Peptide glutamine supplementation for tolerance of intermittent exercise in soccer players

Concurrent Ingestion of Alkaline Water and L-Glutamine Enhanced Salivary α-Amylase Activity and Testosterone Concentration in Boxing Athletes

Athletes often take sport supplements to reduce fatigue and immune disturbances during or after training. This study evaluated the acute effects of concurrent ingestion of alkaline water and L-glutamine on the salivary immunity and hormone responses of boxers after training. Twelve male boxing athletes were recruited in this study. During regular training, the participants were randomly divided into three groups and asked to consume 400 mL of alkaline water (Group A), 0.15 g/kg body weight of L-glutamine with 400 mL of water (Group G), and 0.15 g/kg of L-glutamine with 400 mL of alkaline water (Group A+G) at the same time each day for three consecutive weeks. Before and immediately after the training, saliva, heart rates, and the rate of perceived exertion were investigated. The activity of α-amylase and concentrations of lactoferrin, immunoglobulin A (IgA), testosterone, and cortisol in saliva were measured. The results showed that the ratio of α-amylase activity/total protein (TP) significantly increased after training in Group A+G but not in Group A or G, whereas the ratios of lactoferrin/TP and IgA/TP were unaffected in all three groups. The concentrations of salivary testosterone after training increased significantly in Group A+G but not in Group A or G, whereas the salivary cortisol concentrations were unaltered in all groups. In conclusion, concurrent ingestion of 400 mL of alkaline water and 0.15 g/kg of L-glutamine before training enhanced the salivary α-amylase activity and testosterone concentration of boxers, which would be beneficial for post-exercise recovery.

Rapid indirect separation of glutamine enantiomers by micellar electrokinetic chromatography. Analysis of dietary supplements

Glutamine is the most abundant free proteinogenic α-amino acid. It is naturally produced in the organism and acts as a precursor for the synthesis of different biologically important molecules (such as proteins or nucleotides). However, under stressful conditions, the organism is unable to produce it in enough amounts to function properly. Thus, glutamine (Gln)-based supplements have become increasingly popular over the last decade. Since legal regulations establish that amino acid-based dietary supplements must contain only the L-enantiomer and not the racemate, adequate chiral methodologies are required to achieve their quality control. In this work, an analytical methodology based on the use of micellar electrokinetic chromatography is proposed for the rapid enantiomeric determination of DL-Gln in dietary supplements. Using (+)-1-(9-fluorenyl)-ethyl chloroformate as a derivatizing agent and ammonium perfluorooctanoate as separation medium, the Gln diastereoisomers formed under optimal conditions were separated in 8 min with a resolution of 2.8. The analytical characteristics of the method were evaluated in terms of linearity, precision, accuracy, and limits of detection/quantitation, and they were found appropriate for the analysis of L-Gln-based dietary supplements.

Hydrolyzed whey protein enriched with glutamine dipeptide attenuates skeletal muscle damage and improves physical exhaustion test performance in triathletes

Purpose

To investigate the effects of hydrolyzed whey protein enriched with glutamine dipeptide on the percentage of oxygen consumption, second ventilatory threshold, duration and total distance covered, and skeletal muscle damage during an exhaustion test in elite triathletes.

Methods

The study was a randomized, double-blinded, placebo-controlled, crossover trial. Nine male triathletes performed a progressive incremental test on a treadmill ergometer (1.4 km h^-1·3 min^-1) 30 min after ingesting either 50 g of maltodextrin plus four tablets of 700 mg hydrolyzed whey protein enriched with 175 mg of glutamine dipeptide diluted in 250 ml of water (MGln) or four tablets of 700 mg maltodextrin plus 50 g maltodextrin diluted in 250 ml of water (M). Each athlete was submitted to the two dietary treatments and two corresponding exhaustive physical tests with an interval of one week between the interventions. The effects of the two treatments were then compared within the same athlete. Maximal oxygen consumption, percentage of maximal oxygen consumption, second ventilatory threshold, and duration and total distance covered were measured during the exhaustion test. Blood was collected before and immediately after the test for the determination of plasma lactate dehydrogenase (LDH) and creatine kinase (CK) activities and lactate concentration (also measured 6, 10, and 15 min after the test). Plasma cytokines (IL-6, IL-1β, TNF-α, IL-8, IL-10, and IL-1ra) and C-reactive protein levels were also measured.

