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Modification of immune responses to exercise by carbohydrate, glutamine and anti-oxidant supplements
Abstract
Immunosuppression in athletes involved in heavy training is undoubtedly multifactorial in origin. Training and competitive surroundings may increase the athlete's exposure to pathogens and provide optimal conditions for pathogen transmission. Heavy prolonged exertion is associated with numerous hormonal and biochemical changes, many of which potentially have detrimental effects on immune function. Furthermore, improper nutrition can compound the negative influence of heavy exertion on immunocompetence. An athlete exercising in a carbohydrate-depleted state experiences larger increases in circulating stress hormones and a greater perturbation of several immune function indices. The poor nutritional status of some athletes may predispose them to immunosuppression. For example, dietary deficiencies of protein and specific micronutrients have long been associated with immune dysfunction. Although it is impossible to counter the effects of all of the factors that contribute to exercise-induced immunosuppression, it has been shown to be possible to minimize the effects of many factors. Athletes can help themselves by eating a well-balanced diet that includes adequate protein and carbohydrate, sufficient to meet their energy requirements. This will ensure a more than adequate intake of trace elements without the need for special supplements. Consuming carbohydrate (but not glutamine or other amino acids) during exercise attenuates rises in stress hormones, such as cortisol, and appears to limit the degree of exercise-induced immunosuppression, at least for non-fatiguing bouts of exercise. Evidence that high doses of anti-oxidant vitamins can prevent exercise-induced immunosuppression is also lacking.
... Intensified exercise leads to a two-phase change in the concentrations of lymphocytes. It has been reported the increase of the current lymphocytes (lymphocytosis) immediately after the exercising and the concentration return to lower contents of pre-exercise levels during the initial steps of recovery and before coming back to the rest levels [5]. ...
... Long and heavy exercises are associated with numerous of biochemical and hormonal changes and have the potentially adverse effects on the immune system [5]. It has been noted that even if the exercise level has gradually increased, it may not be at risk of inflammation, but the released hormones due to stress of exercise will induced as annoying factors [9]. ...
Aim: The aim of the present study was to evaluate and compare the effects of short-term and long-term strength training increasingly on neutrophils, lymphocytes and monocytes blood factors in untrained male students Khatam University of Behbahan. Methods: For this purpose, 45 male students between 18-22 years were selected. Subjects were categorized into three groups of 15 subjects randomly. These include a control Group 1, Group 2 with short-term strength training increasingly and Group 3 with long-term strength training increasingly. In order to examine data distribution between groups of Kolmogorov-Smirnov test for equality of variances assumption of intra-group study, Levene's test was used. To investigate the effectiveness of the practice of paired t-test was used. In a comparison test between the selected parameters in one-way analysis of variance was used for independent samples and to analyze and compare three groups of variables, Tukey test was used. The significance level for all tests was p ≥ 0.05 and statistical analysis was performed using SPSS statistical software. Results: The results showed that after a strength training, mean difference of the variable Neutrophil percentage in training groups and control group in post-test was significant p=0.016. Mean difference of the variable lymphocytes percentage in training groups and control group in post-test was not significant p=0.217. Mean difference of the variable monocytes percentage in training groups and control group in post-test was not significant p=0.114. Conclusion: These results suggest that cell-mediated immunity in young boys is influenced by the intensity and duration of exercise.
... From different studies, it is stated that different intensity of physical exercise will have different effects on leukocytes (Neves et al., 2015). Vitamin C supplementation reduces the risk of upper respiratory tract infection in endurance athletes, giving Vitamin C 600 mg for 3 weeks to 90-km ultramarathon athletes has been shown to reduce the incidence of upper respiratory tract infection symptoms (Gleeson & Bishop, 2000). Therefore, this research is important because it provides an in-depth understanding of the provision of vitamin C for the needs of the body. ...
The purpose of study was to determine the effect of vitamin C supplementation on maximum physical activity on the total of leukocytes. Research method used a quasi-field experiment with pre-test design and post-test control group design. The study subjects consisted of four male non-athletes, aged 20-22 years. The number of leukocytes was measured before and after vitamin C supplementation with a dose of 100 mg and 500 mg in maximum activity, namely running to fatigue. Data normality was tested by Kolmogorov Smirnov and paired sample t-test was used to test for differences in the total of leukocytes before and after vitamin C supplementation. The results showed that the average number of respondents' leukocytes increased after maximal physical activity (∆ = 6,775) and after vitamin C supplementation 100 mg (∆ = 1300) and 500 mg (∆ = 550). Paired t-test showed a significant difference (p = 0.019) between the total of leukocytes before and after maximum physical activity. There was no significant difference between the supplementation of vitamin C at a dose of 100 mg (p = 0.09) and a dose of 500 mg (p = 0.95) on the total of leukocytes before and after maximum physical activity. So, it is concluded that maximum physical activity increases the number of leukocytes. However, there was no difference in the number of leukocytes before and after maximum physical activity in the supplementation of 100 mg and 500 mg of vitamin C
... К числу активно применяемых в спортивной практике неспецифических средств, обладающих иммунокоррегирующим действием, необходимо отнести глутамин, вводимый в состав средств специализированного спортивного питания [524]. Достаточный уровень плазменного глютамина является важным фактором для нормальной работы клеток иммунной системы, и он снижается у спортсменов после упражнения на выносливость. ...
В многотомном научном издании впервые на большом объеме собственных результатов и данных литературы впервые проанализирован и обобщен опыт разработки, доклинического изучения, клинических и специальных испытаний и апробаций высококвалифицированными спортсменами различных фармакологических средств поддержки здоровья и работоспособности.
Издание предназначено для специалистов в областях фундаментальной и спортивной медицины, фармакологии, военной медицины и медицины экстремальных состояний, связанных с решением вопросов управления функциональным состоянием человека, работоспособностью,
восстановлением функциональных постстрессорных нарушений здоровья, а также для спортсменов, студентов и аспирантов медицинских, фармацевтических и спортивных вузов.
... A spike in glutamate may be associated with the provision of NADPH via the action of NADP+-dependent malic enzyme, which plays an important role in increasing a reduced glutathione concentration, thus enhancing antioxidant defenses and delaying apoptosis via stabilization of neutrophil mitochondria (Philip Newsholme 2001). Glutamate may also serve as a precursor for glutathione synthesis in macrophages and monocytes and as such may play a direct role in antioxidant defenses in these cells (Gleeson and Bishop 2000). This pathway connects with the urea cycle and ultimately results in the formation of arginine and thus of a substrate for inducible nitric oxide synthase (Murphy and Newsholme 1998). ...
Introduction
Chronic hepatitis B (CHB) affects 257 million individuals worldwide with an annual estimated mortality rate of 880,000 individuals. Accurate diagnosis of the stage of disease is difficult, and there is considerable uncertainty concerning the optimal point in time, when treatment should be started.
Objectives
By analyzing and comparing the metabolomes of patients at different stages of CHB and comparing them to healthy individuals, we want to determine the metabolic signature of disease progression and develop a more accurate metabolome-based method for diagnosis of disease progression ultimately giving a better basis for treatment decisions.
Methods
In this study, we used the combination of transient elastography and serum metabolomics of 307 serum samples from a group of 90 patients with CHB before and under treatment (with a follow-up time up to 10 years) at different progression stages over the clinical phases and 43 healthy controls..
Results
Our data show that the metabolomics approach can successfully discover CHB changing from the immune tolerance to the immune clearance phase and show distinctive metabolomes from different medical treatment stages. Perturbations in ammonia detoxification, glutamine and glutamate metabolism, methionine metabolism, dysregulation of branched-chain amino acids, and the tricarboxylic acid (TCA) cycle are the main factors involved in the progression of the disease. Fluctuations increasing in aspartate, glutamate, glutamine, methionine and 13 other metabolites are fingerprints of progression.
Conclusions
The metabolomics approach may expand the diagnostic armamentarium for patients with CHB. This method can provide a more detailed decision basis for starting medical treatment.
... 55 shortness of time and the absence of strenuous exercise, carbohydrate consumption, lack of loading glutamine has been shown to increase stress hormones such as cortisol affects the immune system. 56 Plasma concentrations of glutamine metabolic demands of different sport suggests that may replace the rest period; deplaz dietary factors can affect the concentration of glutamine. 57 The effect of carbohydrate intake from plasma glutamine concentrations, shows that through the muscle glycogen concentration. ...
... Improvements in the way an individual responds to a stressful situation can be monitored by physiological markers such as cortisol, IGF-1, and epinephrine. When the body is unable to respond to increased levels of stress, amplified by the combination of training stress and various outside stressors with inadequate recovery (i.e., environmental factors, sleep deprivation, diet), various circulating hormone concentrations are affected, and therefore, operational and cognitive performance perpetually deteriorates (Gleeson and Bishop, 2000). However, it is possible to maintain a limited psychosomatic control over stressors in an attempt to mitigate the harmful effects of hormonal dysfunction during times of heightened stress (Davidson et al., 2003;Robinson et al., 2003;Carlson et al., 2004Carlson et al., , 2007Matousek et al., 2010). ...
Mental skills training (MST) has been suggested to reduce stress in civilian and athletic populations, however, whether these techniques and practices transfer to a military population are unknown. Therefore, the purpose of this study was to evaluate two MST programs against a baseline condition, training-as-usual (TAU), during an intense, active-duty, military training environment. Two hundred and three Marines enrolled in the United States Marine Corps’ Basic Reconnaissance Course participated in this effort (n = 203; age = 22.7 ± 3.3 years; height = 178 ± 6.35 cm; weight = 97.7 ± 8.3 kg; Mean ± SD). Each Marine was assigned to one of three groups, Mindfulness-Based Mind Fitness Training (MMFT), General Mental Skills Training (GMST), or TAU. Operational and cognitive performance measures, as well as, physiological metrics were obtained across three training phases (phase 1–3). Furthermore, phase 3 was sub-divided into pre-ambush, ambush and post-ambush time points. Significant group × time interactions were found for the total number of errors committed on the sustained attention response task (p = 0.004); as well as, plasma cortisol (p < 0.0001) and insulin-like growth factor-1 (IGF-1; p < 0.0001). There were mixed results between groups on operational performance tasks with the MST groups tending to perform better than TAU the more time participants had with MST instruction. During ambush, the differences among groups were especially pronounced for measures of information processing that one would expect MST to enhance: coordinates recall, plot time, and plot accuracy (p < 0.001), with improvements ranging from 24.7 to 87.9% for the MST conditions when compared to TAU. These data demonstrate that independent of the specific type of MST program, the fundamental characteristics of stress regulation embedded within each MST program may enhance performance and cognitive function during time of heightened stress.
... Still, protein plus carbohydrate ingestion is insufficient to prevent overtraining Halson et al., 2004;Witard et al., 2011;D'lugos et al., 2016;Svendsen et al., 2016). Other nutritional interventions, such as anti-oxidant intake to protect against exercise-induced oxidative stress, fail to negate overtraining (Gleeson & Bishop, 2000;Meeusen & Watson, 2007). In contrast, consistent anti-oxidant intake may even inhibit beneficial training adaptations (Merry & Ristow, 2016). ...
Key points:
•Overload training is required for sustained performance gain in athletes (functional overreaching). However, excess overload may result in a catabolic state which causes performance decrements for weeks (non-functional overreaching) up to months (overtraining).
•Blood ketone bodies can attenuate training- or fasting-induced catabolic events. Therefore, we investigated whether increasing blood ketone levels by oral ketone ester (KE) intake can protect against endurance training-induced overreaching. •We show for the first time that KE intake following exercise markedly blunts the development of physiological symptoms indicating overreaching, and at the same time significantly enhances endurance exercise performance. •We provide preliminary data to indicate that growth differentiation factor 15 (GDF15) may be a relevant hormonal marker to diagnose the development of overtraining. •Collectively, our data indicate that ketone ester intake is a potent nutritional strategy to prevent the development of non-functional overreaching and to stimulate endurance exercise performance.
Abstract:
It is well known that elevated blood ketones attenuate net muscle protein breakdown, as well as negate catabolic events, during energy deficit. Therefore, we hypothesized that oral ketones can blunt endurance training-induced overreaching. Fit male subjects participated in two daily training sessions (3 weeks, 6 days/week) while receiving either a ketone ester (KE, n = 9) or a control drink (CON, n = 9) following each session. Sustainable training load in week 3 as well as power output in the final 30 min of a 2-h standardized endurance session were 15% higher in KE than in CON (both P < 0.05). KE inhibited the training-induced increase in nocturnal adrenaline (P < 0.01) and noradrenaline (P < 0.01) excretion, as well as blunted the decrease in resting (CON: -6 ± 2 bpm; KE: +2 ± 3 bpm, P < 0.05), submaximal (CON: -15 ± 3 bpm; KE: -7 ± 2 bpm, P < 0.05) and maximal (CON: -17 ± 2 bpm; KE: -10 ± 2 bpm, P < 0.01) heart rate. Energy balance during the training period spontaneously turned negative in CON (-2135 kJ/day), but not in KE (+198 kJ/day). The training consistently increased growth differentiation factor 15 (GDF15), but ∼2-fold more in CON than in KE (P < 0.05). In addition, delta GDF15 correlated with the training-induced drop in maximal heart rate (r = 0.60, P < 0.001) and decrease in osteocalcin (r = 0.61, P < 0.01). Other measurements such as blood ACTH, cortisol, IL-6, leptin, ghrelin and lymphocyte count, and muscle glycogen content did not differentiate KE from CON. In conclusion, KE during strenuous endurance training attenuates the development of overreaching. We also identify GDF15 as a possible marker of overtraining.
... This pathway is linked to the urea cycle and ultimately results in formation of arginine, a substrate for inducible nitric oxide synthase. Glutamate may also serve as a precursor for glutathione synthesis, which may play a direct role in antioxidant defenses [Gleeson & Bishop, 2000]. Hence, based on the intervention effects of L2 on amino acids metabolism, it is pos- Note: s, singlet; d, doublet; t, triplet; q, quartet; m, other multiplet; dd, doublet of doublets. ...
