intentions to drop out, and saliva secretory immunoglobulin A (SIgA). Thirty-two field hockey players completed questionnaires and...

The physical, mental and hormonal responses to short-term intensified training in well-trained cyclists with a high carbohydrate nutritional intervention

The purpose of this study was to examine sex differences in oral-respiratory mucosal immunity and the incidence, severity and duration of upper respiratory symptoms (URS) episodes in endurance athletes during a 16-week winter training period. Blood was collected from 210 subjects (147 men and 63 women) at the start and end of the study for determin...

Aim. Our aims were to determine the influence of plasma total 25-hydroxy vitamin D (25(OH)D) status on the plasma cytokine concentrations in athletes and the in vitro effects of different doses of 1, 25 dihydroxyvitamin D3 (1, 25(OH)2D3) on multiantigen stimulated cytokine production by whole blood and peripheral blood mononuclear cell (PBMC) cultu...

RESULTS: Both WP+AFRTop and WP+RegTop resulted in a ~1.8 fold greater cumulative ΔHb relative to CON (p ≤ 0.05). When both clothing ensembles were compared, EHL and ΔHb were similar at the end of all four exercise and recovery periods (all p > 0.05). In parallel, the cumulative ΔHb for all exercise/recovery cycles was not different between WP+AFRTo...

Upper respiratory tract infections are particularly prevalent during intensified training (IT) or competition, and in athletes suffering from overreaching (OR). High carbohydrate intake may play a role in prevention of OR and alleviate potential immunosuppression. PURPOSE: To determine the effects of IT and carbohydrate supplementation on plasma ho...

This study was designed to determine the effects of a period of supplementation with a 14-strain probiotics supplement on salivary antimicrobial proteins (AMPs) at rest and in response to an acute bout of prolonged exercise in active, healthy adults. In this study, 11 participants (age: 22 ± 1 years, weight: 69.5 ± 12.2 kg, body mass index: 23.0 ±...

Elevated antigen-stimulated anti-inflammatory cytokine production appears to be a risk factor for upper respiratory tract illness in athletes. The purpose of this study was to determine the effects of prolonged exercise and hydration on antigen-stimulated cytokine production. Twelve healthy males cycled for 120 min at 60% on two occasions, either e...

Athletes undergoing intensive training schedules have chronic exposure to stress-induced hormones such as cortisol that can depress immune function. We compared the circulating levels of T cell receptor excision circles (TREC), a marker of recent thymic emigrants, as well as the levels of naïve and memory subsets in a group of elite endurance athle...

High intensity training regimens appear to put athletes at a higher risk of illness. As these have been linked to alterations in the proportions of differentiated T cells, how training load affects these populations could have important implications for athlete susceptibility to disease. This study examined the effect of a winter training season on...

Aims. To evaluate the possible additive effects of beetroot juice plus caffeine on exercise performance. Methods. In a randomized, double-blinded study design, fourteen healthy well-trained men aged 22 ± 3 years performed four trials on different occasions following preexercise ingestion of placebo (PLA), PLA plus 5 mg/kg caffeine (PLA+C), beetroot...

Antimicrobial proteins (AMPs) in saliva including secretory immunoglobulin A (SIgA), lactoferrin (SLac) and lysozyme (SLys) are important in host defence against oral and respiratory infections. This study investigated the effects of hydration status on saliva AMP responses to endurance exercise. Using a randomized design, 10 healthy male participa...

The chapter begins by discussing the impact of intensive exercise training on immune function and susceptibility to infection in athletes. It then reviews the evidence that diet and nutritional supplements can modify immune responses to exercise and reduce infection incidence, symptom severity or duration in endurance athletes.

The purpose of this study was to examine the influence of vitamin D status on mucosal and systemic immunity and the incidence, severity and duration of upper respiratory tract illness (URTI) episodes in endurance athletes during a 16-week winter training period. Blood was collected from 225 subjects at the start of the study and plasma was analysed...

Aim. The purpose of this study was to compare the accuracy and clinical implications of three commercial enzyme-linked immunosorbent assay (ELISA) kits (Eagle Biosciences, Immundiagnostik, and MicroVue) with a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the measurement of serum 25(OH)D concentration. Methods. Bloo...

