Using in vitro and in vivo state-of-the-art methodologies the researchers showed that muscle injury, ischemia and aged-related muscle wasting are conditions characterized by reduced glutamine. One reason for this is the loss of glutamine production by the muscle itself because of its damage.

Berardi explains, "Using genetic tools and pharmacological drugs inhibiting GLUD1, an enzyme that metabolizes glutamine, we could prevent the post-injury drop in glutamine. This resulted in the overproduction of glutamine by inflammatory cells , named macrophages, reaching the muscle after damage.

The newly produced glutamine could be used by muscle stem cells to quickly regenerate the damaged muscle tissue. We found the same thing in acute as well as chronic degenerative conditions, such as aging, leading to a faster muscle functional recovery. This study reveals glutamine as a sensor molecule whose levels in the muscle tissue control a regenerative program and suggests that GLUD1 is a therapeutic target that could enable opportunities for muscle regeneration after acute injury or chronic degenerative conditions such as aging.

Mazzone emphasizes the potential of their discovery: "This provides hope for the treatment of degenerative muscle conditions, including trauma, ischemia and aging.

The latter in particular represents an important challenge for healthcare with an increasing average age of the global population, accompanied by aged-related sarcopenia. In a joined effort with VIB Discovery Sciences and the Centre for Drug Design and Discovery, we are currently developing and testing more selective GLUD1 inhibitors for chronic muscle wasting conditions including muscular dystrophy.

More information: Min Shang et al. Macrophage-derived glutamine boosts satellite cells and muscle regeneration, Nature DOI: html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission.

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An observer blinded to the group allocations performed the tissue analysis and scored the severity of organ injury.

The severity of liver injuries observed in the tissue sections was scored as follows: 0, minimal or no evidence of injury; 1, mild injury consisting of cytoplasmic vacuolation and focal nuclear pyknosis; 2, moderate to severe injury with extensive nuclear pyknosis, cytoplasmic hypereosinophilia, and loss of intercellular borders; and 3, severe necrosis with disintegration of the hepatic cords, hemorrhage, and neutrophil infiltration Ke et al.

All evaluations were performed on five fields per section and five sections per organ by a blinding observer. The collected data were analyzed using SPSS for Windows v The continuous variables have been expressed in Mean ± SD, and an independent t -test was employed to analyze and compare the tissue injury score between prevention and treatment group.

The analysis of variance ANOVA was applied to examine the differences of CK-MM and blood cell count between three groups. The significance level for all statistical comparisons was set as α less than or equal to 0.

The skeletal muscle damage biomarker CK-MM was analyzed. The data showed that timing of the oral intake affects the reduction of serum CK-MM level. The CK-MM level of untreated vehicle group was elevated after exhaustive exercise and reached its highest point at 24 h after exercise Figure 1. The serum CK-MM level of the prevention group was elevated at 12 h.

The treatment group exhibited almost no elevation. FIGURE 1. The comparison of CK-MM levels between groups. The CK-MM levels of treatment group were lower than those in prevention group at 12 and 24 hs. Complete blood count analysis was performed at various time points after exercise treatment.

Hematocrit showed a similar trend to RBC. The average HCT was significantly higher in the treatment group 12 h after exercise and reached a maximum difference at 24 h. We also observed that PLT improved to a similar extent as RBC did.

The average PLT was considerably higher in the treatment group after exercise 12 h and had a maximum improvement at 24 h.

The average PLT of the treatment group in p24 was In this part, we found that oral intake of glutamine elevated RBC, HCT, and PLT amounts only in the treatment group.

FIGURE 2. The comparison of blood count levels between groups. Treatment group had higher RBC A , HCT B and PLT C values than those in prevention group at 24 hs. The HE staining results indicated tissue injuries in the cardiac muscles Figure 3A , kidneys Figure 3B , and liver Figure 3C in the prevention group, with average respective scores of 1.

The treatment group had less tissue injury in the cardiac muscles Figure 3D , kidneys Figure 3E , and liver Figure 3F , with average respective scores of 0 Figure 3G , 1.