A heteropolysaccharide, named L2, from Lentinula edodes has been proved to possess immunostimulating and anti-ageing activities in previous studies, but its acting mechanism was not completely understood. In this study, ¹H NMR spectroscopy approach was employed to investigate the metabolic profiles of the urine from adult mice after L2 intervention. Using principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA), 22 potential biomarkers were found to be mainly involved in some metabolic pathways: amino acid metabolism, energy metabolism, lipid metabolism, tricarboxylic acid (TCA) cycle, urea cycle and gut microbiota metabolism. Among them, the significantly altered metabolites include: elevated glutamate (75%) and creatine (64%); decreased proline (65%), betaine (58%), fucose (63%) and dimethylamine (59%). In conclusion, the present data is helpful to understand the mechanisms related to previously confirmed immunomodulation and anti-aging effects of L2, and provide valuable information for mining new functions of L2.
... This increases lipid Öznur AKYÜZ, Ph.D., associate professor, Department of Sports Health, School of Physical Education and Sports, Celal Bayar University. (Gleeson & Bishop, 2000). Formation of reactive oxygen species (ROS) and many defense mechanisms got advanced in the body to prevent damage caused by them. ...
... This increases lipid Öznur AKYÜZ, Ph.D., associate professor, Department of Sports Health, School of Physical Education and Sports, Celal Bayar University. (Gleeson & Bishop, 2000). Formation of reactive oxygen species (ROS) and many defense mechanisms got advanced in the body to prevent damage caused by them. ...
In the last 80 years, Portugal has suffered profound political, demographic, social, and economic changes, from a dictatorial regime to a democratic system, from a young population society to an ageing population society, and from a rural economy to a service economy. In terms of education, it has progressed from an education for the elites, with a compulsory education period of about three years, to an education for everyone and for a longer period, in which the compulsory education extended to 12 years. The educational resources planning has not always been well adjusted to the conceptual and legislative framework and to the demographic and socioeconomic needs, but the recent community funding (2007-2013) has created the conditions to give a fresh impetus to the planning of infrastructures and to rethink their assumptions, and Portugal now has schools which are more well adapted to the characteristics of modern Portuguese society. This research project seeks to understand the current state of education in Portugal through the analysis of its main tendencies in recent decades, illustrating the relation between the purpose of education, political decisions and social dynamics, and the educational resources planning through the evolution of the school network over this period. This research paper is based upon a thorough diachronic documentary research, focusing on case studies of high and low density territories in central Portugal, which leads to the gathering of evidence that, despite the national guidelines, the country has not progressed at a uniform rate and that there is a strong interference of the different territorial dynamics in the choices made and in the results achieved.
... The later comment about spiny plants that have just emerged from the ground suggests that Galen [22] was aware of the importance of what we now know to be micro-nutrients, although he would have been totally unaware of the existence of such compounds, just of their apparent effect, perhaps through studies involving their absence from a balanced diet. This in turn raises the aspect of micro-nutrients, and the connection between a well-balanced diet and the immune system, which has been shown to be of considerable importance in terms of athletic performance [56]. ...
With the preparations for the Olympics 2016 in Rio came a series of demands to the sports world in terms of attaining optimal physical performance for the many disciplines represented at today’s Olympics. In the light of this, we have focused on the dietary and physiological requirements of a modern Olympic athlete and contrast these with those of ancient Greek and Roman athletes. Our particular emphasis has been on the source of nutrients, historical dietary trends, and the search for the optimal sports diet, that is to say a diet that will ensure the attainment of an athlete’s full potential. In reality, nothing has changed between the ancient and modern athletes. To be optimal, a sports diet should be nutritionally balanced, whilst accommodating the genetic and environmental requirements, the gender and age needs, the demands of the sports discipline, as well as addressing any cultural dietary restrictions.
... Immune cytokines such as IL-6 have very high metabolic rates [5], and therefore fuel availability before, during and after exercise is of greater concern for athletes. Others [21] have found that compared to high-CHO diets, low-CHO diets significantly impaired immune response (e.g., higher cortisol release, neutrophilia, leucocytosis, neutrophil:lymphocyte ratio, and IL-6; and lower plasma glutamine) following 1-h of cycle ergometer exercise performed at 70% of their individual VO 2 max. A very low-CHO diet implies a very high-fat dietary content, which has been shown detrimental to immune function. ...
Abstract: The aim of the study was to alter the underlying initial energy status of athletes and to compare markers of intestinal permeability, hepatic structure, immune function, gastrointestinal symptoms, and physical performance during and after high-intensity and long-duration aerobic exercise. In a crossover design, 11 males (36.6 ± 4.9 yrs., 1.7 ± 0.1 m, 74.5 ± 7.7 kg, 17.2 ± 6.6% body fat, VO2max 57.4 ± 7.4 ml·kg-1·min-1) underwent two individual isoenergetic diets designed to either deplete (carbohydrates [CHO] = 21.27%, fat = 67.64%, protein = 11.36%) or maintain (CHO = 63.46%, fat = 25.36%, protein = 11.18%) their hepatic and muscular glycogen content. These diets and accompanying exercise sessions were performed by each participant in the days before completing a duathlon (5-km run, 30-km cycling, 10-km run). Blood samples were obtained before, immediately and 1- and 2-h following the duathlon for determination of insulin (IN), glucagon (GL), glucose, lipopolysaccharide binding protein (LBP), interleukin-6 (IL-6), aspartic aminotransferase (AST), and alanine aminotransferase (ALT) markers. Oxygen consumption (VO2), ratings of perceived exertion (RPE), respiratory exchange ratio (RER), body core temperature, and fat and CHO oxidation rates were recorded for each participant. Gastrointestinal symptoms were assessed by survey before and after exercise. A change in metabolic state as demonstrated by the IN/GL ratio (Low-CHO diet = .28 ± .10 vs. High-CHO diet = .38 ± .21; p < .05) was obtained. Performance did not differ between trials. Regardless of the diet, the AST/ALT ratio following exercise and in the recovery phase indicated hepatocyte parenchyma structural damage. No significant correlations between AST, ALT, and performance were found in either the low or the high CHO diets trials. A combined effect between dietary regimen and measurement time (p = .004) was observed for glucose concentration. Blood glucose concentration was higher immediately following duathlon in the HC diet trial (5.52 ± 1.25 mmol/l) than in the HF diet trial (4.15 ± .88 mmol/l), and remained higher 1- and 2-h following duathlon. One-hour following duathlon the blood glucose levels in the HF diet were lower (hypoglycemia) than normal (3.9 – 6.1 mmol/l; p < .05). Exercise caused an increase in IL-6 in both dietary conditions (p �< 0.05). Regardless of the dietary trial, exercise allowed a higher bacterial translocation from rest to exercise (p < � 0.05); however, no significant correlations between endotoxin levels, body core temperature and gastrointestinal symptoms were found. In conclusion, duathlon performance was not altered by modest changes in dietary CHO or fat composition. Increased markers of endotoxemia and immune function observed with the high-intensity exercise were unrelated to hepatic function and/or gastrointestinal complaints before and after exercise.
Resumen: El propósito del estudio fue alterar el estado metabólico inicial de atletas y comparar los marcadores de permeabilidad intestinal, estructura hepática, respuesta inmunológica, síntomas gastrointestinales y el rendimiento físico durante y después de un ejercicio aeróbico de alta intensidad y larga duración. Se utilizó un diseño cruzado aleatorio en el que 11 hombres (36.6 ± 4.9 años, 1.7 ± 0.1 m, 74.5 ± 7.7 kg, 17.2 ± 6.6% grasa corporal, VO2máx 57.4 ± 7.4 ml·kg-1·min-1) consumieron en distintas ocasiones dos dietas isoenergéticas, las cuales estaban diseñadas para reducir (carbohidratos [CHO] = 21.27%, grasas = 67.64%, proteínas = 11.36%) o para mantener (CHO = 63.46%, grasas = 25.36%, proteínas = 11.18%) el contenido de glucógeno hepático y muscular. Estas dietas, junto con sesiones de entrenamiento físico, fueron completadas por cada participante en los días previos a la realización de un duatlón (5 km carrera, 30 km ciclismo, 10 km carrera). Se obtuvieron muestras de sangre antes, durante, inmediatamente finalizado el duatlón y una y dos horas después de la finalización del mismo para el análisis de insulina (IN), glucagon (GL), glucosa y los marcadores proteína reconocedora de lipopolisacáridos (LBP), interleucina 6 (IL-6), aspartato aminotransferasa (AST), y alanina aminotransferasa (ALT). A cada participante se le midió el consumo de oxígeno (VO2), la valoración del esfuerzo percibido (VEP), la tasa de intercambio respiratorio (RER), la temperatura central, y las tasas de oxidación de CHO y grasas. Los síntomas gastrointestinales fueron determinados por medio de una encuesta. Se encontró un cambio en el estado metabólico inicial interpretado por la relación IN/GL (dieta baja CHO = .28 ± .10 vs. dieta alta CHO = .38 ± .21; p < .05). El rendimiento no fue diferente entre los dos tratamientos experimentales. Independientemente de la dieta, la relación AST/ALT posterior al ejercicio y en la fase de recuperación indicó un daño estructural en la parénquima del hepatocito. No se encontraron correlaciones significativas entre AST, ALT y el rendimiento físico cuando los atletas consumieron la dieta alta o baja en CHO. Para la glucosa sanguínea, se encontró una interacción entre el régimen dietético y el tiempo de medición (p = .004), por medio del cual la concentración de glucosa sanguínea fue mayor inmediatamente después de finalizado el duatlón cuando los atletas consumieron una dieta alta en CHO (5.52 ± 1.25 mmol/l) en comparación a cuando consumieron una dieta alta en grasas (4.15 ± .88 mmol/l). Estas diferencias se mantuvieron hasta las dos horas posteriores a la finalización del duatlón e incluso una hora después del mismo los niveles de glucosa en la condición de dieta alta en grasa fueron menores (hipoglicemia) a los valores normales (3.9 – 6.1 mmol/l; p < .05). El ejercicio causó un aumento significativo en la concentración de IL-6 en ambas condiciones de dietas experimentales (p <� 0.05). Sin importar el tipo de dieta, se encontró una mayor translocación bacteriana de la condición de reposo a la de ejercicio (p �< 0.05); sin embargo, no se encontraron correlaciones significativas entre los niveles de endotoxinas, la temperatura central y los síntomas o molestias gastrointestinales. Se concluye que el rendimiento en el duatlón no fue alterado por cambios modestos en la composición de CHO o grasas en la dieta. Aunque se observó un aumento significativo en los marcadores de endotoxemia y la respuesta inmune cuando los atletas ejecutaron el ejercicio a una alta intensidad, éstos no se relacionaron con marcadores de estructura hepática o síntomas de molestias gastrointestinales.
... The importance of adequate carbohydrate (CHO) to support the high training loads of elite athletes is well known (Graham and Adamo 1999;Jacobs and Sherman 1999); however, CHO availability may also be an important factor in maintaining immunocompetence. Low CHO diets are associated with higher plasma cortisol levels both during resting conditions (Anderson, Rosner, Khan, et al. 1987) and exercise (Gleeson and Bishop 2000a;Mitchell, Pizza, Paquet, et al. 1998), which in turn exerts a negative impact on immune function (Brenner, Shek, Zamecnik, et al. 1998). High plasma cortisol concentrations are associated with an inability to maintain blood glucose homeostasis during prolonged exercise (Felig, Cherif, Minagawa, et al. 1982). ...
Light to moderate exercise has been associated with an increase in immune function and reduced risk of infectious diseases. Conversely, heavy exercise has been implicated in suppression of many immune parameters and a concomitant increased risk of infectious diseases. Infections can result in lost training time and negatively affect the performance of the elite athlete. Exercising during an infection can also increase the risk of secondary complications, such as viral myocarditis and post-viral fatigue syndrome. In addition to immunosuppression, other factors responsible for increased infection rates among athletes are close bodily contact with other people during training and competition, and environmental factors during the pursuit of sporting activities that increase exposure to pathogens. Although there is a generally higher risk of infection among athletes compared to the general population, some sports are associated with a particularly high risk for certain infections. These are skin infections in rugby and wrestling, infections of the foot in long-distance runners, and ear infections in those involved in water sports. Upper respiratory tract infections are the most frequently reported disability among all athletes and are the cause of more lost training days than all other infections put together. Transmission of blood-borne pathogens, although very uncommon in the athletic setting, are the cause of the most serious infections an athlete may develop. When considering the negative impact of infections on performance, it seems prudent that athletes use interventions to decrease the immunosuppressive effects of heavy exercise, and to minimize exposure to pathogens as far as practically possible. Management of the infected athlete is especially important if there is to be a speedy return tofull training, and if the incidence of a relapse or secondary complications are to be minimized.
... The increase in CD8+ lymphocytes found presently in the exercised group was accompanied by a rise in the level of leptin. Although this apparent association did not reach the level of significance (possibly due to the sample size), we consider that leptin contributed to the changes observed in these lymphocytes, although other factors related to exercise may also have played a role, such as the mobilization of lymphocytes to the blood stream [25,95] Additionally, the consumption of carbohydrates during exercise generally has a positive influence on the immune response [96]. This could explain the greater percentage of CD8+ cells observed presently with the carbohydrate-rich diet in exercised animals, although we did not find any reports on a possible relation between this diet and CD8+ lymphocytes. ...
Although diet and exercise clearly have an influence on immune function, studies are scarce on the effect caused by exercise and the consumption of a carbohydrate-rich or fat-rich diet on the peripheral immune system. The aim of the present study was to evaluate the effect of exercise and the two aforementioned unbalanced diets on young Balb/c mice, especially in relation to BMI, the level of glucose, and the percentage of lymphocyte subpopulations in peripheral blood. The changes found were then related to the synthesis of leptin and adiponectin as well as the production of oxidative stress. The increase in BMI found with the carbohydrate-rich and fat-rich diets showed correlation with the levels of leptin and adiponectin. An increase in leptin and a decrease in adiponectin directly correlated with an increase in total lymphocytes and CD4+ cells and with a decrease in B cells. The increase in leptin also correlated with an increase in CD8+ cells. Glycemia and oxidative stress increased with the two unbalanced diets, negatively affecting the proliferation of total lymphocytes and the percentage of B cells, apparently by causing alterations in proteins through carbonylation. These alterations caused by an unbalanced diet were not modified by moderate exercise.
