Question

Given the current body of research, are carnitine supplements effective for improving endurance performance?

Answer 1

Ans) Yes. There is scientific consensus that endurance performance is improved.

Explaination:

- L-carnitine also helps improve endurance by inhibiting the build-up of lactic acid, one of the primary causes of fatigue. L-carnitine has also been shown to reduce the accumulation of metabolic wastes during exercise. This helps increase workload output during exercise and enhancing recovery post-exercise.

- It is clear that carnitine has an important metabolic role in the exercising muscle. However, the specific functions of carnitine and acylcarnitine and the effect of supplementation remain to be elucidated. The design of future investigations should carefully address the following issues:

1) Assay methodology—The radioenzymatic assay is appropriate for total carnitine measurements, but it should be used with caution to measure fractions of acylcarnitines. Bench-top gas chromatography-mass spectrometry methodologies should be further developed to measure specific acylcarnitines in a large number of samples. Caution should be used in the use of a carnitine concentration value as an indicator of the carnitine status in another cell type. Plasma, red blood cells, white blood cells, urine, and muscle should all be evaluated in each investigation.
2) Chemical form of supplementation—Published investigations concerning exercise have all used free carnitine as the chemical form that is used in supplementation. Acetylcarnitine and propionylcarnitine should be evaluated for their use in supplementation.
3) Timing of supplementation—The time relationship of the dose of carnitine supplementation to the time of exercise has varied from investigation to investigation and may be the cause of some of the variability of the results. The time relationship of dose and exercise needs to be carefully evaluated.
4) Dose of supplementation—In studies with carnitine supplementation, higher doses than are found in most diets have been used. The optimal dose has not be defined.
5) Physical training of subjects—Physical training alters muscle metabolism, including the metabolism of carnitine. All investigations should use subjects who have the same level of training as the individuals for whom the data will be utilized.
6) Intensity of exercise—The intensity of exercise alters muscle metabolism, including the metabolism of carnitine. All investigations should use the intensity of exercise for which the data will be utilized.
7) Animal studies—Some experimental questions require techniques that are too invasive to be performed in humans and thus require animals. Although rodents have been used for most experiments in the past, they are not the best animal model because their muscle metabolism is significantly different from that of humans. Swine would be a better choice.
8) Practical requirements—Carnitine is sufficiently stable to withstand long-term storage. It does have a bitter aftertaste, but it can be masked with citrus flavor. Carnitine has been found to be safe under most circumstances. However, more is not necessarily better, and investigations of patients with different pathophysiologies have indicated that better results can sometimes be obtained with lower doses.