These data of histological examination indicated that the treatment group had a more substantial reduction in damage, especially cardiac and renal damage, compared with the prevention group Figure 3. FIGURE 3. The histological finding and tissue injury score between prevention and treatment group.

The histological examination of prevention A—C and treatment group D—F. The prevention group had higher tissue injury score on the Heart G and kidney H than those in treatment group. There was no significant difference between groups on the liver I.

We found that glutamine can reduce skeletal muscle damage caused by exhaustive exercise, and the treatment group had a greater reduction in damage than the prevention group did Figure 1. We also found that oral intake of glutamine elevated RBC, HCT, and PLT amounts only in the treatment group Figure 2.

A histological examination indicated that the treatment group had a more substantial reduction in damage, especially cardiac and renal damage, compared with the prevention group Figure 3.

The results of this study indicated that the effect of supplementing L-glutamine after exercise was more satisfactory than that before exercise. The tissue section results demonstrated that glutamine not only protected muscles under exhaustive exercise but also prevented damage to specific organs.

After exhaustive exercise, because of the continued contraction of skeleton muscles and enhanced circulation stress, both skeletal and cardiac muscles are damaged. Markers of skeletal and cardiac muscle damage, such as serum biomarker CK-MM, indicated damage after exercise, and the damage could also be found in histopathology examinations Amelink et al.

Studies have demonstrated that supplementation with glutamine has beneficial effects on reducing the parameters of muscle damage and inflammation in exercise rats Bowtell et al. Similarly, in our study, the serum CK-MM level of the untreated vehicle group was elevated after exhaustive exercise and reached its highest point at 24 h after exercise Figure 1.

Decreased glutamine concentrations typically correlate with the severity of the underlying disease process, with large amounts of glutamine catabolized in muscle at the time of damage. Concentrations only gradually recover in the later stage of healing Durkalec-Michalski et al.

During exhaustive exercise, the protein metabolism of muscles increases. At this time, glutamine can assist in gluconeogenesis, generating glucose to be used by the muscles, promoting energy metabolism and antioxidant capacity, reducing organ damage, and contributing to the synthesis and repair of muscle tissue.

Under exhaustive exercise, glutamine in the body is used in substantial quantities, resulting in a decreased glutamine concentrations Afonso et al. We further found that the intake timing will notably affect the beneficial effect of glutamine for exhaustive exercise.

This might cause by a short half-life of glutamine. Glutamine was more effective when taken orally after rather than before exhaustive exercise. We also found that the RBC level increased substantially upon the post-exercise intake of glutamine Figure 2.

Previous researchers have demonstrated that glutamine is an essential source for glutathione synthesis in human erythrocytes Whillier et al.

During exhaustive exercise, because of elevated oxidative stress and overloaded cardiac output, RBC becomes oxidative damaged Smith, No study has discussed whether glutamine mitigates oxidative damage on RBC or enhances the regeneration of RBC after exhaustive exercise.

We found that the RBC level increase and accordingly glutamine might enhance the regeneration of RBC upon oral intake after exercise Figure 2.

The differences between the prevention and treatment groups were not only with respect to RBC concentration, but also regarding tissue damage for histological examinations. The treatment group showed more considerable damage reduction in the cardiac muscle and kidneys than the prevention group showed.

Figures 3G, H The primary cause for this difference in damage reduction might be the maldigestion of glutamine during exercise. Eating before exhaustive exercise often causes maldigestion; furthermore, body temperature increases during exercise until rest.

Research has demonstrated that in a hot environment, intestinal permeability is reduced by glutamine supplementation Pugh et al. Therefore, glutamine intake is more beneficial after rather than before exhaustive exercise. Relative to the prevention group, the treatment group had a more considerable reduction in the damage to their cardiac muscles and kidneys.

Our results revealed that the timing of glutamine oral intake influences outcomes, such as improved organs protection and elevated RBC concentration in blood.

Although the conditions of sports practice in humans are far different from those that can be applied in laboratory rats, these results might suggest athletes take supplements at the proper timing after exhaustive exercise.

