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Author
Title The Influence of Ambulation Speed and Corresponding Mechanical Variables on Articular Cartilage Metabolism
URL
Publication Date
Degree PhD
Degree Level doctoral
University/Publisher Brigham Young University
Abstract During ambulation, lower-extremity joint angles and net moments influence knee joint load. It is unclear which mechanical variables most strongly correlate with acute articular cartilage (AC) catabolism in response to ambulation. Purpose: To determine which mechanical variables are most strongly correlated to acute AC catabolism, and to test the acute effect of ambulation speed on AC catabolism, while controlling for load frequency. Methods: 18 able-bodied subjects (9 male, 9 female; age = 23 ± 2 y; mass = 68.3 ± 9.6 kg; height = 1.70 ± 0.08 m) completed three separate ambulation sessions: slow (preferred walking speed), medium (+50% of walking speed), and fast (+100% of walking speed). For each session, subjects completed 4000 steps on an instrumented treadmill while ten high-speed cameras recorded synchronized video data. Various, discrete, three-dimensional joint kinematic and kinetic variables were averaged across 20 total stance phases (5 stance phases at 1000, 2000, 3000, and 4000 steps). Blood samples were collected pre-, post-, 30-min post-, and 60-min post-ambulation. Serum cartilage oligomeric matrix protein (COMP) concentration was determined using an enzyme-linked immunosorbent assay. A stepwise multiple linear regression analysis was used to evaluate the relationships between serum COMP change and lower-extremity joint angles and moments. A mixed model ANCOVA was used to evaluate serum COMP concentration between sessions across time. Results: Peak ankle inversion, knee extension, knee abduction, hip flexion, hip extension, and hip abduction moment, and knee flexion angle at impact, explained 61.4% of the total variance in serum COMP change (p < 0.001), due to ambulation. COMP concentration increased 28%, 18%, and 5% immediately after ambulation for the running, jogging, and walking sessions, respectively. All sessions were significantly different immediately post-ambulation (p < 0.01). Conclusion: Certain lower-extremity joint mechanics are associated with acute AC catabolism, due to ambulation. Several key mechanical variables (e.g., peak knee extension, knee abduction, and hip abduction moments) explain much regarding the variance in serum COMP increase. These lower-extremity variables can be used to predict acute AC catabolism, allowing researchers and clinicians to better predict and/or understand AC catabolism. Additionally, when load frequency is controlled, increased ambulation speed acutely results in increased AC catabolism. Ambulation speed does not, however, influence serum COMP elevation duration. Joint mechanics and load frequency appear to be responsible for the magnitude of COMP increase, while duration of COMP elevation post-ambulation is dictated by load frequency.
Subjects/Keywords ambulation; mechanics; articular cartilage; COMP; Exercise Science
Language en
Rights License: http://lib.byu.edu/about/copyright/
Country of Publication us
Format application: pdf
Record ID oai:scholarsarchive.byu.edu:etd-5033
Repository byu
Date Retrieved
Date Indexed 2018-12-13

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…acute bout of physical activity. Identifying strong predictors of AC catabolism due to exercise could give researchers and clinicians mechanical clues on mechanisms associated with AC loss. Cartilage oligomeric matrix protein (COMP), is an…

…extracellular non-collagenous proteoglycan that helps organize the cartilage matrix and contribute to its load bearing capability26,27. Elevated resting serum COMP concentration reflects cartilage degradation in an OA population28,29 and is associated with early…

…stages of OA and OA progression30,31. For ablebodied individuals, serum COMP concentration increases in response to physical activity, indicating the catabolic effect of exercise-induced load on AC32-34. Relative to walking, greater serum COMP

…concentrations are found after running for the same duration33,35. It is unclear, however, whether serum COMP concentration increases more for running, relative to walking, due to altered mechanics or simply due to the different frequency of applied load (…

…running involves a greater frequency than walking). No one has simultaneously measured serum COMP concentration and movement mechanics during able-bodied ambulation across various speeds. Such a study could potentially (1) identify which…

…mechanical variables are most strongly associated with acute AC catabolism, as reflected by COMP, and (2) provide additional insight regarding the effect of load magnitude and frequency, across a wide range of ambulation speeds (i.e., walking…

…mechanical variables previously associated with knee load would positively correlate to serum COMP concentration increases, due to ambulation, across various ambulation speeds. We also hypothesized that, while controlling for load frequency, serum COMP

…influence of preceding physical activity (e.g., walking to the data collection site) on serum COMP concentration33. Subjects then stood for 10 min, to allow for body fluid distribution to adjust to the vertical posture, while we applied reflective…

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