Late-life exercise shows rejuvenating effects on cellular level

For people who hate working out, here’s more bad news: It can also keep you younger. Not just looking younger, but actually looking younger, on an epigenetic level. By now, the benefits of exercise have been well established, including increased bone and muscle strength, improved mobility and endurance, and a lower risk of heart disease, diabetes, and high blood pressure.

But younger?

A study recently published in aging cell, “Exercise in old age mitigates epigenetic aging of skeletal muscle,” suggests that this might be the case. The article was written by a team of seven researchers from three institutions, including Kevin Murach, assistant professor in the U of A Department of Health, Human Performance, and Recreation. Murach’s grant from the National Institutes of Health funded the study, and was one of three co-first authors.

bootcamp for mice

While the document is packed with data, reflecting the use of various analytical tools, the experiment that generated the data was relatively straightforward. Laboratory mice nearing the end of their natural lives, at 22 months, were allowed access to a weighted exercise wheel. Mice generally do not require coercion to run and will do so voluntarily. Older mice run six to eight kilometers a day, mostly in spurts, while younger mice can run 10 to 12 kilometers. The weighted wheel ensured that they built muscle. While there is no direct analog to most human exercise routines, Murach compared it to “a soldier carrying a heavy backpack for many miles.”

When the mice were studied after two months of progressively running with weights on the wheel, the epigenetic age of the mice was determined to be eight weeks younger than age-matched sedentary mice: 24 months. Murach noted that while the specific strain of mice and their housing conditions can affect life expectancy, “historically, they start to drop out after 24 months at a significant rate.” Needless to say, when its lifespan is measured in months, an extra eight weeks – roughly 10 percent of that lifespan – is a remarkable gain.

Methylation, my dear Watson

The science behind this, while complicated, relies heavily on a biological process known as DNA methylation. a recent New York Times An article reviewing Murach’s work on muscle memory described methylation “as a process in which groups of atoms, called methyl clumps, they stick to the outside of genes like tiny barnacles, making the genes more or less likely to turn on and make particular proteins.”

As the body ages, it tends to increase DNA methylation, or even hypermethylation, at gene promoter sites in muscle. “Changes in DNA methylation throughout life tend to occur in a somewhat systematic way,” Murach explained, “to the point where you can look at a person’s DNA from a given tissue sample and predict quite accurately his chronological age. Because of this, researchers can use one of several “methylation clocks” to determine the age of a DNA sample.

DNA methylation, aging and exercise

While the paper strengthens the case for exercise, there is still much to learn. Although the connection between methylation and aging is clear, the connection between methylation and muscle function is less clear. Murach is not yet ready to say that reversal of methylation with exercise is a cause of better muscle health. “That’s not what the study was created for,” he explained. However, he intends to conduct future studies to determine whether “changes in methylation result in altered muscle function.”

“If so, what are the consequences of this?” he continued. “Does the changes at these very specific methylation sites have an actual phenotype that comes out of that? Is that what’s causing aging or is it just associated with it? Is it something that happens along with a variety of other things that happen during the aging process? So that’s what we don’t know.”