Between initial contact and weight acceptance, which ankle muscles contract and what type?

Between initial contact and weight acceptance, which ankle muscles contract and what type?

• A. Dorsiflexors, eccentric
• B. Plantar flexors, eccentric
• C. Dorsiflexors, concentric
• D. Plantar flexors, concentric

Answer: (A)

During initial contact and the loading response, the foot lands and the body begins to accept weight. The ankle would naturally tend to plantarflex as body weight loads onto the foot, so the dorsiflexors (primarily tibialis anterior) act to brake that motion. They contract eccentrically—lengthening while generating force—to control the amount and speed of plantarflexion, ensuring a smooth transition to full foot-flat and stable weight acceptance. If the dorsiflexors contracted concentrically, they would lift the foot rather than allow a controlled lowering, which isn’t what's needed in this phase. Plantar flexors would be more involved later for push-off, not during this initial loading period.

During initial contact and the loading response, the foot lands and the body begins to accept weight. The ankle would naturally tend to plantarflex as body weight loads onto the foot, so the dorsiflexors (primarily tibialis anterior) act to brake that motion. They contract eccentrically—lengthening while generating force—to control the amount and speed of plantarflexion, ensuring a smooth transition to full foot-flat and stable weight acceptance. If the dorsiflexors contracted concentrically, they would lift the foot rather than allow a controlled lowering, which isn’t what's needed in this phase. Plantar flexors would be more involved later for push-off, not during this initial loading period.