Periods of immobilization contributes to loss of muscle mass and strength, which are slow to recover when mobility is regained. Few protein sources have been identified that are capable of preserving muscle mass during immobilization. Recent work has identified plant-derived peptides with bioactivity, and a peptide network from Vicia faba (NPN_1) was found to protect against muscle loss in a mouse hind-limb unloaded model. However, the effectiveness of this peptide during disuse and remobilization in humans has not been determined. This was the goal of a study conducted by Weijzen and colleagues and they report their results in the June 2023 issue of The Journal of Nutrition.

Participants were 30 young (24 ± 5 year old) men randomly assigned to ingest either 10 g of NPN_1 or an isonitrogenous control composed of milk protein concentrate (MPC) twice daily. Participants underwent 7 days of one-legged knee immobilization and 14 days of ambulatory recovery. Quadricep cross-sectional area and myofibrillar protein synthesis rate were determined at study initiation at the end of immobilization and recovery periods.

Quadricep cross sectional area decreased with immobilization for both groups (5.4 cm2 and 3.3 cm2 for the NPN_1 and MPC, respectively), and remobilization provided partial recovery of the loss (0.8 cm2 and 1.1 cm2 for the NPN_1 and MPC, respectively). There was no diet-induced difference in the loss of myofibrillar protein synthesis rates during immobilization, however, during remobilization the rate of myofibrillar protein synthesis was greater in those consuming the NPN_1 supplement. The authors concluded that NPN_1 and MPC result in similar losses of muscle mass and myofibrillar protein synthesis rates during immobilization, but NPN_1 resulted in greater myofibrillar protein synthesis rates during recovery.


Weijzen MEG, Holwerda AM, Jetten GHJ, Houben LHP, Kerr A, Davis H, et al. Vicia faba peptide network supplementation does not differ from milk protein in modulating changes in muscle size during short-term immobilization and subsequent remobilization, but increases muscle protein synthesis rates during remobilization in healthy young men. Journal of Nutrition, Volume 153, Issue 6, June 2023, Pages 1718-1729,

Images via