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

Effect of Glutamine Supplementation on Muscular Damage Biomarkers in Professional Basketball Players

Scientific evidence supports the role of L-glutamine in improving immune function. This could suggest a possible role of L-glutamine in recovery after intense exercise. To this end, the present report aimed to study if oral L-glutamine supplementation could attenuate muscle damage in a group of players of a mainly eccentric sport discipline such as basketball. Participants (n = 12) were supplemented with 6 g/day of glutamine (G group) or placebo (P group) for 40 days in a crossover study design (20 days with glutamine + 20 days with placebo and vice versa). Blood samples were obtained at the beginning and at the end of each period and markers from exercise-induced muscle damage were determined. The glutamine supplemented group displayed significantly low values of aspartate transaminase, creatine kinase and myoglobin in blood, suggesting less muscle damage compared to the placebo. In addition, adrenocorticotropic hormone levels were lower in the glutamine supplemented group than in the placebo. As a result, the circulating cortisol levels did not increase at the end of the study in the glutamine supplemented group. Altogether, the results indicate that glutamine could help attenuate exercise-induced muscle damage in sport disciplines with predominantly eccentric actions.

Anti-fatigue effects of pea (Pisum sativum L.) peptides prepared by compound protease

In this study, the anti-fatigue effect of pea peptides in mice was explored. Mice were administrated with pea peptides for 30 days and then anti-fatigue related experiments and assays were performed. Swimming times of mice fed with pea peptides were very significantly longer than those of mice from control group in weight-loaded swimming test. Pea peptides showed very significant effect on decreasing level of blood urea nitrogen and blood lactic acid, increasing content of muscle glycogen and hepatic glycogen. Insulin level and lactate dehydrogenase activity was also improved by pea peptides treatment. Pea peptides demonstrated strong antioxidant activity in vivo test. Moreover, supplementation of pea peptides could improve immunity by increasing phagocyte activity, stimulating sIgA secretion and decreasing the pro-inflammatory cytokines in mice. These findings indicated that pea peptides had strong anti-fatigue effect in mice.

Glutamine as an Anti-Fatigue Amino Acid in Sports Nutrition

Glutamine is a conditionally essential amino acid widely used in sports nutrition, especially because of its immunomodulatory role. Notwithstanding, glutamine plays several other biological functions, such as cell proliferation, energy production, glycogenesis, ammonia buffering, maintenance of the acid-base balance, among others. Thus, this amino acid began to be investigated in sports nutrition beyond its effect on the immune system, attributing to glutamine various properties, such as an anti-fatigue role. Considering that the ergogenic potential of this amino acid is still not completely known, this review aimed to address the main properties by which glutamine could delay fatigue, as well as the effects of glutamine supplementation, alone or associated with other nutrients, on fatigue markers and performance in the context of physical exercise. PubMed database was selected to examine the literature, using the keywords combination “glutamine” and “fatigue”. Fifty-five studies met the inclusion criteria and were evaluated in this integrative literature review. Most of the studies evaluated observed that glutamine supplementation improved some fatigue markers, such as increased glycogen synthesis and reduced ammonia accumulation, but this intervention did not increase physical performance. Thus, despite improving some fatigue parameters, glutamine supplementation seems to have limited effects on performance.

Effects of wheat peptide supplementation on anti-fatigue and immunoregulation during incremental swimming exercise in rats

This study elucidated the effects of wheat peptide administration on anti-fatigue and immunoregulation functions in rats.

Exercise-induced immunodepression in endurance athletes and nutritional intervention with carbohydrate, protein and fat-what is possible, what is not?

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.

Importance of exercise immunology in health promotion

Chronic physical exercise with adequate intensity and volume associated with sufficient recovery promotes adaptations in several physiological systems. While intense and exhaustive exercise is considered an important immunosuppressor agent and increases the incidence of upper respiratory tract infections (URTI), moderate regular exercise has been associated with significant disease protection and is a complementary treatment of many chronic diseases. The effects of chronic exercise occur because physical training can induce several physiological, biochemical and psychological adaptations. More recently, the effect of acute exercise and training on the immunological system has been discussed, and many studies suggest the importance of the immune system in prevention and partial recovery in pathophysiological situations. Currently, there are two important hypotheses that may explain the effects of exercise and training on the immune system. These hypotheses including (1) the effect of exercise upon hormones and cytokines (2) because exercise can modulate glutamine concentration. In this review, we discuss the hypothesis that exercise may modulate immune functions and the importance of exercise immunology in respect to chronic illnesses, chronic heart failure, malnutrition and inflammation.

