Fujii, Tomoko
(2016)
Physical activity, body composition, thigh composition and structural changes in the knees of older adults.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
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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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| 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 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/27306 |
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