Stages in the walking cycle
Walking is a complex learned behaviour which requires complex coordination of different segments of the lower limb in order to walk. We have to balance over one leg while controlling a forward motion. During walking, one foot is always in contact with the ground. The walking cycle, also known as the gait cycle can help us understand the biomechanics behind walking. The cycle can be divided up into two stages, the stance phase which accounts for 60% of the cycle and the swing phase which accounts for the other 40%.
The first part of the stance phase is initial contact, also known as the heelstrike. Here, the foot is inverted and dorsiflexed as it makes contact with the ground.
During the loading response the foot becomes flat and makes contact with the ground through planterflexion by using the ankles rocker motion. During midstance the full bodyweight is taken up by the white leg. The other leg(in this case the shaded leg)in this part of the cycle starts its swing phase. Terminal stance is where the heel is starting to come off the ground when pushing on that leg because the foot is becoming everted and plantarflexed. The bodyweight will be thrown forward while the white leg is acting as a single supporting foot.
The last phase is the pre-swing phase, here full plantarflexion takes place. There is a very brief amount of double support here as the other leg(shaded leg) takes some of the body weight as well.
The first part of the swing phase is known as the initial swing, here the foot is off the ground and the limb accelerates forward because of the heavy weight of the limbs. During the midswing, the limb is directly underneath the body and the foot is dorsiflexed as it is swinging to stop the toes from dragging on the ground. The last phase is known as the terminal swing, here the momentum of the limb needs to be slowed down so that it can come in contact with the ground and be ready for the initial contact for the next cycle.
Muscles used during walking
Different muscles are active during different times of the walking cycle. During the stance phase, the dorsiflexors such as the anterior tibilas are active during the heelstrike. The gluteus maximus and the hamstring, which are the hip extensors extend the hip early in the stance phase because the leg needs to be pulled back. During the loading response, the knee is flexed by the quadriceps so that we have a stable base to take our bodyweight. During midstance, the pelvis is stabilised by the gluteus medius and gluteus minimus which are hip abductors. During midstance and terminal stance, the triceps surae, also known as the calf muscles are active so that they can pull the leg and begin plantarflexion of the foot. The rectus femoris are then active during the preswing phase to lift and flex the hip.
During the swing phase, hip flexors such as Ilias psoas, sartorius, rectus femoris help to lift the leg off the ground early in the swing phase so that the leg does not drag on the ground. The end of the swing phase is brought up by the gluteus maximus to act against thigh momentum. The hamstrings also become active to flex the knee and the dorsiflexors contract to prevent the toes from dragging on the ground.