The Effects of Aging and How Exercise Counteracts Them

• Motor neurons die, particularly from age 60 onward. This causes connections between muscle fibers to wither — and that, in turn, eventually leads to loss and shrinking of muscle fibers. As a result, muscles get smaller and a person gets weaker, says Sandra Hunter, an associate professor of exercise science at Marquette University in Milwaukee. "Physical activity can offset some of that," she says. "But there is this biological aging process going on — the neurons will die regardle...

 Studies Showing the Benefits of Exercise

Scientists are also encouraged by studies on mice with a certain genetic mutation that makes them age prematurely — complete with graying and thinning fur, cataracts, hearing loss, smaller brains, enlarged hearts, anemia and thin and weak muscles — hallmark symptoms of growing older. To test whether it was possible to slow or reverse the process in these mice, a team led by Dr. Mark Tarnopolsky, a professor of pediatrics and medicine at McMaster University in Ontario, Canada, had the ro...