Can Exercise Keep You Young?

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Can Exercise Keep You Young? - NYTimes.com

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice — PNAS

Indeed, in heartening new research published last week in The Proceedings of the National Academy of Sciences, exercise reduced or eliminated almost every detrimental effect of aging in mice that had been genetically programmed to grow old at an accelerated pace.

In the experiment, Dr. Tarnopolsky and his colleagues used lab rodents that carry a genetic mutation affecting how well their bodies repair malfunctioning mitochondria, which are tiny organelles within cells. Mitochondria combine oxygen and nutrients to create fuel for the cells — they are microscopic power generators.

The mice that Dr. Tarnopolsky and his colleagues used lacked the primary mitochondrial repair mechanism, so they developed malfunctioning mitochondria early in their lives, as early as 3 months of age, the human equivalent of age 20. By the time they reached 8 months, or their early 60s in human terms, the animals were extremely frail and decrepit, with spindly muscles, shrunken brains, enlarged hearts, shriveled gonads and patchy, graying fur. Listless, they barely moved around their cages. All were dead before reaching a year of age.

Except the mice that exercised.

Half of the mice were allowed to run on a wheel for 45 minutes three times a week, beginning at 3 months. These rodent runners were required to maintain a fairly brisk pace, Dr. Tarnopolsky said: “It was about like a person running a 50- or 55-minute 10K.” (A 10K race is 6.2 miles.) The mice continued this regimen for five months.

At 8 months, when their sedentary lab mates were bald, frail and dying, the running rats remained youthful. They had full pelts of dark fur, no salt-and-pepper shadings. They also had maintained almost all of their muscle mass and brain volume. Their gonads were normal, as were their hearts. They could balance on narrow rods, the showoffs.

But perhaps most remarkable, although they still harbored the mutation that should have affected mitochondrial repair, they had more mitochondria over all and far fewer with mutations than the sedentary mice had. At 1 year, none of the exercising mice had died of natural causes. (Some were sacrificed to compare their cellular health to that of the unexercised mice, all of whom were, by that age, dead.)
 
Hormesis.

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Proposed model of mitochondrial dysfunction in aging. Toxic reactive oxygen species (ROS) generated during normal biological activity gradually impair cellular homeostatic pathways that defend against cellular stress and damage mitochondrial constituents, including the electron transfer chain (ETC) and mtDNA. Oxidative insults to mitochondria, in turn, impair the life-sustaining functions of the organelle – such as energy transduction, biogenesis of metabolites, Ca2+homeostasis and regulation of redox biology – with age, thereby contributing to a vicious cycle of accumulating mitochondrial damage that culminates in a mitochondrial functional crisis. This ultimately results in cell death and aging.


Seo AY, Joseph A-M, Dutta D, Hwang JCY, Aris JP, Leeuwenburgh C. New insights into the role of mitochondria in aging: mitochondrial dynamics and more. J Cell Sci 2011;123(15):2533-42. New insights into the role of mitochondria in aging: mitochondrial dynamics and more -- Seo et al. 123 (15): 2533 -- Journal of Cell Science

A decline in mitochondrial function plays a key role in the aging process and increases the incidence of age-related disorders. A deeper understanding of the intricate nature of mitochondrial dynamics, which is described as the balance between mitochondrial fusion and fission, has revealed that functional and structural alterations in mitochondrial morphology are important factors in several key pathologies associated with aging. Indeed, a recent wave of studies has demonstrated the pleiotropic role of fusion and fission proteins in numerous cellular processes, including mitochondrial metabolism, redox signaling, the maintenance of mitochondrial DNA and cell death. Additionally, mitochondrial fusion and fission, together with autophagy, have been proposed to form a quality-maintenance mechanism that facilitates the removal of damaged mitochondria from the cell, a process that is particularly important to forestall aging. Thus, dysfunctional regulation of mitochondrial dynamics might be one of the intrinsic causes of mitochondrial dysfunction, which contributes to oxidative stress and cell death during the aging process. In this Commentary, we discuss recent studies that have converged at a consensus regarding the involvement of mitochondrial dynamics in key cellular processes, and introduce a possible link between abnormal mitochondrial dynamics and aging.
 

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I thought it's very well established that excercise had life extending benefits - among others - and that it was an example of hormesis. I should have been more descriptive in making the connection. Sorry!
 
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