Effects of supplementation with free glutamine and the dipeptide alanyl-glutamine on parameters of muscle damage and inflammation in rats submitted to prolonged exercise

In this study, we investigated the effect of the supplementation with the dipeptide L-alanyl-L-glutamine (DIP) and a solution containing L-glutamine and L-alanine on plasma levels markers of muscle damage and levels of pro-inflammatory cytokines and glutamine metabolism in rats submitted to prolonged exercise. Rats were submitted to sessions of swim training for 6 weeks. Twenty-one days prior to euthanasia, the animals were supplemented with DIP (n = 8) (1.5 g.kg(-1)), a solution of free L-glutamine (1 g.kg(-1)) and free L-alanine (0.61 g.kg(-1)) (G&A, n = 8) or water (control (CON), n = 8). Animals were killed at rest before (R), after prolonged exercise (PE-2 h of exercise). Plasma concentrations of glutamine, glutamate, tumour necrosis factor-alpha (TNF-alpha), prostaglandin E2 (PGE2) and activity of creatine kinase (CK), lactate dehydrogenase (LDH) and muscle concentrations of glutamine and glutamate were measured. The concentrations of plasma TNF-alpha, PGE2 and the activity of CK were lower in the G&A-R and DIP-R groups, compared to the CON-R. Glutamine in plasma (p < 0.04) and soleus muscle (p < 0.001) was higher in the DIP-R and G&A-R groups relative to the CON-R group. G&A-PE and DIP-PE groups exhibited lower concentrations of plasma PGE2 (p < 0.05) and TNF-alpha (p < 0.05), and higher concentrations of glutamine and glutamate in soleus (p < 0.001) and gastrocnemius muscles (p < 0.05) relative to the CON-PE group. We concluded that supplementation with free L-glutamine and the dipeptide LL-alanyl-LL-glutamine represents an effective source of glutamine, which may attenuate inflammation biomarkers after periods of training and plasma levels of CK and the inflammatory response induced by prolonged exercise.

Performance-enhancing sports supplements: role in critical care

Many performance-enhancing supplements and/or drugs are increasing in popularity among professional and amateur athletes alike. Although the uncontrolled use of these agents can pose health risks in the general population, their clearly demonstrated benefits could prove helpful to the critically ill population in whom preservation and restoration of lean body mass and neuromuscular function are crucial. Post-intensive care unit weakness not only impairs post-intensive care unit quality of life but also correlates with intensive care unit mortality. This review covers a number of the agents known to enhance athletic performance, and their possible role in preservation of muscle function and prevention/treatment of post-intensive care unit weakness in critically ill patients. These agents include testosterone analogues, growth hormone, branched chain amino acid, glutamine, arginine, creatine, and beta-hydryoxy-beta-methylbutyrate. Three of the safest and most effective agents in enhancing athletic performance in this group are creatine, branched-chain amino acid, and beta-hydryoxy-beta-methylbutyrate. However, these agents have received very little study in the recovering critically ill patient suffering from post-intensive care unit weakness. More placebo-controlled studies are needed in this area to determine efficacy and optimal dosing. It is very possible that, under the supervision of a physician, many of these agents may prove beneficial in the prevention and treatment of post-intensive care unit weakness.

Impact of trapping and handling on Leukocyte Coping Capacity in bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus)

Small mammals are routinely live-trapped and subsequently handled for a range of ecological and behavioural studies. Despite the techniques commonly employed being potentially stressful for the individual animals involved, it has hitherto been difficult to quantify the physiological impact. Here, we report on the first instance of using the Leukocyte Coping Capacity technique (LCC) in bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus) to investigate the physiological impact of routine trapping and handling techniques. Twenty microlitres of blood were obtained from 40 animals, of which 25 were handled following standard protocols and 15 were not. We found that even a short period of acute stress is sufficient to trigger an immune response which was measurable using the LCC technique. These results further validate the use of the LCC technique for measuring the physiological impact of standard trapping and handling treatments on wild mammals.

Immunity in a variable world

Immune function is likely to be a critical determinant of an organism's fitness, yet most natural animal and plant populations exhibit tremendous genetic variation for immune traits. Accumulating evidence suggests that environmental heterogeneity may retard the long-term efficiency of natural selection and even maintain polymorphism, provided alternative host genotypes are favoured under different environmental conditions. 'Environment' in this context refers to abiotic factors such as ambient temperature or availability of nutrient resources, genetic diversity of pathogens or competing physiological demands on the host. These factors are generally controlled in laboratory experiments measuring immune performance, but variation in them is likely to be very important in the evolution of resistance to infection. Here, we review some of the literature emphasizing the complexity of natural selection on immunity. Our aim is to describe how environmental and genetic heterogeneities, often excluded from experimentation as 'noise', may determine the evolutionary potential of populations or the potential for interacting species to coevolve.

