A new study from Ontario, Canada has found that exercise, particularly resistance training, rejuvenates muscle tissue in healthy senior citizens and hence reverses aging in human skeletal muscle.
Researchers examined gene expression profiles in tissue samples from 25 healthy men and women older than age 65, before and after they did six months of resistance training twice a week and compared them to tissue samples from younger healthy men and women age 20 to 35.
The gene expression profiles or molecular "fingerprints" focused on the function of mitochondria -- the "powerhouse" of cells. Earlier research suggests that mitochondrial dysfunction has something to do with the loss of muscle mass and functional impairment, which is commonly seen in older people.
The study, co-led by Buck Institute faculty member Simon Melov, PhD, and Mark Tarnopolsky, MD, PhD, of McMaster University Medical Center in Hamilton, Ontario, was the first to look at the gene expression profile, or the molecular "fingerprint", of aging in healthy disease-free humans.
The study demonstrated that there was a decline in mitochondrial function with age in older adults. Nevertheless, exercise upturned the genetic fingerprint back to levels similar of younger adults. Results also show that prior to exercise training, the older adults were 59 percent weaker than the younger ones. But with strength training, the older adults became only 38 percent weaker than the young adults.
"We were very surprised by the results of the study. We expected to see gene expressions that stayed fairly steady in the 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, which is an additional incentive to exercise as you get older," said Melov.
Future studies are being considered to find out if resistance training has any genetic impact on other types of human tissue, such as those that comprise organs. Researchers also want to resolve whether endurance training (running, cycling) impacts mitochondrial function and the aging process. The most recent study also points to particular gene expressions that could be used as starting points for chemical screenings that could lead to drug therapies that would modulate the aging process.
"The vast majority of aging studies are done in worms, fruit flies and mice; this study was done in humans," said Melov. "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."