... Outros estudos reforçam a idéia de que a imunossupressão observada em atletas submetidos a treinos extenuantes está relacionada à elevação na concentração de cortisol (35,36) . Também já existem fortes evidências de que o consumo de carboidrato durante o exercício pode atenuar a elevação do cortisol, e a conseqüente imunossupressão (6,(35)(36)(37) . Estas evidências científicas demonstram a importância da modulação neuroendócrina sobre o sistema imunológico durante o exercício extenuante. ...
El objetivo del presente estudio fue el de evaluar la conducta de algunas variables fisiológicas durante una sesión de entrenamiento de nado sincronizado cumplido en la fase de la preparación para los Juegos Olímpicos de Atenas 2004. MATERIALES Y MÉTODOS: La muestra usada se constituyó por el dueto (24 ± 0 años) representante de Brasil en Atenas 2004. La colección de datos fue cumplida durante una sesión de entrenamiento con una duración de 198 minutos. Los entrenamientos empezaron con la parte física, mientras era seguida por la parte técnica. Para la determinación de la glicemia y de la concentración de b-hidroxibutirato el experimentador usó Optium® con las cintas respectivas. Las concentraciones del cortisol y de las enzimas lactico deshidrogenasa (LDH) y creatinquinase (CK) fueron medidas por el radio-imuno-ensayo (DPC©) con equipos comerciales (CELM®), respectivamente. La asistencia de la frecuencia del corazón (FC) fue cumplida con elfrecuencímetro Polar®. RESULTADOS: La reducción fue observada (~2%) en el peso corporal. La glicemia también presentó una caída (~30%) comparada con el valor obtenido al principio del entrenamiento. En contra de la salida, se observó una elevación en la concentración del cortisol (en saliva 22% y plasmático 29%) y del b-hidroxibutirato (~340%). No se observó una alteración significante en la concentración plasmática de CK y de LDH. El control de la de FC demostró a los 198 minutos de la sesión de entrenamiento, que 36,5 ± 0,7 minutos eran cumplidos en una intensidad ligera; 103,5 ± 0,7 minutos en una intensidad moderada, 54,0 ± 2,1 minutos en la intensidad alta y 4,0 ± 0,0 minutos en una intensidad muy alta. CONCLUSIONES: La pérdida de peso indica que el remplazo hidrico no se adaptó. La reducción en el glicemia y el aumento en la concentración de los cuerpos cetónicos y de cortisol ellos refuerzan la importancia del suplementación de hidratos de carbono durante el entrenamiento de larga duración. La conducta de FC demuestra que la sesión de entrenamiento fué cumplida en una intensidad moderada, sin embargo en los momentos breves de intensidad alta, mientras, las rutinas eran cumplidas.
... Prolonged, strenuous exercise has been associated with a temporal depression of host defence, increasing susceptibility to opportunistic infections [1,2]. Almost certainly, this immunosuppression is multifactorial in origin [3,4]. Reductions in salivary immunoglobulin A secretion [5][6][7], natural killer cell activity [8], lymphocyte proliferative response [5,9], and impaired neutrophil phagocytic function [10] following prolonged exercise have been suggested as some of the possible mechanisms and likely explain, at least in part, why elite endurance athletes appear particularly prone to upper respiratory tract infections [11]. ...
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 euhydrated or moderately hypohydrated (induced by fluid restriction for 24 h). Blood samples were collected before and after exercise and following 2 h recovery for determination of cell counts, plasma cortisol, and in vitro antigen-stimulated cytokine production by whole blood culture. Fluid restriction resulted in mean body mass loss of 1.3% and 3.9% before and after exercise, respectively. Exercise elicited a significant leukocytosis and elevated plasma cortisol, with no differences between trials. IL-6 production was significantly reduced 2 h postexercise (), while IL-10 production was elevated postexercise (). IFN-γ and IL-2 production tended to decrease postexercise. No significant effect of hydration status was observed for the measured variables. Prolonged exercise appears to result in augmented anti-inflammatory cytokine release in response to antigen challenge, possibly coupled with acute suppression of proinflammatory cytokine production, corresponding with studies using mitogen or endotoxin as stimulant. Moderate hypohydration does not appear to influence these changes.
... Immune cytokines such as IL-6 have very high metabolic rates [5], and therefore fuel availability before, during and after exercise is of greater concern for athletes. Others [21] have found that compared to high-CHO diets, low-CHO diets significantly impaired immune response (e.g., higher cortisol release, neutrophilia, leucocytosis, neutrophil:lymphocyte ratio, and IL-6; and lower plasma glutamine) following 1-h of cycle ergometer exercise performed at 70% of their individual VO 2 max. A very low-CHO diet implies a very high-fat dietary content, which has been shown detrimental to immune function. ...
The purpose of the study was to compare the acute hepatic response to diet modification and exercise-induced endotoxemia, and to determine if associations exist between liver damage markers, body core temperature, and IL-6 responses to a laboratory-based duathlon. Eleven moderately-trained healthy males followed a low-carbohydrate (CHO) and a high CHO diet to change their glycogen stores two-days before completing a duathlon. Blood samples were obtained at rest, immediately after and 1- and 2-h following the duathlon for determination of endotoxin-lipopolysaccharide binding protein (LPS-LBP) complex, IL-6, and liver integrity markers AST, ALT, and AST/ALT ratio. Hydration status and body core temperature were assessed at rest, during, and after the duathlon. Athletes were more dehydrated and had higher AST/ALT ratios in the low- compared to the high-CHO diet trial regardless of the measurement time (p<0.05). IL-6 increased from resting to immediately after, 1- and 2-h following duathlon regardless of the diet (p<0.05). A higher LPS-LBP complex concentration was observed from rest to immediately after the duathlon. No significant correlations were found between LPS-LBP complex levels and body core temperature. In conclusion, athletes on a low-CHO diet showed higher hepatic structural damage and finished more dehydrated compared to athletes on a high-CHO diet. Body core temperature and LPS-LBP complex levels were unrelated beyond the increase in body core temperature explained by exercise. No significant associations were found between body core temperature, IL-6 and LPS-LBP complex concentrations.
... Carbohydrate depletion has been implicated in immune suppression and susceptibility to tuberculosis, gastrointestinal infections in children and respiratory infections in athletes. [27][28][29] There are also many chronic inflammatory diseases of humans for which a single precipitating pathogen has not been identified and for which the predisposing factors are likely to be pre-requisites for the development of clinical disease. These include such syndromes as inflammatory bowel disease, cardiovascular disease, 'post-viral' encephalitis/myocarditis and autoimmune conditions. ...
This study investigated the hypothesis that dietary deficiency of readily available carbohydrate (raCHO) modifies the immune response of lambs to the gastrointestinal nematode Trichostrongylus colubriformis. Sixty helminthologically naive Merino lambs were fed throughout the experiment diets containing three levels of raCHO that provided adequate, moderate or low intakes according to recommended standards and were given primary or both primary and secondary infections of T. colubriformis. A further 20 uninfected lambs received the low diet for 9 weeks, after which they were returned to the standard diet. Immune status was assessed by the measurement of plasma and jejunal antibody concentrations and blood and jejunal cell numbers and function. Diets low in carbohydrate resulted in a failure of the lambs to gain weight and decreases in plasma glucose concentration, blood lymphocytes expressing CD8 or Tcrgammadelta, monocytes, eosinophils, platelets and red blood cells, jejunal and plasma antibody concentrations, lymphocyte proliferation to worm antigen and numbers of jejunal CD8(+) and Tcrdeltagamma(+) lymphocytes, eosinophils and CD1b(+) dendritic cells. Thus, a low dietary concentration of raCHOs impaired the constitutive availability of lymphocytes and antigen-presenting cells, and the cellular and humoral immunological responses. A hypothesis is suggested for the mechanism and for the possible wider implications.
... Ingibjörg Jonsdottir highlights the important interactions of neuropeptides, particularly opioids, in modulation of immune functions to exercise. 17 An overview of the effect of nutrition on the immune responses to exercise, by Michael Gleeson and Nicolette Bishop, outlines the requirements for optimum performance in competitive athletes and the dangers of inappropriate oversupplementation. 18 The data on whether competitive athletes have an increased incidence of infections compared with the general community has been inconclusive. However, it is generally agreed that the period of vulnerability for elite athletes coincides with the intense training undertaken immediately prior to or during a competition and may not follow the normal seasonal patterns observed in the general community. ...
The review articles in this special feature reflect the current status of knowledge in the field of exercise immunology, with a focus on how exercise affects the human immune system and the health implications for resistance to infections and neoplastic diseases. In an Olympic year, the emphasis of exercise immunology research tends to be on elite athletes and the prevention of infections in the quest for optimum performance. However, research presented in this issue also covers recreational athletes, as well as highlighting the benefits of exercise for our ageing population.
In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~ 60% of energy intake, 5–8 g·kg− 1·d− 1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~ 1.6 g·kg− 1·d− 1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g.kg− 1·d− 1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150–400 Kcal·h− 1 (carbohydrate, 30–50 g·h− 1; protein, 5–10 g·h− 1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450–750 mL·h− 1 (~ 150–250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., > 575 mg·L− 1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.
Rapidly dividing and proliferating cells required high rates of glutaminolysis. It is not only for energy but also for the precursor of many biosynthetic pathways used for macromolecule synthesis. In response to antigenic challenge, lymphocytes also utilize glutamine at high rate for rapid multiplication and proliferation. Skeletal muscle play the major role in glutamine homeostasis as it is the major site of glutamine synthesis to maintain the plasma glutamine concentration. Mononuclear cells cannot synthesize glutamine due to absence of its intracellular glutamine synthase but they possess a high-intracellular activity of glutaminase. So, lymphocytes must be supplied with glutamine from the plasma to accomplish its metabolic requirements. Heavy exercise decreases plasma glutamine concentration that may causes immune depression due to reduced supply of glutamine to lymphocytes. However, glutamine supplement was unable to abolish the exercise induced decline in salivary IgA. Though glutamine supplementation decreases the number of upper respiratory tract infection (URTI) in athletes. Glutamine supplementation abolished exercise induced decrease in plasma glutamine but not exercise-induced impaired lymphocyte functions
(PDF) EFFECT OF EXERCISE INDUCED GLUTAMINE ON IMMUNE FUNCTION.. Available from: https://www.researchgate.net/publication/327959383_EFFECT_OF_EXERCISE_INDUCED_GLUTAMINE_ON_IMMUNE_FUNCTION [accessed Feb 07 2021].
Fatigue, mood disturbances, under performance and gastrointestinal distress are common among athletes during training and competition. The psychosocial and physical demands during intense exercise can initiate a stress response activating the sympathetic-adrenomedullary and hypothalamus-pituitary-adrenal (HPA) axes, resulting in the release of stress and catabolic hormones, inflammatory cytokines and microbial molecules. The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including metabolism, endocrine, neuronal and immune function. The gut microbiome and its influence on host behavior, intestinal barrier and immune function are believed to be a critical aspect of the brain-gut axis. Recent evidence in murine models shows that there is a high correlation between physical and emotional stress during exercise and changes in gastrointestinal microbiota composition. For instance, induced exercise-stress decreased cecal levels of Turicibacter spp and increased Ruminococcus gnavus, which have well defined roles in intestinal mucus degradation and immune function.
Diet is known to dramatically modulate the composition of the gut microbiota. Due to the considerable complexity of stress responses in elite athletes (from leaky gut to increased catabolism and depression), defining standard diet regimes is difficult. However, some preliminary experimental data obtained from studies using probiotics and prebiotics studies show some interesting results, indicating that the microbiota acts like an endocrine organ (e.g. secreting serotonin, dopamine or other neurotransmitters) and may control the HPA axis in athletes. What is troubling is that dietary recommendations for elite athletes are primarily based on a low consumption of plant polysaccharides, which is associated with reduced microbiota diversity and functionality (e.g. less synthesis of byproducts such as short chain fatty acids and neurotransmitters). As more elite athletes suffer from psychological and gastrointestinal conditions that can be linked to the gut, targeting the microbiota therapeutically may need to be incorporated in athletes’ diets that take into consideration dietary fiber as well as microbial taxa not currently present in athlete’s gut.
The purpose of this study was to investigate the effect of ingestion of fluids with different carbohydrate concentrations (0, 1.5, and 7%) on the acute immune stress responses after high-intensity long-distance running. Continuous 18- to 20-km run was performed at 75% of maximal oxygen uptake with carbohydrate supplementation (CHO7%, 7% carbohydrate solution) and low-carbohydrate supplementation (low- CHO1.5%, 1.5% carbohydrate solution) in a randomized, double-blind, placebo (PLA) controlled design. Seven recreational runners (4 men and 3 women) completed all 3 trials. Blood was collected at baseline (PRE) and immediately after the run (POST). The running task induced significant (p # 0.05) increases in leukocyte (white blood cells), neutrophil, and interleukin-6 (IL-6) counts in every trial. There was a significant (p # 0.05) increase in cortisol with PLA and low- CHO1.5% but not with CHO7%. Increase in total leukocyte and neutrophil concentration was significantly lower with CHO7% compared with PLA (p ≤ 0.05). Postexercise IL-6 levels were significantly elevated when compared with baseline in all conditions (p ≤ 0.05). Interleukin-6 (IL-6) concentrations did not differ significantly between trials. LowCHO1.5% sport drink did not significantly differ from PLA in measured variables, which indicated that the amount and rate of carbohydrate ingestion (15 g, 10 g·h-1) in low-carbohydrate sport drink was not enough to significantly protect from the stress induced by high-intensity long-distance running, whereas the ingestion of CHO7% (45 g·h-1) blunted the significant cortisol response and significantly decreased the leukocyte response.
The following points summarize the text: - Too little body fat results in deterioration of health and performance and can be associated with eating disorders. The nutritional strategy to promote fat-free muscle gain in a short time is not the most suitable since 60-70% of the weight gained is fat.- To intake enough calories will help the athletes in their performance, metabolic basal rate, health, body composition and final aesthetic body.- In terms of carbohydrate and protein needs, athletes need to consume 5-10 g/kg of carbohydrates and 1-2 g/kg of proteins per day (the combination of whey and casein protein is one of the best options), in order to guarantee the recovery. These quantities will depend on the volume and frequency training protocol. In relation to fat intake, it has been recommended to consume at least 0.5-lg/kg per day and under isocaloric proportions distributed among saturated, monounsa-turated, and polyunsaturated fat (avoiding trans fats). - For the gastric emptying and the intestinal absorption, the most important characteristic of a fluid replacement beverage during a sport session, is the carbohydrates and not the electrolytes concentration. A solution containing 5-7% carbohydrate might be considered optimal and the sucrose (saccharose or table sugar) would be a good option.
