Highly interesting articles in the journal Science. Last week it reported on how exercise destroys senescent cells in mature adults. This week it reports how this process prolongs youthful health. (Science 16 July, 2021, pg. 281 ff).

Cellular senescence is a phenomenon characterized by the cessation of cell division. In experiments conducted during the early 1960s, Leonard Hayflick and Paul Moorhead observed that normal human fetal fibroblasts in culture reach a maximum of approximately 50 cell population doublings before becoming senescent.

Cell senescence has been attributed to prevention of carcinogenesis, and more recently, aging, development, and tissue repair. Such cells play a role in the aging phenotype, in aging-associated diseases, and in frailty and sarcopenia. In addition, senescent astrocytes and microglia contribute to neurodegeneration.

Senescent cell load and the secretome increase as we age. This drives inflammation, tissue damage, further infection, inflammation-related pathology, and death.

The removal of senescent cells through physical activity such as physical work and exercise appears to reduce inflammation to below the “young” threshold, allowing disease resolution and survival.

So there’s much truth to what Helen Hayes reportedly said: “If you rest, you rust”.