Affiliation: PSU School of Community Health
Funding Period: 2007 - 2009
Funding Source: ORCATECH Roybal Pilot Grant
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Abstract
Assessment of physical activity among older adults is of particular public health significance because there are a wide variety of fitness levels in this age group, and the presence of chronic conditions may limit participation in physical activity. Declines in cognitive function may increase recall bias and can further limit the use of questionnaires. Thus, there is a need to objectively assess multiple dimensions of physical activity in older adults using non-invasive technologies that are biologically valid. This project aims to examine and compare methods for the assessment of physical activity intensity in older adults. Specifically, recent advances in accelerometer technology allow the simultaneous measurement of heart rate and accelerometer output, which may provide more precise measurements of daily physical activity over either method alone. Of particular interest in this study of older adults is intensity. The specific aims of this pilot study are:
- To determine the relationship between activity level as measured by accelerometry and heart rate response objectively measured during normal daily life of older adults; and
- To assess level of misclassification between physical activity intensity cut-offs using accelerometry technology and heart rate data in older adults.
The significance of this pilot study is the potential to refine and calibrate ambulatory physical activity monitoring technologies for use in older adults. Participants will be recruited from the Willamette View Retirement Living Facilities and from the Senior Adult Learning Center of Portland State University. For this pilot project we propose to recruit 20 subjects, 10 from each of the following age groups 65-79, and 80+ years with equal distribution of men and women.
Measurement of habitual daily physical activity will be made using the Actical Physical Activity Monitors to provide objective and quantifiable measures of physical activity while the heart rate will be obtained through the Actiheart, a compact heart rate recorder (Mini Mitter, Respironics Co. Bend, OR). Descriptive statistics will be calculated and a non-parametric Wilcoxon Test for paired data will be used to examine differences between methods. Kappa statistic will be used to examine the extent to which the two methods (heart rate and accelerometry) classify the physical activity of participants into various categories (e.g., “inactive”, “low”, “moderate to vigorous”). A Kappa of greater than 0.60 will be considered good agreement. Using the heart rate as the criterion for comparison, sensitivity, specificity, and positive predictive values will also be calculated. We will further evaluate the optimum accelerometry cut-offs for the elderly by recalculating sensitivity and specificity based on changing the published cut-offs until a balanced sensitivity and specificity has been reached.