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Physical activity, body composition, thigh composition and structural changes in the knees of older adults

Fujii, Tomoko (2016) Physical activity, body composition, thigh composition and structural changes in the knees of older adults. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Osteoarthritis of the knee (knee OA) is a major cause of disability. The effect of physical activity and sedentary time on knee structural changes in older adults has not been established. Recent studies highlight the metabolic aspect of knee OA, but whether higher weight or metabolic mechanisms are more important is unknown. First, physical activity level was defined based on subjectively measured energy expenditure in total and for exercise in the Health, Aging and Body Composition Study. In older adults without knee pain, being lifestyle active or an exerciser was associated with two times higher odds of severe cartilage damage in the medial tibiofemoral joint compared with being inactive, suggesting vulnerability of knee cartilage to higher physical activity levels. In older adults with knee pain, those watching TV for ≥7 hours/week had over two times higher odds of bone marrow lesion (BML) in the whole knee, and ≥14 hours/week with 2.6 times higher odds of severe cartilage damage in the medial compartment compared with <7 hours/week. Next, body composition from DXA, and abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) areas on CT were examined. Higher appendicular lean mass rather than total body fat mass was associated with knee structural changes. Greater VAT area per weight was not positively associated with knee outcomes. Significant associations between greater SAT area and higher odds of knee structural changes found only in women were not explained by inflammatory markers, adipokines, or cardiometabolic risk factors. Lastly, thigh fat composition on CT and knee extensor strength were examined. Higher thigh density reflecting lower intramuscular fat, specifically quadriceps in men and hamstring in women, and higher knee extensor strength per quadriceps area in women were associated with lower odds of structural changes. Generally, no association with structural change was found for thigh intermuscular adipose tissue area or thigh SAT area. These findings support the importance of mechanical mechanisms rather than metabolic mechanisms. This dissertation has the important public health implication that weight control, good muscle quality and proper levels of physical activity are recommended for knee OA prevention and control in older adults.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Fujii, Tomokotof7@pitt.eduTOF7
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairBoudreau, Robert M.BoudreauR@edc.pitt.eduROB21
Committee MemberMiljkovic, Ivamiljkovici@edc.pitt.eduIVM1
Committee MemberStrotmeyer, Elsa S.strotmeyere@edc.pitt.eduELSST21
Committee MemberBrach, Jenniferjbrach@pitt.eduJBRACH
Committee MemberKwoh, C
Date: 29 June 2016
Date Type: Publication
Defense Date: 11 April 2016
Approval Date: 29 June 2016
Submission Date: 23 March 2016
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 199
Institution: University of Pittsburgh
Schools and Programs: School of Public Health > Epidemiology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: knee osteoarthritis, MRI, physical activity, body composition, intramuscular fat, older adults
Date Deposited: 29 Jun 2016 17:26
Last Modified: 01 May 2021 05:15


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