While L-carnitine has several functions in the body, it’s best known for shuttling fat into the portion of cells known as mitochondria. Fat is burned, or oxidized, in the mitochondria in a process called beta-oxidation. Carnitine is essential for that process.
Glycine-propionyl-L-carnitine is a specialized form of carnitine that’s particularly beneficial for heart function. The heart prefers fat as an energy source, and GPLC is used therapeutically to treat heart failure and poor blood circulation. Studies show that GPLC has more affinity for muscle than other forms of L-carnitine, and they suggest that using GPLC may boost exercise efficiency by lowering lactic acid and causing fat to be used more efficiently as an energy source.
Fifteen experienced weight-trained men were given 4.5 grams a day of either GPLC or a placebo. They were also given carbohydrates to promote insulin release, as insulin fuels carnitine uptake into tissues.
Under normal circumstances nitric oxide release occurs with turbulent blood flow, such as that induced by exercise. NO is synthesized and released in the endothelium, or lining of blood vessels. In that manner, NO inhibits the clumping of blood platelets and expands the diameter of blood vessels. The net effect is increased blood flow and, in the case of bodybuilding exercise, increased muscle pump and delivery of nutrients and oxygen to working muscle.
The study showed that NO release was significantly higher in those who took the GPLC supplement than it was in those who took the placebo. As to how GPLC works in relation to NO, the authors weren’t sure. One theory is that it inhibits an oxidative enzyme that rapidly degrades NO because of an increase in free radicals. Another theory is that GPLC augments the activity of endothelial nitric oxide synthase, the enzyme in the blood vessel walls that produces NO from arginine.
GPLC may be a useful adjunct to NO supplements, since it independently augments NO release and has no known side effects. It provides other benefits, such as increased muscle and heart efficiency, along with lower lactic acid production during intense exercise. In that sense, it would be complementary with beta-alanine, which is mainly used to control the higher acidity levels produced during exercise. GPLC also helps maintain androgen cell receptors, which increases the anabolic efficiency of testosterone. In fact, some pre-inary studies suggest that GPLC may be of use in treating male impotence.
Application: Try a few grams of glycine propionyl-L-carnitine along with your arginine-based nitric oxide precursor for a more powerful vasodilating effect—a.k.a. a full-blown pump with streakng vascularity.
Bloomer, R.J., et al. (2007). Glycine propionyl-L-carnitine increases plasma nitrate/nitrite in resistance-trained men. J Int Soc Sports Nutr. 4:22.
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