Simulated Deep Flexion With Muscle Loading: Whole Leg Versus Knee Kinematics

Many activities of daily living during work, exercise, religious worship, and hobbies require deep knee flexion. Activities such as rising from a low chair or getting into or out of a bath require between 100° and 160° of knee flexion [1]. Other activities such as kneeling or squatting to pick an item off the ground can be difficult with a limited range of motion. Beside deep knee flexion being important for daily living activities, it is essential in non-Western cultures that commonly sit in deep knee-bending positions. In vitro studies looking at knee function often focus solely on the knee joint, ignoring the effect of the muscle, ligament, and tendon constraints of the ankle, and simplifying or neglecting muscle loads. The effects of these assumptions on kinematics are unknown. The purpose of this study was to compare a squatting activity for: 1) whole leg versus knee specimens, and 2) different combinations of quadriceps and hamstrings loading.