Author: Falishia Sloan
Institution: Eastern Virginia Medical School
Date: May 2007
Scientists let by Simon Melov, PhD of the Buck Institute and Mark Tarnopolsky MD,PhD of McMaster University Medical Center have found that exercise, in addition to improving the way people feel and operate, can revitalize muscle tissue in healthy senior citizens.
The researchers studied gene expression profiles in healthy, aging, disease-free people, with an average age of 70. Samples of muscle tissue were taken before and after the subjects launched their exercise regime to determine the effect on their muscles.
The subjects, 25 older but healthy men and women, spent six months participating in resistance training at McMaster University. The twice-weekly sessions included exercise in which all muscle groups experienced 30 contractions, about equal to a training session at a fitness center. Resistance training for participants was on regular gym equipment and strength tests were based on knee flexion.
While past studies have been done on other animals, this study was the first to study the gene expression profile of aging and healthy humans.
"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."
After six months, the scientists took muscle tissue samples from the thighs of the participants in order to study gene expression profiles. These profiles focused on age-specific mitochondrial function, as previous studies have suggested that the dysfunction of the mitochondria play a role in muscle mass loss and decreased function found in older people. They found that, while mitochondrial function did decline with age, the strength of the older adults, already known to be 59% weaker than younger adults, had increased by about 50% after the exercise. The results from the study were compared to results from muscle tissue taken from younger men and women with an average age of 26. The scientists observed that the exercise actually reversed the genetic fingerprint back to levels observed in the younger adults.
"We were very surprised by the results of the study," said Melov. "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."
After four months, co-first author Tarnopolksy followed up with the participants, who, while no longer doing formal training at a gym, were still doing strength exercises at home.
"They were still as strong, they still had the same muscle mass," said Tarnopolsky. "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."
Written by Falishia Sloan