Carnitine is one of those supplements that most people have heard of, but may have never taken the time to get to know better. Often regarded as an amino acid (though it falls somewhere on the spectrum between amino acid and a vitamin), it is considered conditionally essential, since your body can make it under normal conditions, but occasionally may still necessitate exogenous consumption.
Being hard-core athletes, your body is hardly ever performing under “normal” conditions, to show how you may be opening up a deficiently in this amino acid without ever knowing it.
One thing’s for sure- regardless of where you are, there is a high likelihood that carnitine can help you reach your destination faster.
The Many Faces Of Carnitine
When reading carnitine supplement labels, it is natural to get overwhelmed by the many types available, including L-Carnitine, L-Carnitine L-Tartrate, and Acetyl-L-Carnitine. Are they all the same? Yes, and no.
For instance, L-Carnitine is considered the purest manifestation of its form, but boasts the poorest absorption. This is enhanced in the L-Tartrate version, and even better in the Acetyl-L formulation, though this form is best suited for enhancing cognitive function as it crosses the blood-brain barrier efficiently.
For this reason, the L-Tartrate version is usually preferred for its role in athletic enhancement, whilst Acetyl-L-Carnitine is mainly sought after as a nootropic agent. But don’t let that fool you, as it possesses virtually the same properties following conversion within the body.
Let’s examine how carnitine can help you achieve more in the gym.
Carnitine Stimulates The Synthesis Of Androgen Receptors
Prior to the discovery of carnitine stimulating the production of more androgen receptors, this was a fantasy only imagined in the minds of researchers and athletes alike. Yes, carnitine if one of the very few things that can bring about an increase in the number of androgen receptors found in the male body, as well as “upregulating” them, or making more sensitive to the effects of androgens[i].
But why is this important? Because it is considered the rate limiting step on how fast you can build muscle. A good analogy to put this into perspective would be to consider testosterone as “passengers” at a bus terminal, and the buses as “androgen receptors”.
There is a limited number of buses/seats, which means that only so many people can be accommodated at once. Increase the number of buses (receptors), and in turn more passengers can board and get to where they need to be (the testosterone).
Thus, carnitine is one of the few things that can yield greater results than that obtained from increasing testosterone levels only. As a result, greater muscle synthesis occurred, and better preservation of lean muscle tissue while dieting or trying to reduce body fat.
The Fat Transporter
No, we aren’t talking about that legendary movie series starring Jason Statham, but actually one of carnitine’s primary roles; a carrier, so to speak.
Carnitine (in its L form) is obtained via diet, and is particularly abundant in red meat, where it helps transport fat across cell membranes and into the mitochondria; essentially the furnace of a muscle cell to be utilized for fuel. You will have an exceedingly difficult time making use of fat if you are deficient in this amino, such as is common if you are a vegan.
While its ability to enhance fat transport into the mitochondria occurs all day long, you can reap the greatest benefit at the post-workout interval, enhancing the utilization of this energy reserve over glycogen, which speeds up the process of body recomposition.
A study conducted by the University of Nottingham investigated the administration of 2 g of carnitine first thing in the morning with 80 g high glycaemic carbohydrate, and followed up four hours later for a total of 24 weeks. The other group consumed the carb only.
The results? During low intensity cycling the group given carnitine reduces the usage of glycogen by 55 percent, and enhanced the usage of fat by the same amount[ii]. This is exciting news for anyone needing to get rid of fat preferentially while holding on to precious muscle glycogen stores[iii].
In order to pull off successful weight loss, a multifaceted approach works best. This almost certainly involves calorie restriction, which is a beast in its own right. This is because along with the reduction in calories comes the dreaded low energy phenomenon, coupled with fatigue.
This is especially evident if you rely primarily on carbohydrates for fuel, as a sudden sharp reduction in its supply will cause energy levels to plummet, and performance to suffer.
Carnitine can help mitigate this to an extent. By helping to enhance the utilization of fat, a greater amount of ketone bodies are produced to help deal with the carbohydrate crash. This, plus the fact that the glycogen stores in muscles aren’t as rapidly depleted can help explain how a little carnitine can go a far way.
The exact Nottingham study also observed that the subject using carnitine were able to cycle an average of 25 percent longer than those not given carnitine, as well as finding out that lactic acid levels were lower, and muscle Creatine levels higher.
Fatigue reduction was also evident in other aspects of life, and also benefited that leading to erectile dysfunction in older men[iv].
Enhanced Recovery And Milder DOMS
DOMS- better known as delayed onset muscle soreness, is that pesky all-over muscle specific ache that makes you just want to lay in bed all day and do nothing, but it doesn’t need to be that way. Given, for many it indicates that muscle damage galore has ensue, with subsequent rebuilding of stronger, and larger muscles.
But spending days in pain for the gain? There must be a better way. And carnitine can do just that. Small doses- as little as 1000 mg daily, can help to significantly reduce muscle pain and associated indicators of damage[v], allowing for rapid recovery and return to form. These findings have been confirmed in human subjects, making its utilization an exciting one.
This, and the fact that carnitine helps enhance production of nitric oxide[vi] and prevents its breakdown means that improved blood flow likely goes a long way in clearing metabolic by-products and delivering nutrients to support an ideal anabolic environment.
Carnitine, whether in its L-Tartrate, or L-Acetyl form will deliver roughly equivalent actions mentioned above, although the acetyl version is often preferred as a nootropic agent. The important thing, is to shoot for at least 1 g of either, best when taken after your workout or with food.
The varied uses of carnitine make it stand out in a sea of supplements looking to be the next big thing, as it is truly a powerhouse for your health and physique goals.
[i] Kraemer WJ, Spiering BA, Volek JS, et al. Androgenic responses to resistance exercise: effects of feeding
and L-carnitine. Med Sci Sports Exerc. 2006 Jul;38(7):1288-96. Erratum in: Med Sci Sports Exerc. 2006 Oct;38(10):1861. PubMed PMID: 16826026.
[ii] Wall BT, Stephens FB, Constantin-Teodosiu D, Marimuthu K, Macdonald IA, Greenhaff PL. Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. J Physiol. 2011;589(Pt 4):963–973. doi:10.1113/jphysiol.2010.201343
[iii] Natali, Andrea et al.Effects of acute hypercarnitinemia during increased fatty substrate oxidation in man
Metabolism - Clinical and Experimental, Volume 42, Issue 5, 594 - 600
[iv] Cavallini G, Caracciolo S, Vitali G, Modenini F, Biagiotti G. Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging. Urology. 2004 Apr;63(4):641-6. PubMed PMID: 15072869.
[v] Volek JS, Kraemer WJ, Rubin MR, Gómez AL, Ratamess NA, Gaynor P. L-CarnitineL-tartrate supplementation favorably affects markers of recovery from exercisestress. Am J Physiol Endocrinol Metab. 2002 Feb;282(2):E474-82. PubMed PMID:11788381.
[vi] Bloomer RJ, Tschume LC, Smith WA. Glycine propionyl-L-carnitine modulates lipid peroxidation and nitric oxide in human subjects. Int J Vitam Nutr Res. 2009 May;79(3):131-41. doi: 10.1024/0300-98188.8.131.52. PubMed PMID: 20209464.