A staggering 80 percent of U.S. adults aren't meeting the federal physical activity recommendations for both aerobic exercise and muscle-strengthening activity, according to government statistics out today.

Overall, only 1 in 5 adults are getting the recommended amounts of exercise, according a report by the U.S. Centers for Disease Control and Prevention.

The news was less disappointing for aerobic exercise, with 51.6 percent of adults getting the recommended amount, than it was for muscle-strengthening activities, with only 29.3 percent getting the recommended amount, the report said.

The data are based on self-reported information from the Behavioral Risk Factor Surveillance System; an annual phone survey of adults aged 18 and over conducted by state health departments.

The report found that the highest proportion of adults meeting those guidelines were in the West (24 percent) and the Northeast (21 percent). Meanwhile, hispanics, women, the elderly and obese adults were less likely to meet the guidelines.

"Although only 20 percent of adults are meeting the overall physical activity recommendations, it is encouraging that half the adults in the United States are meeting the aerobic guidelines and a third are meeting the muscle-strengthening recommendations," said Carmen D. Harris, M.P.H, epidemiologist in CDC's physical activity and health branch.

"This is a great foundation to build upon, but there is still much work to do. Improving access to safe and convenient places where people can be physically active can help make the active choice the easy choice."

The U.S. Department of Health and Human Services issued the Physical Activity Guidelines for Americans in 2008 to help the public understand the appropriate amount of physical activity needed to promote a healthy lifestyle. According to the guidelines, adults should get at least two and a half hours a week of moderate-intensity aerobic activity such as walking, or an hour and 15 minutes a week of vigorous-intensity aerobic activity, such as jogging.

In addition, adults should do muscle-strengthening activities, such as push-ups, sit-ups or activities using resistance bands or weights. These exercises should be done two or more days a week and work all major muscle groups, the guidelines suggested.

The report was published in the May 3 issue of the Morbidity and Mortality Weekly Report, a CDC publication.