Daily supplementation of L-glutamine can reduce the skeletal muscle damage caused by exhaustive exercise and that the timing of the oral intake affects the reduction. Glutamine as a treatment more considerably reduced damage than it had as a prophylactic.

We also observed that the oral intake of glutamine could elevate RBC, HCT, and PLT only after exhaustive exercise. It seems like the proper timing for taking glutamine supplements is after exercise. However, the further clinical trial is needed in the future study.

The animal study was reviewed and approved by the Institutional Animal Care and Use Committee of Tzu Chi University IACUC No: C-CL: Conceptualization, and prepared the original draft.

C-YK: Designed the animal study, analyzed the data, and wrote the original draft. W-TW: Performed the histological examination, supervised the study and data collection. R-PL: Conceptualization, supervised the study, completed the final manuscript.

All authors contributed to the article and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers.

Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. Afonso, J. The effectiveness of post-exercise stretching in short-term and delayed recovery of strength, range of motion and delayed onset muscle soreness: A systematic review and meta-analysis of randomized controlled trials.

PubMed Abstract CrossRef Full Text Google Scholar. Amelink, G. Exercise-induced muscle damage in the rat: The effect of vitamin E deficiency.

American Dietetic AssociationDietitians of CanadaAmerican College of Sports Medicine Rodriguez, N. American College of Sports Medicine position stand. Nutrition and athletic performance.

Sports Exerc. Amin, M. Exercise-induced downregulation of serum interleukin-6 and tumor necrosis factor-alpha in Egyptian handball players. Saudi J. Anz, A. Exercise-mobilized platelet-rich plasma: Short-term exercise increases stem cell and platelet concentrations in platelet-rich plasma.

Arthroscopy 35 1 , — Banfi, G. Metabolic markers in sports medicine. Baumert, P. Genetic variation and exercise-induced muscle damage: Implications for athletic performance, injury and ageing. Beck, W. Melatonin has an ergogenic effect but does not prevent inflammation and damage in exhaustive exercise.

Bowtell, J. Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. Coqueiro, A. Effects of glutamine and alanine supplementation on muscle fatigue parameters of rats submitted to resistance training.

Nutrition 65, — Glutamine as an anti-fatigue amino acid in sports nutrition. Nutrients 11 4 , Cruzat, V. Effects of supplementation with free glutamine and the dipeptide alanyl-glutamine on parameters of muscle damage and inflammation in rats submitted to prolonged exercise.

Cell biochem. Dupuy, O. An evidence-based approach for choosing post-exercise recovery techniques to reduce markers of muscle damage, soreness, fatigue, and inflammation: A systematic review with meta-analysis.

Durkalec-Michalski, K. The effect of multi-ingredient intra-versus extra-cellular buffering supplementation combined with branched-chain amino acids and creatine on exercise-induced ammonia blood concentration and aerobic capacity in taekwondo athletes.

Sports Nutr. Durmuş, İ. Exercise-based cardiac rehabilitation has a strong relationship with mean platelet volume reduction. Gleeson, M. Dosing and efficacy of glutamine supplementation in human exercise and sport training. Grassi, A. Is platelet-rich plasma prp effective in the treatment of acute muscle injuries?

A systematic review and meta-analysis. Sports Med. Ke, C. Vitamin D3 reduces tissue damage and oxidative stress caused by exhaustive exercise. Koch, A. The creatine kinase response to resistance exercise. Neuronal Interact. PubMed Abstract Google Scholar.

Lippi, G. Epidemiological, biological and clinical update on exercise-induced hemolysis.

Conclusion: The therapeutic effect of L-glutamine after exhaustive exercise was more effective than preventive before exercise. Acute muscle damage often occurs after exhaustive exercise and also causes levels of lactatic acid, creatine kinase CK , aspartate aminotransferase AST , alanine aminotransferase ALT , and lactate dehydrogenase in serum to increase Baumert et al.

Exercise, especially exhaustive exercise, defined as exercise till unable to move, causes an inflammatory response and damage to multiple organs, including skeletal muscles, the respiratory system, the liver, and the kidneys Ke et al.

