Diagnosing Muscle Loss

By Jane Farrell

Researchers have come up with a way of measuring the age-related loss of muscle mass and strength, and the discovery could lead someday to consistent diagnosis and even treatment for the condition.

The loss of muscle mass and strength, also known as sarcopenia, could put up to 50 percent of seniors at risk of disability. Until now, though, there’s been no consensus on how it should be measured. But a new collection of articles appearing in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences lays out an set of criteria for diagnosing sarcopenia.

“Low muscle mass and weakness are common and potentially disabling in older adults, but in order to become recognized as a clinical condition, criteria for diagnosis should be based on clinically relevant thresholds and independently validated,” the authors wrote in the lead article of the series.

The researchers’ findings indicate that evaluations of grip strength (the force applied by the hand to grip an object) and lean mass could be used in identifying sarcopenia. In reaching this conclusion, scientists working on the Sarcopenia Project, a federal/private sector effort, combined data from nine large studies of older people. They analyzed the participants for grip strength, gait speed, body mass index (BMI), and appendicular lean mass (ALM), a measurement of muscle mass in the arms and legs. The total sample included more than 26,000 participants, with men having an average age of 75.2 years, and women 78.6 years.

Based on their analyses, the investigators recommend that weakness be defined as grip strength less than 57 pounds for men and 35 pounds  or less in women, and low muscle mass defined as an ALM-to-BMI ratio of less than 0.789 for men and 0.512 for women.

Both of these criteria were linked with increased risk of developing mobility impairment over three years of follow-up.

The researchers noted that many of the participants were healthy, and said further study was needed on people who were not in good health.