Peptide glutamine supplementation for tolerance of intermittent exercise in soccer players

OBJECTIVE

To investigate whether supplementation of carbohydrate together with peptide glutamine would increase exercise tolerance in soccer players.

METHODS

Nine male soccer players (mean age: 18.4 +/- 1.1 years; body mass: 69.2 +/- 4.6 kg; height: 175.5 +/- 7.3 cm; and maximum oxygen consumption of 57.7 +/- 4.8 ml x kg(-1) x min(-1)) were evaluated. All of them underwent a cardiopulmonary exercise test and followed a protocol that simulated the movements of a soccer game in order to evaluate their tolerance to intermittent exercise. By means of a draw, either carbohydrate with peptide glutamine (CARBOGLUT: 50 g of maltodextrin + 3.5 g of peptide glutamine in 250 ml of water) or carbohydrate alone (CARBO: 50 g of maltodextrin in 250 ml of water) was administered in order to investigate the enhancement of the soccer players' performances. The solution was given thirty minutes before beginning the test, which was performed twice with a one-week interval between tests.

RESULTS

A great improvement in the time and distance covered was observed when the athletes consumed the CARBOGLUT mixture. Total distance covered was 12750 +/- 4037m when using CARBO, and 15571 +/- 4184m when using CARBOGLUT (p<0.01); total duration of tolerance was 73 +/- 23 min when using CARBO and 88 +/- 24 min when using CARBOGLUT (p<0.01).

CONCLUSION

The CARBOGLUT mixture was more efficient in increasing the distance covered and the length of time for which intermittent exercise was tolerated. CARBOGLUT also reduced feelings of fatigue in the players compared with the use of the CARBO mixture alone.

Consumo de aminoácidos de cadeia ramificada não afeta o desempenho de endurance

A suplementação com aminoácidos de cadeia ramificada (BCAA) é uma das manipulações dietéticas mais populares entre atletas engajados em atividades de endurance. Entretanto, o papel ergogênico destes aminoácidos ainda não está totalmente estabelecido. Portanto, o objetivo do presente trabalho foi avaliar o efeito do consumo de BCAA sobre o exercício de endurance realizado até a exaustão. A fim de provocar redução do estoque de glicogênio muscular e, por conseguinte, maximizar a utilização dos BCAA, os sujeitos (n=17) foram submetidos a uma sessão prévia de exercício (corrida realizada a 75% do VO2max por 40 min seguida por 2 tiros a 90% do VO2max por 10 min cada um). Subseqüentemente, após o consumo aleatório de BCAA (77 mg.kg-1) ou placebo, seguindo modelo duplo cego cruzado, os participantes executaram um teste para determinação da capacidade de endurance (corrida a 90% do Limiar anaeróbio) até a exaustão. Ambos os experimentos, BCAA e placebo, foram separados por uma semana. Com relação ao tempo até a exaustão e a distância percorrida, nenhuma diferença foi detectada entre as condições experimentais. (Placebo: 50,1±8,9 vs BCAA: 52,4±4,5 min, respectivamente) (Placebo: 8,8±1,3 vs BCAA: 9,1±0,6 km, respectivamente). Além disto, também não foi evidenciada diferença na concentração plasmática de glicose, de lactato e de amônia entre ambas condições experimentais. Em conclusão, a suplementação de BCAA não afetou o desempenho de endurance em um teste de corrida até a exaustão.

Glutamine concentration and immune response of spinal cord-injured rats

BACKGROUND/OBJECTIVES

Glutamine plays a key role in immune response. Spinal cord injury (SCI) leads to severe loss of muscle mass and to a high incidence of infections. This study investigated the acute effect of SCI (2 and 5 days) on the plasma glutamine and skeletal muscle concentrations and immune responses in rats.

METHODS

A total of 29 adult male Wistar rats were divided as follows: control (C; n = 5), sham-operated (S2; n = 5) and spinal cord-transected (T2; n = 7). They were killed on day 2 after surgery/transection (acute phase). Another set was sham-operated (S5; n = 5), spinal cord-transected (T5; n = 7), and killed at day 5 after surgery/transection (secondary phase). Blood was collected; the white portion of the epitrochlearis and gastrocnemius muscles and the red portion of soleus muscles were dissected to measure the glutamine concentration. Gut-associated lymphocytes and peritoneal macrophages were obtained for immune parameters measurements.

