Accuracy and repeatability of the Yale physical activity survey in assessing physical activity of older adults.

The purpose of this study was to extend the initial evaluation of the Yale Physical Activity Survey to assess physical activity in older adults. The survey yields three indicators of physical activity reflecting activities performed during a typical week of the previous month (Total Time, Total Energy Expenditure) and the past month (Total Activity Summary Index). Questionnaire validity was studied in 56 men and women, ages 56 to 86 years, by comparing the average of 3- or 7 day 24-hr. physical activity records (n=56), predicted maximal oxygen consumption (VO2 max) (n = 23) and the sum of three skinfold measurements. Two-week repeatability was estimated by calculating an intraclass coefficient using an analysis of variance with repeated measures. Spearman rhos were used to study questionnaire validity. Analysis showed the survey was easily administered and scored and exhibited moderate-to-good repeatability. For the first administration the Total Energy Expenditure Index was significantly associated with the physical activity diary (r = .27). On the second administration, correlations were significant for the physical activity diary with the Total Energy Expenditure Index (r = .30), the Total Activity Summary Index (r = .36), and the Total Time Index (r = .27), and for VO2 max and the Total Time Index (r = .49) and Total Activity Summary Index (r = .64). Relative to the criterion measures used in this study, some validity was evident for the second administration in this relatively active and healthy sample of older adults.