Beneficial for athletes L-leucine has gained attention in the fitness and sports community due to its potential to enhance muscle recovery, reduce muscle soreness, and support exercise performance. It may also play a role in preserving lean muscle mass during periods of calorie restriction or ageing.

L-leucine is one of the nine essential amino acids, which are building blocks of proteins that the body cannot produce on its own and must obtain from the diet. It plays a crucial role in protein synthesis and muscle growth, making it a popular supplement among athletes and fitness enthusiasts.

Here are some key points about L-leucine and its role in muscle mass and fitness:

1. Protein synthesis: L-leucine activates a signalling pathway called the mammalian target of rapamycin (mTOR), which plays a central role in muscle protein synthesis. By activating mTOR, L-leucine helps stimulate the production of new proteins, leading to muscle growth and repair.
2. Muscle recovery: L-leucine has been shown to support muscle recovery and reduce muscle damage after intense exercise. It can help minimise muscle breakdown, promote repair, and enhance the overall recovery process.
3. Leucine threshold: There is a concept known as the leucine threshold, which suggests that a certain threshold of leucine in the blood needs to be reached to maximise muscle protein synthesis. Consuming an adequate amount of dietary protein that includes leucine-rich sources, such as meat, fish, dairy products, and plant-based protein sources like soy and legumes, can help meet this threshold.
4. Branched-chain amino acids (BCAAs): L-leucine is part of a group of three essential amino acids called branched-chain amino acids, which also include L-isoleucine and L-valine. BCAA supplements often contain a higher ratio of leucine compared to the other two amino acids, as leucine is considered the most potent stimulator of muscle protein synthesis.
5. Timing and dosage: While individual needs may vary, the typical dosage of L-leucine as a supplement ranges from 2 to 5 grams per day. It is often recommended to consume it around exercise, as this is when muscle protein synthesis is most responsive. Combining L-leucine with a source of carbohydrates and protein, such as a post-workout shake, can further enhance its effects.
6. Balanced nutrition: While L-leucine supplementation can be beneficial, it’s important to remember that it should not replace a well-rounded, balanced diet. Meeting your daily protein requirements through whole food sources should be the primary focus, as they provide a wide range of essential nutrients that support overall health and fitness.