Where is the ground reaction force located during the midswing phase?

During the midswing phase of gait, the lower limb is advancing forward and the ground reaction force (GRF) acts on the foot as it swings. Typically, the location of the GRF can be understood by analyzing its interactions with the center of mass and the positions of the joints engaged in weight bearing.

In this phase, the foot is off the ground, which means that the force being exerted from the ground is no longer directly beneath the foot, but rather is aligning with the other leg's joint configuration during the swing. The ground reaction force will be posterior to the ankle and knee because these joints are in a flexed posture with the leg progressing forward. When the swing leg moves forward, the moment arm for the GRF in relation to the ankle and knee is posterior, essentially leading to a moment that encourages flexion at these joints.

At the hip, the ground reaction force tends to shift anteriorly due to the forward momentum of the leg. This positioning serves to maintain balance and stability while allowing the swing phase to progress smoothly, preparing the limb for the next phase of gait, which is heel strike.

Thus, the configuration described positions the ground reaction force as being posterior to both the ankle and the knee, aligning correctly with