Ingestion of a Whey Plus Collagen Protein Blend Increases Myofibrillar and Muscle Connective Protein Synthesis Rates

ABSTRACT Purpose: Ingestion of whey protein increases myofibrillar but not muscle connective protein synthesis rates. Recently, we defined a whey and collagen protein blend (5:1-ratio) to optimize post-prandial plasma amino acid availability. Here, we assessed the ability of this blend to increase myofibrillar and muscle connective protein synthesis rates at rest and during early recovery from exercise. Methods: In a randomized, double-blind, parallel design, 28 men (age: 25 ± 5 y; BMI: 23.6 ± 2.3 kg/m 2 ) were randomly allocated to ingest either 30 g of protein (25 g whey/5 g collagen; BLEND, n = 14) or a non-caloric placebo (PLA, n = 14) following a single session of unilateral leg resistance-type exercise. Participants received primed continuous L-[ ring - 13 C 6 ]-phenylalanine infusions with blood and muscle biopsy samples collection for 5 hours post-prandially to assess myofibrillar and muscle connective protein synthesis rates. Results: Protein ingestion strongly increased plasma amino acid concentrations, including plasma leucine and glycine concentrations ( P < 0.001), with no changes following placebo ingestion ( P > 0.05). Post-prandial myofibrillar and muscle connective protein synthesis rates were higher in the exercised compared to the rested leg ( P < 0.001). In addition, myofibrillar protein synthesis rates were higher in BLEND compared to PLA in both the rested (0.038 ± 0.008 and 0.031 ± 0.006%·h −1 , respectively; P < 0.05) and exercised (0.052 ± 0.011 and 0.039 ± 0.009%·h −1 , respectively; P < 0.01) leg. Muscle connective protein synthesis rates were higher in BLEND compared to PLA in the rested (0.062 ± 0.013 and 0.051 ± 0.010%·h −1 , respectively; P < 0.05), but not the exercised (0.090 ± 0.021 and 0.079 ± 0.016%·h −1 , respectively; P = 0.11) leg. Conclusions: Ingestion of a whey (25 g) plus collagen (5 g) protein blend increases both myofibrillar and muscle connective protein synthesis rates at rest and further increases myofibrillar but not muscle connective protein synthesis rates during recovery from exercise in recreationally active, young men.