Published: May 3, 2013 | Updated: May 6, 2013

Image from MedPageToday.com

By John Gever , Deputy Managing Editor, MedPage Today

Action Points

• Government guidelines recommend certain amounts of both aerobic and muscle-strengthening exercises.
• A telephone survey indicated that about one in five U.S. adults report engaging in enough of both aerobic and muscle-strengthening activities to meet the guidelines. Nationwide, approximately half of U.S. adults met the aerobic activity guideline, and less than one-third met the muscle-strengthening guideline.

Just over 20% of U.S. adults get as much aerobic and muscle-strengthening exercise as recommended in government guidelines, CDC researchers said.

Using data from the large Behavioral Risk Factor Surveillance System survey in 2011, with about 450,000 respondents, Carmen Harris, MPH, and colleagues at the CDC found that 20.6% of respondents indicated that their non-occupational physical activity reached levels recommended in the 2008 Physical Activity Guidelines for Americans issued by the U.S. Department of Health and Human Services.

On the plus side, however, half the respondents reported enough aerobic activity to meet the guideline recommendation for that type of exercise, and almost 30% reached the goal for muscle-strengthening activity, the researchers indicated in the May 3 issue of Morbidity and Mortality Weekly Report.

The guidelines call for adults to engage in these forms of activity, outside of work, at the following levels:

• Aerobic: at least 150 minutes/week of moderate-intensity, 75 minutes/week of vigorous exercise, or a combination of the two such that, by multiplying the duration of vigorous activity in minutes by two, the total is at least 150 minutes/week
• Muscle-strengthening: at least two episodes of such activity per week

Men were more likely than women to meet these goals, together and individually. Harris and colleagues also found a strong age effect, in which the percentage of respondents indicating that they met the goals declined with increasing age.

Both findings largely reflected lower participation in muscle-strengthening activities in women and older respondents. For aerobic activity, the disparities by gender and age were much smaller.

For example, 34.4% of men and 24.5% of women met the muscle-strengthening guideline, whereas 53.1% of men and 50.2% of women achieve the aerobic activity goal, Harris and colleagues reported.

Other factors strongly associated with success in meeting the guidelines were educational attainment (positive correlation) and body mass index (negative).

Only 12% of respondents without a high school diploma met goals for both aerobic and muscle-strengthening activity, compared with 27.4% of college graduates (P<0.05). Similarly, 13.5% of individuals classed as obese and 21.9% of those classified as overweight met both goals, versus 25.8% of normal and underweight respondents (P<0.05 for both comparisons to normal/underweight).

Race/ethnicity was less of a factor, with Hispanics showing slightly lower rates of goal attainment than other groups. African Americans showed relatively high participation in muscle strengthening but lower levels of aerobic activity than whites or “other” races.

Geographically, respondents in western states had the highest levels of goal attainment (23.5% for both goals) and those in the South had the lowest (18.7%).

States in the Deep South and Appalachian regions had attainment levels as low as 13%. The highest rates were seen in Colorado (27.3% for both goals) followed by the District of Columbia (26.3%).

Harris and colleagues noted that the CDC has previously recommended a number of local policies to encourage exercise participation, such as opening school recreation facilities to adults after-hours and designing streets to be more bike-friendly.

Limitations to the analysis included self-report of physical activity types and durations, a survey response rate of 50%, and the specific survey question on exercise which asked respondents to describe their participation in their top two physical activities.

“Some respondents classified as not meeting the aerobic guideline criteria might have met the criteria if information about additional aerobic activities or regular, aerobic job duties had been included in the analysis,” the researchers indicated.