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Quantifying Physical Activity in Community Dwelling Older Adults Using Accelerometry

Talkowski, Jaime Berlin (2008) Quantifying Physical Activity in Community Dwelling Older Adults Using Accelerometry. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Background: A physically inactive lifestyle is associated with an increased risk for a variety of chronic diseases and health conditions. One population at greatest risk of physical inactivity is older adults. Studies: The specific aims for my dissertation research focused on further development of the Actigraph accelerometer to measure physical activity in community dwelling older adults. I proposed to first further define what an "activity count" from the Actigraph accelerometer represents. By comparing Actigraph counts to raw accelerometry, oxygen consumption and pedometer step count data at usual and slow walking speeds we found that counts per second were correlated with raw accelerometry and energy cost. Actigraph counts, raw acceleration, pedometer step counts and oxygen consumption were higher for usual versus slow walking conditions as expected. We were able to formulate a regression equation to estimate energy cost from Actigraph counts in community dwelling older adults. For the next project, I investigated the reliability and validity of the various ways to present data from the Actigraph accelerometer. All Actigraph measurement units of interest were highly correlated with each other as well as with performance based measures of mobility, function, age and self reported physical activity. Actigraph counts per minute and standard deviations of counts were able to distinguish between low and high mobility and functioning groups. Using ROC curves, we established a cut off value of 150 counts per minute to detect mobility and function problems. Finally, I determined meaningful change values of physical activity measured by the Actigraph over a 12 week exercise intervention in community dwelling older adults with walking difficulty. We found a value of 30 counts per minute to indicate substantial change beyond spurious error. Actigraph counts per minute did not change over the course of exercise intervention. However, people who were more active at baseline exhibited improvements in mobility and functional measures compared to those who were less active at baseline.Conclusion: From the projects described above, Actigraph counts have been validated in older adults against raw accelerometry, oxygen consumption, mobility, function, and self-reported physical activity measures. Inter-rater reliability was excellent for the multiple outputs of the Actigraph accelerometer. Actigraph counts per minute data output is our recommendation since it is the default output, has the least amount of processing, produces high inter-rater reliability and validity against mobility and function.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Talkowski, Jaime Berlinjberlin@pitt.eduJBERLIN
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBrach, Jenniferjbrach@pitt.eduJBRACH
Committee MemberVanSwearingen, Jessiejessievs@pitt.eduJESSIEVS
Committee MemberCham,
Committee MemberStudenski, Stephaniesas33@pitt.eduSAS33
Committee MemberPerera, Subashanpereras@dom.pitt.eduKSP9
Date: 8 September 2008
Date Type: Completion
Defense Date: 21 July 2008
Approval Date: 8 September 2008
Submission Date: 30 July 2008
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Institution: University of Pittsburgh
Schools and Programs: School of Health and Rehabilitation Sciences > Rehabilitation Science
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: accelerometry; geriatrics; physical activity
Other ID:, etd-07302008-160330
Date Deposited: 10 Nov 2011 19:55
Last Modified: 15 Nov 2016 13:47


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