Abstract: "Aging is characterized by a decline in the ability of tissue repair and regeneration after injury. In skeletal muscle, this decline is largely driven by impaired function of muscle stem cells (MuSCs) to efficiently contribute to muscle regeneration. We uncovered a cause of this aging-associated dysfunction: a cellular survivorship bias that prioritizes stem cell persistence at the expense of functionality. With age, MuSCs increased expression of a tumor suppressor, N-myc down-regulated gene 1 (NDRG1), which, by suppressing the mammalian target of rapamycin (mTOR) pathway, increased their long-term survival potential but at the cost of their ability to promptly activate and contribute to muscle regeneration. This delayed muscle regeneration with age may result from a trade-off that favors long-term stem cell survival over immediate regenerative capacity."
Stumbled onto this because I've been using TCM (in consultation with an herbalist) for blood pressure, relatively successfully, for a couple of years. Of course they didn't have blood pressure cuffs in the Ming or Han dynasties, so we're not really treating blood pressure... Researching astragalus and di huang is what led me to it.
So ERa down-regulates NDRG1 and there is less Era activation when we age. Evolution is all fun, but before reaching for anything like that we can apply basic knowledge around that path.
> In skeletal muscle, this decline is largely driven by impaired function of muscle stem cells (MuSCs)
I take it that as mitosis (cell division) gets slower with age, there's also simply no way aging muscles could potentially not heal more slowly?
So slower mitosis and then in addition to that muscle cells going into a "less repair, more survival" mode. Darn, sucks to get old.
Species that evolved before the Devonian period tend not to age and instead grow through their entire lives. There is no mechanistic understanding for the wild variation in species lifespans.
So the natural question in these studies is what would happen if we simply told the muscles not to age this way. It’s plausible that this aging schedule evolved due to other factors independent of the biological constraints. It’s also plausible that evolution removed some other important components for longer lived stem cells.
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I thought Satchel Paige said it, but apparently not. He did say "I generally don’t like running. I believe in training by rising gently up and down from the bench. "
Which also fits the "don't prematurely age the stem cells"
Consider an average person's 72/min resting heartbeat. That will be (726024365.25=) 37,869,120 heartbeats per year or ~379 million/decade.
Now, add strenuous running or cycling 5 hours/week, maybe a 10mi run, and a bunch of 20-60 minute runs. Call that average 180 beats/minute. That adds ((180-72)30052=) 1,684,800 beats/year, or +16 million per decade.
The average person's 37,869,120 beats/yr divided by the exercising person's 27,349,920 yields a ratio of 1.3846. So, based on heartbeat count alone, the exerciser will live 38% longer.
BUT, this kind of training will dramatically reduce the resting heartbeat. Training far less than this, my resting heartrate declined into the high-40s-low-50s, and has remained consistent for decades of mostly maintenance training. Most recent six month average is 52 beats/min. with far less than 5hr/week training, but let's use that. That means the resting heartrate is 27,349,920 beats/year, plus the added 1,684,800 exercise beats, making it 29,034,720 beats/year or ~290 million beats per decade.
That means the exercising person 'spends' 8,834,400 FEWER* heartbeats per year, or saves 89 million heartbeats per decade.
https://www.cnn.com/2019/02/08/politics/donald-trump-exercis...