Patellofemoral dysfunctions due to abnormal force loading are significant problems for dancers. Increased jump length was predicted to require increased quadriceps force during landing, which would increase patellofemoral forces and pressures. Six female dancers performed 10 traveling jumps each at 30, 60, and 90% maximum jump displacements (JDs). A sagittal view of the landing onto a force platform (500 Hz) was filmed (100 fps). Repeated-measures ANOVA (JD) and Scheffé post hoc analyses (p < .05) showed that greater peak patellofemoral pressures occurred at longer JDs and the corresponding times to these events decreased and knee flexion increased. Previous research and these findings indicate that different regions of the patella may endure higher loads at greater JDs even though the contact areas increase with greater patellofemoral forces. However, greater knee flexion and velocity could indicate more rapid distribution of load to various patellar regions, which would reduce the time any given patellofemoral region would be subjected to high loads.
Kathy J. Simpson and Eugene G. Jameson are with the Department of Exercise Science, The University of Georgia, Athens, GA 30602-3654. Susan Odum is with the Department of Kinesiology, Bowling Green State University, Bowling Green, OH 43403.