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Scientific studies have shown that as we age, both our mental and physical abilities begin to decline.

Research on sedentary seniors has shown that between the age of 40 and 50, we can lose more than 8 percent of our muscle mass. The atrophy can increase to more than 15 percent per decade after age 75.

The results may seem grim. But, the trouble with those studies is that the test subjects have largely been sedentary adults, as Andrew Wroblewski and his colleagues point out in their recent study published in The Physician and Sports Medicine Journal.

Masters athletes keep their muscle over time

Relatively few researchers have looked at how the muscles of masters athletes – individuals who exercise routinely – decline, or don’t, as they get older. To look at this cross-section of society, Wroblewski and his team took muscle and body composition measurements of 40 high-level recreational athletes.

The subjects, 20 men and 20 women, ranged in age from 40 to 81 years and practiced their sport, primarily running, biking and/or swimming, four to five times per week.

Aging alone does not affect muscle mass or strength

By measuring lean muscle mass, body fat composition and mid-thigh muscle area, along with taking MRI scans of the athletes’ quadriceps, the researchers observed that these masters competitors preserved muscle mass even as they aged.

The results showed that mid-thigh muscle mass and lean mass did not increase with age. But it didn’t decrease either. And, the older athletes seemed to maintain their muscle mass even though their body fat increased, relative to the younger competitors in the study.

These observations suggest that body fat was accumulating in places other than within the muscles, which is better for maintaining muscle strength. Tests on the subjects’ quads strength also showed that it did not decline with age either.

Use or lose it, it’s true

In other words, this new study flat out contradicts all of the previous research suggesting that all of us will lose muscle mass and strength simply by growing older.

Instead, the authors argue, the muscles atrophy because they aren’t being used. They also suggest that if more individuals stress their muscles as they age, it may reduce  the physical decline, falls and loss of independence that frustrate and inhibit many senior citizens.

The authors also note that it’s these aspects of aging that tend to increase health care costs, so if each individual continues to develop their muscles as they age, the exercise could channel those unspent billions back into the economy.

MRI scans of the quad of a 40-year-old triathlete, a 70-year-old triathlete and a 74-year-old sedentary man. Credit: Wroblewski et. al.

Citation: Wroblewski, A., et. al. Chronic Exercise Preserves Lean Muscle Mass in Masters Athletes. The Physician and Sportsmedicine. Volume: 39, No.3. DOI: 10.3810/psm.2011.09.1933

Ashley Yeager is a science writer and a triathlete. Follow her on twitter at @tri_science.