In the rear support phase, which sequence of joints is involved in the triple extension?

In the rear support phase, which sequence of joints is involved in the triple extension?

• A. Hip, knee, and ankle
• B. Shoulder, elbow, and wrist
• C. Ankle, knee, and hip
• D. Hip, ankle, and knee

Answer: (A)

The main idea here is the triple extension, where propulsion comes from a coordinated push of the hip, knee, and ankle. In the rear support phase, the hip extends first to drive the thigh backward, setting up the leg to straighten through the knee, and then the ankle plantarflexes to push off the ground. This proximal-to-distal sequence optimizes how force is transferred into forward momentum. Since propulsion in sprinting doesn’t involve the upper-body joints in this leg-drive moment, and the order shown (hip first, then knee, then ankle) best matches how the leg generates push-off, the sequence hip, knee, and ankle is the correct one.

The main idea here is the triple extension, where propulsion comes from a coordinated push of the hip, knee, and ankle. In the rear support phase, the hip extends first to drive the thigh backward, setting up the leg to straighten through the knee, and then the ankle plantarflexes to push off the ground. This proximal-to-distal sequence optimizes how force is transferred into forward momentum. Since propulsion in sprinting doesn’t involve the upper-body joints in this leg-drive moment, and the order shown (hip first, then knee, then ankle) best matches how the leg generates push-off, the sequence hip, knee, and ankle is the correct one.