Results

A single dose of MGln increased the percentage of maximal oxygen consumption, second ventilatory threshold duration, and total distance covered during the exhaustion test and augmented plasma lactate levels 6 and 15 min after the test. MGln also decreased plasma LDH and CK activities indicating muscle damage protection. Plasma cytokine and C-reactive protein levels did not change across the study periods.

Conclusion

Conditions including overnight fasting and a single dose of MGln supplementation resulted in exercising at a higher percentage of maximal oxygen consumption, a higher second ventilatory threshold, blood lactate levels, and reductions in plasma markers of muscle damage during an exhaustion test in elite triathletes. These findings support oral glutamine supplementation's efficacy in triathletes, but further studies require.

Effects of carbohydrate and glutamine supplementation on cytokine production by monocytes after exercise in hypoxia: A crossover, randomized, double-blind pilot study

OBJECTIVES

The aim of this study was to evaluate the combined effects of carbohydrate (CHO) and glutamine (Gln) supplementation on cytokine production by monocytes after exercise until exhaustion performed in hypoxia.

METHODS

Fifteen physically active men underwent three exercises until exhaustion with an intensity of 70% maximal oxygen intake at a simulated height of 4500 m under the following supplementation: placebo, CHO (maltodextrin 8%/200 mL for 20 min), and CHO + Gln (Gln 20 g/d for 6 d and maltodextrin 8%/200 mL for 20 min) during exercise and for 2 h of recovery. Analysis of variance for repeated measures followed by the Tukey's post hoc test was realized and P < 0.05 was considered statistically significant.

RESULTS

Oxygen saturation of arterial blood (SaO₂%) decreased in the three trials compared with baseline. Two hours post-exercise, the SaO₂% was high in CHO + Gln condition compared with placebo. Two hours after exercise, interleukin (IL)-1β decreased compared with post-exercise in placebo and was lower compared with baseline in the CHO + Gln condition. Tumor necrosis factor-α decreased 2 h after exercise compared with baseline and pre-exercise in the CHO + Gln condition. No changes were observed in myeloperoxidase or IL-6 production. Two hours after exercise, Gln decreased compared with baseline and post-exercise in placebo and decreased 2 h after exercise in relation to post-exercise in the CHO condition. Gln increased post-exercise compared with pre-exercise in the CHO + Gln condition. Although erythropoietin did not change in this condition, it was high post-exercise and 2 h after exercise in the placebo condition compared with baseline and 2 h after exercise compared with baseline and pre-exercise in the CHO condition.

CONCLUSIONS

Gln supplementation for 6 d before exercise, associated with CHO supplementation during exercise, was able to revert Gln reduction after exercise and after 2 h of recovery and may have contributed to reducing tumor necrosis factor-α production, suggesting a possible anti-inflammatory effect of supplementation.

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.

The effect of glutamine supplementation on athletic performance, body composition, and immune function: A systematic review and a meta-analysis of clinical trials

BACKGROUND & AIM

This systematic review and meta-analysis of available evidence was conducted to obtain a conclusive result on the effects of glutamine supplementation on athletes.

METHODS

Systematic review and meta-analysis. Data related to body mass, lean body mass, body fat percentage, Vo2 max, lymphocytes, leukocytes and neutrophil counts were extracted to determine the effects of GLN on performance outcomes.

DATA SOURCES

The literature search was conducted across the databases Pubmed, Scopus, ISI Web of Science, SID (Scientific Information Database) and Cochrane Central Register of Controlled Trials, covering a period up to January 2017.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Clinical trials evaluating glutamine supplementation outcomes on athletes aged over 18 were included.

RESULTS

A total of 47 studies were included in the systematic review, and 25 trials matched the inclusion criteria for the meta-analysis. According to the meta-analysis, glutamine has a significant effect on weight reduction (WMD = -1.36 [95% CI: -2.55 to -0.16], p = 0.02). Moreover, neutrophil numbers were reduced following glutamine intake at doses greater than 200 mg/kg body weight (WMD = -605.77 [95% CI: -1200.0 to 52.1]; P = 0.03). Also, supplementation by glutamine dipeptide resulted in higher blood glucose after exercise (WMD = 0.51 [95% CI: 0.18, 0.83] mmol/l; P = 0.002). There was no association between glutamine ingestion and other outcomes investigated.

CONCLUSION

According to this meta-analysis, generally, glutamine supplementation has no effect on athletics immune system, aerobic performance, and body composition. However, the current study showed that glutamine resulted in greater weight reduction. In addition, the present study suggests that the efficacy of glutamine supplementation on neutrophil numbers could be affected by supplement type and dose.

