L-Glutamine – What Is It and What Does It Do?

L-Glutamine – What Is It and What Does It Do?

L-Glutamine – What Is It and What Does It Do?

Glutamine is the most abundant amino acid found in our blood and makes up approximately 60% of the amino acid pool in our muscles. It is constructed by combining an amino acid compound and glutamic acid.

Glutamine is an amino acid known for its role as a substrate for protein synthesis. This means it is used during skeletal muscle contraction when we exercise, and without its presence our gut wrenching exercise sessions may be hampered.

This amino acid is an important anabolic precursor for muscle growth following exercise. In fact it the anabolic effects of glutamine include both an increase in protein synthesis (muscle hypertrophy or increased number of muscle cells) and increases in muscle cell expansion and filling with creatine, water and carbohydrate (muscle cell volumisation or “the pump”).

Increased glutamine content in muscle allows glutamine to suppress the oxidation (breakdown) of the branched chain amino acid leucine, and enhances the disposal of leucine without release of free radicals. Remember, free radicals are atoms with an unpaired electron which react with oxygen to reek havoc and result in cell damage.

The presence of leucine is key for muscle growth as it regulates the initiation of protein synthesis, acting as a trigger for muscle tissue development. Therefore, if glutamine can prevent leucine breakdown, it can be put to better use to facilitate muscle synthesis.

The concentration of glutamine also ensures a positive nitrogen balance which is required for muscle protein synthesis. There is also evidence that glutamine can also reduce muscle tissue catabolism (breakdown) by counteracting the effects of the stress chemical cortisol. Cortisol is an adrenal stress hormone which can lead to proteolysis (protein tissue breakdown) and reduced physical performance.

Training intensely (as we all try to do) or performing exhausting exercise such as marathon running, has a profound effect on the glutamine levels in your body. In fact levels may decrease even as much as 20-30%.

It has been shown that a significant reduction (24%) in plasma glutamine concentration was caused by day 3 following an intense eccentric strengthening session for the biceps, triceps, hamstrings and quadriceps which lasted until at least day 9 following the session.

Another study demonstrated that two hours following 40 repetitions of a leg press at 80% 1 rep max, glutamine levels in the quadriceps had been reduced by 34% in the type I muscle fibres, and 29% in the type II fibres.

Natural glutamine reduced = limited muscle growth!

As such if glutamine homeostasis is altered, it is likely that the aim for muscle growth during these exercises will be limited! The resulting effect on performance will be reduced strength, reduced power, reduced endurance and longer time to recovery.

It is postulated that the reduction in glutamine levels is a result of increased glutamine removal by the liver and increased use of glutamine by the kidneys and the immune system. It is also thought that such reductions of glutamine may contribute to a susceptibility to infection. The effect of over-training has also shown that this susceptibility may continue after several weeks of rest.

What Are The Benefits Of Glutamine To Me?

We have established the role of glutamine in our muscles, and discussed the risk of glutamine depletion following intense exercise.

Now we need to ask- can this be rectified with increasing glutamine intake and if so what are the specific benefits I can expect?

Below I outline these potential benefits.

✓ More gains!
In combination with protein (casein or whey) glutamine assists an increase of muscle protein synthesis by 8.3% (compared to protein alone, or protein with other essential amino acids).

✓ Quicker Recovery!
Reduces time to full muscle recovery of strength following exercise and protects against the negative effects of oxidative stress chemicals following intense exercise, therefore improving the beneficial effects of high intensity training on muscle protein synthesis.

✓ Less Muscle Wastage!
When part of an amino acid stack glutamine contributes to the suppression of the loss of muscle following periods of extended rest (e.g. post injury or surgery).

✓ Feel less tired!
Glutamine reduces the perception of fatigue in football players (in combination with l-carnitine and carbohydrate).

✓ More lean muscle!
In combination with intense training glutamine can assist increases in body mass and, more importantly to us all, lean body mass.

✓ Improved Power!
Improvements in initial rate of power production as demonstrated by an improved vertical jump performance compared to a placebo supplement.

✓ Better Endurance!
Increases running performance by increasing the time until muscular exhaustion.

✓ Less DOMS!
Diminishes post work out soreness.

✓ Better Immunity!
Reduces the incidence of infection in trauma and surgical patients and reduces the length of time spent in hospital.Also, improves intestinal function and reduces susceptibility to infection in athletes during the post training period; and assists restoration of key immune system markers (e.g. T cell counts, immunoglobulin A serum) following heavy load resistance training reducing risk of infection post training.

✓ Quicker reactions!
Improves reaction time following exhaustive endurance exercise.

✓ A Stronger heart!
Enhances cardiac hormone levels to assist better management of heart function and blood pressure.

✓ Improved Power!
Improvements in initial rate of power production as demonstrated by an improved vertical jump performance compared to a placebo supplement.

Obviously there are dietary sources of glutamine, which include beef, chicken, fish, eggs, beans, dairy products, cabbage, spinach and beets. However, many of us may also like to supplement glutamine in powder or tablet forms, as consuming sufficient food stuffs may be impractical immediately following exercise- during the window when our glutamine is depleted the most.


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