Andrew Huberman· PhD
aging impairs the efficiency of muscle protein synthesis I see so it's a runaway train if you start getting sarcopenia
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aging impairs the efficiency of muscle protein synthesis I see so it's a runaway train if you start getting sarcopenia
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So, what's important to point out there is that as we age, the sensitivity of your muscles to turn on mTOR, something that is very good, is lowered. Meaning you're going to need more exercise and more protein to turn it on, which we know is associated with all the benefits mechanistically I mentioned Alzheimer's Parkinson's etc., that huge list.
if you give an enriched source of essential amino acids more protein uh you can actually make the adult look just like the 16-year-old
and then of course anabolic resistance I think is the biggest issue and and something that truthfully up in until two years ago I just wasn't paying enough attention to I I wasn't appreciating that my older patients had a had an additional problem that younger patients didn't have with respect to that signal
and as you get older you should start to move that number higher and higher because of what's called anabolic resistance so as we get older um the muscles become less sensitive to the effects of the amino acids
as we get older um the muscles become less sensitive to the effects of the amino acids
and by the way as you age that those requirements go up due to anabolic resistance
as you age that those requirements go up due to anabolic resistance
as we age we develop something called anabolic resistance which means that it is harder and harder for our muscles to synthesize and grow new muscle cells with the given amount of amino acids which are the building blocks in protein that we get by eating protein and and therefore we actually need more and more protein to overcome that
But we have to continue to get these essential amino acids so that we can maintain rebuilding and repairing which the efficiency of that changes as we age. Anabolic resistance, protein efficiency decreases. Those are or that is one reason why we need dietary protein just to maintain
However, as we age, we face anabolic resistance, where our muscles don't respond to amino acids as effectively.
For older people, for reasons that we're beginning to unravel now, I think, what happens is now the sensitivity of that dimmer switch. The leucine comes and you, sort of, get this response. In a younger person, you might get that. So we need more leucine or more branched chains or more essential amino acids, which translates into more. You need more protein to trigger the whole turning the protein synthetic process on.
I think as you get older, what happens is that the bricks that are coming in aren't used as efficiently. But we're still pulling bricks out of the wall, and that, sort of, tips the balance and we begin to lose muscle mass.
older folks tend to believe not just resistant to the anabolic influence of protein or amino acid ingestion or essential amino acid ingestion they seem to be anabolically resistant to um resistance exercise or an acute barrel of resistance exercise across a like a a wide range of loading spectrums so there is one paper out there that has looked at the synthetic response across that and older people and seen it somewhat diminished
if you do that the same uh if you do that in older people and you give them the same 20 gram of protein they show a lesser stimulation of muscle protein synthesis and they do not reach that same level and certainly not the maximum level so that's what they now call anabolic resistance
after exercise aging does reduce the sensitivity of lucing and other amino acids it takes a larger dose of protein or Lucine to stimulate the same muscle protein synthesis response for someone who is older compared to a younger adult
but a big player here is a phenomenon called anabolic resistance so as we age our muscles become less responsive to amino acids meaning they don't trigger muscle protein synthesis in response to protein intake as effectively
Um, as we age, we become less responsive to amino acids. So, it doesn't have the same anabolic effect that it does when you're younger. Amino acids are much more anabolic in a 30-year-old than they are in a 70-year-old, unless they're training. Physical activity and particularly resistance training reensitizes the muscles to amino acids so that it's almost like you're younger again.