What Nutrient Can Help Shed Fat & Improve Muscle Soreness?

L-carnitine is a conditionally essential amino acid concentrated in muscle tissue and the heart. It is derived primarily in the diet from meat sources and is required in greater quantities by muscle tissue during periods of intense training or exercise. The body can make L-carnitine in the liver, kidneys, brain and testes from the amino acids lysine and methionine. However, this is not possible in muscle tissue. Muscle tissue lacks the enzyme – butyrobetaine hydroxylase – needed to form L-carnitine. This is a critical reason why high circulating levels of carnitine, from food or supplementation, are needed to maintain optimal levels in muscle tissue.

Supplementation with L-carnitine can benefit athletes and the general population, because it has been shown to increase free fatty acid oxidation (fat-burning), reduce muscular damage post-exercise, improve oxygenation of muscles, and decrease post-exercise delayed onset muscle soreness (DOMS). L-carnitine facilitates the transport of fatty acids into the mitochondria of muscle cells where they can be oxidized or ‘burned’ for energy during aerobic metabolism. Carnitine is the ‘gate-keeper’ that allows the fatty acids to cross over an impassable membrane. Without carnitine, fatty acids could not shuttle through the membrane into the mitochondrial ‘furnace’ to be burned for fuel. A recent study done in Germany examined the effects of supplementing with 3g of L-carnitine daily over a ten-day period and researchers observed significant changes in fatty acid metabolism. The subjects displayed increased oxidation of palmitic acid, demonstrating an improved ability to burn fats compared to placebo. Fats are a superior energy source to proteins and carbohydrates as they release 9 kcal of energy versus only 4kcal for proteins and carbohydrates. Athletes are effectively more than doubling their potential energy supplies by tapping into this mechanism facilitated by L-carnitine.

Another study, involving 10 resistance-trained men supplementing with 2g of L-carnitine daily for 3 weeks showed marked improvements in recovery after 5 sets of squats performed for 15-20 repetitions. Blood markers for exercise-induced muscle damage were measured and after intense exercise they were reduced by 40% in the carnitine group versus placebo. The ability to minimize muscle damage post-training allows athletes to recover more quickly and maintain training intensity in subsequent exercise bouts. Researchers suggested the proposed mechanism of action is improved oxygen delivery to muscle tissues, which results in quicker recovery and therefore greater potential improvement in training capacity for athletes. The therapeutic dose for L-carnitine is 2-3g daily in divided doses, as no additional benefits were seen in studies using higher dosages.

Dr Marc Bubbs ND, CSCS, ART

References

  1. Muller DM et al. Effects of oral L-Carnitine supplementation on in-vivo long chain fatty acid oxidation in healthy adults. Metabolism 2002 Nov;51(11):1389-91
  2. Volek et al. L-Carnitine L-tartrate supplementation favourably affects markers of recovery from exercise stress. Am J Physiol Endocrinol Metab 2002 Feb;282(2):E474-82.
  3. Spring BA et al. Effects of L-carnitine L-tartrate supplementation on muscle oxygenation responses to resistance exercise. J Strength Cond Res. 208 Jul:22(4):1130-5