In 2008 new guidelines for physical activity were released by the United States Department of Health and Human Services. The Physical Activity Guidelines for Americans (PAGA) recommend that adults obtain at least 150 minutes/week of moderate-intensity physical activity, or 75 minutes/week of vigorous-intensity physical activity, or a combination of moderate and vigorous physical activity¹. These levels are those necessary for substantial health benefits which include decreasing the risk of premature death; decreasing the risk of diseases such as heart disease, stroke, some cancers, type 2 diabetes, osteoporosis, and depression; decreasing the risk of high blood pressure and high cholesterol; and improving the ability to function in every day life. The guidelines are very similar to previous recommendations but provide more flexibility in how physical activity is accumulated across the week. Previously the guidelines stated that at least 30 minutes on a given day were necessary as a minimum². Now, however, there is no daily minimum as long as physical activity is performed in 10-minute bouts and accumulates to the recommended amounts for the week.

So how are we doing measuring up to these guidelines?
According to self-reported data from the National Health and Nutrition Examination Survey (NHANES), approximately 62% of U.S. adults achieved the recommended amounts of activity³. However, accelerometer data revealed that less than 10% of adults met the requirement. An accelerometer is a device that is worn, in this case on the hip, that monitors body movement and records the duration and intensity of activity.

So why the big difference?
The authors of the study have a few thoughts on this. They feel that it is possible that self-reported physical activity is overestimated for a number of reasons, the first being because people want to be viewed favorably by others. This generally causes overreporting of good behavior and underreporting of bad behavior. They also present the possibility that some of the NHANES survey questions could have been misinterpreted. The survey asked questions about frequency and duration of physical activity performed during transportation, household, and leisure time activities. It is quite possible that some of these activities were viewed as moderate-intensity when in reality they may have been of low-intensity. And lastly, participants may have reported activity of all durations versus just those that occurred in 10-minute bouts or more.

They also feel that even though accelerometry is an objective measurement tool, that it is possible that it underestimated physical activity in this study. Because the monitors were worn on the hip, they tend to best estimate activity that is locomotive in nature such as walking or running. They cannot accurately assess upper body activities, nor can they account for movements that require extra effort (intensity), like walking up hill or carrying a load. Even biking and many household activities have the potential to be underestimated by this monitor.

What does this all mean?
Regardless of how you measure it, the bottom line is Americans need to move more! We are not meeting the minimum physical activity recommendations needed to benefit our health. Below are some tips to help you achieve the guidelines.

• Ditch your car and try more active modes of transportation.
• Pick up the pace while doing household chores.
• Take walk breaks at lunch.
• Reduce the time you spend being inactive for example watch a little less TV.
• Choose exercise that you find fun.
• Do your own yard work or wash your own car.
• Make time for family walks for example after dinner or on Saturday mornings.
• Play with your kids.

While all activity is good and burns additional calories, in order for it to count towards the recommendations it needs to be moderate-intensity. You don’t have to break out in a sweat but you should feel like you are pushing yourself a bit. This should cause an increase in your breathing and a warm feeling in your muscles. You should be able to carry on a conversation but not sing easily. Look back at this previous blog for a good guide on how to judge if your walk is at a moderate-intensity.

There is some good news in the study. It does appear that Americans are slightly more active than they have been in the past; but again, well below what is needed for health improvements.

We want to know. What do you think we are closer to—10% of Americans meeting the recommendations or 62%? What do you do to try to get in the required amount of activity and at the proper intensity? Let us know on our Facebook page.

References
¹GovTrack.us S. 2748-110th Congress (2008). Physical Activity Guidelines for Americans Act of 2008, GovTrack.us (database of federal legislation) www.govtrack.us/congress/bill.xpd?bill=s110 27488&tab=analysis.
²Pate RR, Pratt M, Blair SN, et al. Physical activity and public health. A recommendation from the CDC and the American College of Sports Medicine. JAMA 1995; 273(5): 402-407.
³Tucker JM, Welk GJ, & Beyler NK. Physical Activity in U.S. Adults: Compliance with the Physical Activity Guidelines for Americans. Am J Prev Med 2011; 40(4): 454-461.