Not only does exercise make most people feel better, perform physical tasks better and reduce the risk of disability due to arthritis, it now appears that exercise – specifically, resistance training – actually rejuvenates muscle tissue in healthy senior citizens.

What Problem Was Studied?

Several studies have suggested that dysfunction of mitochondria -- the “powerhouse” of the cell -- is involved in the loss of muscle mass and functional impairment commonly seen in older people. Studies have shown that in older adults, there is a decline in mitochondrial function with age. To understand this decline better and to determine what effect exercise may have on that decline, Simon Melov, PhD, and Mark Tarnopolsky, MD, PhD, of McMaster University Medical Center in Hamilton, Ontario, led a team to analyze gene expression involved in age-related mitochondrial function.

What Was Done in the Study?

A group of 25 healthy older men and women (average age of 70 years) had muscle tissue samples taken and compared to the gene profile from muscle samples taken from 26 younger healthy men and women (average age 21 years).  Fourteen of the older adults completed six months of twice-weekly resistance training and the results were then compared to the younger adults. The older adults were relatively active (golfing, walking, gardening, tennis, cycling three or more times a week but were not competitive athletes) and healthy; the younger adults were relatively inactive or participated in modest recreational activities, and none were athletes. These inclusion criteria allowed the investigators to study the effect of aging with subjects selected to be matched for activity level and not merely the effect of inactivity. None of participants took medication or had diseases that could alter mitochondrial function.

The resistance training was done on standard gym equipment. The twice-weekly sessions ran an hour in length and involved 30 contractions of each muscle group involved. Strength was tested based on knee extension, and tissue samples were taken from thigh muscles.

What Were the Study Results?

Dr. Tarnopolsky and others have shown that mitochondrial dysfunction is associated with the aging process, and results in the current study showed that mitochondrial dysfunction was the most common “theme” to emerge from the gene expression profile.

Exercise resulted in a reversal of the genetic profile back to levels similar to those seen in the younger adults. Furthermore, the resistance training increased the older group’s muscle strength. Before exercise training, the older adults were 59% weaker than the younger adults; but after training, the strength of the older adults improved by about 50%, such that they were only 38% weaker than the young 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.”

In a four-month follow-up after the study was complete, Tarnopolsky said most of the older adults were no longer doing formal exercise in a gym, but most were doing resistance exercises at home, lifting soup cans or using elastic bands. “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.”

What Does This Mean for People With Arthritis?

This study gives people one more reason to get physically active. Not only will it help attain or maintain a healthy weight and reduce the risk of disability due to arthritis, this study now shows that it may actually reverse the biologic aging that takes place in muscle cells. “The proven, long-lasting benefits of exercise for people with arthritis are clear,” said Patience White, MD, chief public health officer, Arthritis Foundation. “These study results further emphasize the importance of leading an active lifestyle.”

“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, said Melov.”

Future studies are being designed to determine if resistance training has any genetic impact on other types of human tissue, such as those that comprise organs. Researchers also want to determine whether endurance training (walking, cycling) impacts mitochondrial function and the aging process.

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