Effects of Carbohydrate and Glutamine Supplementation on Oral Mucosa Immunity after Strenuous Exercise at High Altitude: A Double-Blind Randomized Trial

This study analyzed the effects of carbohydrate and glutamine supplementation on salivary immunity after exercise at a simulated altitude of 4500 m. Fifteen volunteers performed exercise of 70% of VO_2peak until exhaustion and were divided into three groups: hypoxia placebo, hypoxia 8% maltodextrin (200 mL/20 min), and hypoxia after six days glutamine (20 g/day) and 8% maltodextrin (200 mL/20 min). All procedures were randomized and double-blind. Saliva was collected at rest (basal), before exercise (pre-exercise), immediately after exercise (post-exercise), and two hours after exercise. Analysis of Variance (ANOVA) for repeated measures and Tukey post hoc test were performed. Statistical significance was set at p < 0.05. SaO₂% reduced when comparing baseline vs. pre-exercise, post-exercise, and after recovery for all three groups. There was also a reduction of SaO₂% in pre-exercise vs. post-exercise for the hypoxia group and an increase was observed in pre-exercise vs. recovery for both supplementation groups, and between post-exercise and for the three groups studied. There was an increase of salivary flow in post-exercise vs. recovery in Hypoxia + Carbohydrate group. Immunoglobulin A (IgA) decreased from baseline vs. post-exercise for Hypoxia + Glutamine group. Interleukin 10 (IL-10) increased from post-exercise vs. after recovery in Hypoxia + Carbohydrate group. Reduction of tumor necrosis factor alpha (TNF-α) was observed from baseline vs. post-exercise and after recovery for the Hypoxia + Carbohydrate group; a lower concentration was observed in pre-exercise vs. post-exercise and recovery. TNF-α had a reduction from baseline vs. post-exercise for both supplementation groups, and a lower secretion between baseline vs. recovery, and pre-exercise vs. post-exercise for Hypoxia + Carbohydrate group. Five hours of hypoxia and exercise did not change IgA. Carbohydrates, with greater efficiency than glutamine, induced anti-inflammatory responses.

Fatigue and pacing in high-intensity intermittent team sport: an update

With the advancements in player tracking technology, the topic of fatigue and pacing in team sport has become increasingly popular in recent years. Initially based upon a pre-conceived pacing schema, a central metabolic control system is proposed to guide the movement of players during team sport matches, which can be consciously modified based on afferent signals from the various physiological systems and in response to environmental cues. On the basis of this theory, coupled with the collective findings from motion-analysis research, we sought to define the different pacing strategies employed by team sport players. Whole-match players adopt a 'slow-positive' pacing profile (gradual decline in total running intensity), which appears to be global across the different team sports. High-intensity movement also declines in a 'slow-positive' manner across most team sport matches. The duration of the exercise bout appears to be important for the selected exercise intensity, with the first introduction to a match as a substitute or interchange player resulting in a 'one bout, all out' strategy. In a limited interchange environment, a second introduction to the match results in a 'second-bout reserve' strategy; otherwise, the 'one bout, all out' strategy is likely to be adopted. These pacing profiles are proposed to reflect the presence of a central regulator that controls the movement intensity of the player to optimize performance, as well as avoiding the harmful failure of any physiological system. The presence of 'temporary fatigue' reflects this process, whereby exercise intensity is consciously modulated from within the framework of a global pacing schema.

Effect of glutamine and maltodextrin acute supplementation on anaerobic power

Purpose

The aim of this study was to investigate whether supplementation of carbohydrate together with peptide glutamine would prevent anaerobic power decrease during repeated competitions.

Methods

Twenty eight physical education male students voluntarily participated in the study. Subjects were randomly divided on a maximal power (Max power) output value basis into four groups: 1) G group (oral ingestion of glutamine at the dose of 0.25 g/kg body mass in 250 ml of water), 2) M group (a single carbohydrate at a concentration of 50g of maltodextrin in 250 ml of water), 3) GM group (carbohydrate at a concentration of 50g of maltodextrin + glutamine at the dose of 0.25 g/kg body mass in 250 ml of water) and, 4) P group (just 250 ml of water and 30 gram sweetener). Each subject performed three times Running-based Anaerobic Sprint Test (RAST) with intervals of 1 hour. Max power, Minimal power (Min power) and fatigue were calculated for each participant.

