All three joints perform the final propulsive movements during toe-off. The plantar flexors plantar flex, pushing off from the ground and returning from dorsiflexion in midstance. This can either occur by releasing the elastic load from an earlier mid/forefoot strike or concentrically contracting from a heel strike. With a forefoot strike, both the ankle and knee joints will release their stored elastic energy from the footstrike/absorption phase. The quadriceps group/knee extensors go into full knee extension, pushing the body off of the ground. At the same time, the knee flexors and stretch reflex pull the knee back into flexion, adding to a pulling motion on the ground and beginning the initial swing phase. The hip extensors extend to maximum, adding the forces pulling and pushing off of the ground. The movement and momentum generated by the hip extensors also contributes to knee flexion and the beginning of the initial swing phase.