During exhaustive exercise, inflammatory responses such as leukocyte aggregation can be identified in muscle tissue Peake et al. Muscle damage can occur when weaker sarcomeres are destroyed during muscle contraction or when a coupling mechanism stimulated through muscle excitation leads to excessive muscle lengthening Negro et al.

In addition, protein catabolism is greater than protein anabolism during exhaustive exercise. In the metabolic pathway of protein catabolism, the nitrogen-containing pathway must first undergo transamination Gleeson, ; Coqueiro et al. Glutamine in the muscle is converted into glutamic acid to facilitate transamination, and the glutamine concentration in the body thus decreases after exhaustive exercise Trivedi et al.

Therefore, a moderate amount of glutamine supplementation may assist in reducing muscle damage resulting from exhaustive exercise Gleeson, Glutamine is not only nutritious but also able to regulate other bioactivities in the body. The animal study indicates that oral supplementation with L-glutamine and alanine in the free form can effectively maintain glutamine stores, leading to lower levels of proinflammatory biomarkers such as TNF-a, IL-1β and IL-6 Cruzat et al.

Additionally, the study shows that these supplementations can also have beneficial effects on biomarkers of muscle damage and inflammation such as muscle glycogen and plasma creatine kinase isozyme CK after a period of training.

The study also found that while glutamine and alanine supplementation improved some fatigue markers, it did not improve exercise performance Coqueiro et al. Moreover, glutamine affects many bioactivities in the digestive system and the immune system in the human body. In the digestive system, glutamine supplements can accelerate rapidly dividing cells and reduce splanchnic bed damage in the intestines, liver, and pancreas Coqueiro et al.

In the immune system, glutamine downregulates lymphocyte count, macrophage count, and the expression of proinflammatory cytokines, such as interlukin-1 IL-1 , IL-2, Interferon-gamma Amin et al. Glutamine supplementation for human exercise was demonstrated to effectively reduce tissue and organ damage and promote glycogen synthesis, providing nutritional support for the immune system, and preventing infection Bowtell et al.

Muscle metabolism parameters such as creatine kinase isozyme MM CK-MM were used as an indicator for muscle damage. The serum level of CK-MM typically increases after exercise Banfi et al. During exercise, local hypoxia in skeletal muscles, accumulation of metabolites, and an increase in free radicals cause cell membrane damage and increased permeability.

At this time, CK-MM in muscle cells penetrates the cell membrane and enters the blood, which is the same process that leads to an increase of CK-MM after exhaustive exercise Koch et al.

Platelet count also decreases after exercise and this decrease might be related to exercise-based cardiac rehabilitation that decreases mortality in patients with coronary artery disease Anz et al.

Researchers also have reported that supplementation after exercise exerts many beneficial effects; especially in muscle recovery and connective tissue damage Grassi et al.

Although studies have demonstrated that glutamine has beneficial effects for exercise, a crucial factor remains unclear. Researchers have been focused on the effect of glutamine on immunoregulation and muscle damage during exercise, and no other organ pathology observation for the use of glutamine has been undertaken.

Furthermore, no study has discussed whether various intake timings affect glutamine bioactivity in exhaustive exercise. If glutamine supplementation has a treatment effect after exercise, then glutamine supplementation may be has a preventive effect before exercise.

Nevertheless, there is no research show which is better to have glutamine supplementation before or after exercise. Thus, the purpose of this study was to examine the differential effect of glutamine supplementation before and after exercise to identify the optimal timing of glutamine supplementation.

We hypothesize that glutamine supplementation before exercise may have a similar effect to after exercise. Besides, glutamine regulates not only the immune cells but also other tissues or blood cells, such as RBC and platelets. In this study, animal experimentation was conducted to explore the difference in the effect of L-glutamine supplementation at different times i.

The Sprague—Dawley rat model was applied. The eighteen experimental animals were randomly divided into three groups, namely, the vehicle group no glutamine treatment , the prevention group administered glutamine before exhaustive exercise , and the treatment group administered glutamine after exercise.