Failure in antimicrobial activity contributes to high morbidity and mortality in the geriatric population. Little is known about the potential effect of resistance training (RT) on the functional properties of the innate immunity. This study aimed to investigate the influence of long-term RT on the endocytic and oxidative activities of neutrophils and monocytes in healthy older women. Our results indicate that the phagocytosis index (PhI) of neutrophils (but not of monocytes) in the RT-adapted group was significantly higher (í µí± < 0.001; effect size, (í µí±) = 0.90, 95% CI: [0.75–1.04]) compared to that in sedentary subjects. In contrast, the oxidative activity of either neutrophils or monocytes was not significantly influenced by RT. Also, total energy and carbohydrate intake as well as serum IL6 levels had a significant influence on the phagocytic activity of neutrophils (í µí± = 0.04), being considered in the model. Multivariate regression identified the physical condition of the subject (í µí»½ = 0.425; í µí± = 0.01) as a significant predictor of PhI. In conclusion, circulating neutrophils of older women adapted to a long-term RT program expressed higher phagocytic activity.
Sports drinks are developed on the basis of scientific research; aiming at adapting to the change of organism functions. The reasonable nutrient composition of sports drinks can improve functional status. Sports nutrition supplements are more and more accepted by the public in alleviating fatigue and enhancing athletic performance with appropriate usage. Varied sports supplements are developed to meet various requirements. This study reviewed recent advances in the effects of major sports supplements on athletic performance. The powerful means outside of sports training which is used after competitive sports is concerned by training sector all the time. The means of nutritional supplements plays a very important role in improving athletic ability.
The modern data of immunophysiology and immunopathology in sport’s
basis are represented in this edition. There is information about hemopoiesis and
immunogenesis as a standard and after heavy sport surcharges. The principles of
prophylaxis and compensation of sportsmen’s immunity disorders are expounded.
There are prescription of compensative immunotherapy approaches.
This edition is made for sport doctors, rehabilitologists, immunologists and
generalists. Of course, this book will be useful for scientists, students of sport,
biology and medical institutes.
The review articles in this special feature reflect the current status of knowledge in the field of exercise immunology, with a focus on how exercise affects the human immune system and the health implications for resistance to infections and neoplastic diseases. In an Olympic year, the emphasis of exercise immunology research tends to be on elite athletes and the prevention of infections in the quest for optimum performance. However, research presented in this issue also covers recreational athletes, as well as highlighting the benefits of exercise for our ageing population.
INTRODUÇÃO: O triatlo Ironman se caracteriza por ser uma atividade de longa duração em que alterações orgânicas agudas estão presentes. OBJETIVO: verificar a ocorrência de dano muscular e sua relação com o perfil imunológico em triatletas do Ironman – Brasil. MÉTODOS: A amostra de sangue foi obtida de 21 atletas em três momentos: dois dias antes da prova (pré), imediatamente após a prova (pós) e seis dias após a prova (seis dias pós), em que foram analisadas de forma isolada as variáveis creatinoquinase (CK), os leucócitos totais, linfócitos, subtipos de linfócitos CD4+ e CD8+, e relação CD4+/CD8+ e a correlação da CK como marcador de dano muscular, com as demais variáveis. RESULTADOS: As diferenças significativas foram observadas nos leucócitos pré (média: 6.242,9 mm3; DP: 1.233,3) e pós (média: 18.398,1 mm3; DP: 3.904,0; p < 0,0001); pós (média: 18.398,1 mm3; DP: 3.904,0) e seis dias pós (média: 6.396,4 mm3; DP: 1.299,8; p < 0,0001); CK pré (média: 173,2 U/l; DP: 103,7) e pós (média: 2.339,4 U/l; DP: 1.729,0; p < 0,0001), CK pré (média: 173,2 U/l; DP: 103,7) e seis dias pós (média: 368,1 U/l; DP: 274,4; p < 0,0053); CK pós (média: 2.339,4 U/l; DP: 1.729,0) e seis dias pós (média: 368,1 U/l; DP: 274,4; p < 0,0003); CD4+/CD8+ pré (média: 1,9; DP: 0,8) e seis dias pós (média: 2,4; DP: 1,1: p < 0,00032). CONCLUSÃO: Houve dano muscular no período pós-prova imediato e melhora do perfil imunológico após o sexto dia.
Neuromuscular electrical stimulation (NMES) of the lower limbs is an emerging training strategy in patients with COPD. The efficacy of this technique is related to the intensity of the stimulation that is applied during the training sessions. However, little is known about tolerance to stimulation current intensity and physiological factors that could determine it. Our goal was to find potential physiological predictors of the tolerance to increasing NMES stimulation intensity in patients with mild to severe COPD.
20 patients with COPD (FEV1 = 54±14% pred.) completed 2 supervised NMES sessions followed by 5 self-directed sessions at home and one final supervised session. NMES was applied simultaneously to both quadriceps for 45 minutes, at a stimulation frequency of 50 Hz. Spirometry, body composition, muscle function and aerobic capacity were assessed at baseline. Cardiorespiratory responses, leg discomfort, muscle fatigue and markers of systemic inflammation were assessed during or after the last NMES session. Tolerance to NMES was quantified as the increase in current intensity from the initial to the final NMES session (ΔInt).
Mean ΔInt was 12±10 mA. FEV1, fat-free-mass, quadriceps strength, aerobic capacity and leg discomfort during the last NMES session positively correlated with ΔInt (r = 0.42 to 0.64, all p≤0.06) while post/pre NMES IL-6 ratio negatively correlated with ΔInt (r = -0.57, p = 0.001). FEV1, leg discomfort during last NMES session and post/pre IL-6 ratio to NMES were independent factors of variance in ΔInt (r2 = 0.72, p = 0.001).
Lower tolerance to NMES was associated with increasing airflow obstruction, low tolerance to leg discomfort during NMES and the magnitude of the IL-6 response after NMES.
ClinicalTrials.gov NCT00809120.
The purpose of this study was to investigate the effect of ingestion of fluids with different carbohydrate concentrations (0 %, 1.5 % and 7 %) on the acute immune stress responses after high-intensity long-distance running. Continuous 18-20 kilometers run was performed at 75% of maximal oxygen uptake with carbohydrate supplementation (CHO7%, 7% carbohydrate solution) and low-carbohydrate supplementation (lowCHO1.5%, 1.5% carbohydrate solution) in a randomized, double-blind, placebo (PLA) controlled design. Seven recreational runners (four males and three females) completed all three trials. Blood was collected at baseline (PRE) and immediately after the run (POST). The running task induced significant (p<0.05) increases in leukocyte (WBC), neutrophil and interleukin-6 (IL-6) counts in every trial. There was a significant (p<0.05) increase in cortisol with PLA and lowCHO1.5% but not with CHO7%. Increase in total leukocyte and neutrophil concentration was significantly lower with CHO7% compared to PLA (p<0.05). Post-exercise IL-6 levels were significantly elevated when compared to baseline in all conditions (p<0.05). IL-6 concentrations did not differ significantly between trials. LowCHO1.5% sport drink did not significantly differ from PLA in measured variables, which indicated that the amount and rate of carbohydrate ingestion (15 g, 10 g [BULLET OPERATOR] h) in low carbohydrate sport drink was not enough to significantly protect from the stress induced by high-intensity long-distance running whereas, the ingestion of CHO7% (45 g [BULLET OPERATOR] h) blunted the significant cortisol response and significantly decreased the leukocyte response.
GROUPS OF AMINO ACIDS, AS WELL AS INDIVIDUAL AMINO ACIDS, HAVE BEEN STUDIED FOR THEIR ROLES IN PROTEIN BALANCE, HORMONE SECRETION, IMMUNE FUNCTION, OR CAPACITY TO BE CONVERTED TO VARIOUS ANABOLIC OR ANTICATABOLIC METABOLITES. SPECIFIC AMINO ACIDS WITH EXTENSIVE ANALYSIS INCLUDE THE ESSENTIAL AMINO ACIDS, BRANCHED CHAIN AMINO ACIDS, ARGININE, TAURINE, GLUTAMINE, β-ALANINE, AND THE LEUCINE METABOLITE, β-HYDROXY-β-METHYLBUTYRATE. THE PURPOSE OF THIS ARTICLE IS TO ANALYZE THE POSSIBLE ROLES AND PRACTICAL APPLICATIONS OF THESE AMINO ACIDS IN THE REGULATION OF BODY COMPOSITION AND PERFORMANCE IN ANAEROBIC AND AEROBIC SPORTS.
Butyrate delivery to the large bowel may positively modulate commensal microbiota and enhance immunity.
To determine the effects of increasing large bowel butyrate concentration through ingestion of butyrylated high amylose maize starch (HAMSB) on faecal biochemistry and microbiota, and markers of immunity in healthy active individuals.
Male and female volunteers were assigned randomly to consume either two doses of 20 g HAMSB (n = 23; age 37.9 +/- 7.8 y; mean +/- SD) or a low amylose maize starch (LAMS) (n = 18; age 36.9 = 9.5 y) twice daily for 28 days. Samples were collected on days 0, 10 and 28 for assessment of faecal bacterial groups, faecal biochemistry, serum cytokines and salivary antimicrobial proteins.
HAMSB led to relative increases in faecal free (45%; 12-86%; mean; 90% confidence interval; P = 0.02), bound (950%; 563-1564%; P < 0.01) and total butyrate (260%; 174-373%; P < 0.01) and faecal propionate (41%; 12-77%; P = 0.02) from day 0 to day 28 compared to LAMS. HAMSB was also associated with a relative 1.6-fold (1.2- to 2.0-fold; P < 0.01) and 2.5-fold (1.4- to 4.4-fold; P = 0.01) increase in plasma IL-10 and TNF-alpha but did not alter other indices of immunity. There were relative greater increases in faecal P. distasonis (81-fold (28- to 237-fold; P < 0.01) and F. prausnitzii (5.1-fold (2.1- to 12-fold; P < 0.01) in the HAMSB group.
HAMSB supplementation in healthy active individuals promotes the growth of bacteria that may improve bowel health and has only limited effects on plasma cytokines.
• Prolonged exercise results in a progressive decline in glycogen content and a concomitant increase in the release of the cytokine interleukin-6 (IL-6) from contracting muscle. This study tests the hypothesis that the exercise-induced IL-6 release from contracting muscle is linked to the intramuscular glycogen availability. • Seven men performed 5 h of a two-legged knee-extensor exercise, with one leg with normal, and one leg with reduced, muscle glycogen content. Muscle biopsies were obtained before (pre-ex), immediately after (end-ex) and 3 h into recovery (3 h rec) from exercise in both legs. In addition, catheters were placed in one femoral artery and both femoral veins and blood was sampled from these catheters prior to exercise and at 1 h intervals during exercise and into recovery. • Pre-exercise glycogen content was lower in the glycogen-depleted leg compared with the control leg. Intramuscular IL-6 mRNA levels increased with exercise in both legs, but this increase was augmented in the leg having the lowest glycogen content at end-ex. The arterial plasma concentration of IL-6 increased from 0.6 ± 0.1 ng l−1 pre-ex to 21.7 ± 5.6 ng l−1 end-ex. The depleted leg had already released IL-6 after 1 h (4.38 ± 2.80 ng min−1 ( P −1). A significant net IL-6 release was not observed until 2 h in the control leg. • This study demonstrates that glycogen availability is associated with alterations in the rate of IL-6 production and release in contracting skeletal muscle.
O objetivo do presente estudo foi avaliar o comportamento de variáveis fisiológicas durante uma sessão de treino de nado sincronizado realizada na fase de preparação para as Olimpíadas de Atenas 2004. Materiais e métodos: A amostra utilizada foi constituída pelo dueto (24 ± 0 anos) representante do Brasil em Atenas 2004. A coleta de dados foi realizada durante uma sessão de treinamento com duração de 198 minutos. O treino se iniciou com a parte física, seguida da parte técnica. Para a determinação da glicemia e da Cocentração de β-hidroxibutirato foi utilizado o monitor Optium® com suas respectivas tiras. As concentrações de cortisol e das enzimas lactato desidrogenase (LDH) e creatina quinase (CK) foram detereinadas por radioimunoensaio (DPC©) e kits comerciais (CELM®), respectivamente. O acompanhamento da freqüência cardíaca (FC) foi realizado com o freqüêncimetro Advantage Polar ®. Resultados: Foi observada redução (~2%) do peso corporal. A glicemia também apresentou queda (~30%) em comparação ao valor obtido no início do treino. Em contrapartida, foi observada elevação na concentração de cortisol (salivar 22% e plasmática 29%) e de β-hidroxibutirato (~340%). Não foi observada alteração significativa na concentra- ção plasmática de CK e de LDH. O acompanhamento da FC demonstrou que dos 198 minutos que constituíram a sessão de treino, 36,5 ± 0,7 minutos foram realizados em intensidade leve; 103,5 ± 0,7 minutos em intensidade moderada, 54,0 ± 2,1 minutos em intensidade alta e 4,0 ± 0,0 minutos em intensidade muito alta. Conclusões: A perda de peso indica que a reposição hídrica não foi adequada. A redução na glicemia e o aumento na concentração de corpos cetônicos e de cortiços reforçam a importância da suplementação de carboidrato durante o treino de longa duração. O comportamento da FC demonstra que a sessão de treinamento foi realizada em uma intensidade moderada, porém com breves momentos de intensidade alta, nos quais foram realizadas as rotinas.