Results

There was a significant decrease in Max and Min power in P group in time series (P<0.05). Furthermore, regarding the Max and Min power, there was significant difference between P and GM group in third bout indicating stronger influence of combination of maltodextrin and glutamine in comparison with pure consumption of glutamine and maltodextrin (P< 0.05).

Conclusions

It seems acute supplementation of glutamine and maltodextrin combination, 2 hours before exercise is more efficient in prevention of anaerobic power decrease than consumption of a pure carbohydrate or glutamine in repeated bouts of RAST protocol. Thus, supplementation with both carbohydrate and peptide glutamine improved the physical performance of athletes during repeated competitions. Obviously, it is necessary to do further studies.

Effect of a pre-workout energy supplement on acute multi-joint resistance exercise

The effect of a pre-workout energy supplement on acute multi- joint resistance exercise was examined in eight resistance-trained college-age men. Subjects were randomly provided either a placebo (P) or a supplement (S: containing caffeine, taurine, glucuronolactone, creatine, β-alanine, and the amino acids; leucine, isoleucine, valine, glutamine and arginine) 10 minutes prior to resistance exercise. Subjects performed 4 sets of no more than 10 repetitions of either barbell squat or bench press at 80% of their pre-determined 1 repetition- maximum (1RM) with 90 seconds of rest between sets. Dietary intake 24 hours prior to each of the two training trials was kept constant. Results indicate that consuming the pre-workout energy drink 10 minutes prior to resistance exercise enhances performance by significantly increasing the number of repetitions successfully performed (p = 0.022) in S (26.3 ± 9.2) compared to P (23.5 ± 9.4). In addition, the average peak and mean power performance for all four sets was significantly greater in S compared to P (p < 0.001 and p < 0.001, respectively). No differences were observed between trials in subjective feelings of energy during either pre (p = 0.660) or post (p = 0.179) meaures. Similary, no differences between groups, in either pre or post assessments, were observed in subjective feelings of focus (p = 0.465 and p = 0.063, respectively), or fatigue (p = 0.204 and p = 0.518, respectively). Results suggest that acute ingestion of a high-energy supplement 10 minutes prior to the onset of a multi-joint resistance training session can augment training volume and increase power performance during the workout. Key pointsConsumption of a pre-workout energy supplement containing caffeine, taurine, glucuronolactone, creatine, β-alanine, and amino acids consumed 10 minutes prior to a bout of resistance exercise enhances the total number of repetitions performed during the exercise bout.Power outputs for each repetition during the workout were significantly greater when using the supplement compared to placebo.Ingestion of supplement did not have any significant effect on subjective measures of fatigue, energy and focus.

Estudo de publicações em periódicos gerais de artigos sobre ortopedia e aparelho locomotor

Os autores estudam o perfil de publicação de artigos sobre ortopedia e área de interesse em aparelho locomotor em revistas gerais, não específicas de ortopedia, com registro no PUBMED, em um período de dois anos. Selecionados 67 artigos com distribuição heterogênea entre as revistas estudadas foi constatada presença de 26,47% de artigos com desenho de intervenção e 38% com desenho observacional. Os dados são comentados.

Improved time to exhaustion following ingestion of the energy drink Amino Impact

BACKGROUND

The purpose of this study was to examine the effect of a commercially available energy drink on time to exhaustion during treadmill exercise. In addition, subjective measures of energy, focus, and fatigue were examined

METHODS

Fifteen subjects (9 men and 6 women; 20.9 +/- 1.0 y; 172.1 +/- 9.1 cm; 71.0 +/- 9.4 kg; 16.9 +/- 9.7% body fat) underwent two testing sessions administered in a randomized, double-blind fashion. Subjects reported to the laboratory in a 3-hr post-absorptive state and were provided either the supplement (SUP; commercially marketed as Amino Impact) or placebo (P). During each laboratory visit subjects performed a treadmill run (70% VO2 max) to exhaustion. Mean VO2 was measured during each endurance exercise protocol. Subjects were required to complete visual analog scales for subjective measures of energy, focus and fatigue at the onset of exercise (PRE), 10-mins into their run (EX10) and immediately post-exercise (IP).

RESULTS

Time to exhaustion was significantly greater (p = 0.012) during SUP than P. Subjects consuming the supplement were able to run 12.5% longer than during the placebo treatment. Subjects consuming SUP reported significantly greater focus (p = 0.031), energy (p = 0.016), and less fatigue (p = 0.005) at PRE. Significant differences between groups were seen at EX10 for focus (p = 0.026) and energy (p = 0.004), but not fatigue (p = 0.123). No differences were seen at IP for either focus (p = 0.215), energy (p = 0.717) or fatigue (p = 0.430).

