Details from a new study linking this compound with muscle recovery

L-carnitine is a natural compound comprised of the amino acids lysine and methionine. Its primary function in the body is to transport fatty acids across cell membranes so that they can be metabolized in the mitochondria. Some endurance athletes supplement with l-carnitine in the belief that it increases the body’s fat-burning efficiency during exercise. Unfortunately, studies have repeatedly shown that l-carnitine supplementation has no effect on fat utilization either at rest or during exercise and no effect on endurance performance. While l-carnitine is essential for fat utilization during exercise, it appears that athletes get as much as they need in the diet (mostly by eating meat) and that supplementation offers no additional benefit.

New Research on Muscle Recovery

A study conducted recently at the University of Connecticut, however, suggests another possible benefit of l-carnitine supplementation: enhanced post-exercise muscle recovery. Eighteen men and women received either a daily l-carnitine supplement or placebo for three weeks, then performed a single weightlifting workout. After a one-week “washout” period, the entire protocol was repeated, with the subjects who received the placebo the first time getting the supplement the second time.

The researchers found that biomarkers of muscle stress were significantly reduced after the weightlifting session when preceded by three weeks of l-carnitine supplementation. The study’s authors concluded, “These findings support our previous findings of l-carnitine in younger people that such supplementation can reduce chemical damage to tissues after exercise and optimize the processes of muscle tissue repair and remodeling.”

A Closer Look

But here’s what those in half-marathon training, marathon training, and triathlon training really need to know about this study: L-carnitine supplementation made no difference in how quickly muscle strength and power were restored after the workout. Since the whole point of accelerating muscle recovery through supplementation is to hasten the restoration of muscle function specifically, these results offer little cause for excitement.

It is also worth mentioning that the participants in this study were non-athletes. Supplements that are found to have physiological effects in non-athletes often have no effects in athletes, because training has the same effects as the supplements.

The Bottom Line

So while l-carnitine supplementation is safe, it seems to be useless in terms of enhancing endurance sports performance. If the results of the University of Connecticut study are enough to make you curious, however, you can find l-carnitine supplements in both pill and liquid forms at most supplement retail stores. Typical recommended dosages are 1 to 2 grams daily.