229. Pedometer-Measured Physical Activity and Health Behaviors in United States Adults
Source: Medicine & Science in Sports & Exercise, 2010, 42: 1819-1825
Commentary by Professor Adrian Bauman, Cluster for Physical Activity and Health (CPAH), University of Sydney
The paper describes a large sample of adults who wore pedometers to objectively assess their physical activity levels. The pedometer sample was from 1100 US adults, who were part of the “America on the Move” study. The study was based on a population sample, but those participating in America on the Move, although showing geographic diversity could still be considered a somewhat selected sample. Whether the selection bias means that their pedometer step counts were below or are above what you would expect from a true representative sample is not clear but that should be borne in mind when thinking about the results of this study.
The results show that the average American adult only took around 5000 steps per day, with males taking about 400 steps more per day than females. There was an age related decline, with those over 50 taking substantially fewer steps than younger age groups. There are also relationships with educational status, and some geographic variation. Those who were obese took around 1500 steps per day less than those who were not overweight or obese.
There were also interesting gradients with reported physical activity. There was a dose response relationship between the number of days that people exercised and increases in step counts. There was also a dose response relationship between self rated physical activity level and step counts. Those who reported sitting ‘more than 9 hours a day’ typically walked around 1400 steps less than those who sat only ‘1-5 hours per day’.
The results of this study show how inactive Americans are, even compared to population studies in other countries that have used pedometers. This includes studies in Switzerland, Australia and Japan. It does mean that in terms of total physical activity, America reports fairly low rates, even in 2003 when these data were collected. This implies that the low amount of “total physical activity” undertaken by adult Americans might be one contributor to the obesity epidemic in that particular country.
The study also demonstrates the feasibility of carrying out large scale population-based pedometer studies. This provides objective measures of physical activity participation that may be quite different to those that we obtained from self reported data. This is an important addition to the literature, and indicates the feasibility of objectively measured physical activity estimates for our populations.
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