RESULTS

Glutamine concentration in the plasma, gastrocnemius, and soleus muscles in rats with SCI were significantly reduced but not in the epitrochlearis muscle in the acute (2 days) and secondary (5 days) phases. Phagocytic response was reduced in the acute phase but increased in the secondary phase in rats with SCI. Superoxide production, on the other hand, was significantly increased at days 2 and 5 after SCI, and CD8+ lymphocytes subset decreased significantly on days 2 and 5.

CONCLUSIONS

Our results showed reduction in plasma glutamine and skeletal muscle concentrations after spinal cord transection. They also suggest that SCI and glutamine reduction contribute to an alteration in immune competence.

Protective effects of polysaccharide from Euphorbia kansui (Euphorbiaceae) on the swimming exercise-induced oxidative stress in mice

The present study examined the effects of derivatives of galactosides and glucosides in a polysaccharide extract from Euphorbia kansui (Euphorbiaceae) on exercise-induced oxidative stress in mice. Exhaustive swimming exercise significantly increases the degree of lipid peroxidation in terms of malondialdehyde content and reduces the antioxidant activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Our findings revealed that chronic oral treatment with the extract elevates enzymatic activities of SOD and GPx accompanied by a corresponding decrease in malondialdehyde. The antioxidative activities of these compounds against exercise-induced oxidative stress are correlated with various activities such as reducing the production of superoxide and hydroxyl radicals, inhibiting lipid peroxidation, enhancing antioxidative defenses, and increasing the production of SOD and GPx activity and expression in different tissues. These compounds may be involved in glycogen metabolism to meet the requirement of working skeletal muscles and act as antioxidants by terminating the chain reaction of lipid peroxidation to maintain the morphological stability of mitochondria in spinal motor neurons. These observations suggest that E. kansui has antioxidative and antifatigue properties and can be given as prophylactic and (or) therapeutic supplements for increasing antioxidant enzyme activities and preventing lipid peroxidation during strenuous exercise.

Efeito de diferentes protocolos de treinamento de força sobre parâmetros morfofuncionais, hormonais e imunológicos

O objetivo do estudo foi examinar a influência de dois diferentes protocolos de treinamento de força sobre parâmetros antropométricos (peso, IMC, massa gorda), funcionais (teste de 1-RM e teste de repetições máximas) e relacionados ao sistema endócrino (concentração de testosterona e de cortisol) e ao sistema imunológico (concentração de glutamina e de IgG). Participaram do estudo 12 homens treinados (27,4 ± 4,8 anos). Esses indivíduos foram aleatoriamente divididos em dois grupos, que posteriormente foram submetidos a dois protocolos de treinamento distintos: Múltiplas séries (MS) e Tri-set (TS). Amostras de sangue foram coletadas antes e depois de uma sessão de exercício de força, no início e no final do período de oito semanas de treinamento. Não foram observadas alterações nos parâmetros morfo-funcionais (com exceção do teste de repetições máximas para o agachamento). Com relação aos parâmetros endócrinos, foi observado que o TS provocou aumento significativo do cortisol, imediatamente após a sessão de treino, tanto no início como no final das oito semanas (p < 0,05). Ao observar o comportamento da relação testosterona para cortisol (T:C), pode-se notar um marcante aumento no grupo submetido ao protocolo MS após oito semanas de treinamento (p < 0,05). Com relação aos parâmetros imunológicos, não foi observada alteração na concentração de imunoglobulina G. A concentração de glutamina sofreu decréscimo após oito semanas em ambos os grupos. Esse decréscimo foi mais acentuado no grupo TS (p < 0,05). Os resultados obtidos sugerem que o método TS impôs maior estresse ao organismo. Além disso, os dados também indicam que o protocolo MS promove um ambiente mais propício ao anabolismo, após oito semanas de treinamento. Entretanto, ambos os métodos falharam em promover alterações significativas nos parâmetros morfofuncionais.

Exhaustive physical exercise increases the number of colonic preneoplastic lesions in untrained rats treated with a chemical carcinogen

Aberrant crypt foci (ACF) have been used for early detection of factors that influence colorectal carcinogenesis in rats. It has been observed that exhaustive exercise increases free radical DNA oxidative damage and depresses immune function, events also related to the increased risk for cancer development. Fifteen days after a single exhaustive swimming bout in untrained rats treated with a colon carcinogen, we observed a statistically significant increased number of ACF when compared to the non-exercised group. Thus, we concluded that exhaustive exercise increased the susceptibility for colon cancer in rats. From our finding and literature data, we hypothesize that, similarly to the suggested relationship between exercise and infections, exercise could be protective against cancer or it could increase the risk for this disease depending on its type, dose and duration.