09/25/2002 - Because it is so prominent in supplements these days, Dr. Di gives us the ins and outs of Glutamine, and what it can mean to athletic training.
Many of the formulations in the APT Nutrition line of Nutritional supplements, including our MRP LoCarb Meal Replacement Shakes, contain a good dose of glutamine peptides. That's because glutamine is absorbed faster as peptides rather than free glutamine and also because the peptides give us the advantages, not only of the free glutamine, but also of the bioactive peptide forms. The combination leads to beneficial synergistic effects on the protein synthesis and recuperation.
Wht Is Glutamine & How Can It Help Me?
Glutamine is one of the most important amino acids in the body in that it fuels both the gut and immune system and maximizes protein synthesis. Besides being so versatile, or perhaps because of that, recent studies and articles suggest that glutamine can be used as a marker of over-training.1,2,3
There are several markers that can be used to determine if someone is over-trained.4 One of them may be by measuring glutamine.
A study last year looked at various parameters of successful training, including glutamine, and found that although none of the other parameters measured (including serum hormone and cortisol levels) showed any significant changes during the training season, glutamine levels correlated with the degree of successful training, which was measured by improvements in performance. The elevations in plasma glutamine concentration observed in response to long-term balanced training in this study may be distinguishable from previous reports of decreased glutamine concentrations in over-trained athletes. Making it a potentially valuable tool in the monitoring of over-training in athletes.
The other side of the coin of course is to see if the use of supplemental glutamine has a positive effect on both preventing and alleviating the over-training syndrome. I believe that it would since glutamine not only increases protein synthesis and decreases protein breakdown but it also has positive effects on the immune system, which in turn can affect various parameters of the over-training syndrome.
As well, glutamine has recently been shown that it may act both as a substrate and as a regulator of gluconeogenesis (the production of glucose from other substrates such as amino acids, glycerol and lactic acid).5 This is important because it provides a vital supply of fuel for muscles and other tissues including the brain, and may thus improve muscle and cognitive function during training and help attenuate some aspects of over-training.
Glutamine is showing itself to be one of the most versatile and useful nutrients for sports performance. For example, a study published this year showed that glycogen resynthesis rates were higher after ingestion of a drink containing glutamine and other peptides in comparison to a drink containing just free glutamine.6
Even more interesting was a study published last year. This study looked at the effects of glutamine in promoting whole body carbohydrate storage and muscle glycogen resynthesis during recovery from exhaustive exercise.7
In this study, postabsorptive subjects (subjects have no digestion going on in the GI tract so that no nutrients are forthcoming from any food ingested) completed a glycogen-depleting exercise protocol. After their exercise they consumed 330 ml of one of three drinks, 18.5% glucose polymer solution, 8 g glutamine in 330 ml glucose polymer solution, or 8 g glutamine in 330 ml placebo. In addition, they received a primed constant infusion of glucose for 2 hours.
The authors found that Plasma glutamine concentration was increased after consumption of the glutamine drinks and that oral glutamine alone promoted storage of muscle glycogen to an extent similar to oral glucose polymer. Ingestion of glutamine and glucose polymer together promoted the storage of carbohydrate outside of skeletal muscle, the most feasible site being the liver. While we still need more studies to nail down all the specifics of the effects of glutamine on sports performance and exercise, the bottom line is, supplemental glutamine can have significant effects on many aspects of your training and help you achieve your sports and fitness goals.
1. Walsh NP, Blannin AK, Robson PJ, et al., Glutamine, exercise and immune function. Links and possible mechanisms. Sports Med 1998 Sep;26(3):177-91.
2. Rowbottom, D. G., D. Keast, P. Garcia-Webb, et al., Training adaptation and biological changes among well-trained male triathletes. Med Sci Sports Exerc Vol. 29, No. 9, pp. 1233-1239, 1997.
3. Rowbottom DG, Keast D, Morton AR. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Med 1996 Feb;21(2):80-97.
4. McKenzie DC. Markers of excessive exercise. Can J Appl Physiol 1999 Feb;24(1):66-73.
5. Perriello G, Nurjhan N, Stumvoll M, et al., Regulation of gluconeogenesis by glutamine in normal postabsorptive humans. Am J Physiol 1997; 272 (3 Pt 1): E437-E445.
6. van Hall G, Saris WH, van de Schoor PA, et al., The effect of free glutamine and peptide ingestion on the rate of muscle glycogen resynthesis in man. Int J Sports Med 2000 Jan;21(1):25-30.
7. Bowtell JL, Gelly K, Jackman ML, et al., Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. J Appl Physiol 1999 Jun;86(6):1770-7.