Only 30.2 percent of adults in the United States engage in muscle-strengthening activities — such as lifting weights, working with resistance bands, or doing calisthenics like push-ups and sit-ups — for the recommended two or more sessions a week, according to a study published recently in the American Journal of Preventive Medicine.

And six in 10 American adults don’t do any muscle-strengthening activities on a regular basis, the study also found.

Those are pretty feeble numbers — and troubling ones. For, as the study also found, engaging in muscle-strengthening activities for even a single session a week is associated with a reduced risk of type 2 diabetes, obesity and cancer. Last month, another group of researchers reported that such activities are also linked to a reduced risk of stroke and heart attack.

All of those benefits occur independently of any aerobic activities, such as walking, running or biking.

The authors of the current study recommend that health officials put more effort into promoting muscle-strengthening as well as aerobic exercise. Both types of activities are needed for optimal health, they stress.

“We hope that these findings put [muscle-strengthening exercises] front and center on the agenda as a key health behavior in the prevention and management of chronic diseases,” said Jason Bennie, the study’s lead author and an epidemiologist at the University of Southern Queensland in Australia, in a released statement.

Study details

Bennie and his colleagues analyzed data collected from almost 400,000 Americans aged 18 and older who participated in the 2015 U.S. Behavioral Risk Factor Surveillance System survey, which the Centers for Disease Control and Prevention (CDC) has been conducting annual for more than three decades.  About half (52 percent) of the respondents were women, while 64 percent were white, 56 percent were employed and 48 percent earned $50,000 or more a year. In addition, more than two-thirds (65 percent) of the respondents were overweight or obese and only 32 percent reported that they were in good health.

Among the survey’s questions about health-related behaviors was one that asked the participants how often they had done muscle-strengthening activities during the previous month. They were told not to include aerobic activities in their answer, but rather “activities using your own body weight like yoga, sit-ups or push-ups and those using weight machines, free weights or elastic bands.”

Only 30.2 percent of the respondents said they had done muscle-strengthening exercises the recommended two or more times per week. That was much lower than the 51 percent who met the minimum guidelines for aerobic exercise.

In addition, 57.8 percent of the respondents reported doing no muscle-strengthening activities.

Women, white adults and older people, as well as those with lower incomes, lower levels of education and in poorer health, were the groups most likely to say they didn’t engage in such exercises.

“These findings underscore the importance of targeting these population subgroups in future [muscle-strengthening exercise] public health interventions,” the study’s authors conclude.

The researchers also found that compared with people who did no muscle-strengthening exercises, those who did work on strengthening their bodies were less likely to have type 2 diabetes, cancer or coronary heart disease. The researchers reached those results after adjusting for potential confounders, such as age, smoking, body mass index (BMI) and amount of weekly aerobic activity.

Making muscles work

The study was observational, so it can’t prove that muscle-strengthening exercises are associated with better health outcomes. Although the researchers took into account several confounders, other factors not adjusted for in the analysis might explain the study’s results. The obvious one is that people who are already unhealthy may be more likely to avoid exercising.

The study also relied on a single self-report from the participants about their muscle-strengthening exercise habits. Those reports may not be accurate.

Still, there is a growing consensus among health officials that people need to focus on muscle-strengthening in addition to — and separate from — aerobic exercise.

So, what should all of us be doing to get stronger?

The U.S. government’s 2018 Physical Activity Guidelines define muscle-strengthening activities as those that “make muscles do more work than they are accustomed to doing. That is, they overload the muscles.”

“Muscle-strengthening activities count if they involve a moderate or greater level of intensity or effort and work the major muscle groups of the body — the legs, hips, back, chest, abdomen, shoulders, and arms,” the guidelines add.

Adults should do such exercises at least two days a week — and the exercises should be done to the point “at which it would be difficult to do another repetition.”

For tips on what those exercises should look like, go to the Mayo Clinic’s website. It has some great how-to videos that demonstrate a series of exercises for strengthening the body. Older people, however, may find the National Institute on Aging’s exercises more helpful.

Of course, if you have health issues or concerns, you should talk with your doctor before starting any exercise program.

FMI: An abstract of the study can be found on the American Journal of Preventive Medicine’s website, although the full study is behind a paywall.