Active Voice: Glory Days at Six Years of Age — A Worrisome Pattern of Low Physical Activity in U.S. Children and Youth
By Catrine Tudor-Locke, Ph.D., FACSM

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.

Catrine Tudor-Locke, Ph.D., FACSM is the director of the Walking Behavior Laboratory at the Pennington Biomedical Research Center in Baton Rouge. She is a walking behavior researcher and an expert in the use of objective physical activity monitoring devices to assess and intervene on ambulatory activity. She has worked to establish standardized measurement protocols and to develop theory-based programs – all aimed at producing a definitive answer to the question of “how many steps are enough?” This commentary presents Dr. Tudor-Locke’s views related to the research article she and her colleagues published in the Dec. 2010 Medicine & Science in Sports & Exercise®.

In Dec. 2010, my colleagues (Drs. William Johnson and Peter Katzmarzyk) and I published “Accelerometer-determined steps per day in U.S. Children and Youth” in Medicine & Science in Sports & Exercise®. The data for the analysis was based on 2,610 children (6-11 years of age) and youth (12-19 years of age) participating in the 2005-2006 National Health and Nutrition Examination Survey (NHANES) Physical Activity Monitor (PAM) component. The accelerometer model (ActiGraph AM-7164) used is a research instrument designed to be sensitive to even very low force steps. In order to provide steps/day values more comparable with pedometers (that are more likely to be adopted by practitioners and lay public), we removed these low force steps during the analysis. Since the NHANES is a nationally representative survey, our findings can be generalized to the U.S. population.

We observed that six-year-old boys in the U.S. take approximately 12,000 steps per day, and these values decrease steadily throughout youth until they average approximately 9,500 steps per day at 18 years of age. U.S. girls take about 10,000 steps per day at six years of age and their values also steadily decline until they average approximately 6,000 steps per day at 18 years of age. These steps per day values are considerably lower than those reported for children and youth from other countries. Although the choice of instrumentation may impact the exact values compared to studies using other technologies, what remains clear is an overall decreasing steps per day pattern in both sexes that portrays a disconcerting early peak at six years of age. In contrast, a recent 13-country review of pedometer-determined physical activity collected around the world reported an increase in steps per day from 6 to 11-12 years of age before a subsequent decline is observed. It is tempting to point out that Bruce Springsteen’s “Glory Days” might be referring to six-year-olds in the U.S. However, the evidence of such a pattern is a non-trivial finding that carries with it disturbing ramifications, among them increased risk for obesity and cardiometabolic diseases, as well as early morbidity and mortality compared to previous generations.

Confronted with such a portentous finding, public health efforts, including policy and environmental initiatives, need to be immediately re-doubled to counteract this pattern of reduced overall physical activity in American children and youth but also its apparently premature peak. To assist us with this goal, the 2010 U.S. National Physical Activity Plan provides a clear set of recommendations, strategies and tactics organized in eight societal sectors including: 1) business and industry; 2) education; 3) health care; 4) parks, recreation fitness and sports; 5) public health; 6) transportation; 7) land use; and 8) community design, volunteer and nonprofit sectors. It is necessary that we work together to implement such multi-pronged and collective efforts to establish a new normative behavior pattern in line with evidence that supports the robust and wide-ranging benefits of a physically activity lifestyle at all ages.