There is clear evidence that environmental pollutants, such as benzo[a]pyrene (B[a]P), can have detrimental effects on the immune system, whereas the underlying mechanisms still remain elusive. Jurkat T cells share many properties with human T lymphocytes and therefore are an appropriate model to analyze the effects of environmental pollutants on T cells and their activation. Since environmental compounds frequently occur at low, not acute toxic concentrations, we analyzed the effects of two subtoxic concentrations, 50 nM and 5 μM, on non- and activated cells. B[a]P interferes directly with the stimulation process as proven by an altered IL-2 secretion. Furthermore, B[a]P exposure results in significant proteomic changes as shown by DIGE analysis. Pathway analysis revealed an involvement of the AhR independent Nrf2 pathway in the altered processes observed in unstimulated and stimulated cells. A participation of the Nrf2 pathway in the change of IL-2 secretion was confirmed by exposing cells to the Nrf2 activator tBHQ. tBHQ and 5 μM B[a]P caused similar alterations of IL-2 secretion and glutamine/glutamate metabolism. Moreover, the proteome changes in unstimulated cells point towards a modified regulation of the cytoskeleton and cellular stress response, which was proven by western blotting. Additionally, there is strong evidence for alterations in metabolic pathways caused by B[a]P exposure in stimulated cells. Especially the glutamine/glutamate metabolism was indicated by proteome pathway analysis and validated by metabolite measurements. The detrimental effects were slightly enhanced in stimulated cells, suggesting that stimulated cells are more vulnerable to the environmental pollutant model compound B[a]P.
Assessing psychological stress and mental workload within work-based scenarios relies heavily upon qualitative, subjective, self-assessment techniques, many of which were originally intended for identifying specific pathological disorders and have reduced sensitivity when evaluating everyday stressors. Quantitative measures involve monitoring changes in the cardiopulmonary system and stress hormone concentration. Although these (e.g. heart rate and blood pressure) provide a basic, reactive indication of the presence of a psychological stressor, many are subject to influence by other bio-mechanisms, or are unable to provide rapid results due to complex laboratory analysis. This study demonstrates how immune responsiveness, known to be influenced by psychological stress, can be used to assess changes in mental workload. Healthy male and female subjects (aged between 26 and 55 years) provided capillary blood samples before and after completing the same, basic, driver-related tasks followed by a simple manoeuvre in two unfamiliar motor vehicles. Using a chemiluminescent technique termed Leukocyte Coping Capacity (LCC), the ability of leukocytes to produce reactive oxygen species in vitro was assessed. Significant post-stressor changes in leukocyte activity were demonstrated between treatment groups. These findings add weight to the proposition that leukocyte activation is a useful quantitative measure of psychological stress and mental loading in humans. This study demonstrates the diagnostic ability of LCC for use during ergonomic evaluation, however the potential industrial applications for this technique are numerous and diverse.
Heavily exercising endurance athletes experience extreme physiologic stress, which is associated with temporary immunodepression and higher risk of infection, particularly upper respiratory tract infections (URTI). The aim of this review is to provide a critical up-to-date review of existing evidence on the immunomodulatory potential of selected macronutrients and to evaluate their efficacy. The results of 66 placebo-controlled and/or crossover trials were compared and analysed. Among macronutrients, the most effective approach to maintain immune function in athletes is to consume ≥6% carbohydrate during prolonged exercise. Because inadequate nutrition affects almost all aspects of the immune system, a well-balanced diet is also important. Evidence of beneficial effects from other macronutrients is scarce and results are often inconsistent. Using a single nutrient may not be as effective as a mixture of several nutritional supplements. Due to limited research evidence, with the exception of carbohydrate, no explicit recommendations to reduce post-exercise URTI symptoms with single macronutrients can be derived.
Widespread use of supplements is observed among world athletes in different fields. The aim of this study was to estimate the prevalence and determinants of using supplements among body builder athletes.
This cross-sectional study was conducted on 250 men and 250 women from 30 different bodybuilding clubs. Participants were asked to complete a self-administered standardized anonymous check-list.
Forty nine percent of the respondents declared supplement use. Men were more likely to take supplements than women (86.8% vs. 11.2%, p = 0.001). Reasons for using supplements were reported to be for health (45%), enhancing the immune system (40%) and improving athletic performance (25%). Most athletes (72%) had access to a nutritionist but underused this resource. Coaches (65%) had the greatest influence on supplementation practices followed by nutritionists (30%) and doctors (25%) after them.
The prevalence of supplement use among bodybuilders was high. Sex, health-related issues and sport experts were determinant factors of supplement use.
Natural immunity is influenced by exercise. Physical activity induces increased circulating levels of a number of cytokines, IL-6 more than any other cytokine is produced in large amounts in response to exercise. Recently, it has been demonstrated that IL-6 is produced locally in contracting skeletal muscles and that the net release from the muscle can account for the exercise-induced increase in arterial IL-6 concentration. IL-6 stimulates the production of a number of anti-inflammatory cytokines such as IL-fra and IL-10 and works in a hormone-like fashion, IL-6 also stimulates cortisol production. In the recovery phase of heavy exertion, a cortisol-induced shift in leukocyte subsets is seen. Thus, dominant features in the post-exercise period are lymphopenia, neutrophilia and a marked suppressed natural killer cell activity are seen. In addition secretory IgA is inhibited.This chapter focuses on the effect of exercise on natural immunity. Over the past 20 years a variety of studies have demonstrated that exercise induces considerable changes in the immune system. The interactions between exercise, stress and the immune system provide a unique opportunity to link basic and clinical physiology, and to evaluate the role of underlying stress and immunophysiological mechanisms. It has been suggested that exercise represents a quantifiable model of physical stress [1,2] as many clinical physical stressors (e.g., surgery, trauma, burn, sepsis) and environmental factors such as hyperthermia and hypoxia induce a pattern of hormonal and immunological responses that have similarities to the cellular response to exercise [3].
Effects of 50, 100 and 200 mg/kg body weight of the alcoholic and hydro-alcoholic extract of leaves of M. olifera were studied on various immune paradigms like delayed type hypersensitivity reaction using SRBC as an antigen, determination of antibody titer, neutrophil adhesion test as an indicator for neutrophil index, total leucocyte count in cyclophosphamide induced immunosuppressed animals and carbon clearance assay as a measure of phagocytic activity. Hydro-alcoholic extract of M. olifera substantially enhanced cellular immune response, humoral immune response, neutrophil index and phagoctic activity in doses of 100 and 200 mg/kg body weight. The ethanolic extract (200 mg/kg body weight) was efficient in improving immune response. The results suggest that M. olifera has a significant role to play as an immune stimulator.
Although much work has been conducted to quantify the long-term physiological effects of psychological stress, measures of short-term, low-level stress have been more elusive. This study assessed the effect of exposure of volunteers to a mild, brief, psychologically stressful event, on the functional ability of leukocytes in whole blood to respond to phorbol 12-myristate 13-acetate (PMA) in vitro. Volunteers operated a car electric window and adjusted it to 4 pre-determined positions. Between each operation the mechanism's polarity was covertly altered (group B) or remained unaltered (group A). For each treatment group 10 different subjects provided capillary blood samples pre- and post-stressor. Using a chemiluminescent technique termed leukocyte coping capacity, the ability of leukocytes to produce reactive oxygen species (ROS) in vitro was assessed. ROS release differed significantly at 10 min post-stressor between treatment groups, suggesting exposure to acute psychological stress leads to a reduced ability to respond to bacterial challenge.
The aim of this study was to investigate the postexercise concentrations in IL-6 and TNF-α during maximal 6000 meter time trial in conditions with improved performance capacity.
Nine highly trained male rowers (age 19.67±1.0; height 190.67±4.24 cm; weight 91.07±6.24 kg) participated. Subjects were asked for body composition measurement and two 6000 meter all-out rowing ergometer trial separated by one year.
The 6000 meter rowing ergometer performance was significantly improved during one year period from from Test 1 to Test 2 (from 330.3±21.9 W to 349.2±20.3 W, P<0.05). No significant changes were observed in the anthropometrical parameters. Postexercise cortisol and IL-6 were significantly increased during both testing sessions, while TNF-α was only increased after Test 2 when compared to pretest values. Postexercise and post 30 values of TNF-α were significantly higher at Test 2 compared to Test 1, while only Post 30 values of IL-6 were significantly higher at Test 2 compared to Test 1. There were no significant relationship between postexercise IL-6 and TNF-α concentrations and the 6000 meter rowing ergometer performance (r=-0.101 - -0.617; P>0.05) and no signigficant relationships between the measured body compositional and blood biochemical parameters. Postexercise changes in IL-6 concentration were significantly related to changes in performance (r=-0.667 and r=-0.865 for POST and POST 30, respectively; P<0.05).
In conclusion improvements in performance resulted in higher postexercise concentrations of IL-6 and TNF-α in highly trained male rowers.
Interleukin 6 (IL-6) response was studied during two ultra endurance events-one laboratory 24 h protocol (9 men) with exercise intensity set to 60% of VO(2max) and one Adventure Race over 6 days (12 men/6 women) with a self-selected race pace, including rests, of about 38% of VO(2max). In the 24-h protocol IL-6 level was elevated from 0.76 ± 0.48 pg mL(-1) at rest to 7.16 ± 2.70 pg mL(-1) at 6 h, and increased further to 10.58 ± 1.04 pg mL(-1) at 12 h, but remained thereafter unchanged at 24 h, (10.89 ± 0.36 pg mL(-1)). All participants had nearly identical values at 12 and 24 h, supporting intensity as main determinant in the IL-6 response during prolonged exercise since exercise duration did not increase IL-6 level after 12 h. Possible confounding factors do not seem to influence the IL-6 concentration during the longer races (>12 h), but might very well do so during shorter exercise bouts. In the 6-day race IL-6 increased from rest to 24 h, but thereafter there was no change in plasma IL-6 value until the end of the race (mean 143.5 h). There was no elevation of TNF-α in any of the protocols, suggesting that the competitors were free from systemic inflammation. We conclude that during endurance exercise lasting >12 h intensity, and not duration, is the main determinant of the IL-6 response, while during shorter exercise bouts both intensity and duration contribute to the accumulation of IL-6 in plasma.
The effects of stress on the mucosal immune responses in inflammatory disorders of the gut, as well as on salivary and intestinal IgA levels are well known. However, its effects on the structure and function of the NALT have not yet been reported, and are examined in the present study. Balb/c mice were submitted to restraint stress for 3h per day during 4 or 8d. The immunohistochemistry and flow cytometric analysis revealed that repeated restraint stress (4 and 8d) decreased the percentage, compared to the control group, of CD3(+) and CD4(+) T cells, without affecting the percentage of CD8(+) T cells or B220(+) cells (B cells). The numbers of IELs (CD4(+) and CD8(+) T cells) were lower at 4d of stress and higher at 8d. IgA(+) cells in NALT and nasal IgA levels showed a similar pattern, being significantly lower at 4d of stress and significantly higher at 8d. In summary, repeated restraint stress altered the distribution and number of lymphocytes and IgA(+) cells in nasal mucosa, probably due to changes in norepinephrine and corticosterone levels.
Objective: The aim of this study was to determine the body composition, dietary intake and supplement use among training olympic and ironman distance triathletes residing in the Western Cape region. Design: Descriptive, analytical, cross-sectional study design Setting: Western Cape Province (South Africa) Subjects: Triathletes residing in the Western Cape region registered with Triathlon South Africa (N = 26) Outcome measures: Percentage body fat, total energy intake, macro– and micronutrient intake, use and reasons for use of nutritional supplements or nutritional ergogenic aids. Results: The mean age of the men and women was 37.9 [Standard Deviation (SD) 6.82] and 37.5 (9.6) years respectively. The corresponding mean amount of training per week for men and women respectively were 15.1 (4.1) and 15.3 (4.7) hours. The percentage body fat as determined by multi-frequency bio-electrical impedance analysis of the men and women were 12.97% (4.3) and 21.4% (6.3) respectively. The mean dietary macronutrient intake as determined by a three day food record for men was for total energy intake 14 534.7kJ (4509.8), carbohydrate intake 5.3g/kg body weight (BW) (1.9), protein intake 2.0g/kg BW (0.5) and fat intake 34.6% (10.31) of total energy requirements. Dietary micronutrients not reaching 67% of dietary reference intakes (DRI) from food alone included iodine (44%) and fluoride (49%). Vitamin C (154%). Micronutrient intake above upper limit (UL) was sodium (213%), manganese (162%) and niacin (228%). The dietary macronutrient intake for women was for total energy intake 9004.1kJ (2368.8), carbohydrate intake 3.5g/kg BW (1.0), protein intake 1.2g/kg BW (0.2) and fat intake 29.8% of total energy intake (6.0). Micronutrients not reaching 67% of the DRI were chloride (61%), iodine (31%) and fluoride (52%). Micronutrient intake above the UL was vitamin C (218%) and manganese (174%). The dietary intake of the men was inadequate in carbohydrate, provided sufficient energy and protein and excessive fat. The dietary intake of the women was inadequate in total energy and carbohydrate, with an adequate protein intake and excessive fat intake. Although the sample size was very small, some associations were found between dietary intake and clinical health status. Seventy three percent of the triathletes use over the counter dietary supplements. The supplements used most often included carbohydrate supplements (81%), multivitamin and mineral supplements (81%) single vitamins (65%), protein supplements (100%), single minerals (58%), antioxidants (54%) and herbal supplements (42%). Most popular reasons for consuming supplements included recovery (62%), increasing energy supply (61%), enhancing immune function (50%), exercise performance enhancement (46%), increasing muscle mass (54%) and to make up for an inadequate diet or nutrient replacement (31%). Conclusion: Percentage body fat of the men and women were at the upper end of the range associated with elite athletes. The athletes have a fairly good intake of macro– and micro-nutrients. Inadequate habitual carbohydrate intake can be attenuated by the vast majority of the triathletes taking additional carbohydrate supplementation. Supplements were used widely among the athletes, whether it is scientifically proven to be beneficial or not. Thesis (MNutr (Interdisciplinary Health Sciences. Human Nutrition))--University of Stellenbosch, 2008.
El agua posee propiedades térmicas ya que contribuye a mantener la temperatura corporal constante, especialmente durante la práctica de un ejercicio prolongado en un ambiente caluroso y húmedo. El sodio es el principal catión perdido por el sudor. Los autores revisan las causas y consecuencias de la pérdida debido al ejercicio: la deshidratación, la hipohidratación y la hiponatremia, así como las consecuencias, en primer lugar, la disminución del rendimiento deportivo y, en segundo lugar, el deterioro funcional de músculos y tendones. Se revisan las distintas modalidades y recomendaciones para una correcta hidratación: previa al ejercicio, durante el ejercicio y la rehidratación después del ejercicio. Se analizan las ventajas de una rehidratación postejercicio con una bebida moderadamente alta en sodio (0,15 g/100 ml) en comparación con una bebida con un bajo contenido en sodio (0,07 g/100 ml), junto con una ingesta del 150% de la pérdida de peso por deshidratación.
