THE IN VIVO RESPONSE OF KNEE ARTICULAR CARTILAGE TO RUNNING AND BICYCLING

Abstract

Background Knee osteoarthritis is a degenerative joint disease characterized by damaged cartilage, tendons, ligaments, synovium, and bone. Knee osteoarthritis causes joint pain, reduced joint function, and decreased quality of life and is the leading cause of chronic disability in older adults. Two of the major risk factors for knee osteoarthritis are increasing age and obesity. To decrease the occurrence of knee osteoarthritis in our aging population, it is important that we identify exercises that are safe for people with or at risk of knee osteoarthritis. Purpose The main purpose of this thesis was to compare the acute response of knee cartilage composition to two common aerobic activities, running and bicycling, of equal total load. To address the primary purpose, we first sought to determine the reliability and validity of measuring loading repetition during running (steps) and bicycling (pedal-revolutions) using accelerometry. Methods 1) Twenty-two healthy adults completed running and bicycling activity bouts (five-minutes) while wearing six accelerometers: two at each the waist, thigh and shank. Accelerometer and video data were collected during each activity. 2) Fifteen healthy men completed running and bicycling activities of equal cumulative load that were preceded and followed by a series of magnetic resonance images. Results 1) Excellent reliability (ICC≥.99; SEM≤1.0) and validity (Pearson≥.99) were found for step and pedal revolution measurements taken by an accelerometer placed at the shank. 2) Bicycling did not cause significant changes in cartilage composition (p=0.274); however, running did cause a change in cartilage composition (p=0.002). Conclusion Findings from this thesis suggest that to acquire reliable and valid step and pedal revolution measurement, accelerometers should be placed on the shank. Furthermore, bicycling causes no statistical changes in knee cartilage, while running does. Bicycling may therefore be used to combat obesity and maintain cardiovascular health in individuals with compromised joint health.