Glutamine and immune functionAfter hard training our immune function is at its lowest, this is particularly true for endurance events. This places ours bodies at risk of infections after such events. One study cited by Bean (2007) concluded that marathon runners that took 5g of glutamine straight after and two hours after the event had a reduced occurrence of illness in the week after the race. Just 19% of the glutamine-supplemented athletes noted any form of illness or infection compared to 51% of the athletes that received a placebo (fake supplements with no active ingredients). A similar conclusion was noted by Castell et al (1996) who found that 81% of the athletes that took 5g of glutamine during and after either a marathon or ultra marathon showed no signs of upper respiratory tract infections the week after the events compared to just 49% of those that did not take a glutamine supplements. It is thought that supplementary glutamine is used directly by the immune system as energy rather then the immune system taking it out of the blood for fuel, hence ensuring that there is a much lower declined in blood glutamine levels while making it more available to be used by the immune system if required.
Overtraining and recoveryOvertraining is a state where the body has insufficient time to recover from the stress of exercise before the next session takes places. This can lead to a host of problems including muscle loss, poor performance, change in mood and chronic fatigue. It has been noted that overtrained athletes have low levels of both blood and muscle glutamine and that increasing these levels during times of increased intensity or volume of training can prevent the risk of overtraining syndrome. It is thought that hard training leads to depletion of glutamine due to the bodies inability to make as much as the body requires as both the liver and immune system need more to keep working them at a optimal level (Shepherd, 2005). It has also been suggested that when glutamine supplements are taken after exercise with carbohydrates that it enhances the storage of carbohydrate in the muscles by up to 25% (Bowtell et al, 1999). This ensures that there is muscle fuel available for future sessions and further reduces the risk of overtraining while improving recovery and future exercise performance, this is ideal for those on low carb diets looking to maximise glycogen storage with a limited carb intake.
Glutamine supplements and body compositionGlutamine has been associated with improving cell volume, this means that it helps pull fluid inside a cell, this makes a muscle appear fuller. A muscle cell that is well hydrated can exert more force and has a greater potential to grow in size (Rowbottom et al, 1996). It has also been found that using glutamine supplements can cause a four-fold increase in growth hormone release, which may encourage protein synthesis (muscle building) while also reducing levels of a stress hormone called cortisol, which breaks muscle down (Gleeson, 2008). This reduction in cortisol is particularly important for those that are on a calorie restricted diet as cortisol levels are increased directly inline with a decrease in calories (the fewer calories you eat, the higher your cortisol levels will be) this places people on very low calorie diets at a disadvantage and results in excessive loss of muscle tissue, causing a drop in metabolism. This makes it harder to lose weight and easier to regain it once calorie intake is increased. Glutamine supplements may limit muscle breakdown during a dieting phase, helping maintain metabolic rate, which would aid fat loss.
Who should use glutamine supplements?Glutamine supplements are useful to take before and after training and during prolonged exercise to help maximise the recover from training 5g is recommended at each time. It may be worth introducing glutamine supplements to a diet and supplement regime when training volume and intensity is increased or when a new training programme is started as it may reduce the muscle soreness that often experienced when training is changed or quickly advanced. Weight trainers looking to bulk up, athletes looking to recover faster, prevent overtraining and illness and dieters looking to minimise muscle loss could all benefit from supplementing with glutamine.
When to use glutamine supplementsL-glutamine is the standard supplement used, this means it is an isolated form of an amino acid and has no other amino acids in the powder, this is useful as it means that it doesn't have to fight with other amino acids for absorption from the stomach. Others suggestions that taking L-glutamine powder before bed may aid growth hormone release during sleep and reduce muscle breakdown over the fasting night time period. Glutamine is a simple supplement with a host of benefits regardless of training goals.
Further readingBean, A (2007) Sports Supplements: Which nutritional supplements really work. A and C Black, London Bowtell JL, Gelly K, Jackman ML, Patel A, Simeoni M, Rennie MJ (1999) Effects of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. Journal of Applied Physiology: 86; 1770 - 7 Casrtrell LM, Poortmans JR, Newsholmes EA (1996) Does glutamine have a role to play in reducing infections in athletes. European Journal of Applied Physiology: 73: 488 – 90 Gleeson (2008) Dosing & efficancy of glutamine supplementation in human exercise & sports training. The Journal of Nutrition: 138: 2045s – 2049s Parry- Billings, M, Evans J, Calder PC, Newsholme, EA (1990) Does glutamine contribute to immune suppression after major burns? Lancet; 336:523 –5 Rowbottom DG, Keast D, Morton AR (1996) The emerging role of glutamine as an indicator of exercise stress and overtraining. The Journal of Sports Medicine; 21(2): 80 - 97 Shephard RJ (2005) Chronic fatigue syndrome: A brief review of functional disturbance and potential therapy. Journal of Sports Medicine and Physical Fitness: 45; 381 - 392