The three groups engaged in the same exercise program. Blood samples were collected at different times, and CK-MM was tested to assess muscle tissue damage. After the experiment, heart, kidney, and liver tissue sections were dissected to measure tissue damage. The animal study was performed according to institutional protocols of the Institutional Animal Care and Use Committee of Tzu Chi University IACUC No: Experimental rats, with body weights between and g, were ordered from LASCO animal center Taipei, Taiwan.

The rats were housed in a controlled environment of 22°C ± 1°C with a 12 h light-dark cycle. Food pellets and water were provided ad libitum. Before the beginning of the day experiment, the rats were trained to exercise on a treadmill.

After 14 days, the rats were transitioned to exercising on a treadmill and underwent exhaustive exercise. The rats were randomly grouped into a vehicle group, treatment group, and prevention group.

The vehicle group received 0. The actual mean dose of L-glutamine administered was between 0. The prevention group received the same single-dose glutamine 1 hour before the exercise.

During this period, polyethylene catheters PE were inserted into the right femoral artery to collect blood samples Ke et al. The femoral artery catheter was also connected to an electrophysiological amplifier Gould Instruments, Cleveland, OH, United States to monitor arterial pressure and heart rate.

The surgical incision was less than 0. After the surgery, the animals were placed in a metabolic cage and awakened soon thereafter. The rats were allowed free access to food and water.

Maximum running times were attained for each rat, and the maximum running time was 30 min. Exhaustion was defined in accordance per previous studies Ke et al.

Specifically, exhaustion was concluded to have occurred when the rat was unable to maintain pace with the treadmill and when the rat lay flat on the treadmill and remained on the grid at the back of the treadmill for a period of 30 s despite being gently pushed with sticks or breathed upon.

The blood samples were collected before exercise, 12 h and 24 h after exercise. These samples were placed into heparinized tubes and measured immediately for blood cell counts Sysmex K, NY, United States.

The samples were then centrifuged at 3, × g for 10 min. After centrifugation, supernatant was collected and the level of CK-MM was measured within 1 hour by using an automatic biochemical analyzer COBAS INTEGRA , Roche Diagnostics, Basel, Switzerland. Euthanasia was conducted 24 h after treatments.

The rats were deeply anesthetized using isoflurane inhalation and then blood withdrawal was performed for euthanasia. The heart, kidneys, and liver were removed immediately.

An observer blinded to the group allocations performed the tissue analysis and scored the severity of organ injury. The severity of liver injuries observed in the tissue sections was scored as follows: 0, minimal or no evidence of injury; 1, mild injury consisting of cytoplasmic vacuolation and focal nuclear pyknosis; 2, moderate to severe injury with extensive nuclear pyknosis, cytoplasmic hypereosinophilia, and loss of intercellular borders; and 3, severe necrosis with disintegration of the hepatic cords, hemorrhage, and neutrophil infiltration Ke et al.

All evaluations were performed on five fields per section and five sections per organ by a blinding observer. The collected data were analyzed using SPSS for Windows v The continuous variables have been expressed in Mean ± SD, and an independent t -test was employed to analyze and compare the tissue injury score between prevention and treatment group.

The analysis of variance ANOVA was applied to examine the differences of CK-MM and blood cell count between three groups. The significance level for all statistical comparisons was set as α less than or equal to 0. The skeletal muscle damage biomarker CK-MM was analyzed. The data showed that timing of the oral intake affects the reduction of serum CK-MM level.

The CK-MM level of untreated vehicle group was elevated after exhaustive exercise and reached its highest point at 24 h after exercise Figure 1.

The serum CK-MM level of the prevention group was elevated at 12 h. The treatment group exhibited almost no elevation. FIGURE 1. The comparison of CK-MM levels between groups. The CK-MM levels of treatment group were lower than those in prevention group at 12 and 24 hs.

Complete blood count analysis was performed at various time points after exercise treatment. Hematocrit showed a similar trend to RBC. The average HCT was significantly higher in the treatment group 12 h after exercise and reached a maximum difference at 24 h.

