Sarcopenia is the name given to more severe manifestations of the characteristic age-related loss of muscle mass and strength that occurs in all older people. A review of the literature will find ongoing debates over many possible contributing causes of this muscle degeneration, some with better evidence than others, many related to one another: lower dietary intake of protein in the elderly; a failure to correctly process dietary amino acids, particularly leucine; degeneration in the connections between muscle and nervous system; declining activity in muscle stem cell populations; chronic inflammation such as that produced by senescent cells; lack of exercise, particularly strength training; and so forth. From where I stand, I’d say the stem cell explanation is by far the most robust, but then one has to think about why the stem cell populations are in decline.
Sarcopeniaamino acidsparticularly leucineconnections between muscle and nervous systemin muscle stem cell populationschronic inflammationproduced by senescent cellsparticularly strength trainingstem cellstem cell populations are in decline
The open access paper here weighs in with thoughts on age-related changes in the types and behavior of bacteria in the gut as a contributing cause of sarcopenia. A great deal of attention has been given to the gut microbiome in
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