Author(s): KAISER, J., AUSSIEKER, T., VAN LIESHOUT, G.A.A., KUIN, L.M.E., TROMMELEN, J., SENDEN, J.M., VAN KRANENBURG, J.M.X., GOESSENS, J.P.B., BAAR, K., SNIJDERS, T., VAN LOON, L.J.C., Institution: MAASTRICHT UNIVERSITY, Country: NETHERLANDS, Abstract-ID: 1470

INTRODUCTION:
Collagen ingestion has been suggested to stimulate muscle connective protein remodeling. However, ingestion of a single bolus of collagen peptides does not seem to further augment post-exercise muscle connective protein synthesis rates. It has been hypothesized that the proposed benefits of collagen ingestion on post-exercise muscle connective protein remodeling are more evident when assessed over a more prolonged period of post-exercise recovery.
METHODS:
In a randomized, double-blind, parallel design, 20 recreationally active male adults (age: 24±4 y; BMI: 24±4 kg/m2) were allocated to ingest either 4 boluses of hydrolyzed collagen (40, 20, 20 and 20 g; COLL, n=10) or a non-caloric placebo (PLA, n=10) distributed throughout 8 hours of post-exercise recovery from a single bout of unilateral leg resistance-type exercise. Participants received primed continuous L-[ring-13C6]-phenylalanine infusions with blood and muscle biopsy samples collected frequently to assess muscle connective protein synthesis rates at rest and during 8 hours of post-exercise recovery. Time-dependent variables were analyzed by two-way repeated measures ANOVA with time as within-subject factor and treatment as between-subject factor. Non-time-dependent variables were compared between treatment groups by an independent t-test. A statistical level of P<0.05 was accepted. All data were analyzed in SPSS and are expressed as mean±SD.
RESULTS:
Collagen ingestion increased the availability of circulating essential and non-essential amino acids (all P<0.001). Plasma leucine concentrations increased within 30 min after the ingestion of the initial bolus of collagen (P<0.001) and remained higher throughout the entire recovery period compared to placebo (with average values at 161±13 vs 116±14 µmol/L, respectively; P<0.001). Collagen ingestion strongly increased post-prandial hydroxyproline (iAUC 162±26 vs -1±1 mmol/L x 480 min), proline (iAUC 225±40 vs -14±4 mmol/L x 480 min), and glycine (iAUC 320±85 vs -7±5 mmol/L x 480 min) availability when compared to placebo (all P<0.001). Collagen ingestion resulted in higher muscle connective protein synthesis rates in both the rested (0.069±0.017 vs 0.052±0.011 %/h; P=0.018), and exercised leg (0.094±0.024 vs 0.058±0.009 %/h; P<0.001) when compared to the placebo ingestion.
CONCLUSION:
Collagen ingestion during 8 hours of post-exercise recovery increases plasma amino acid availability, with a sustained increase in circulating proline and glycine concentrations. The increase in plasma amino acid availability stimulates muscle connective protein synthesis rates both at rest and during recovery from exercise, which may support connective tissue remodeling in healthy active males.