La utilización de complementos dietéticos ergogénicos se ha insaturado rápidamente en los deportes individuales por el deseo de aumentar el rendimiento deportivo durante actividades deportiva. El incremento en la utilización de oxigeno durante el ejercicio conduce a un aumento de la utilización mitocondrial que no se apareja con un aumento del aporte de oxígeno, lo que puede conducir a la producción de radicales libres. La producción de éstos es una secuela del aumento del consumo de oxígeno concomitante con el ejercicio, y tiene una estrecha relación con el daño muscular. Para evitar este daño muscular el cuerpo contiene un sistema de defensa de antioxidantes detallado que depende del aporte dietético de vitaminas y minerales y la producción endógena de compuestos como la glutation y diferentes enzimas como las catalasas. Ahora bien, lo que no se sabe con seguridad si este sistema de defensa, que se ve incrementado cuando se realiza ejercicio de manera continuada en el tiempo, es suficiente para neutralizar los radicales libres generados en algunas modalidades deportivas muy intensas. Para analizar esto existe números estudios que intentan demostrar la mejora en el rendimiento gracias a una suplementación de antioxidantes como la vitamina E. Estos estudios son algunos contradictorios, aunque se puede afirmar que en ciertas circunstancias y en ciertas modalidades una suplementación de vitamina E es recomendable para disminuir los daños producidos por los radicales libres.
This study determined the effect of dehydration and rehydration (DR) on performance, immune cell response, and tympanic temperature after high-intensity rowing exercise.
Seven oarswomen completed two simulated 2000-m rowing race trials separated by 72 h in a random, cross-over design. One trial was completed in a euhydrated (E) condition and the other using a DR protocol.
The DR condition resulted in a 3.33+/-0.14% reduction in body mass (P<.05) over a 24-h period followed by a 2-h rehydration period immediately before the simulated rowing race. There was a greater change in tympanic temperature observed in the DR trial (P<.05). There were increases in the blood concentration of leukocytes, lymphocytes, lymphocyte subsets (CD3+, CD3+/4+, CD3+/8+, CD3-/16+, CD4+/25+; P<.05) and decreases in lymphocyte proliferation and neutrophil oxidative burst activity immediately following the simulated race (P<.05) in both trials. Blood leukocyte and neutrophil concentrations were greater after exercise in the DR trial (P<.05). Whereas most immune measures returned to resting values after 60 min of recovery in both trials, lymphocyte proliferation and the concentrations of CD3+/4+ and CD4+/25+ cells were significantly lower than before exercise. Blood leukocyte and neutrophil concentrations were significantly higher before and after exercise in the E trial.
The effects of dehydration/rehydration did not negatively influence simulated 2000-m rowing race performance in lightweight oarswomen but did produce a higher tympanic temperature and had a differential effect on blood leukocyte, neutrophil, and natural killer (CD3-/16+) cell concentrations after exercise compared with the euhydrated state.
Glutamine is the most abundant free amino acid in human muscle and plasma and is utilised at high rates by rapidly dividing cells, including leucocytes, to provide energy and optimal conditions for nucleotide biosynthesis. As such, it is considered to be essential for proper immune function. During various catabolic states including surgical trauma, infection, starvation and prolonged exercise, glutamine homeostasis is placed under stress. Falls in the plasma glutamine level (normal range 500 to 750 μmol/L after an overnight fast) have been reported following endurance events and prolonged exercise. These levels remain unchanged or temporarily elevated after short term, high intensity exercise. Plasma glutamine has also been reported to fall in patients with untreated diabetes mellitus, in diet-induced metabolic acidosis and in the recovery period following high intensity intermittent exercise. Common factors among all these stress states are rises in the plasma concentrations of cortisol and glucagon and an increased tissue requirement for glutamine for gluconeogenesis. It is suggested that increased gluconeogenesis and associated increases in hepatic, gut and renal glutamine uptake account for the depletion of plasma glutamine in catabolic stress states, including prolonged exercise. The short term effects of exercise on the plasma glutamine level may be cumulative, since heavy training has been shown to result in low plasma glutamine levels ( Since injury, infection, nutritional status and acute exercise can all influence plasma glutamine level, these factors must be controlled and/or taken into consideration if plasma glutamine is to prove a useful marker of impending overtraining.
We examined the effects of a low-carbohydrate (CHO) diet on the plasma glutamine and circulating leukocyte responses to prolonged strenuous exercise. Twelve untrained male subjects cycled for 60 min at 70% of maximal oxygen uptake on two separate occasions, 3 days apart. All subjects performed the first exercise task after a normal diet; they completed the second exercise task after 3 days on either a high-CHO diet (75 +/- 8% CHO, n = 6) or a low-CHO diet (7 +/- 4% CHO, n = 6). The low-CHO diet was associated with a larger rise in plasma cortisol during exercise, a greater fall in the plasma glutamine concentration during recovery, and a larger neutrophilia during the postexercise period. Exercise on the high-CHO diet did not affect levels of plasma glutamine and circulating leukocytes. We conclude that CHO availability can influence the plasma glutamine and circulating leukocyte responses during recovery from intense prolonged exercise.
An epidemiologic study of Los Angeles Marathon (LAM) applicants was conducted to investigate the relationship between self-reported infectious episodes (IE), training data, and LAM participation. Eight days before the LAM, 4926 of 12,200 applicants were randomly selected, and sent a pilot-tested four page questionnaire, which was received 7 days after the LAM. The 2311 respondents were found to be 2.0 yr older and 7.6 min faster than other LAM finishers (p less than .01). Univariate and multivariate analyses (logistic regression) were conducted to test the relationship between IE and km/wk of running (6 total categories). The final model tested controlled for age, marital status, reported sickness in other members of the runner's home, perceived feelings of stress in response to personal training regimens, and the suppressive effect of sickness on regular training. In runners training greater than or equal to 97 vs less than 32 km/wk, the odds ratio (OR) for IE during the 2 month period prior to the LAM was 2.0 (95% confidence interval (CI) 1.2-3.4). A test for trend showed an increase in OR with increase in km/wk category (p = .04) which was largely explained by the increased odds of reported sickness in the greater than or equal to 97 km/wk category. Of the 1828 LAM participants without IE before the LAM, 236 (12.9%) reported IE during the week following the LAM vs 3 of 134 (2.2%) similarly experienced runners who did not participate, OR = 5.9 (95% CI 1.9-18.8). These data suggest that runners may experience increased odds for IE during heavy training or following a marathon race.
The interaction between nutrition and immunity is complex and the study of potentially critical factors needs multidisciplinary analysis. The purpose of this article is to characterize briefly several approaches to the evaluation of human immune function with specific emphasis on immune interaction networks and to summarize some aspects of nutritional impact on expression of immune function.
This randomized, double-blind, placebo-controlled study was designed to determine the influence of 6% carbohydrate (C) vs. placebo (P) beverage ingestion on cytokine responses (5 total samples over 9 h) to 2.5 h of high-intensity running (76.7 +/- 0.4% maximal O2 uptake) by 30 experienced marathon runners. For interleukin-6 (IL-6), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C immediately postrun (753 vs. 421%) and 1.5 h postrun (193 vs. 86%) [F(4,112) = 3.77, P = 0.006]. For interleukin-1-receptor antagonist (IL-1ra), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C 1.5 h postrun (231 vs. 72%) [F(2,50) = 6.38, P = 0.003]. No significant interaction effects were seen for bioactive IL-6 or IL-1 beta. The immediate postrun plasma glucose concentrations correlated negatively with those of plasma cortisol (r = -0.67, P < 0.001); postrun plasma cortisol (r = 0.70, P < 0.001) and IL-6 levels (r = 0.54, P = 0.003) correlated positively with levels of IL-1ra. Taken together, the data indicate that carbohydrate ingestion attenuates cytokine levels in the inflammatory cascade in response to heavy exertion.
This randomized, double-blind, placebo-controlled study was designed to determine the influence of carbohydrate supplementation on the granulocyte and monocyte response to 2.5 h of high-intensity running [76.7 +/- 0.4% of maximal oxygen consumption (VO2max)]. Thirty experienced marathon runners (VO2max 53.4 +/- 1.0 mL.kg-1.min-1, age 41.5 +/- 1.4 y) were randomly assigned to carbohydrate-supplement (n = 17) and placebo (n = 13) groups. Subjects rested for 10-15 min before a blood sample was taken at 0715, and then ingested 0.75 L carbohydrate beverage or placebo. At 0730 subjects began running at 75-80% of VO2max for 2.5 h, and drank 0.25 L carbohydrate or placebo fluid every 15 min. Immediately after the 2.5-h run (1000), another blood sample was taken, followed by 1.5-h, 3-h, and 6-h recovery samples. Carbohydrate supplementation had a significant effect compared with placebo on the pattern of change in plasma glucose and cortisol, and the blood concentration of neutrophils (F[14, 112] = 5.13, P = 0.001) and monocytes (F[14, 112] = 4.78, P = 0.001), but not on blood granulocyte and monocyte phagocytosis or oxidative burst activity after 2.5 h of intensive running.
This randomized, double-blind, placebo-controlled study was designed to determine the influence of vitamin C supplementation on the immune response to 2.5 hr of high-intensity running. Twelve experienced marathon runners (VO2 max 51.6 +/- 1.5 ml.kg-1.min-1, age 40.5 +/- 2.0 years) were randomized into vitamin C (1,000 mg/day for 8 days) or placebo groups. On the test day, subjects ran at 75-80% VO2 max for 2.5 hr, with five blood samples taken before and for 6 hr after. Blood samples were analyzed for cortisol and catecholamines; leukocyte subsets; interleukin-6; natural killer cell activity; lymphocyte proliferation as induced by concanavalin A, phytohemagglutinin, and pokeweed mitogen; and granulocyte phagocytosis and activated oxidative burst. Compared with placebo, vitamin C supplementation had no significant effect on the pattern of change in any of these hormonal or immune measures following 2.5 hr of intensive running.
There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis of this pattern in the medical screening of elite athletes during both especially intense and light training periods.
Plasma amino acid analysis was undertaken in three situations. (1) A medical screening service was offered to elite athletes during an intense training period before the 1992 Olympics. Screening included a blood haematological/biochemical profile and a microbial screen in athletes who presented with infection. The athletes were divided into three groups who differed in training fatigue and were considered separately. Group A (21 track and field athletes) had no lasting fatigue; group B (12 judo competitors) reported heavy fatigue at night but recovered overnight to continue training; group C (18 track and field athletes, one rower) had chronic fatigue and had been unable to train normally for at least several weeks. (2) Athletes from each group were further screened during a post-Olympic light training period. (3) Athletes who still had low amino acid levels during the light training period were reanalysed after three weeks of additional protein intake.
(1) The pre-Olympics amino acid patterns were as follows. Group A had a normal amino acid pattern (glutamine 554 (25.2) micromol/l, histidine 79 (6.1) micromol/l, total amino acids 2839 (92.1) micromol/l); all results are means (SEM). By comparison, both groups B and C had decreased plasma glutamine (average 33%; p<0.001) with, especially in group B, decreased histidine, glucogenic, ketogenic, and branched chain amino acids (p<0.05 to p<0.001). None in group A, one in group B, but ten athletes in group C presented with infection: all 11 athletes had plasma glutamine levels of less than 450 micromol/l. No intergroup differences in haematological or other blood biochemical parameters, apart from a lower plasma creatine kinase activity in group C than in group B (p<0.05) and a low neutrophil to lymphocyte ratio in the athletes with viral infections (1.2 (0.17)), were found. (2) During post-Olympic light training, group A showed no significant amino acid changes. In contrast, group B recovered normal amino acid levels (glutamine 528 (41.4) micromol/l, histidine 76 (5.3) micromol/l, and total amino acids 2772 (165) micromol/l) (p<0.05 to p<0.001) to give a pattern comparable with that of group A, whereas, in group C, valine and threonine had increased (p<0.05), but glutamine (441 (24.5) micromol/l) and histidine (58 (5.3) micromol/l) remained low. Thus none in group A, two in group B, but ten (53%) in group C still had plasma glutamine levels below 450 micromol/l, including eight of the 11 athletes who had presented with infection. (3) With the additional protein intake, virtually all persisting low glutamine levels increased to above 500 micromol/l. Plasma glutamine rose to 592 (35.1) micromol/l and histidine to 86 (6.0) micromol/l. Total amino acids increased to 2761 (128) micromol/l (p<0.05 to p<0.001) and the amino acid pattern normalised. Six of the ten athletes on this protein intake returned to increased training within the three weeks.
Analysis of these results provided contrasting plasma amino acid patterns: (a) a normal pattern in those without lasting fatigue; (b) marked but temporary changes in those with acute fatigue; (c) a persistent decrease in plasma amino acids, mainly glutamine, in those with chronic fatigue and infection, for which an inadequate protein intake appeared to be a factor.
To determine the effect of carbohydrate (CHO) status on immune responses after long-duration exercise, on two occasions, 10 men completed a glycogen-depleting bout of cycle ergometry followed by 48 h of either a high-CHO diet (HiCHO; 8.0 g CHO/kg) or a low-CHO diet (LoCHO; 0.5 g CHO/kg). After the 48 h, subjects completed a 60-min ride at 75% maximal O2 uptake (EX). Blood samples were taken predepletion, pre-EX, post-EX, and 2 and 24 h post-EX and were assayed for leukocyte number and function, glucose, glutamine, and cortisol. The glucose responses were significantly higher in the HiCHO (4.62 +/- 0.26 mM) vs. the LoCHO (3.19 +/- 0.15 mM) condition post-EX, and glutamine was significantly higher in the HiCHO (0.472 +/- 0.036 mM) vs. the LoCHO (0.410 +/- 0.025 mM) condition throughout. Cortisol levels were significantly greater in the LoCHO (587 +/- 50 nM) vs. the HiCHO (515 +/- 62 nM) condition throughout the trial. Lymphocyte proliferation (phytohemagglutinin) was significantly depressed after exercise. However, there was no difference between conditions, and the depression was not correlated with elevations in cortisol. Circulating numbers of leukocytes, neutrophils, lymphocytes, and lymphocyte subsets were significantly greater in the LoCHO vs. the HiCHO condition at the post-EX and 2 h post-EX time points. These data indicate that the exercise and diet manipulation altered the number of circulating leukocytes but did not affect the decrease in lymphocyte proliferation that occurred after exercise.