CONCLUSIONS

Results of this study indicate that the supplement Amino Impact can significantly increase time to exhaustion during a moderate intensity endurance run and improve subjective feelings of focus, energy and fatigue.

Importance of the different posterolateral knee static stabilizers: biomechanical study

PURPOSE

The purpose of this study was to evaluate the relative importance of the different static stabilizers of the posterolateral corner of the knee in cadavers.

METHODS

Tests were performed with the application of a varus and external rotation force to the knee in extension at 30 and 60 degrees of flexion using 10 cadaver knees. The forces were applied initially to an intact knee and then repeated after a selective sectioning of the ligaments into the following: section of the lateral collateral ligament; section of the lateral collateral ligament and the popliteofibular complex; and section of the lateral collateral ligament, the popliteofibular complex and the posterolateral capsule. The parameters studied were the angular deformity and stiffness when the knees were submitted to a 15 Newton-meter varus torque and a 6 Newton-meter external tibial torque. Statistical analysis was performed using the ANOVA (Analysis of Variance) and Tukey's tests.

RESULTS AND CONCLUSION

Our findings showed that the lateral collateral ligament was important in varus stability at 0, 30 and 60 degrees. The popliteofibular complex was the most important structure for external rotation stability at all angles of flexion and was also important for varus stability at 30 and 60 degrees. The posterolateral capsule was important for varus stability at 0 and 30 degrees and for external rotation stability in extension.

LEVEL OF EVIDENCE

Level IV (cadaver study).

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.

Examination of the efficacy of acute L-alanyl-L-glutamine ingestion during hydration stress in endurance exercise

BACKGROUND

The effect of acute L-alanyl-L-glutamine (AG; Sustamine) ingestion on performance changes and markers of fluid regulation, immune, inflammatory, oxidative stress, and recovery was examined in response to exhaustive endurance exercise, during and in the absence of dehydration.

METHODS

Ten physically active males (20.8 +/- 0.6 y; 176.8 +/- 7.2 cm; 77.4 +/- 10.5 kg; 12.3 +/- 4.6% body fat) volunteered to participate in this study. During the first visit (T1) subjects reported to the laboratory in a euhydrated state to provide a baseline (BL) blood draw and perform a maximal exercise test. In the four subsequent randomly ordered trials, subjects dehydrated to -2.5% of their baseline body mass. For T2, subjects achieved their goal weight and were not rehydrated. During T3 - T5, subjects reached their goal weight and then rehydrated to 1.5% of their baseline body mass by drinking either water (T3) or two different doses (T4 and T5) of the AG supplement (0.05 g.kg-1 and 0.2 g.kg-1, respectively). Subjects then exercised at a workload that elicited 75% of their VO2 max on a cycle ergometer. During T2 - T5 blood draws occurred once goal body mass was achieved (DHY), immediately prior to the exercise stress (RHY), and immediately following the exercise protocol (IP). Resting 24 hour (24P) blood samples were also obtained. Blood samples were analyzed for glutamine, potassium, sodium, aldosterone, arginine vasopressin (AVP), C-reactive protein (CRP), interleukin-6 (IL-6), malondialdehyde (MDA), testosterone, cortisol, ACTH, growth hormone and creatine kinase. Statistical evaluation of performance, hormonal and biochemical changes was accomplished using a repeated measures analysis of variance.

RESULTS

Glutamine concentrations for T5 were significantly higher at RHY and IP than T2 - T4. When examining performance changes (difference between T2 - T5 and T1), significantly greater times to exhaustion occurred during T4 (130.2 +/- 340.2 sec) and T5 (157.4 +/- 263.1 sec) compared to T2 (455.6 +/- 245.0 sec). Plasma sodium concentrations were greater (p < 0.05) at RHY and IP for T2 than all other trials. Aldosterone concentrations at RHY and IP were significantly lower than that at BL and DHY. AVP was significantly elevated at DHY, RHY and IP compared to BL measures. No significant differences were observed between trials in CRP, IL-6, MDA, or in any of the other hormonal or biochemical measures.

CONCLUSION

Results demonstrate that AG supplementation provided a significant ergogenic benefit by increasing time to exhaustion during a mild hydration stress. This ergogenic effect was likely mediated by an enhanced fluid and electrolyte uptake.