A substance that the body cannot produce on its own is responsible for many functions that determine the proper growth of muscle tissues. How does lysine work in the body and is it worth using in every sport? We invite you to read on.
Contents
Why is lysine important in an athlete’s diet?
Lysine is an exogenous amino acid, meaning the human body cannot synthesize it on its own and it must be supplied with the diet. It belongs to the protein amino acids and plays a significant role in the synthesis of body proteins, including muscle proteins. For athletes, this is particularly important because intense training increases the demand for amino acids necessary for tissue repair and adaptation. Lysine participates in the formation of collagen and elastin, influences the stability of protein structures, and supports the proper utilization of other amino acids, making it an important element of a diet aimed at developing and maintaining muscle mass.
The effect of lysine on post-workout regeneration
In the context of post-exercise recovery, lysine can play a supportive role in the repair processes occurring in muscles and connective tissues. Training, especially high-intensity training, leads to micro-damage to muscle fibers, which require efficient synthesis of new proteins for their rebuilding and strengthening. An adequate supply of lysine promotes these processes, supporting muscle regeneration and the healing of micro-injuries. Additionally, this amino acid indirectly participates in energy metabolism, for example, through its involvement in carnitine synthesis, which can be important for the efficient utilization of fatty acids as an energy source. As a result, lysine can contribute to shortening recovery time, improving training adaptation, and better readiness of the body for subsequent exercise units.
Lysine and muscle mass building
One of the significant, though often overlooked, mechanisms by which lysine can indirectly influence muscle mass building is its involvement in carnitine synthesis. Lysine, along with methionine, is a key substrate for the production of this compound, which plays a fundamental role in the energy metabolism of cells. Carnitine is responsible for transporting long-chain fatty acids to the mitochondria, where they undergo β-oxidation and are used as an energy source. In the context of sports training, an efficient energy production process is important not only for exercise capacity but also for protecting muscle proteins from excessive breakdown.
By supporting carnitine synthesis, lysine can promote more efficient use of fats as energy fuel, which allows for limiting the use of amino acids for energy purposes. Such a mechanism can indirectly support anabolic processes, enabling better allocation of amino acids for muscle protein synthesis. For athletes aiming to develop muscle mass, this means a potentially beneficial metabolic environment in which the body manages energy more efficiently, supports training adaptations, and creates conditions conducive to the growth and maintenance of muscle tissue.
Lysine in the diet of endurance and strength athletes
The demand for lysine varies depending on the type of sport practiced and the intensity of training loads. Athletes, both endurance (e.g., long-distance runners) and strength (e.g., bodybuilders or sprinters), often have an increased demand for exogenous amino acids compared to people with sedentary lifestyles or moderate physical activity. In practice, athletes’ lysine requirements may exceed standard recommendations for adults (approximately 30-38 mg/kg body weight per day) and can even reach 40-45 mg/kg body weight per day, especially with high physical activity, to support a positive nitrogen balance and training adaptation.
In endurance athletes, a high intake of lysine can contribute to a more efficient use of amino acids in the repair processes of muscle fiber micro-injuries occurring during prolonged exertion and to the strengthening of structural proteins of connective muscle tissue and tendons. In strength disciplines, where the goal is to maximize muscle mass and strength gains, lysine – as part of the full amino acid profile essential for protein synthesis – becomes crucial for maintaining a positive nitrogen balance and optimizing muscle remodeling after intense resistance training. Research suggests that overall amino acid intake, including lysine, is usually high in athletes, reflecting their increased demand related to metabolic and anabolic adaptations 1.
It is also worth emphasizing the synergistic action of lysine with other metabolically and anabolically important amino acids. Leucine, a BCAA branched-chain amino acid, acts as a strong activator of the mTOR pathway, which regulates muscle protein synthesis and can support hypertrophy – particularly important for strength athletes. Arginine, in turn, participates in nitric oxide synthesis and can improve blood flow and nutrient delivery to working muscles, which in turn has a potential impact on endurance and regeneration. Lysine and arginine can also influence hormone balance (e.g., by modulating growth hormone secretion), which in theory promotes anabolic processes and training adaptations, although these mechanisms require further clinical research, especially in athletes2.
Lysine supplementation in sport – practical tips
Lysine supplementation may be considered primarily in situations where its dietary intake is insufficient or when the body’s demand significantly increases, which often applies to physically active individuals. Specific groups include:
- amateur athletes training intensely,
- people on elimination diets (e.g., vegan),
- athletes in periods of increased training load, weight reduction, or convalescence after injuries.
In such conditions, lysine can support the maintenance of a proper nitrogen balance, tissue regeneration, and metabolic processes essential for exercise adaptation.
In practice, doses used in physically active individuals are usually higher than general nutritional norms and most often fall within the range of about 1.5-3 g of lysine per day, depending on body weight, training intensity, and the type of sport practiced.
In strength athletes, for whom muscle protein synthesis and post-workout regeneration are priorities, lysine supplementation may be particularly justified during periods of muscle mass building or very intense resistance training. Conversely, in endurance athletes, lysine can support tissue repair processes and indirectly energy metabolism, especially with high training volumes and the risk of increased protein catabolism. It is most often recommended to take lysine in divided doses (e.g., in the form of supplements like BestProtect, containing 400 mg of lysine, protein preparations enriched with lysine, etc.) throughout the day or in conjunction with a post-workout meal, remembering that supplementation should be a complement, not a substitute, for a well-balanced diet rich in complete protein sources.
Bibliography:
- M. Baranauskas et al., Dietary Intake of Protein and Essential Amino Acids for Sustainable Muscle Development in Elite Male Athletes, Nutrients, No. 15/2023, issue 18.
- Pocket Chemical Dictionary, Katowice: Videograf II, 2004, p. 228,
- D. E. Matthews, Review of Lysine Metabolism with a Focus on Humans, The Journal of Nutrition, No. 150/2020, Suppl 1.
- CW. Xiao, A. Hendry, L. Kenney, l-Lysine supplementation affects dietary protein quality and growth and serum amino acid concentrations in rats, Scientific Reports, No. 13/2023