To educate yourself further on the recent research findings when it comes to exercise and aging, the two articles below are must reads!

Muscle mass linked to aging

From Wednesday's Globe and Mail
May 23, 2007 at 9:52 AM EDT

If you want a taste of the Fountain of Youth, try pumping iron. That's the message that emerges from a new Canadian study that shows that resistance training actually reverses aging - at least in muscle tissue."With a little weight training we managed, to a certain extent, to turn back the hands of time," Mark Tarnopolsky, director of the neuromuscular and neurometabolic clinic at McMaster University in Hamilton and co-author of the study, said in an interview. "Resistance training reversed the effects of aging in skeletal muscles," he said.

Participants in the research project, who lifted light weights for a mere two hours a week, were able to improve their muscle strength by 50 per cent during the six-month study period. Researchers, however, did not merely measure muscle strength in the traditional sense of the term. Rather, they measured the gene expression of muscles - more specifically how many mitochondria they produce.

Mitochondria are tiny biochemical power plants in cells that convert food into energy, and tiny changes in mitochondrial DNA have been pegged as the key component of aging. "The reason we get weaker, thinner and have less endurance as we age is that there are fewer genes making mitochondria," Dr. Tarnopolsky said. Loss of muscle mass is a major problem among seniors, leaving many frail; about one in four people over 80 have lost so much muscle mass that they cannot carry out many activities of daily living. But the new research suggests that process can be slowed, or even reversed, by stimulating muscles with weight training. (A future study will examine if endurance training, such as running or cycling, has similar effects.)

To conduct the study, which is published in today's edition of the online medical journal Public Library of Science, researchers recruited 25 healthy seniors (average age 70) and an equal number of university students (average age 26.) They all had muscle biopsies and 24,000 genes were compared in each participant; 600 genes were markedly different between the older and younger participants. At the outset, both groups had similar activity levels but the young people were, not surprisingly, much stronger. Initially, the seniors were 59 per cent weaker than the young adults. But after six months of twice-weekly weight training, they were 38 per cent weaker. More important, the gene expression profile (or genetic fingerprint) of the seniors had changed noticeably, looking a lot more like that of the younger folk.

"We were surprised by the results," said Simon Melov, director of genomics at the Buck Institute for Age Research in Novato, Calif., and co-author of the study. "We expected to see gene expressions that stayed fairly steady in older adults. The fact that their genetic fingerprints so dramatically reversed course gives credence to the value of exercise not only as a means of improving health, but of reversing the aging process itself," he said. Barbara Ford, a 72-year-old retiree and study participant, said that she is not conversant with the science but that there's no question she feels healthier and younger as a result of the weight training. "I don't know exactly what they were after with the muscle biopsy and their tests, but I can tell you I don't feel 72. I don't feel a day over 60." Mrs. Ford said she recognizes that being active, physically and mentally, is essential to good health, but having an established program in the gym made it a lot easier to do so, and weight training was a lot more fun that she would ever have imagined. "It was a great experience. I felt stronger and had more stamina. My grandchildren said I had Popeye muscles," she said with a laugh.

Keeping your DNA fit

Researchers find exercise buffs have "younger" cells.

By Faye Flam
Inquirer Staff Writer
As if gray hair, brittle bones and wrinkles weren't bad enough, scientists say that as you age, the very DNA in your trillions of cells starts to fray, unravel and disintegrate.

Now there may be something you can do to slow the inevitable - exercise.

A study published yesterday hints that fitness buffs appear to have "younger" DNA than the chronically sedentary. The finding could help scientists understand the effects of exercise and aging at a molecular level. In theory, it might also motivate people to get off the couch. "This is a provocative paper and an interesting piece of research," said Jack Guralnik, an epidemiologist at the National Institute on Aging who wrote an editorial that accompanied the research report in the Archives of Internal Medicine. He cautioned, however, that the old chicken-and-egg question - does exercise preserve healthier DNA, or does healthier DNA enable people to exercise more? - has yet to be answered. "People who choose to exercise are different in so many ways from people who don't," Guralnik said.

The study's authors examined just the ends of DNA strands. Called telomeres, these act something like the plastic caps on shoelaces, preventing the DNA in chromosomes from unraveling. Previous research has shown that older people have shorter ends than younger folks. Indeed, biologists say they shrink every time a cell divides. How, exactly, does this lead to overall decrepitude? Eventually it stops your cells from dividing and replenishing themselves, said Emmanuel Skordalakes, a researcher at the Wistar Institute in Philadelphia. "When the telomeres become short, then you start cutting into actual chromosomes where there are genes essential for our body," he said. To prevent the fraying DNA in all those aging cells from seeding malignant tumors, Skordalakes said, the body turns them dormant. "Your body shuts down more and more cells every day and you become old."

Not everyone's DNA ages at the same rate. Some people may start off with sturdier telomeres than others, or perhaps longer ones, Lynn Cherkas, the new study's lead author, said in an interview from London, where she is a researcher at King's College. To try to separate the influences of heredity and lifestyle, she studied twins. Analyzing a British database containing more than 2,401 sets, some fraternal and some identical, she found the heavy exercisers had relatively long telomeres - comparable to those of couch potatoes 10 years younger. She defined the heavy exercisers as those who put in more than three hours a week running, cycling, pumping iron, or other vigorous activity. Sedentary twins put in less than 16 minutes a week on average. What she found most compelling were the results of her comparison of 67 pairs in which one exercised much more than the other. Among those, the exercising twin had longer telomeres than his or her more sedentary counterpart.

How exercise might achieve such an anti-aging feat remains a mystery, though it may become clearer in the future as scientists at Wistar and elsewhere continue investigating the workings of telomeres. They do know that while our bodies lose telomeres over time, an enzyme called telomerase helps reset the clock in embryos. That allows babies to be born young. Tinkering with nature may alter that reset: A few years ago scientists discovered that Dolly the sheep and some other cloned animals had unusually short telomeres, as if they had been born old.

OK, then, why not just take telomerase injections? Well, for one thing, they might encourage abnormal cells to divide out of control. "Telomerase is a marker for cancer," Skordalakes said. "We're trying to understand how the enzyme works in detail so we can design drugs to stimulate telomerase activity and not to cause cancer," he said. "It's a very fine line." As a follow-up study, Cherkas said she's tracking the same twins and their telomeres over a period of 10 years.

And Guralnik said that while Cherkas had examined telomere length in white blood cells, he would also like to see a range of follow-ups - to investigate whether, for example, the exercise effect applies to telomeres in brain, liver, skin and other cells. "We have a lot to learn," he said. Of course, scientists already have a strong case that exercise can stave off many of the ailments associated with growing old, as opposed to the condition itself, Guralnik said. "Exercise is one of the best ways for people to postpone some of the negative outcomes of aging."

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