Effects of Carnitine Supplementation on Exercise-Induced Muscle Damage: A Randomized Controlled Trial

What Was Tested

In this not phased trial, researchers set out to test L-Carnitine.

This clinical study aims to investigate the effects of L-carnitine supplementation on recovery following high-intensity interval exercise in young athletes.

L-carnitine plays an important role in energy metabolism by facilitating the transport of long-chain fatty acids into the mitochondria for oxidation.

It had two arms (groups): L-Carnitine Supplementation Group (experimental) and Placebo Group (placebo comparator).

Participants in this group will receive L-carnitine supplementation for 21 days prior to completing a standardized high-intensity interval exercise protocol. The effects of supplementation on exercise-induced muscle damage, recovery, blood lactate levels, and anaerobic performance will be evaluated.

Participants in this group will receive a placebo supplement identical in appearance to the L-carnitine supplement for 21 days prior to the high-intensity interval exercise protocol.

The registry classes the interventions as dietary supplement and other.

Who Took Part

Enrollment: 30 actual participants took part.

It was open to men only aged from 18 years up to 25 years.

Healthy volunteers could join, not only people with the condition.

Examples of who could join: Male athletes aged 18-25 years. Regularly participating in organized sports training for at least 3 days per week. Healthy individuals with no diagnosed cardiovascular, metabolic, or musculoskeletal disorders. Willingness to comply with the supplementation protocol for 21 days. Agreement to refrain from consuming foods rich in carnitine (e.g., meat and dairy products) during the supplementation period.

The full record lists 7 inclusion and 7 exclusion criteria; among the exclusions: use of dietary supplements (including l-carnitine) within the last 3 weeks; presence of musculoskeletal injury or chronic disease that may affect exercise performance; use of medications that may influence muscle metabolism or recovery.

How the Study Was Run

It was run as a randomized, parallel-group and double-blind study.

The participants were allocated by chance, so the L-Carnitine group and the comparison group should start out alike.

The L-Carnitine group and the comparison group ran side by side rather than switching.

As a double-blind L-Carnitine study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant and investigator.

It started in 2025-05-09 with completion listed for 2025-05-15.

It ran at 1 site in Turkey (Türkiye).

Its stated primary purpose is treatment.

What Was Measured

Researchers chose this as the main measure: Exercise-Induced Muscle Damage (Creatine Kinase and LDH).

It also tracked 6 secondary outcomes, for example Delayed Onset Muscle Soreness (DOMS), Peak Blood Lactate Concentration, Maximal Power Output, Relative Maximal Power Output, Mean Power Output and Relative Mean Power Output.

What This Means in Plain Language

Put simply, this is a not phased, randomized trial of L-Carnitine in 30 people.

Its size is small, so on its own it can only give an early look.

The trial is marked completed; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the L-Carnitine compound page, all human trials.