Which movement will lengthen the fibers of the gastrocnemius?

• A. Dorsiflexion
• B. Plantar Flexion
• C. Inversion
• D. Eversion

Answer: (A)

The gastrocnemius is a two‑joint muscle that crosses both the knee and the ankle. To lengthen its fibers, you need to move the ankle into dorsiflexion (lifting the front of the foot toward the shin). When the ankle dorsiflexes and the knee is kept extended, the muscle is stretched along its full length, so its fibers lengthen. Plantarflexion would shorten it, because pointing the toes down tightens the gastrocnemius. Inversion and eversion mainly affect the foot’s side-to-side motions and don’t place the gastrocnemius under a lengthening stretch.