Author Affiliations: Cooper Institute, Dallas, Tex (Dr Blair); and Stanford University School of Medicine, Stanford, Calif (Dr Haskell).
There is compelling evidence that a sedentary and unfit way of life increases the risk of numerous chronic diseases and conditions and decreases longevity.1,2 Heretofore, exposure assessments of sedentary living habits have included self-reports of physical activity,3- 6 job classifications,7 and measurement of cardiorespiratory fitness.8- 10 All of these methods are subject to misclassification. Self-report questionnaires may not include appropriate questions to fully capture all relevant activities, or individuals may have inadequate or inaccurate recall. Individuals working within the same job classification may have widely varying levels of energy expenditure due to efficiency of performing the same tasks, or the tasks may have different energy requirements. Cardiorespiratory fitness assessments are objective laboratory measurements and are generally an accurate indication of physical activity during the weeks and months preceding the test but also may be influenced by other environmental and genetic factors.
Blair SN, Haskell WL. Objectively Measured Physical Activity and Mortality in Older Adults. JAMA. 2006;296(2):216–218. doi:10.1001/jama.296.2.216