Research article
Physical Activity in U.S. Adults: Compliance with the Physical Activity Guidelines for Americans

https://doi.org/10.1016/j.amepre.2010.12.016Get rights and content

Background

To date, no study has objectively measured physical activity levels among U.S. adults according to the 2008 Physical Activity Guidelines for Americans (PAGA).

Purpose

The purpose of this study was to assess self-reported and objectively measured physical activity among U.S. adults according to the PAGA.

Methods

Using data from the NHANES 2005–2006, the PAGA were assessed using three physical activity calculations: moderate plus vigorous physical activity ≥150 minutes/week (MVPA); moderate plus two instances of vigorous physical activity ≥150 minutes/week (M2VPA); and time spent above 3 METs ≥500 MET-minutes/week (METPA). Self-reported physical activity included leisure, transportation, and household activities. Objective activity was measured using Actigraph accelerometers that were worn for 7 consecutive days. Analyses were conducted in 2009–2010.

Results

U.S. adults reported 324.5±18.6 minutes/week (M±SE) of moderate physical activity and 73.6±3.9 minutes/week of vigorous physical activity, although accelerometry estimates were 45.1±4.6 minutes/week of moderate physical activity and 18.6±6.6 minutes/week of vigorous physical activity. The proportion of adults meeting the PAGA according to M2VPA was 62.0% for self-report and 9.6% for accelerometry.

Conclusions

According to the NHANES 2005–2006, fewer than 10% of U.S. adults met the PAGA according to accelerometry. However, physical activity estimates vary substantially depending on whether self-reported or measured via accelerometer.

Introduction

The Physical Activity Guidelines for Americans (PAGA) released by the USDHHS provide definitive public health recommendations for physical activity.1 The PAGA recommend that adults obtain at least 150 minutes/week of moderate-intensity physical activity (MPA), 75 minutes/week of vigorous-intensity physical activity (VPA), or a combination of moderate and vigorous physical activity (MVPA). The guidelines are conceptually similar to previous recommendations,2, 3 but provide more flexibility in how physical activity is accumulated across the week. Another distinction is that the PAGA increased the VPA guideline from 60 minutes/week (20 minutes × 3 days/week) to 75 minutes/week.

The advisory committee that developed the PAGA made these recommendations based on accumulating evidence that the health benefits from physical activity are primarily dependent on total energy expenditure.4 The committee concluded that the amount of energy expenditure necessary to achieve many of the health benefits was in the range of 500–1000 MET-minutes/week. Based on the standard MET thresholds (3 METs for MPA and 6 METs for VPA), this can be achieved with approximately 150 minutes/week of MPA or 75 minutes/week of VPA. The use of MET-minutes allows the guidelines to focus on total energy expenditure in physical activity.

For effective public health surveillance, it is important to determine the proportion of U.S. adults that meet the guidelines outlined in the PAGA. Compliance with the PAGA was evaluated in one recent study,5 but this relied on self-report data. An earlier study6 examined compliance with previous physical activity recommendations using accelerometry. Although the PAGA are similar to previous recommendations, it is important to understand how the guidelines in PAGA may affect national data for public health surveillance.

The purpose of the current study was to assess self-reported and objectively measured physical activity levels among U.S. adults according to the 2008 PAGA. To date, no studies have compared the physical activity levels of Americans measured from both self-report and accelerometer. Therefore, an ancillary objective of the study was to compare self-report and accelerometer physical activity outcomes, in order to gain insight into the relationship between these two assessment tools.

Section snippets

Study Population

Data for the current study were obtained from the National Health and Nutrition Examination Survey (NHANES) 2005–2006.7 The NHANES uses a multi-stage probability cluster sampling design to provide nationally representative data on a variety of health risks and behaviors, including both self-reported and objective estimates of physical activity.

All counties within the U.S. served as the sampling frame for the NHANES. Within these counties, clusters of households were selected, after which one or

Results

A total of 4773 adults completed both the accelerometer and self-report physical activity measures. Of those, a subsample of 3082 (64.6%) adults met the compliance criteria for Actigraph wear time and did not have any missing data. Nationally representative estimates from the current study were based on this subsample (n=3082).

Discussion

The current study found that 9.5% of men and 7.0% of women achieved the PAGA-recommended levels according to the accelerometry MVPA assessment method. Although much lower than self-reported estimates, the proportion of adults meeting the guidelines according to accelerometry was higher than those presented by Troiano and colleagues.6 Using data from NHANES 2003–2004, Troiano et al. reported that according to MVPA performed in 10-minute bouts, only 2.5% (if aged >60 years) to 3.5% (if aged 20–59

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