During swing phase, most knee flexion and extension is performed how?

During swing phase, most knee flexion and extension is performed how?

• A. By maximal quadriceps contraction only
• B. By soleus activity
• C. By tibialis posterior only
• D. Passively due to forward momentum

Answer: (D)

During swing, the leg is carried forward mainly by momentum and the forward pull of the hip flexors, so the knee’s bending and straightening happen largely passively. Gravity and inertial forces let the knee flex as the leg arcs forward and then extend as it passes through, with the muscles mainly providing control and timing rather than driving the motion. The quadriceps would not be the primary source of knee flexion here; they’re more involved in controlling knee position and in stance phases. The soleus and tibialis posterior act on the ankle and foot, not the knee, so they don’t power knee motion during swing. This is why the best description is that knee flexion and extension during swing are largely passive due to forward momentum.

During swing, the leg is carried forward mainly by momentum and the forward pull of the hip flexors, so the knee’s bending and straightening happen largely passively. Gravity and inertial forces let the knee flex as the leg arcs forward and then extend as it passes through, with the muscles mainly providing control and timing rather than driving the motion. The quadriceps would not be the primary source of knee flexion here; they’re more involved in controlling knee position and in stance phases. The soleus and tibialis posterior act on the ankle and foot, not the knee, so they don’t power knee motion during swing. This is why the best description is that knee flexion and extension during swing are largely passive due to forward momentum.