Which statement best describes sagittal plane ankle rotation in gait?

Which statement best describes sagittal plane ankle rotation in gait?

• A. It reduces downward COM displacement through dorsiflexion and plantarflexion
• B. It increases downward COM displacement
• C. It has no effect on COM
• D. It only affects upper body movement

Answer: (A)

The sagittal plane rotation of the ankle (dorsiflexion and plantarflexion) helps control how high or low the body's center of mass moves during the stance phase of gait. As the foot accepts weight after heel strike, dorsiflexion allows the tibia to progress over the foot, cushioning impact and preventing a rapid, large downward drop of the center of mass. Later, plantarflexion contributes to propulsion and continued progression while maintaining stability, which also helps limit further downward excursion of the center of mass. In this way, ankle motion in the sagittal plane reduces downward COM displacement rather than increasing it, and it certainly influences whole-body movement beyond the upper body.

The sagittal plane rotation of the ankle (dorsiflexion and plantarflexion) helps control how high or low the body's center of mass moves during the stance phase of gait. As the foot accepts weight after heel strike, dorsiflexion allows the tibia to progress over the foot, cushioning impact and preventing a rapid, large downward drop of the center of mass. Later, plantarflexion contributes to propulsion and continued progression while maintaining stability, which also helps limit further downward excursion of the center of mass. In this way, ankle motion in the sagittal plane reduces downward COM displacement rather than increasing it, and it certainly influences whole-body movement beyond the upper body.