The purpose of this study was to examine the influence of previous infection with cytomegalovirus (CMV) or Epstein Barr virus (EBV) on the incidence, severity and duration of upper respiratory tract infections (URTIs) in endurance athletes during a 4-month winter training period. Blood samples were obtained from 236 subjects (166 males and 70 femal...

Regular moderate exercise reduces the risk of infection compared with a sedentary lifestyle, but very prolonged bouts of exercise and periods of intensified training are associated with increased infection risk. In athletes, a common observation is that symptoms of respiratory infection cluster around competitions, and even minor illnesses such as...

Infection incidence among athletes is highest during periods of intensified training and competition and after strenuous long-distance events. Which aspects of depressed immune function are responsible for this increased infection risk are not known, but our hypothesis is that lower salivary immunoglobulin A (IgA) secretion and a higher antiinflamm...

Prolonged exercise and heavy training are associated with depressed immune function which can increase the risk of picking up minor infections. To maintain robust immunity, athletes should eat a well-balanced diet sufficient to meet their energy, carbohydrate, protein, and micronutrient requirements. Dietary deficiencies of protein and specific mic...

Abstract This study examined salivary cortisol and testosterone responses to two, different high-intensity, ∼30-min cycles separated by 2 h rest before and after an 11-day intensified training period. Twelve recreationally active, healthy males completed the study. Saliva samples were collected before, immediately after and 30 min after both bouts...

Chronic low-level inflammation is associated with obesity and increased incidence of cancer and chronic disease states. Regular exercise reduces the risk of some cancers as well as chronic metabolic and cardiorespiratory diseases, in part because exercise exerts anti-inflammatory effects. The anti-inflammatory effects of regular exercise may be med...

This study investigated the salivary secretion rates of antimicrobial proteins in response to prolonged, exhaustive exercise in both stimulated (STIM) and unstimulated (UNSTIM) saliva flow sample methods. Twenty-four trained men cycled for 2.5 h at 60% V ˙ O 2 m ⁢ a x and then to exhaustion at 75% V ˙ O 2 m ⁢ a x . Timed collections of whole saliva...

Although resting immune function is not very different in athletes compared with non-athletes periods of intensified training (overreaching) in already well trained athletes can result in a depression of immunity in the resting state. Illness-prone athletes appear to have an altered cytokine response to antigen stimulation and exercise. Having low...

Highly trained athletes are associated with high resting antigen-stimulated whole blood culture interleukin (IL)-10 production. The purpose of the present study was to examine the effects of training status on resting circulating T regulatory (Treg) cell counts and antigen-stimulated IL-10 production and the effect of acute bout of exercise on the...

International Journal of Exercise Science 6(1) : 81-90, 2013. Monocyte TLR expression has been shown to be reduced after a combination of aerobic and resistance exercise, but more studies considering the influences of different exercise intensities, type and duration on TLR expression are needed. Although there is an agreement about the importance...

Successful training must involve overload, but also must avoid the combination of excessive overload plus inadequate recovery. Athletes can experience short-term performance decrement, without severe psychological, or lasting other negative symptoms. This Functional Overreaching (FOR) will eventually lead to an improvement in performance after reco...

The aims of this study were to identify the time-course of change of salivary testosterone (sT), cortisol (sC) and IgA (SIgA), mood state and performance capacity during a 2-week taper in judo athletes, and to examine the diurnal variation in these salivary markers. Eleven male judo athletes completed 5 weeks of training: 1 week of normal training...

Immune changes and increased susceptibility to infection are often reported in elite athletes. Infectious episodes can often impair training and performance with consequences for health and sporting success. This study monitored the occurrence of episodes of upper respiratory symptoms (URS) and the variation in circulating NK cells, CD56(bright) an...

This study examine the effects of Kaloba (Schwabe Pharma, Germany) supplementation on immune response to prolonged exercise in 9 healthy male recreational athletes (age 21 ± 5 years; BMI 22.4 ± 1.5kg/m2). Participants cycled for 90 min at 60% VO2max on two trials. Participants came in the morning after an overnight fast during each trial. The secon...

