Not only could exercise, especially strength training, make you feel better and perform physical tasks like a well-oil machine, but may even rejuvenate the energy powerhouse deep within your cells.

Researchers said recently that lifting weights may affect senior citizens on the cellular level by essentially turning back the clock on aging muscles.

“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, which is an additional incentive to exercise as you get older,” said Simon Melov, a project leader and a faculty member at the Buck Institute of Age Research in Novato, Calif.

Melov and Dr. Mark Tarnopolsky of McMaster University Medical Center in Hamilton, Ontario, took samples of muscle cells from the thighs of 25 healthy people over 65 who took part in six months of twice-weekly resistance training. The samples were then compared to muscle cells from the thighs of healthy men and women in their 20s.

Changing the 'powerhouse'

The two scientists said they found “dramatic changes” at the genetic level of the seniors: exercise had affected the functioning of mitochondria, the so-called “powerhouses” of cells, which turn nutrients into energy. As a result, the seniors reported that they were enjoying more energy, even being able to pick up their grandchildren for the first time in ages, carry grocery bags filled with food, or run up a flight of steps.

They even improved their overall strength by as much as 50 percent, researchers said.

"The genetic fingerprint of the elderly participants was reversed to that of younger people—not entirely, but enough to say that their genetic profile was more like that of young people than old people,” Melov said.

To get those results, the older people in their exercise regimens used the same type of weight machines that you would find in a gym. They performed three sets of 10 contractions for each muscle group, similar to a standard workout, although with lighter weights.

'Never too late'

Naturally, it helped that all the people in the study were in good shape to start with—able to go shopping, walk the dog, play golf or swim. Tarnopolsky said they picked healthy people for the project so his team could focus on genetic changes related to aging, not cancer or heart disease.

In four months after the study, most of the older adults were no longer doing formal exercises in the gym, but kept up resistance exercises at home, such as lifting soup cans or using elastic bands.

“This shows that it’s never too late to start exercising and that you don’t have to spend your life pumping iron in a gym to reap benefits,” Tarnopolsky said.

Studies suggest that as people get older, the mitochondria in the cells go haywire, resulting in loss of muscle mass and impeding their ability to get around and function. Now, Melov, Tarnopolsky and other researchers want to see if resistance training can affect organs and whether running, cycling and other endurance endeavors can ratchet up mitochondria as people get older.

“The vast majority of aging studies are done in worms, fruit flies and mice; this study was done in humans,” Melov said. “It’s particularly rewarding to be able to scientifically validate something practical that people can do now to improve their health and the quality of their lives, as well as knowing that they are doing something which is actually reversing aspects of the aging process.”

For more information

•  Vigorous Activity Means Less Weight Later

•  Five Tips for Promoting That Youthful Feeling

•  Exercise May Stymie Arthritis in Women

•  Walking Off the Extra Weight and Helping Your Brain

•  Ways to Age Without Aching