Collagen consists of 30% of the total protein in the human body. Collagen is essential for the extracellular matrix of muscles and tendons, and muscle force transmission, flexibility, and adaptability. Collagen peptides have a unique amino acid composition, including hydroxyproline, glycine, and proline (approximately 12%, 22%, and 13%, respectively). Most people do not consume the richest sources of collagen (animal skin, bone broth, and tendons) in the typical Western diet; therefore, supplementation may be warranted.
Studies show that protein intake can augment post-exercise skeletal muscle protein synthesis. Collagen peptides have been shown to help increase skeletal muscle anabolic gene expression and enhance contractile force transmission from muscles to tendons or bones by supporting the extracellular connective tissue. Collagen peptides may also act as signal messengers in anabolic cellular processes in cartilage, tendons, and ligaments.
Leucine, a branched-chain amino acid, is considered a prerequisite stimulator of the mammalian target of rapamycin (mTOR), which has a critical role in muscle protein synthesis. Several studies demonstrate that mTOR can be activated by other amino acids, such as arginine and glycine. Although collagen is low in leucine, the dipeptides and tripeptides in collagen, such as hydroxypropyl-glycine, have signaling properties that induce myoblast differentiation and myotube hypertrophy by activating mTOR signaling pathways. One study found that collagen peptides upregulated the gene expressions, P13K-Akt and mitogen-activated protein kinase (MAPK) involved in skeletal muscle signal transduction after high-load resistance exercise.
Recent randomized controlled trials have demonstrated the muscle signaling effects of collagen peptides post-exercise. In each of these trials discussed below, participants ingested 15 g of collagen peptides dissolved in 250 mL of water within 60 minutes of resistance training on 3 days per week for 12 weeks. For the remaining non-training days, participants ingested the collagen peptides at a similar time of day.
Oertzen-Hagemann and colleagues studied recreationally active young men (n = 25). The collagen group showed increased body mass, fat-free mass, and muscle strength, and 221 upregulated proteins associated with contractile fibers compared to the placebo group.
Jendricke and colleagues studied premenopausal women who were 18 to 50 years of age (n = 77). The collagen group showed improved hand-grip strength and fat-free mass compared to the placebo. The authors posit the improvements were due to increased collagen content in the intramuscular connective tissue and mTOR stimulation.
Zdzieblik and colleagues studied middle-aged, untrained men (n = 97). In their study, the collagen peptide group had a significantly greater increase in fat-free mass compared to the placebo group and a whey protein group.
More research is needed to understand exactly how collagen peptides may help stimulate muscle anabolism in relation to different exercise routines. However, it is suggested by the evidence that the unique amino acids present in collagen peptides act as signaling molecules in post-exercise skeletal muscle anabolism. Therefore, collagen may support muscle mass maintenance, especially for athletes, those recovering from injury, and aging individuals.
By Danielle Moyer, MS, CNS, LDN