This randomized, double-blind, placebo-controlled study examined the influence of 6% carbohydrate ingestion on hormonal and lymphocyte proliferative responses (5 total samples over 9 hours) to 2.5 h of high-intensity running by 30 experienced marathon runners. The T-cell response differed between groups, with the placebo group exhibiting a greater increase immediately post-run and greater decrease at 3 h of recovery. No group differences were observed for Con A-, PHA-, or PWM-induced lymphocyte proliferation. However, when PHA was adjusted per T-cell, group differences were observed, highlighted by a decrease in the placebo group immediately post-run. Glucose and cortisol responses differed between groups, with glucose lower and cortisol higher in the placebo group immediately post-run. Post-run glucose correlated negatively with postrun cortisol (r=-0.670, P< 0.001) and epinephrine (r=-0.540, P=0.002). Post-run cortisol also correlated negatively with total lymphocytes and T-cells at 1.5 hours (r=-0.429, P=0.018 and r=-0.424, P=0.019, respectively) and 3 hours (r=-0.566, P=0.001 and r=-0.523, P=0.003, respectively) of recovery. The pre- to post-run change in glucose correlated to the same changes in PHA/T-cell (r=0.456, P=0.011). The data support an interactive effect of carbohydrate ingestion on plasma glucose and cortisol. The data support an interactive effect of carbohydrate ingestion on plasma glucose and cortisol, T-cell trafficking, and cell-adjusted PHA-induced lymphocyte proliferation following long endurance running.
The literature suggests that a heavy schedule of training and competition leads to immunosuppression in athletes, placing them at a greater risk of opportunistic infection. There are many factors which influence exercise-induced immunosuppression, and nutrition undoubtedly plays a critical role. Misinterpretation of published data and misleading media reports have lead many athletes to adopt an unbalanced dietary regimen in the belief that it holds the key to improved performance. Some sports have strict weight categories, whilst in others low body fat levels are considered to be necessary for optimal performance or seen as an aesthetic advantage. This leads some athletes to consume a diet extremely low in carbohydrate content which, whilst causing rapid weight loss, may have undesirable results which include placing the athlete at risk from several nutrient deficiencies. Complete avoidance of foods high in animal fat reduces the intake of protein and several fat-soluble vitamins. On the other hand, diets with a very high carbohydrate content are usually achieved at the expense of protein.
In addition, anecdotal and media reports have often promoted the supposed performance benefits of certain vitamins and minerals, yet most athletes do not realise that micronutrient supplementation is only beneficial when correcting a deficiency, and to date there is little scientific evidence to substantiate claims that micronutrients act as an ergogenic aid. Moreover, excessive intakes of micronutrients can be toxic.
Deficiencies or excesses of various dietary components can have a substantial impact on immune function and may further exacerbate the immunosuppression associated with heavy training loads. This review examines the role of nutrition in exercise-induced immunosuppression and the effect of both excessive and insufficient nutrient intake on immunocompetence. As much of the present literature concerning nutrition and immune function is based on studies with sedentary participants, the need for future research which directly investigates the relationship between exercise, training, immunity and nutrition is highlighted.
The influence of carbohydrate (C) versus placebo (P) beverage consumption on the immune and hormonal responses to normal rowing training sessions was measured in 15 elite female rowers residing at the U.S. Olympic Training Center. In a randomized, counterbalanced design, the athletes received C or P beverages (double-blind) before, during, and after two 2-hour bouts of rowing (one day apart). Blood samples were collected before, and 5-10 minutes and 1.5 hours after rowing. Metabolic measures indicated that training was performed at moderate intensities, with some high intensity intervals interspersed throughout the sessions (mean oxygen uptake of 2,307+/-169 m x min(-1), 57% of VO2max). Glucose and insulin were significantly lower after two hours of rowing with ingestion of P compared to C. The patterns of change in cortisol, growth hormone, epinephrine, and norepinephrine did not differ between C and P rowing trials. Blood neutrophil cell counts and the neutrophililymphocyte ratio were significantly higher following P versus C rowing sessions. The patterns of change in blood lymphocyte and lymphocyte subset counts, and lymphocyte proliferative responses did not differ between P and C trials, except for a slight difference in NK cell counts and activity. In summary, minimal changes in blood hormonal and immune measures were found following two-hour bouts of training in elite female rowers. Carbohydrate compared to placebo ingestion attenuated the moderate rise in blood neutrophil counts, but had slight or no effects on other immune parameters.
The aim of this study was to determine the effect of carbohydrate (CHO) versus placebo (PLA) beverage consumption on the immune and plasma cortisol responses to a soccer-specific exercise protocol in 8 university team soccer players. In a randomized, counterbalanced design, the players received carbohydrate or placebo beverages before, during and after two 90 min soccer-specific exercise bouts (3 days apart) designed to mimic the activities performed and the distance covered in a typical soccer match. Blood and saliva samples were collected before, during and after the exercise protocol. Plasma lactate concentration increased to approximately 4 mmol x l(-1) at 45 and 90 min of exercise in both treatments (P<0.01). Plasma glucose concentration was significantly lower after 90 min of exercise with ingestion of the placebo than the carbohydrate (PLA: 4.57+/-0.12 mmol x l(-1); CHO: 5.49+/-0.11 mmol x l(-1); P<0.01). The pattern of change in plasma cortisol, circulating lymphocyte count and saliva immunoglobulin A secretion did not differ between the carbohydrate and placebo trials. Blood neutrophil counts were 14% higher 1 h after the placebo trial than the carbohydrate trial (PLA: 4.8+/-0.5x10(9) cells x l(-1); CHO: 4.2+/-0.5x10(9) cells x l(-1); P = 0.06), but the treatment had no effect on the degranulation response of blood neutrophils stimulated by bacterial lipopolysaccharide. We conclude that, although previous studies have shown that carbohydrate feeding is effective in attenuating immune responses to prolonged continuous strenuous exercise, the same cannot be said for a soccer-specific intermittent exercise protocol. When overall exercise intensity is moderate, and changes in plasma glucose, cortisol and immune variables are relatively small, it would appear that carbohydrate ingestion has only a minimal influence on the immune response to exercise.
Monocyte phagocytic function was studied in nine competitive athletes before and after a two-week weight-reduction program of calorie restriction. The phagocytic activity of monocytes before the program was higher in the athletes than in the sedentary controls, but decreased significantly after the weight-reduction program. Furthermore, plasma fibronectin concentrations and the response of lymphocytes to phytohemagglutinin decreased after the calorie restriction. These findings suggest that weight reduction by calorie restriction may adversely affect the integrity of defense mechanisms, even in healthy athletes. Thus, calorie restriction in athletes must be conducted with caution to protect them from adverse effects on their physiologic defense mechanisms.
This compacted overview of the nutrition-immune response connection underscores the role of nutrition as a deterrent to infection. Malnutrition enhances the propensity to and heightens the intensity of infections by weaknening the various host defense mechanisms. Thus: 1. Deficiencies of vitamin A, niacin, riboflavin, folic acid, vitamin B12, pyridoxine, ascorbic acid, iron and protein disrupt the tissue barriers to infection. 2. Protein-calorie, folate, iron, pyridoxine and zinc deprivations markedly depress the cell-mediated immune system. 3. Deficiencies of protein, pyridoxine, folic acid, pantothenic acid, thiamine, biotin, riboflavin, niacin-tryptophan, vitamin A and ascorbic acid inhibit humoral antibody formation in mammalian systems. 4. Vitamin A lack prevents the formation of lacrimal, salivary and sweat gland lysozymes. 5. Complement, properdin, interferon and transferrin concentrations are reduced in those nutritional deficiencies that interfere with protein synthesis. 6. Protein-calorie, iron and folate deficiencies impair phagocytosis by interfering with phagocyte microbial killing power or with phagocyte production. 7. Protein, ascorbic acid and zinc deficiencies retard wound healing that prevents spread of infectious lesions.
Overtraining and long-term exercise are associated with an impairment of immune function. We provide evidence in support of the hypothesis that the supply of glutamine, a key fuel for cells of the immune system, is impaired in these conditions and that this may contribute to immunosuppression. Plasma glutamine concentration was decreased in overtrained athletes and after long-term exercise (marathon race) and was increased after short-term, high intensity exercise (sprinting). Branched chain amino acid supplementation during long-term exercise was shown to prevent this decrease in the plasma glutamine level. Overtraining was without effect on the rate of T-lymphocyte proliferation in vitro or on the plasma levels of interleukin-1 and -6, suggesting that immune function is not impaired in this condition. Given the proposed importance of glutamine for cells of the immune system, it is concluded that the decrease in plasma glutamine concentration in overtraining and following long-term exercise, and not an intrinsic defect in T lymphocyte function, may contribute to the immune deficiency reported in these conditions.
Cytokines such as interleukin 1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin 6 (IL-6) mediate a variety of host responses to trauma and infection, including skeletal muscle proteolysis. This investigation assesses the influence of damaging eccentric exercise on in vitro production and plasma concentrations of cytokines and their relationship to muscle protein breakdown. In a double-blind placebo-controlled protocol, 21 male subjects took vitamin E supplements (800 IU/day) for 48 days, then ran downhill on an inclined treadmill. Twenty-four hours after this single session of eccentric exercise, endotoxin-induced secretion of IL-1 beta was augmented 154% (P less than 0.01) in cells obtained from the placebo subjects, but no significant exercise-related changes were observed in cells from the vitamin E-supplemented subjects. TNF-alpha secretion was also significantly increased 24 h after exercise, but the response was not inhibited by vitamin E. In contrast, IL-6 secretion did not change after exercise, but dietary vitamin E supplementation significantly reduced IL-6 secretion throughout the 12-day period of observation (P = 0.023). Urinary 3-methylhistidine excretion correlated with mononuclear cell secretion of both IL-1 beta (P less than 0.05) and prostaglandin E2 (P less than 0.05), supporting the concept that these mononuclear cell products contribute to the regulation of muscle proteolysis.
The normal immune system has local and systemic components which are influenced by a variety of alterations. Impaired host immunity is associated with neoplasia, protein calorie malnutrition, and the administration of immunosuppressive drugs. It is well accepted that protein calorie malnutrition impairs host immunity with particular detrimental effects on the T-cell system, resulting in increased opportunistic infection and increased morbidity and mortality in hospitalized patients. Individual nutrient substrates may also have a major influence on the immune system. Individual amino acids are often described as essential, based on requirements for optimal growth and maintenance of positive N balance. Arginine has been demonstrated to be essential to the traumatized host and may have tissue-specific properties which influence components of the immune system. Thus, arginine may be of value in clinical situations where the immune system is compromised. In a series of experiments in normal animals, arginine was demonstrated to enhance cellular immune mechanisms, in particular T-cell function. It also has a marked immunopreserving effect in the face of immunosuppression induced by protein malnutrition and increases in tumor burden. In postoperative surgical patients, arginine supplementation results in enhanced T-lymphocyte response and augmented T-helper cell numbers, with a rapid return to normal of T-cell function postoperatively compared with control patients. These data suggest that arginine supplementation may enhance or preserve immune function in high-risk surgical patients and theoretically improve the host's capacity to resist infection.
The nutritional habits of elite athletes competing at a national and international top level were determined. Groups of endurance strength, and team sport athletes participated. All athletes trained at least 1-2 h daily. The purpose of the study was to quantify the mineral and vitamin intake and to identify the magnitude of the nutrient supplementation use.
Information on food intake was obtained by a 4- or 7-day food diary. It was found that calcium and iron intake was positively related to energy intake. In low energy intakes (< 10 MJ) iron intake might be insufficient.
In general, vitamin intake with food was in agreement with the Dutch recommendations. However, if energy intake is high (> 20 MJ) the amount of refined carbohydrate is increased. Consequently, the nutrient density for vitamin B1 drops. Therefore, under these conditions, supplementation for vitamin B1 must be considered. The low vitamin intake found in lower energy intakes can be improved by proper nutritional advice.
In body building and in professional cycling, high dosages of vitamins are used. The other groups of athletes used only moderate quantities of vitamin supplements.
It is concluded that vitamin and mineral intake is sufficient, when energy intake ranges between 10 and 20 MJ/day.
Glucocorticoids have profound and complex effects on the human immune response. However, the precise mechanisms of the corticosteroid-induced immunoregulation in man have not been precisely defined. Intracytoplasmic corticosteroid-specific receptors appear to be an important common pathway for steroid-induced changes, but variations of receptor parameters do not account for the multifaceted effects on the immune system. Human circulating mononuclear cells redistribute out of the intravascular compartment following treatment with corticosteroids. Although certain components at this redistribution phenomenon have been well-characterized, the importance of this compartmental cellular shift with respect to the mechanisms of corticosteroid-induced immunoregulation are less well-defined. Recent observations that activated lymphocytes may be sensitive to the lytic effects of glucocorticoids suggest that under certain situations the elimination of selected subsets of cells may be a relevant mechanism of corticosteroid-mediated immunoregulation in man. Corticosteroid-mediated effects on monocyte function may be an important mechanism of drug-induced immunoregulation in monocyte-dependent responses. In some experimental conditions, corticosteroids inhibit Interleukin 1 production by monocytes. The immunoregulatory effects of corticosteroids on lymphocyte immune responses are complex. In vitro corticosteroids appear to selectively affect early immunoregulatory events as opposed to altering an established response. Multiple sites of steroid-induced modulations of human B cell responses have been defined.
Opinions differ as to whether marathon runners have an increased susceptibility to upper respiratory tract (URT) infections after a race. In an attempt to answer this question, we carried out a prospective study of the incidence of symptoms of URT infections in 150 randomly selected runners who took part in the 1982 Two Oceans Marathon in Cape Town, and compared this with the incidence in individually matched controls who did not run. Runners were questioned on the day before and 2 weeks after the race. Symptoms of URT infection occurred in 33.3% of runners compared with 15.3% of controls, and were most common in those who achieved the faster race times. The incidence in slow runners was no greater than that in controls. Faster runners also experienced more musculoskeletal pain during and after the race. These results suggest a relationship between acute stress and susceptibility to URT infections. Impairment of one or more local mucosal or general host defences may account for this effect.