We also observed that PLT improved to a similar extent as RBC did. The average PLT was considerably higher in the treatment group after exercise 12 h and had a maximum improvement at 24 h. The average PLT of the treatment group in p24 was In this part, we found that oral intake of glutamine elevated RBC, HCT, and PLT amounts only in the treatment group.

FIGURE 2. The comparison of blood count levels between groups. Treatment group had higher RBC A , HCT B and PLT C values than those in prevention group at 24 hs. The HE staining results indicated tissue injuries in the cardiac muscles Figure 3A , kidneys Figure 3B , and liver Figure 3C in the prevention group, with average respective scores of 1.

The treatment group had less tissue injury in the cardiac muscles Figure 3D , kidneys Figure 3E , and liver Figure 3F , with average respective scores of 0 Figure 3G , 1.

These data of histological examination indicated that the treatment group had a more substantial reduction in damage, especially cardiac and renal damage, compared with the prevention group Figure 3. FIGURE 3. The histological finding and tissue injury score between prevention and treatment group.

The histological examination of prevention A—C and treatment group D—F. The prevention group had higher tissue injury score on the Heart G and kidney H than those in treatment group. There was no significant difference between groups on the liver I. We found that glutamine can reduce skeletal muscle damage caused by exhaustive exercise, and the treatment group had a greater reduction in damage than the prevention group did Figure 1.

We also found that oral intake of glutamine elevated RBC, HCT, and PLT amounts only in the treatment group Figure 2. A histological examination indicated that the treatment group had a more substantial reduction in damage, especially cardiac and renal damage, compared with the prevention group Figure 3.

The results of this study indicated that the effect of supplementing L-glutamine after exercise was more satisfactory than that before exercise. The tissue section results demonstrated that glutamine not only protected muscles under exhaustive exercise but also prevented damage to specific organs.

After exhaustive exercise, because of the continued contraction of skeleton muscles and enhanced circulation stress, both skeletal and cardiac muscles are damaged. Markers of skeletal and cardiac muscle damage, such as serum biomarker CK-MM, indicated damage after exercise, and the damage could also be found in histopathology examinations Amelink et al.

Studies have demonstrated that supplementation with glutamine has beneficial effects on reducing the parameters of muscle damage and inflammation in exercise rats Bowtell et al.

Similarly, in our study, the serum CK-MM level of the untreated vehicle group was elevated after exhaustive exercise and reached its highest point at 24 h after exercise Figure 1. Decreased glutamine concentrations typically correlate with the severity of the underlying disease process, with large amounts of glutamine catabolized in muscle at the time of damage.

Concentrations only gradually recover in the later stage of healing Durkalec-Michalski et al. During exhaustive exercise, the protein metabolism of muscles increases. At this time, glutamine can assist in gluconeogenesis, generating glucose to be used by the muscles, promoting energy metabolism and antioxidant capacity, reducing organ damage, and contributing to the synthesis and repair of muscle tissue.

Under exhaustive exercise, glutamine in the body is used in substantial quantities, resulting in a decreased glutamine concentrations Afonso et al.

We further found that the intake timing will notably affect the beneficial effect of glutamine for exhaustive exercise.

This might cause by a short half-life of glutamine. Glutamine was more effective when taken orally after rather than before exhaustive exercise. We also found that the RBC level increased substantially upon the post-exercise intake of glutamine Figure 2.

Previous researchers have demonstrated that glutamine is an essential source for glutathione synthesis in human erythrocytes Whillier et al. During exhaustive exercise, because of elevated oxidative stress and overloaded cardiac output, RBC becomes oxidative damaged Smith, No study has discussed whether glutamine mitigates oxidative damage on RBC or enhances the regeneration of RBC after exhaustive exercise.

We found that the RBC level increase and accordingly glutamine might enhance the regeneration of RBC upon oral intake after exercise Figure 2. The differences between the prevention and treatment groups were not only with respect to RBC concentration, but also regarding tissue damage for histological examinations.

