L-carnitine is a carboxylic acid that behaves like a vitamin. We do not need to ingest L-carnitine directly from food. Our liver and kidneys can produce it from methionine and lysine – two amino acids.
So what does L-carnitine do in our bodies? 95% of the carnitine a person has is stored in his muscle cells. Many athletes believe that supplementing with carnitine will inhibit lactic acid formation and delay the onset of fatigue. Theoretically, this is possible, but research has only shown positive results in nutritionally compromised individuals and not in healthy athletes.
Besides inhibiting lactic acid formation in muscles, L-carnitine also facilitates the metabolism of fatty acids. Weight loss enthusiasts have looked optimistically at L-carnitine as a nutritional supplement that can help them to lose weight. But again, test on living subjects results are not encouraging. It seems that the only proven advantage L-carnitine gives to those who supplement with it, lies in the management of delayed onset muscle soreness (DOMS).
To sum up, L-carnitine does not promote athletic performance. It also does not help you burn fat faster. However, it does quite effectively reduce the pain you need to endure after a heavy workout.
My personal experience with this product is, it does give me a slight ergogenic perk prior to a workout. Nothing fantastic – just warms up your muscles a bit.