The purpose of this study was to examine the effects of a probiotic supplement during 4 mo of spring training in men and women engaged in endurance-based physical activities on incidence of upper respiratory tract infections (URTI) and mucosal immune markers. Sixty-six highly active individuals were randomized to probiotic (n = 33) or placebo (n =...

This study examined the effect of training load on upper respiratory tract infection (URTI) incidence in men and women engaged in endurance-based physical activity during winter and sought to establish if there are training-associated differences in immune function related to patterns of illness. Seventy-five individuals provided resting blood and...

An individual's level of physical activity influences their risk of infection, most likely by affecting immune function. Regular moderate exercise reduces the risk of infection compared with a sedentary lifestyle, but very prolonged bouts of exercise and periods of intensified training are associated with an increased risk of infection. There are s...

Regular exercise reduces the risk of chronic metabolic and cardiorespiratory diseases, in part because exercise exerts anti-inflammatory effects. However, these effects are also likely to be responsible for the suppressed immunity that makes elite athletes more susceptible to infections. The anti-inflammatory effects of regular exercise may be medi...

Elite level athletes seem to be prone to illness especially during heavy training phases. The aim of this study was to investigate the influence of long term intensive training on the functional features of innate immune cells from high competitive level swimmers, particularly the production of inflammatory mediators and the possible relationship w...

Acute antioxidant supplementation may modulate oxidative stress and some immune perturbations that typically occur following prolonged exercise. The aims of the present study were to examine the effects of acutely consuming dark chocolate (high polyphenol content) on plasma antioxidant capacity, markers of oxidative stress and immunoendocrine respo...

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period ev...

The purpose of this study was to examine factors influencing susceptibility to upper respiratory tract infections (URTI) in 18-35-year-old men and women engaged in endurance-based physical activity during the winter months. Eighty individuals (46 males, 34 females) provided resting blood and saliva samples for determination of markers of systemic i...

The purpose of this study was to examine the effects of a probiotic supplement during 4 mo of winter training in men and women engaged in endurance-based physical activities on incidence of upper respiratory-tract infections (URTIs) and immune markers. Eighty-four highly active individuals were randomized to probiotic (n = 42) or placebo (n = 42) g...

Hormonal responses to exercise could be used as a marker of overreaching. A short exercise protocol that induces robust hormonal elevations in a normal trained state should be able to highlight hormonal changes during overreaching. This study compared plasma and salivary cortisol and testosterone responses to 4 exercise trials; these were (a) conti...

An ever-growing volume of peer-reviewed publications speaks to the recent and rapid growth in both scope and understanding of exercise immunology. Indeed, more than 95% of all peer-reviewed publications in exercise immunology (currently >2, 200 publications using search terms "exercise" and "immune") have been published since the formation of the I...

The physical training undertaken by athletes is one of a set of lifestyle or behavioural factors that can influence immune function, health and ultimately exercise performance. Others factors including potential exposure to pathogens, health status, lifestyle behaviours, sleep and recovery, nutrition and psychosocial issues, need to be considered a...

The purpose of this study was to examine sex differences in immune variables and upper respiratory tract infection (URTI) incidence in 18-35 year-old athletes engaged in endurance-based physical activity during the winter months. Eighty physically active individuals (46 males, 34 females) provided resting venous blood samples for determination of d...

Several studies have reported that some immune cell functions including monocyte Toll-like receptor (TLR) expression and antigen presentation are temporarily impaired following acute bouts of strenuous exercise, which could represent an 'open window' to upper respiratory tract infection (URTI). However, we do not know the time course of effects of...

This study investigated the effect of a fed or fasted state on the salivary immunoglobulin A (s-IgA) response to prolonged cycling. Using a randomized, crossover design, 16 active adults (8 men and 8 women) performed 2 hr of cycling on a stationary ergometer at 65% of maximal oxygen uptake on 1 occasion after an overnight fast (FAST) and on another...

Fatigue is often a consequence of physical training and the effective management of fatigue by the coach and athlete is essential in optimizing adaptation and performance. In this paper, we explore a range of practical and contemporary methods of fatigue management for Olympic athletes. We assesses the scientific merit of methods for monitoring fat...

