Collagen Peptide Supplementation during Training Does Not Further Increase Connective Tissue Protein Synthesis Rates

Introduction Protein supplementation increases postexercise muscle protein synthesis rates and, as such, supports exercise-induced muscle conditioning. Collagen protein has been suggested as the preferred protein source to stimulate muscle connective protein synthesis rates during recovery from exercise. Here we assessed the effects of hydrolyzed collagen peptide supplementation on both myofibrillar as well as muscle connective protein synthesis rates during 1 wk of strenuous resistance exercise training. Methods In a randomized, double-blind, parallel design, 25 young men (24 ± 3 yr, 76.9 ± 6.4 kg) were selected to perform 1 wk of intense resistance-type exercise training. Subjects were randomly assigned into two groups receiving either 15 g hydrolyzed collagen peptides (COL) or a noncaloric placebo (PLA) twice daily during the intervention. Subjects were administered deuterated water ( ²H2O) daily, with blood and skeletal muscle tissue samples being collected before and after the intervention to determine daily myofibrillar and muscle connective protein synthesis rates. Results Post-absorptive plasma glycine, proline, and hydroxyproline concentrations increased following collagen peptide supplementation (P < 0.05) and showed higher levels when compared with the placebo group (P < 0.05). Daily muscle connective protein synthesis rates during the intervention period exceeded myofibrillar protein synthesis rates (1.99 ± 0.38 vs 1.34 ± 0.23%·d ^-1, respectively; P < 0.001). Collagen peptide supplementation did not result in higher myofibrillar or muscle connective protein synthesis rates (1.34 ± 0.19 and 1.97 ± 0.47%·d ^-1, respectively) when compared with the placebo group (1.34 ± 0.27 and 2.00 ± 0.27%·d ^-1, respectively; P > 0.05). Conclusions Collagen peptide supplementation (2 × 15 g daily) does not increase myofibrillar or muscle connective protein synthesis rates during 1 wk of intense resistance exercise training in young, recreational athletes.