1. We have investigated the effects of moderate long-term exercise on protein turnover in fed man by measuring the extent of whole-body nitrogen production, the labelling of urinary ammonia from ingested [15N]glycine and plasma, muscle and urine free amino acid concentrations.
2. Judged both from nitrogen production, and from the extent of 13CO2 production from ingested l-[l-13C]leucine, exercise causes a substantial rise in amino acid catabolism.
3. Amino acids catabolized during exercise appear to become available through a fall in whole-body protein synthesis and a rise in whole-body protein breakdown. After exercise, protein balance becomes positive through a rise in the rate of whole-body synthesis in excess of breakdown.
4. Studies of free 3-methylhistidine in muscle, plasma and urine samples suggest that exercise decreases the fractional rate of myofibrillar protein breakdown, in contrast with the apparent rise in whole-body breakdown.
The effect of megadoses of vitamin E was studied in 13 adult males and five young boys. Three hundred milligrams of vitamin E as dl-alpha-tocopheryl acetate, given daily for a period of 3 weeks produced a significant depression in the bactericidal activity of the leukocyte and the mitogen induced lymphocyte transformation. The delayed hypersensitivity of the skin to phytohemagglutinin was, however, not affected by the supplementation. The implication of the study and the discrepancy between the in vitro and the in vivo results of the cell-mediated immunity are discussed.
During exercise, leucocytes are recruited to the blood, and if muscle damage occurs the cytokine level is enhanced. After prolonged, intense exercise the number of lymphocytes in the blood is reduced, and the function of natural killer cells is suppressed; furthermore, secretory immunity is impaired. During this time of immunodepression, often referred to as 'the open window', the host may be more susceptible to micro-organisms bypassing the first line of defence. This is of interest to top athletes who perform frequent severe exercise. Clinical observations regarding an increased risk of infections in top athletes are compatible with this model. However, in those performing regular moderate exercise the immune system will often be temporarily enhanced and this will protect these individuals from infections.
A growing body of evidence suggests that the prevalence of eating disorders and excessive concerns regarding body weight in certain subpopulations of female athletes are increasing. The pressure on female athletes to improve their performances and physiques, coupled with the general sociocultural demand placed on all women to be thin, often results in attempts to achieve unrealistic body size and body weight goals. For some female athletes the pressure to achieve and maintain a low body weight leads to potentially harmful patterns of restrictive eating or chronic dieting. This paper seeks to further delineate the characteristics of a recently identified subclinical eating disorder in female athletes: anorexia athletica. Research studies that support the existence of subclinical eating disorders will be reviewed. In addition, the possible physiological and psychological consequences of subclinical eating disorders will be explored.
This study determined whether daily supplementation with 600 mg vitamin C would reduce the incidence of symptoms of upper-respiratory-tract (URT) infections after participation in a competitive ultramarathon race (> 42 km). Ultramarathon runners with age-matched controls were randomly divided into placebo and experimental (vitamin C-supplemented) groups. Symptoms of URT infections were monitored for 14 d after the race. Sixty-eight percent of the runners in the placebo group reported the development of symptoms of URT infection after the race; this was significantly more (P < 0.01) than that reported by the vitamin C-supplemented group (33%). The duration and severity of symptoms of URT infections reported in the vitamin C-supplemented nonrunning control group was also significantly less than in the nonrunning control group receiving the placebo (P < 0.05). This study provides evidence that vitamin C supplementation may enhance resistance to the postrace URT infections that occur commonly in competitive ultramarathon runners and may reduce the severity of such infections in those who are sedentary.
We studied the in vitro production of interleukin-2 in nine healthy volunteers who added 18 g/day of fish-oil concentrate rich in n-3 polyunsaturated fatty acids to their normal Western diet for a period of 6 weeks. Interleukin-2 synthesis from stimulated peripheral blood mononuclear cells was suppressed from 6.2 ng/ml at baseline to 2.2 ng/ml 10 weeks after the end of n-3 fatty acid supplementation (65% decrease; P = .04). At the same time phytohemagglutinin-induced proliferation of mononuclear cells was suppressed by 70% from the presupplement level. Interleukin-2 production returned to the premedication level at the end of the studies. The results suggest that the effect of dietary n-3 fatty acids in some diseases may be mediated in part by decreased production of interleukin-2 and decreased mononuclear cell proliferation.
Exercise of a sufficient intensity and duration has been shown to increase indicators of oxidative stress. Oxidative stress has been indicated in skeletal muscle, liver, blood, and in expired air samples as indicated by the by-products of lipid peroxidation. Antioxidants are known to reduce oxidative-radical-induced reactions. This paper presents information concerning the effects of exercise on vitamin E and C concentrations in several tissues. This paper also discusses the effects of supplementation of vitamin E and vitamin C on their ability to alter exercise-induced lipid peroxidation. This paper indicates that limited information is available concerning the effects of both vitamins on exercise-induced oxidative stress. The viability of antioxidants alone and in conjunction with each other in preventing exercise-induced lipid peroxidation requires further investigation.
Exercise participation can modulate interactions between nutritional status and immune function in at least three ways. Athletes and health conscious exercisers may occasionally adopt an unusual diet: megadoses of vitamins, large quantities of protein, carbohydrate or polyunsaturated fat, specific amino acid supplements, or an overall energy deficit. Prolonged exercise may also deplete glycogen reserves, leading to competition between the muscles and immune cells for key amino acids. Finally, an increased intake of antioxidants may protect the active person against an augmented production of reactive species associated with increased tissue metabolism and minor muscle injuries. Despite many potential mechanisms for a disturbance of immune function, most changes in nutritional status are short-lived, and there is little evidence that resistance to infection is reduced, with the possible exceptions of ultraendurance events, chronic overtraining and drastic attempts to reduce body mass.
There is an increased risk of infections in athletes undertaking prolonged, strenuous exercise. There is also some evidence that cells of the immune system are less able to mount a defence against infections after such exercise. The level of plasma glutamine, an important fuel for cells of the immune system, is decreased in athletes after endurance exercise; this may be partly responsible for the apparent immunosuppression which occurs in these individuals. We monitored levels of infection in more than 200 runners and towers. The levels of infection were lowest in middle-distance runners, and highest in runners after a full or ultramarathon and in elite rowers after intensive training. In the present study, athletes participating in different types of exercise consumed two drinks, containing either glutamine (Group G) or placebo (Group P) immediately after and 2 h after exercise. They subsequently completed questionnaires (n = 151) about the incidence of infections during the 7 days following the exercise. The percentage of athletes reporting no infections was considerably higher in Group G (81%, n = 72) than in Group P (49%, n = 79, p < 0.001).
Athletes' nutritional needs are principally determined by their training load (the intensity x frequency x duration of daily workouts) and body mass. Analyses of the diets of track and field competitors and marathon runners reveal a macronutrient composition similar to that of weight-matched, inactive individuals. Male athletes generally ingest adequate dietary energy to meet their daily energy expenditure and all vitamin and mineral needs. However, the energy intake of most female athletes is less than might be anticipated based on their training load. As a result, intakes of iron, calcium, vitamin B12 and zinc are often below the recommended daily allowances. Compared with the recommendations of sports nutritionists and exercise physiologists, the majority of athletes consume a diet which might be considered significantly deficient in carbohydrate (CHO). Although there is currently little scientific support for increasing the proportion of daily energy intake from CHO above the 45-55% (approximately 5 g kg BM-1 day-1) chronically consumed by most athletes, such a regimen would probably improve an athlete's training capacity, especially when rapid recovery from intense activity is required.
Although research on the role of single nutrients in immune function is extensive, this is not the case for multiple nutrients and subsequent nutrient-nutrient interactions. After presenting a brief overview of immune function, the authors consider reports that examine imbalance of more than one nutrient and interactive effects on immunocompetence. Availability of one nutrient may impair or enhance the action of another in the immune system, as reported for nutrients such as vitamin E and selenium, vitamin E and vitamin A, zinc and copper, and dietary fatty acids and vitamin A. Nutrient-nutrient interactions may negatively affect immune function. For example, excess calcium interferes with leukocyte function by displacing magnesium ions, thereby reducing cell adhesion. Because of consumer interest in supplementation to improve immune function, the potential for harm exists. Research is needed to improve knowledge in this area so that recommendations can be made with more confidence.
The literature reveals a paradoxical response of the immune and host defense systems to endurance exercise apparent stimulation following long-term regular training and suppression in response to acute exposure to exhaustive endurance exercise. Several epidemiological surveys have confirmed a clinical manifestation of immunosuppression in the form of increased incidence of upper respiratory tract infection symptoms following participation in competitive marathon and ultramarathon running events. Prerace training status and racing intensity have been related to the incidence of this symptomatology during the postrace fortnight. Nutritional intervention studies have shown the antioxidant nutrient, vitamin C, to be effective in reducing the incidence of upper respiratory tract infection symptoms following competitive distance events. Laboratory studies have revealed this vitamin to be the first line of defense in neutralizing the auto-oxidative activity of phagocytes. It is hypothesized that exercise-induced neuroendocrine stimulation of the oxidative burst in neutrophils increases the rate of release of reactive oxygen species and that these are, in turn, neutralized by high plasma ascorbate levels. Enhancing intrinsic antioxidant defense by increasing exogenous antioxidant intake is thus theorized to be of long-term benefit to serious endurance athletes engaged in heavy training and competition.
The immunologic response to exercise comprises numerous alterations within the immune system, but how these processes are regulated is still largely unknown. Exercise-related immunological changes include signs of inflammation, such as release of inflammatory mediators, activation of various white blood cell lines and complement, and induction of acute phase proteins. Nevertheless, signs of immunosuppression, such as decreased T and B cell function or impaired cytotoxic or phagocytic activity, can also be observed. Some data suggest that essential fatty acids help regulate inflammatory processes, modulating both cytokine release and the acute phase response. Positive effects of changing dietary essential fatty acids have been demonstrated in chronic inflammatory diseases. In contrast, little is known about the contribution of fatty acids to the exercise-induced immunologic reaction. Essential fatty acids may determine alterations within the immune system following exercise. Therefore, future studies are necessary to evaluate the influence of the fatty acid composition on the inflammatory or immunosuppressive component following heavy exertion.
Strenuous physical exercise induces oxidative stress. There may be a number of sources of this oxidative stress, including mitochondrial superoxide production, ischaemia-reperfusion mechanisms and auto-oxidation of catecholamines. Severe or prolonged exercise can overwhelm antioxidant defences, which include vitamins E and C and thiol antioxidants, which are interlinked in an antioxidant network, as well as antioxidant enzymes. Evidence for oxidative stress and damage during exercise comes from direct measurement of free radicals, from measurement of damage to lipids and DNA, and from measurement of antioxidant redox status, especially glutathione. There is little evidence that antioxidant supplementation can improve performance, but a large body of work suggests that bolstering antioxidant defences may ameliorate exercise-induced damage, suggesting that the benefits of antioxidant intervention may be for the long term rather than the short term.
This randomized, double-blind, placebo-controlled study was designed to determine the influence of carbohydrate supplementation on the natural killer cell response to 2.5 h of high-intensity running (76.7 +/- 0.4% VO2max). Thirty experienced marathon runners (VO2max 53.4 +/- 1.0 mL x kg[-1] x min[-1], age 41.5 +/- 1.4 yr) were randomized into carbohydrate supplement (N = 17) and placebo (N = 13) groups. Subjects rested for 10-15 min before a blood sample at 0715, and then ingested 0.75 L of carbohydrate beverage (Gatorade) or placebo. At 0730, subjects began running at 75-80% VO2max for 2.5 h and drank 0.25 L of carbohydrate or placebo fluid every 15 min. Immediately after the 2.5 h run (1000), another blood sample was taken, followed by 1.5 h, 3 h, and 6-h recovery samples. Carbohydrate supplementation versus placebo had a significant effect on the pattern of change in glucose, cortisol, and the blood concentration of natural killer cells ([F (4,25) = 3.79, P = 0.015], but not natural killer cell activity following 2.5 h of intensive running.
This study examined whether oral glutamine supplementation abolishes some of the exercise-induced changes in lymphocyte functions following long-term intense exercise. A group of 16 marathon runners participating in The Copenhagen Marathon 1996 were placed randomly in either a placebo (n = 7) or a glutamine receiving group (n = 9). Each subject received four doses of either placebo or glutamine (100 mg x kg(-1)) administered at 0, 30, 60, and 90-min post-race. In the placebo group the plasma glutamine concentrations were lower than pre-race values during the post-exercise period [mean 647 (SEM 32) compared to 470 (SEM 22) micromol x 1(-1) 90-min post-race, P < 0.05] whereas glutamine supplementation maintained the plasma glutamine concentration (at approximately 750 micromol x 1(-1)). Glutamine supplementation in vivo had no effect on the lymphokine activated killer (LAK) cell activity, the proliferative responses or the exercise-induced changes in concentrations or percentages of any of the leucocyte subpopulations examined. Glutamine addition in in vitro studies enhanced the proliferative response in both groups. These data would suggest that decreased plasma glutamine concentrations post-exercise are not responsible for exercise-induced decrease in LAK activity and that the influence of glutamine in vitro is not dependent on the plasma glutamine concentration at the time of sampling.
The purpose of the study was to investigate whether a carbohydrate-rich versus fat-rich diet influenced the effect of training on the immune system. Ten untrained young men ingested a carbohydrate-rich diet [65 energy percent (E%) carbohydrate] and ten subjects a fat-rich diet (62E% fat) while endurance training was performed 3-4 times a week for 7 weeks. Maximal oxygen uptake increased by 11% in both groups. Blood samples for immune monitoring were collected before and at the end of the study. Blood samples were also collected, in parallel, from 20 age-matched subjects, and data from these subjects were used to eliminate day-to-day variation in the immunological tests. Independently of diet, training increased the percentage of CD3-CD16+ CD56+ natural killer (NK) cells from [mean (SEM)] 14 (1) % to 20 (3) % (P = 0.05), whereas the NK-cell activity, either unstimulated or