L-Carnitine plays a vital role in the fat metabolism of the body. It's main function is to transport the fat into the mitochondria where it is than burned.

During intense physical activity, the body produce energy intially from carbohydrates. Only once the carbohydrates are used up, fat is being used to produce energy.

At this point it is important to have L-Carnitine to make sure the fat metabolism works properly and so improves endurance.