People who engage regularly in either aerobic or muscle-strengthening exercises are less likely to become obese than people who are sedentary, but doing both types of exercise is more likely to keep excess pounds off than doing one or the other, according to new research.
Interestingly, women appear to benefit even more than men by combining aerobic physical activity with muscle-strengthening exercises.
The study, which was conducted by Australian researchers using U.S. data, appears in the February issue of the journal Obesity.
“Until now most population-level evidence on physical activity for reducing the risk of, or preventing obesity is based on aerobic exercise, such as walking, cycling and jogging, but few studies have previously examined the associations between combining aerobic exercise and muscle-strengthening activities with obesity,” said Jason Bennie, the study’s lead author and a senior research fellow at the University of Southern Queensland, in a released statement.
“From the data we analyzed, it’s great news for people who find it hard to get out and exercise, but can potentially do some strength training at home,” he added.
In the United States, about 40 percent of adults — more than 93 million individuals — have obesity, according to the Centers for Disease Control and Prevention (CDC). The condition increases the risk of many chronic diseases, including heart disease, stroke, type 2 diabetes, osteoarthritis, breast and colon cancer, and dementia.
Reducing illness and early death related to obesity has been a major U.S. public health priority for more than a decade.
Gathering the data
For the current study, Bennie and his co-authors analyzed data from almost 1.7 million U.S. adults who participated in the CDC’s Behavioral Risk Factor Surveillance System (BRFSS) telephone surveys between 2011 and 2017. More than a quarter (27 percent) of the participants were 65 or older and slightly more than half (51.6 percent) were women. Most (65.4 percent) were white, followed by Hispanics (13.5 percent), blacks (11.1 percent), multiracial (5.1 percent) and “other” (4.9 percent).
As part of the survey, the participants were asked about the types of physical activity they had engaged in during the past month, both aerobic (“such as running, calisthenics, golf, gardening or walking”) and muscle-strengthening (“like yoga, sit-ups or push-ups and those using weight machines, free weights, or elastic bands”). They were also asked how often they did those activities.
The researchers grouped the participants into four categories:
- Those who met neither the recommended level of aerobic activity (a minimum of 150 minutes of moderate activity per week) or the recommended level of muscle-strengthening activity (at least two sessions a week).
- Those who met only the aerobic activity recommendation.
- Those who met only the muscle-strengthening recommendation.
- Those who met both recommendations.
Forty percent of the participants met neither guideline, 30.5 percent met only the aerobic activity guidelines, 9.5 percent met only the muscle-strengthening guidelines, and 20.2 percent met both guidelines.
Using height and weight information from the surveys, the researchers calculated the participants’ body mass index (BMI). Those (35.6 percent of the respondents) who had a BMI of 18.5-24.9 were categorized as having a healthy weight, and those (28.9 percent) with a BMI of 30 or higher were categorized as obese.
An analysis of all that data revealed the incidence of obesity was much lower among active people than sedentary ones — even if their exercise routine included only aerobics or only muscle-strengthening activities.
But the incidence of obesity was lowest — significantly so — among people who regularly combined muscle-strengthening exercises with aerobics. Not only were they 50 percent less likely to have obesity than sedentary people, they were also 20 percent less likely to have obesity than those who did just aerobics or just muscle-strengthening.
These associations were stronger among women than among men. “This suggests,” write Bennie and his colleagues, “that public health physical activity interventions focusing on women could be the most effective for obesity prevention,” particularly since other research has shown that women are currently less likely to do both aerobics and muscle-strengthening exercises.
Limitations and implications
The study’s findings are observational, so they can’t prove a causal relationship between exercise and the risk of having obesity. Still, as the researchers point out in their paper, “there is some clinical evidence suggesting that [muscle-strengthening exercises] combined with [aerobic exercise] may increase lean body mass, more than either activity alone, thus resulting in an increased metabolic rate and/or total energy expenditure among those who engage in both physical activity modes.”
Bennie said he hopes the study’s findings will encourage people to not only exercise more, but to also broaden their current routine.
“Making some changes to your daily routine can make a big difference, like body weight exercises such as squats, sit-ups, or push-ups at home; or join a gym to do weights,” he said.
But “physical activity doesn’t need to be complicated or time-consuming,” he added. “Doing any physical activity is better than none.”
For more information: You can read the study in full on the Obesity website.