Although there are many misunderstood supplements, carnitine is often maligned despite its ability to substantially improves exercise performance and quality of life.
How often do you complain of fatigue or low energy?
Maybe slow recovery and muscle soreness make it hard to train with the intensity you would like?
How often do you cancel your workout due to low training motivation?
These are all issues that could be solved with carnitine!
How Does Carnitine Support Exercise Performance?
At the most basic level, carnitine is a metabolic nutrient, helping the body burn fat, both at rest and during exercise (1). In addition to raising energy levels, especially during times of physical stress, carnitine protects muscle during intense exercise (2). This means lower post-workout muscle soreness as well as faster recovery due to higher rates of protein synthesis and replenishment of glycogen—the energy store in muscle. There’s even some evidence that carnitine improves how your body uses testosterone because it increases the sensitivity of androgen cell receptors that render testosterone active to muscle (3, 4).
Despite these proven benefits, carnitine’s reputation as a performance supplement has suffered from poorly designed studies and misinformation. This article will discuss the exercise literature that has tested the use of carnitine and show you how it can help you overcome the factors that limit athletic performance.
Carnitine Improves Exercise Performance & Reduces RPE
Ten years ago, a breakthrough study found that giving 2 grams of carnitine with 80 grams of carbs twice a day to experienced triathletes for 6 months allowed them to compete longer at a higher intensity with a lower RPE (5). The athletes improved their work output by 35 percent and had an 11 percent increase in performance on a time trial.
How did they do it?
Scientists found that the participants had a 55 percent reduction in the use of muscle glycogen during exercise. The triathletes were relying more on fat to keep them going. Sparing glycogen is a superior technique for improving endurance performance because it means you can use both the fat and glycogen in your body to fuel exercise, allowing you to train harder for longer. When glycogen runs out, it is a performance-limiting factor.
Carnitine also has the ability to decrease muscle damage, pain, and markers of metabolic stress from high-intensity exercise. You’ll be able to lift more weight, complete more reps, or run faster and longer, but with greater ease. For example, the triathletes who took carnitine had a 44 percent decrease in lactate-- the byproduct that makes you “feel the burn” and limits performance. With less lactate buildup, work capacity increases and training will not feel as physically difficult. Yay!
Carnitine Helps Start The Recovery Process
Along with helping you dig deep during training, carnitine it is just as important in the post-exercise recovery period. Carnitine is a potent antioxidant, helping to stabilize cell membranes that can be damaged during exercise or energy metabolism. It protects against oxidative stress that damages muscle tissue and leads to DOMS muscle soreness. One study found that supplementation with carnitine reduced muscle pain, tenderness, and release of creatine kinase—a marker of muscle injury (6).
Carnitine also improves androgen receptor number and sensitivity. This means that testosterone, the best known androgen hormone, is better able to bind with cell receptors to stimulate protein synthesis and repair damaged muscle (3, 4). One study found that older men who took a blended form of carnitine had improvements in symptoms of low testosterone. Incredibly, taking carnitine was just as effective as taking supplemental testosterone in this study (7).
Carnitine Supports Cognitive Performance & Motivation
Carnitine tartrate is the form that is typically used for athletic performance, but another form, known as acetyl-l-carnitine, has neuroprotective properties. Adding the acetyl group allows for carnitine to cross the blood brain barrier and improve biosynthesis of motivating neurotransmitters, such as dopamine, epinephrine, and acetylcholine. For depressed people or those who need to lose weight, it works wonders on motivation and self-initiative, both with training and work-related tasks (8).
How To Take Carnitine
Carnitine is stored in muscle with total carnitine content in the human body being 300 mg per kg (2). That means a 70 kg individual could store about 21 grams in muscle. The body can produce a small amount (about 25 percent of requirements) and the rest has to be gotten from diet.
Meat and animal products are the only source of carnitine, with beef providing about 90 mg per 4 ounces. Vegetarians and people with chronic disease are at highest risk of carnitine deficiency, but meat eaters can also benefit from supplementation.
To get performance results, a few things are important:
First, it takes a long supplementation period to raise muscle carnitine levels. In the study of triathletes, there were no changes in performance after 3 from baseline, but after 6 months those improvements were pronounced and statistically significant (5).
Second, carnitine doesn’t “load” in muscle unless accompanied by high insulin concentrations. This explains why many previous studies have NOT shown increases in muscle carnitine after taking it in multi-gram doses. Taking carnitine with carbohydrates is one way to ensure “loading” but you can also consume carnitine with a protein source that raises insulin, such as whey protein.
If your goal is fat loss or weight management, you may want to be cautious about supplemental carbs. In this case, you can take carnitine with a protein supplement, or there are other insulin-like nutrients that help load carnitine, including fenugreek or alpha lipoic acid. Alternatively, you can take your carnitine as part of any mixed meal that contains some carbohydrates and protein—it’s not required that you take it as part of pre- or post-workout supplement, though some people find doing so improves their motivation to train.
For improvements in exercise performance, studies show benefits from 2 to 4 grams a day, often taken in divided doses, such as 2 grams at breakfast, and 2 grams post-workout.
Carnitine tartrate is the most common form for improving exercise performance, but there is evidence that a blended form that contains acetyl-l-carnitine can be just as effective while supporting mood, cognition, and cardiovascular function. Adding a third form, propionyl l-carnitine, will improve blood flow, support cardiovascular health, and benefit gut health. We offer all three in our Carnitine Synergy, which also combines the thermogenic green tea extract with the brain support amino acid acetyl-l-tyrosine to help you take your training to the next level.