Hydrolyzed collagen supplementation prior to resistance exercise augments collagen synthesis in a dose-response manner in resistance-trained, middle-aged men

Resistance exercise (RE) increases collagen synthesis in young and older men, whereas hydrolyzed collagen (HC) ingestion improves this response to RE in a dose-response manner in young men. However, the collagen synthesis response to RE with and without HC in middle-aged men is unknown. Eight resistance-trained men (age: 49 +/- 8 yr; height: 1.78 +/- 0.02 m; mass: 90 +/- 4 kg) took part in this double-blind, crossover design study and undertook 4 x 10 repetitions of lower-limb RE at maximum load, after consuming 0 g, 15 g, or 30 g vitamin C-enriched HC. We analyzed venous blood samples for N-terminal propeptide of type 1 pro-collagen (PINP), beta-isomerized C-terminal telopeptide of type 1 collagen (beta-CTx), and 18 collagen amino acids throughout all three interventions. The serum PINP concentration x time area-under-the-curve (AUC) was higher following 30 g (169 +/- 28 mu g/mL x h) than 15 g (134 +/- 23 mu g/mL x h, P < 0.05) HC ingestion, and both 15 g and 30 g were higher than 0 g HC (96 +/- 23 <mu>g/mL x h, P < 0.05). RE with 0 g HC showed no change in serum PINP concentration. The AUCs for glycine, proline, hydroxyproline, alanine, arginine, lysine, serine, leucine, valine, and isoleucine were greater with 30 g than 15 g and 0 g HC ingestion (P < 0.05) and greater with 15 g than 0 g HC ingestion (P < 0.05). Plasma beta-CTx concentration decreased after RE independently of HC dose. Our study suggests connective tissue anabolic resistance to RE in middle-aged men but ingesting 15 g HC rescues the collagen synthesis response and 30 g augments that response further. This dose response is associated with the increased bioavailability of collagen amino acids in the blood, which stimulate collagen synthesis.