For ATHLETIC PERFORMANCE, the amino acid L-carnitine boosts energy generation and blood flow, increases endurance, and can maximize the efficiency of oxygen consumption, while reducing lactic acid build up. L-carnitine has major benefits for athletes, helping to improve running speed and enhance oxygen uptake. Studies on high-repetition exercise show that L-carnitine improves muscle recovery.

Amino acids are the building blocks from which proteins are made: Carnitine occurs in several natural varieties: propionyl-L-carnitine is one variant that is produced in many tissues. The L-carnitine form has a key role in energy production.

L-carnitine is a mixed amino acid derivative of lysine, an essential amino acid that our bodies cannot make, and a sulfur-containing amino acid called methionine. The name L-carnitine is derived from the fact that it was first isolated from meat or “carnus” in Latin. Since the human body cannot synthesize lysine, it is essential that it is consumed in foods.

We can get small amounts of L-carnitine from our diets by eating meat and fish, but not enough for a therapeutic effect on athletic performance. Vegetarians and vegans can especially benefit from L-carnitine supplements, as can older adults, because carnitine levels in the body decline with age.

In the body, carnitine is found in nearly all cells, but it is concentrated in tissues like skeletal and cardiac muscle that utilize fatty acids as a dietary fuel. Carnitine is responsible for fueling the fires of energy production at the cellular level.

L-carnitine has a powerful role in releasing energy from fat-rich foods. L-carnitine is essential for transporting long-chain fatty acids across mitochondrial membranes. Once inside mitochondria–the tiny powerhouse organelles that generate energy in every cell–fats are broken down to fuel energy production. The human heart muscle gets 70% of its energy from fat breakdown. The boost from carnitine for cardiovascular energy capability translates to better athletic performance.

L-carnitine also has important circulatory benefits, improving the flow of blood through muscles and other tissues to enhance athletic performance. It boosts the production of vascular or cellular mediators such as nitric oxide which open up blood vessels.

Also, L-carnitine encourages peak performance by helping to remove the body’s waste: It transports toxic metabolic breakdown compounds out of mitochondria, to prevent their accumulation.

Sport enthusiasts know that recovery and regeneration matter, and this has resulted in a professional specialty called “regenerative athletics.” The ability to perform at your best is dependent on sound recovery that balances training and competition stressors. Research with athletes confirms the benefits of L-carnitine for training, competition, and recovery from strenuous exercise including regeneration of the tissues post-workout.

An overview of research examining the value of L-carnitine for athletes summarized the following key points:¹ 

1. The majority of studies report stimulation of lipid metabolism by carnitine with improved efficiency of oxygen consumption and better respiratory quotient. This means that L-carnitine improves the uptake of oxygen from the blood into tissues and helps its actions there, while reducing the amount of carbon dioxide waste in proportion.
2. L-carnitine significantly decreases post-exercise plasma lactate levels. Lactate is a waste product which is formed and cleared continuously under fully aerobic conditions.
3. Recent data from preliminary studies indicate that L-carnitine eases the deleterious effects on tissues of hypoxic training and can speed up recovery from exercise stress. L-carnitine plays a decisive role in preventing cellular damage, and speeds cell repair and recovery from exercise stress.
4.  The uptake of L-carnitine by bone marrow and blood cells may induce at least three beneficial events:
   1. stimulation of hematopoiesis (the formation, development, and differentiation of red blood cells which carry oxygen);
   2. a dose-dependent inhibition of collagen-induced platelet aggregation, meaning a reduced risk of tiny blood clots in proportion to the L-carnitine dose; and
   3. the extension of immune cells’ lifespans by reducing apoptosis, or programmed cell death.
5. Carnitine directly affects gene expression and carnitine-acyltransferase enzymes, improving fatty acid concentrations in cells and muscles, as recently shown.

A 2018 double-blind, randomized, and placebo-controlled study examined the effects of L-carnitine on exercise performance in 23 resistance-trained men males for 9 weeks. The researchers assessed markers including anaerobic capacity and exercise-induced oxidative stress. The positive findings included significant increases in bench and leg press lifting, greater mean and peak power, reduction in post-exercise blood lactate levels, and better total antioxidant capacity. The results published in the Journal of Exercise Biochemistry concluded that “L-carnitine supplementation enhances exercise performance while attenuating blood lactate and oxidative stress responses to resistance training.”²  This means that L-carnitine promoted improved athletic capacity, reduced waste build-up, and less oxidative damage to tissues from exercise.

Another important research trial in 2018 recognized the pivotal role of L-carnitine in preventing fatty acid oxidation and enhancing energy metabolism. The study noted a substantial history of scientific evidence confirming L-carnitine’s efficacy. It listed the following benefits: increased maximum oxygen consumption and higher power output; faster recovery after exercise; alleviated muscle injury; and reduced markers of cellular damage and free radical formation. This was all accompanied by reduction of muscle soreness.

Researchers suggested that these effects were due to “enhanced blood flow and oxygen supply to the muscle tissue via improved endothelial function thereby reducing hypoxia-induced cellular and biochemical disruptions.” This means that L-carnitine improves the function of blood vessel linings–the endothelium–leading to increased blood flow, better oxygen delivery to muscles and tissues, and also less disruption of normal cell function that occurs with hypoxia, or lowered oxygen supply.

The researchers then compared their findings with studies of older adults that showed that L-carnitine brought benefits including increased muscle mass accompanied by a decrease in body weight, and it also reduced physical and mental fatigue. This indicates a key role for L-carnitine in maintaining healthy protein status and blood flow, including to the brain, while preventing age-associated muscle gradation. In addition, L-carnitine preserves healthy homeostasis, or biochemical balance, within mitochondria, the powerhouse organelles in cells that generate energy.^3,4   

An interesting pilot study also in 2018, compared the effects of L-carnitine on metabolic profiles of elite-level athletes. By searching for biomarkers with potential therapeutic implications, the data provided evidence that high-power and high-endurance athletes have a distinct metabolic profile, including: steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. All of these characteristics are improved or encouraged by L-carnitine supplementation.⁵

In our clinic, our athletic patients have seen consistent long-term benefits with L-carnitine. People report improved performance and endurance, faster recovery, more efficient muscle building, and less fatigue and soreness after training. These improvements can steadily increase with 3 to 6 or more months of taking L-carnitine.

Recommendation: L-carnitine 1,000mg, one to three times per day, with any meals, or as directed by your healthcare provider.References