Effects of Cycling Workload and Cadence on Frontal Plane Knee Load

The effect of workload and cadence on sagittal plane knee biomechanics in cycling has been widely studied, however few studies have focused on the frontal plane. Frontal plane knee biomechanics, especially knee abduction moment, is closely related to the severity and progression of knee osteoarthritis. The purpose of this study was to investigate the effects of different workloads and cadences on knee frontal plane kinematics and kinetics. Eighteen subjects participated in this study. A motion analysis system was used to collect five cycles of kinematics during two minutes of cycling in eight testing conditions, which included five workload conditions of 0.5, 1, 1.5, 2, and 2.5 kg at 60 revolutions per minute (RPM), and four cadence conditions of 60, 70, 80, and 90 RPM with 1 kg workload. A custom instrumented pedal was used to collect pedal reaction force (PRF). Increased workloads with constant RPM significantly increased knee abduction moment and knee abduction range of motion (ROM), without any change of peak knee adduction angle. Increased workloads also significantly increased medial, posterior, and vertical pedal PRF, and knee extension moment. Increased cadences with constant workload had no effects on knee abduction moment. In addition, increased cadences increased anterior and vertical PRF, and knee flexion moment. We found two patterns of frontal knee moments among our subjects which deserves further investigation. Further study may be needed to demonstrate the efficacy of appropriate level of workload in the knee osteoarthritis and other deceased populations.