Does collagen increase muscle protein synthesis?

Three measurements: how muscle protein synthesis is measured, and what happened each of the three times collagen was put under the tracer

Does collagen increase muscle protein synthesis is a question that most pages answer by reasoning from amino acid tables, and the honest page answers it from the measurements, because muscle protein synthesis is not a thing that has to be inferred: it is measured directly, in people, by giving a tracer, an amino acid labelled with a heavy isotope, by infusion or by mouth, taking small biopsies of muscle hours apart and measuring how much of the labelled amino acid has been built into muscle protein in the interval, which gives the rate of synthesis in the fraction of interest, the myofibrillar proteins that contract, the mitochondrial proteins that supply energy, or the connective tissue proteins that hold the fibres together and transmit their force. Collagen has been put under the tracer three times in settings that matter to a lifter, and the honest page gives each measurement and its result. The first measurement was in young, healthy, resistance-trained men, the population a lifter belongs to, at rest and after a bout of resistance exercise, the moment at which muscle is most receptive to protein. They were given whey protein or collagen peptides, and the synthesis of myofibrillar protein was measured over the following hours: whey raised myofibrillar protein synthesis above the fasted rate at rest and raised it further after the exercise, as every complete protein does, and collagen peptides did not differ from a placebo in either state, at rest or after exercise, which is to say that the muscle treated the collagen as if nothing had been swallowed. The second measurement was in older women during a period of energy restriction and reduced daily steps, a model of the conditions under which muscle is lost, when a protein supplement should show its value if it has any, given whey or an equal dose of collagen peptides: whey supported muscle protein synthesis through the period, holding the rate up against the conditions pulling it down, and the matched dose of collagen did not, the head-to-head set out on the collagen and muscle recovery page. The third measurement is the one that matters most to the collagen argument, because it tested the one compartment where collagen was expected to score. Muscle is not only contractile protein; around a tenth of it is connective tissue, the collagen-rich matrix that sheathes each fibre, bundles them and runs into the tendon, and the argument for collagen in muscle has always been that even if it does nothing for the myofibrils it might feed this matrix, which is made of the very amino acids collagen carries. The tracer method can measure the synthesis of muscle connective tissue protein separately from the myofibrillar fraction, and when collagen peptides were given to young men around resistance exercise and that fraction was measured, collagen peptide ingestion did not increase the synthesis of muscle connective tissue protein after exercise either; the exercise raised it, as exercise does, and the collagen added nothing to the rise. Three measurements, in the three settings where a yes would have mattered, and three nulls.

Why the roster predicted all three, what the fat-free mass trials measured instead, where collagen's synthesis evidence actually lies, and the worked example

The three nulls were predicted before any of the three measurements was taken, by the amino acid roster, and the honest page gives the prediction because it is what makes the nulls a finding rather than a surprise. Muscle protein synthesis has two requirements that a protein must meet to raise it. The first is a switch: the synthesis of muscle protein is turned on by the arrival of leucine in the blood at a threshold of around 2.5 to 3g in a single sitting, below which the rate barely moves whatever else is present, and whey carries around eleven percent leucine so that a 25g scoop delivers nearly 3g and clears the threshold, while collagen carries around one percent so that a 25g scoop delivers a quarter of a gram and leaves the switch off, which is the leucine arithmetic on the collagen and muscle growth page. The second is material: a muscle protein being synthesised calls for all nine essential amino acids in the proportions the protein's sequence demands, and a chain that calls for one the pool cannot supply stalls at that residue, so that a protein lacking an essential amino acid cannot support synthesis however much of the others it carries; collagen lacks tryptophan entirely and carries the other essentials in small amounts, the roster with its empty seats on the collagen protein and recovery page, so that even a synthesis switched on by some other protein's leucine would run short of material if collagen were the only supply. A protein that cannot flip the switch and cannot supply the material cannot raise muscle protein synthesis, and the three tracer studies found exactly that; the connective tissue null is the interesting one, since the material argument does not apply to it, muscle's matrix being rich in the glycine and proline collagen delivers, and its null says that the matrix, like the tendon, builds in response to the strain the exercise applied and not to the supply the supplement offered, a fed body having glycine and proline enough for the matrix already. What the fat-free mass trials measured instead is the usual reply, and the honest page places it: three trials added 15g a day of collagen peptides to twelve weeks of resistance training and found more fat-free mass and strength than a placebo, in older men with sarcopenia, young men and women, and the placebo in each was silica, an inert powder with no protein, so that the trials compared training plus 15g of protein with training plus nothing and found that adding protein helps, a finding about protein rather than about collagen, and fat-free mass measured by DXA is water, bone and connective tissue as well as muscle, so that the trials did not measure muscle protein synthesis and could not have detected what the tracer studies did. Where collagen's synthesis evidence actually lies is in a different tissue measured a different way: 15g gelatin with vitamin C about an hour before jump rope loading raised a blood marker of collagen synthesis, the N-terminal propeptide of type I procollagen, in healthy men, a marker of connective tissue building that the tendon protocol rests on and that the muscle tracer studies did not contradict, since tendon and the matrix are not myofibrils; a lifter who takes collagen for synthesis takes it for that marker, before the tendon session, and not for the muscle. The worked example is the protein that does not switch synthesis on, sold for the tissues its roster does fill, stated on its true terms: two capsules, 1200mg hydrolysed type 1 marine collagen with 12mg vitamin C at 15% of its reference value plus zinc, 120 for £16.99 at 28p a day, lab tested and UK made, a gram of protein by energy with a hundredth of a gram of leucine, carrying vitamin C's collagen formation sentence for cartilage and bones and no muscle claim, since the register's muscle sentences belong to complete protein and the tracer says collagen is not one. Does collagen increase muscle protein synthesis: no, three times, at rest, after exercise and under restriction, and not even in the muscle's own connective tissue, as the roster said it would not.

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