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From jelly to muscle: collagen and body composition

Collagen has long been equated to junk protein, at least if you’re looking to gain muscle. Could it be underrated for this purpose? A trial of older men tested collagen protein to see if it could boost muscle gain and fat loss.

Study under review: Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial


The term “sarcopenia” refers to the age-related loss of muscle mass, which can lead to a reduction in functional muscular performance and possibly physical disability. Sarcopenia can develop from a variety[1] of factors, including neurological and hormonal changes, chronic inflammation, reduced physical activity, and poor nutrition. It is associated with[1] a number of short and long-term negative health outcomes, including increased insulin resistance, fatigue, frailty, falls[2], and all-cause mortality.

Sarcopenia is classified according to its progression, which is quantified based on the amount of skeletal muscle a person has compared to the sex-specific average for young adults (aged 18-39). This is expressed as the skeletal muscle mass index (SMI = skeletal muscle mass / body mass x 100). Depending on the amount of muscle mass a person has, sarcopenia is considered either class I or class II[3] (the prevalences of each are shown in Figure 1). Class I sarcopenia is present when someone’s SMI is within one to two standard deviations below young adult values, while class II sarcopenia is diagnosed when SMI is more than two standard deviations below young adult values.

Figure 1: Prevalence of sarcopenia over time

It should come as no surprise that resistance training[4] can delay and slow down this age-associated decrease in muscle mass and function. It has also been established that supplemental dietary protein[5] can increase[6] the rate of muscle protein synthesis and decrease[7] muscle protein breakdown after exercise. A 2012 meta-analysis[8] of 22 trials concluded that “protein supplementation increases muscle mass and strength gains during prolonged resistance-type exercise training in both younger and older subjects.”

It’s generally thought that protein consumed after resistance training should be rich in the branched chain amino acid (BCAA) leucine, due to its potential to activate the anabolic mTOR pathway. Whey protein is naturally high in leucine, which is in part why it has become a post-workout staple for muscle building. In contrast, collagen is considered to be of lower biological value due to its low content of the BCAAs leucine, isoleucine, and valine, as well as its total lack of cysteine and the essential amino acid precursor methionine. With that in mind, it may be surprising that at least one study has suggested collagen may in fact be better than whey[9] for maintaining overall nitrogen balance (a way of measuring protein metabolism) during a low-protein diet. This may be due to the type of amino acids prevalent in collagen containing more than one nitrogen atom and/or having a low molecular weight.

Since the effects of collagen protein as a post-workout supplement in older adults with sarcopenia had yet to be studied, this group of German researchers examined the effects of post-workout supplementation with hydrolyzed collagen on muscle mass and muscle function in elderly men with sarcopenia during a three-month resistance training program.

Sarcopenia, the age-associated loss of muscle mass that can lead to functional impairments and disability, has been linked to metabolic disease and is associated with increased risk of all-cause mortality. This is a significant health issue that can be improved through resistance training and/or dietary protein consumption.

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