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Exercise and Longevity: More Complex Than We'd Like
(Wednesday February 24 2010)
 | Given the vast weight of evidence, it would seem straightforward to say that regular exercise is good for health and longevity. But of course, nothing is ever as simple as we'd like in biology: "We know that exercise is good for us, and increasingly we're understanding how it works at the molecular and cellular level: Physical activity boosts levels of heat shock proteins, which help cells resist stress; it also improves mitochondrial function in a manner reminiscent of calorie restriction (CR). Our knowledge is sophisticated enough that we can identify and develop small-molecule exercise mimetics and drugs that improve exercise tolerance. Overall, then, exercise and its molecular/cellular consequences are consistent with longevity assurance pathways and life extension interventions. However, there are complications emerging. ... In blood flow restriction (BFR) exercise, resistance training is combined with pressure cuffs that significantly decrease blood flow to the exercising muscle; it increases protein synthesis in muscle cells and activates the TOR pathway. Now, Fry et al. have shown that in older men (who don't increase muscle mass in response to ordinary resistance training), BFR activates TOR. Superficially, this would seem to represent a contradiction: a lifespan-extending intervention (exercise) activates a lifespan-shortening biochemical signaling pathway (TOR). How might this seeming paradox be resolved?" |
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