The treatment group showed more considerable damage reduction in the cardiac muscle and kidneys than the prevention group showed. Figures 3G, H The primary cause for this difference in damage reduction might be the maldigestion of glutamine during exercise. Eating before exhaustive exercise often causes maldigestion; furthermore, body temperature increases during exercise until rest.

Research has demonstrated that in a hot environment, intestinal permeability is reduced by glutamine supplementation Pugh et al. Therefore, glutamine intake is more beneficial after rather than before exhaustive exercise.

Relative to the prevention group, the treatment group had a more considerable reduction in the damage to their cardiac muscles and kidneys.

Our results revealed that the timing of glutamine oral intake influences outcomes, such as improved organs protection and elevated RBC concentration in blood. Although the conditions of sports practice in humans are far different from those that can be applied in laboratory rats, these results might suggest athletes take supplements at the proper timing after exhaustive exercise.

Daily supplementation of L-glutamine can reduce the skeletal muscle damage caused by exhaustive exercise and that the timing of the oral intake affects the reduction.

Glutamine as a treatment more considerably reduced damage than it had as a prophylactic. We also observed that the oral intake of glutamine could elevate RBC, HCT, and PLT only after exhaustive exercise. It seems like the proper timing for taking glutamine supplements is after exercise.

However, the further clinical trial is needed in the future study. In vitro otherwise known as isolated cells in glass tubes studies, glutamine has been shown to increase muscle anabolism muscle growth when consumed in excess and catabolism muscle loss when not consumed to create a deficit.

The problem with in-vitro is that because these cells are separate from the rest of the body, many mechanisms are not able to happen, making the results not always the same between test tubes and actual people. This difference is proven in other human studies that have shown a failure to induce muscle protein synthesis when dosed the exact same scaling up of course as the vitro studies.

In other small studies also in vitro , it has been reported that glutamine lessens the rate of leucine oxidation, simply meaning it allows more leucine to go towards muscle growth. This might explain the results of other studies that have come before it.

Those participating in hours of endurance exercise without a chance to refuel may be able to achieve more benefits from glutamine in the form of faster recovery or less muscle catabolism dosed at anywhere between grams. Not because more glutamine will provide additional benefits, but because hours of physical activity might actually lower glutamine levels in the body below optimal, causing slower recovery or muscle loss.

This means any recovery or muscle loss prevention will come from returning glutamine stores in the body to their normal levels. This might help us understand why glutamine is less likely to benefit bodybuilding or intense but short training as it will not deplete glutamine stores enough to negatively affect recovery or muscle loss.

Others that might suffer from lower glutamine levels that potentially could benefit the same way as long-distance endurance athletes include individuals who eat a very low amount of protein in their diet, as well as vegans. Beyond exercise-related benefits though, glutamine has proven benefits in the realm of immune health and intestinal health.

Without getting too scientific which has already happened a bit too much in this article already , glutamine is required to produce a protein needed by white blood cells. This protein known as cytokines, and when increased in the body will actually help you fight off bacterial disease and possibly even help with healing wounds.

As for your intestines, the small intestine in particular requires more glutamine than any other part of your body. Simply put, glutamine helps maintain the integrity of the intestinal walls, lowering its permeability sometimes called a leaky gut.

So what does this all mean? Well unfortunately for those of us hoping to use it for increased recovery from weight lifting or increasing muscle protein synthesis, the studies are mixed.

In vitro studies have shown slight benefits, but when converted to actual human subjects these benefits seem to disappear. For those who are deficient in glutamine, such as vegans, individuals eating a very low protein diet or after a very long endurance workout, supplemental glutamine can help restore glutamine stores in their body to baseline.

This will provide them with an anti-catabolism effect of their muscle mass and increased recovery, but only back to the level of healthy individuals. It is naturally found in your body and has no negative side effects up to around 50 grams way more than you would ever need to take.

Who knows, we may find out eventually that it actually does benefit healthy individuals who lift weights once bigger studies have been conducted, but until then, it is important to remain sceptical about any claims made about glutamine in regards to its bodybuilding benefits.

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice.