Does L-carnitine improve endurance?
Mostly no. Three of the four small trials linked here found no change in endurance; the fourth, in five rugby players, found they cycled longer before exhaustion. A 2021 review found no gain in moderate exercise either, but some in short, hard efforts.
What the studies found
“up to 3 g/d GPLC for 8 wk in conjunction with aerobic-exercise training is ineffective for increasing muscle carnitine content and has no significant effects on aerobic- or anaerobic-exercise performance.”
“acute administration of L-carnitine did not affect the metabolism or improve the physical performance of the endurance-trained athletes during the run and did not alter their recovery.”
“the CAR trial significantly increased the exercise endurance time compared with CON trial”
What wider reviews say
These reviews are not linked to the finding on our site. We read them on 7 November 2026 to check that the answer above fits the wider research.
“chronic or acute l-C or GPL-C supplementation did not present improvements on moderate exercise performance.”
“l-C supplementation with 3 to 4 g ingested between 60 and 90 min before testing or 2 to 2.72 g/day for 9 to 24 weeks improved high-intensity exercise performance.”
The details
- What the trials used
- 1 to 3 g a day for 8 weeks, or 2 g taken about 2 hours before exercise. These are the doses studied, not advice on what to take.
- Who was studied
- Healthy adults and trained athletes.
Before you try it
If you take any medicine or have a health condition, ask a pharmacist or doctor before adding a supplement. This page doesn’t link to any product.
How we checked this
This answer comes from one finding on our site, and that finding has been re-checked: each linked study was confirmed on PubMed and read against the finding’s grade, direction and study count. We then read every abstract ourselves on 7 November 2026 and wrote the answer from them, then checked it against recent reviews; the quotes above are copied word for word. If the finding changes, this answer is hidden until it is checked again. How we grade.