The skeletal muscle is the largest metabolic organ in the human body and plays an important role in metabolic health and overall well-being. It is also regarded as an endocrine and paracrine organ, where muscle-derived signaling proteins, called myokines, facilitate communication between the muscles and other organs, such as the liver, pancreas, skeletal system, adipose tissues, and the cardiovascular system. 

Muscular health has been shown to improve body composition, metabolic health, and longevity by decreasing the risk for cardiovascular, musculoskeletal, and metabolic diseases. It can improve health outcomes by balancing the distribution of forces within a joint, increasing basal metabolic rate and bone density, reducing body fat and cardiovascular risk factors, enhancing endothelial function, and promoting cognitive function and psychological well-being. Conversely, periods of physical inactivity, even if they are short periods of immobilization, can contribute to substantial declines in muscle mass and strength and muscle protein synthesis, which are often slow to recover after remobilization and may be further accompanied by reduced metabolic function and insulin sensitivity.

A recent study published in The Journal of Nutrition examined the effect of an innovative ingredient, NPN_1 (PeptiStrong™), on muscle health during periods of immobilization and subsequent remobilization. NPN_1 is a natural peptide network derived from the fava bean (Vicia faba), using a predictive machine learning approach to identify the bioactive peptides with optimal properties, supporting healthy inflammatory responses, muscle health, and protein synthesis. This randomized trial (n = 30) compared the effectiveness of the plant-derived NPN_1 to that of a high-quality animal-derived protein reference, milk protein concentrate, in terms of modulating muscle loss during periods of immobilization and improving protein synthesis during remobilization.

Thirty young men (between the ages of 19 and 29) were subjected to a single-legged knee immobilization using a cast for 7 days, followed by 14 days of recovery. Participants were randomly allocated into two equal groups and supplemented, twice daily, with either 10 g of the fava bean peptides (NPN_1 group) or a milk protein concentrate with a comparable protein level (MPC group). Muscle strength was measured as one-legged knee extension and leg press strength using one-repetition maximum (1RM), which refers to the maximum amount of weight an individual can lift for one repetition of a given exercise using proper technique. Muscle size was also measured using tomography scans to assess the cross-sectional area of the quadriceps. 

The results of this randomized trial showed that both groups experienced similar muscle size loss during immobilization, which significantly decreased quadriceps CSA as compared to baseline, with no significant differences observed between the MPC and NPN_1 groups. Following remobilization, the recovery in quadriceps CSA was also similar between the two groups. Similarly, leg immobilization significantly decreased the 1RM leg extension muscle strength relative to baseline, with no significant differences between the MPC and NPN_1 groups. These results suggest that individuals supplemented with the fava bean peptides experienced similar muscle mass and strength recovery as those supplemented with the milk protein concentrate used as a reference.

Furthermore, individuals supplemented with the fava bean peptide network NPN_1 showed increased myofibrillar protein synthesis rates relative to the MPC group. MPS is a metabolic process that incorporates certain proteins into skeletal muscle after resistance training, supporting muscle mass increase. During immobilization, MPS rates were similar between the NPN_1 and MPC groups, suggesting that the two types of supplementation were comparable in terms of preserving muscle mass during periods of immobilization. During remobilization, however, the MPS rates were greater in the NPN_1 group than in the MPC group, indicating that the Vicia faba peptides increased myofibrillar protein synthesis rates more than the milk protein concentrate. 

The results from this randomized trial suggest that, while both NPN_1 and MPC have similar effects on modulating muscle size loss and muscle strength decline during immobilization, the Vicia faba peptides may offer additional benefits in enhancing protein synthesis during remobilization and recovery. 

Learn more about peptides and muscle health: 

Decoding Peptides: The Body’s Little Helpers

Collagen Peptides to Promote Skeletal Muscle

Bioactive Peptides From the Fava Bean: The Future of Muscular Health?

Muscle Tone Matters: The Key to Optimal Body Composition and Metabolic Health

By Antonia Toupet, PhD