The effects of exercise on aging

From a New York Times magazine article by Bruce Grierson: (full article at www.nytimes.com/.../28athletes-t.html Here, though, is the radical proposition that’s starting to gain currency among researchers studying masters athletes: what if intense training does something that allows the body to regenerate itself? Two recent studies involving middle-aged runners suggest that the serious mileage they were putting in, over years and years, had protected them at the chromosomal level. It appears that exercise may stimulate the production of telomerase, an enzyme that maintains and repairs the little caps on the ends of chromosomes that keep genetic information intact when cells divide. That may explain why older athletes aren’t just more cardiovascularly fit than their sedentary counterparts — they are more free of age-related illness in general. Exactly how exercise affects older people is complicated. On one level, exercise is a flat-out insult to the body. Downhill running tears quadriceps muscles as reliably as an injection of snake venom. All kinds of free radicals and other toxins are let loose. But the damage also triggers the production of antioxidants that boost the health of the body generally. So when you see a track athlete who looks as if that last 1,500-meter race damn near killed him, you’re right. It might have made him stronger in the deal. Exercise training helps stop muscle strength and endurance from slipping away. But it seems to also do something else, maintains Mark Tarnopolsky, a professor of pediatrics and medicine at McMaster University in Hamilton, Ontario (who also happens to be a top-ranked trail runner). Resistance exercise in particular seems to activate a muscle stem cell called a satellite cell. With the infusion of these squeaky-clean cells into the system, the mitochondria seem to rejuvenate. (The phenomenon has been called “gene shifting.”) If Tarnopolsky is right, exercise in older adults can roll back the odometer. After six months of twice weekly strength exercise training, he has shown, the biochemical, physiological and genetic signature of older muscle is “turned back” nearly 15 or 20 years. Motivation may ultimately be the issue. Finding reasons to keep exercising is a universal challenge. Even rats seem to bristle, eventually, at voluntary exercise, studies suggest. Young rats seem intrinsically driven to run on the wheels you put in their cages. But one day those wheels just stop turning. The aging athlete must manufacture strategies to keep pushing in the face of plenty of perfectly rational reasons not to: things hurt, you’ve achieved a lot of your goals and the friends you used to do it for and with are disappearing. But competition can spur people on. “Maintaining your own records in the face of your supposed decline, providing evidence that you’re delaying the effects of aging — these are strong motives,” says Bradley Young, a kinesiology and sports psychology professor at the University of Ottawa. Young studies the factors that make track athletes want to continue competing into old age. A big one is training partners and family — both the encouragement they offer, and the guilt you’d feel letting them down if you quit. When the efforts of medical science converge to simply prolong existence, you envision Updike’s golfer Farrell, poking his way “down the sloping dogleg of decrepitude.” But scientists like Taivassalo and Hepple have a different goal, and exercise — elixir not so much of extended life as extended youthfulness — may be the key to reaching it. James Fries, an emeritus professor at Stanford School of Medicine, coined the working buzz phrase: “compression of morbidity.” You simply erase chronic illness and infirmity from the first, say, 95 percent of your life. “So you’re healthy, healthy, healthy, and then at some point you kick the bucket,” Tarnopolsky says. “It’s like the Neil Young song: better to burn out than to rust.”