There are many factors in mucosal secretions that contribute to innate immunity and the 'first line of defence' at mucosal surfaces. Few studies, however, have investigated the effects of exercise on many of these 'defence' factors. The aim of the present study was to determine the acute effects of prolonged exercise on salivary levels of selected...

Summary Acute exercise is followed by a mobilization of white blood cells, mainly induced by increased levels of catecholamines and cortisol. NK-cells react the most intensive, they can increase fivefold after intensive exercise. Additionally a weak acute-phase reaction occurs. Most of these changes normalize during twenty-four hours. Parameters o...

Decreased secretion rate of salivary markers of mucosal immunity, and in particular salivary immunoglobulin A (s-IgA), have been implicated as risk factors for subsequent episodes of respiratory infection in athletes. IgA is the predominant Ig in mucosal secretions and acts with innate mucosal defences to provide the 'first line of defence' against...

Physical stress induces a marked redistribution of T lymphocytes that may be influenced by carbohydrate (CHO) availability, yet the effect of these on T lymphocyte migration towards infected tissue is unknown. Therefore, the aim of this study was to determine the effect of strenuous exercise and CHO ingestion on subsequent ex vivo lymphocyte migrat...

Some athletes can have high intakes of l-glutamine because of their high energy and protein intakes and also because they consume protein supplements, protein hydrolysates, and free amino acids. Prolonged exercise and periods of heavy training are associated with a decrease in the plasma glutamine concentration and this has been suggested to be a p...

Caffeine is thought to act as a central stimulant and to have effects on physical, cognitive, and psychomotor functioning. To examine the effects of ingesting a performance bar, containing caffeine, before and during cycling exercise on physical and cognitive performance. Twenty-four well-trained cyclists consumed the products [a performance bar co...

The relationship between physiological and psychological stress and immune function is widely recognized; however, there is little evidence to confirm a direct link between depressed immune function and incidence of illness in athletes. To examine the relationship between salivary immunoglobulin A (s-IgA) and upper respiratory infections (URI) in a...

In the present study, we assessed the effects of exercise intensity on salivary immunoglobulin A (s-IgA) and salivary lysozyme (s-Lys) and examined how these responses were associated with salivary markers of adrenal activation. Using a randomized design, 10 healthy active men participated in three experimental cycling trials: 50% maximal oxygen up...

This chapter describes the sources of energy available for muscle force generation. It explains how acute exercise modifies energy metabolism through intracellular effects and the action of hormones. Both the diet before exercise and feeding during exercise influence the hormonal and metabolic responses to exercise. Some dietary components when ing...

Regular moderate exercise is associated with a reduced incidence of infection compared with a completely sedentary state. However, prolonged bouts of strenuous exercise cause a temporary depression of various aspects of immune function (e.g., neutrophil respiratory burst, lymphocyte proliferation, monocyte antigen presentation) that usually lasts a...

Repeated bouts of strenuous exercise have been shown to result in a marked stress response and a suppression of the immune system, consequently increasing an individual's susceptibility to infection. The effectiveness of low-fat milk in attenuating the exercise-induced stress response was compared with that of a commercially-available sports drink....

Antioxidant supplementation may modulate systemic cortisol and interleukin-6 (IL-6) responses to prolonged exercise, but it is unclear whether such effects are also associated with a reduction in the magnitude of immunodepression. The purpose of the present study was to examine the effects of daily vitamin C (L-ascorbic acid, 1000 mg x d(-1)) and v...

The aim of the present study was to investigate possible changes in the plasma IL-6 levels, subjective reporting of sources and symptoms of stress and the innate immune system in response to an acute period of intensified run training in highly trained endurance athletes. Eight healthy endurance trained male subjects (mean +/- SD age 23 +/- 2 years...

The depression of immune cell function that is typically observed after prolonged exercise is thought to be largely mediated by increased concentrations of stress hormones and cytokines as well as, possibly, oxidative stress. The aim of this study was to measure immunoendocrine responses, with acute vitamin C or placebo ingestion, before and during...