What is gait cycle exactly? A gait cycle is a series of events in walking or running, and it is measured from one foot contacts the ground (heel-strike) and to the same foot contacts the ground again. Gait cycle has two phases: the weight bearing or stance phase and the non-weight bearing or swing phase. Each gait cycle begins with an initial contact – or heel-strike – of the leading leg in the stance phase, goes through a swing phase then ends with the next contact of the ground with the same leg. Stance phase: stance phase takes up about 60% of the gait cycle. In this phase the foot is on the ground, and that foot accepts body weight and provides single leg support. It can be subdivided into initial contact (or heel-strike), loading response, mid-stance, terminal stance and pre-swing.- initial contact – or heel strike – occur when the heel of the leading leg contacts the ground. It absorbs shock and stabilises the new position. Hip extends, quads and tibialis anterior contract eccentrically. After heel strike the body weight is being transferred to the leading limb.- loading response – initial double limb stance: occur after the initial contact of the leading leg onto the ground, the foot moves from the heel to the toe making the entire foot in full contact with the ground, the bodyweight is being transferred onto the stance limb, until the opposite limb is elevated. Tibialis anterior and quads contract eccentrically. – in mid-stance – single limb support. The limb is fixed and weight is shifted onto this limb – called single legged stance – and the foot turns into stability mode supporting the opposite limb freely swinging forward till both ankles of the limbs are aligned. Hip extensors and quads contract concentrically. – in terminal stance – single limb support – begins when the supporting heel raise off the ground and ends when the contralateral heel touches the ground. Weight moves ahead of the forefoot, the ankle starts to flex downward and the knee extends and the body is propelling forwards.Pre-swing: is the terminal double-limb support period. It starts when the contralateral heel touches the ground and ends when the ipsilateral limb is elevated. Hip flexors contract.Swing phase: takes up about 40% of the gait cycle. In this phase the foot is off the ground and moving forward. In this phase the limb advances. It can be subdivided into Initial swing, Mid-swing and Terminal swing. Initial swing: – toe off. It begins when the foot leaves the ground till full knee flexion occurs, the swinging limb is positioned directly under the body and directly opposite the stance limb. mid-swing: it begins right after knee flexion and ends when the tibia is in a vertical position. Tibialis anterior,extensor hallicus longus, extensor digitorum longus, and peroneus teritus contract. Terminal (late) swing: it begins when the tibia passes beyond plumb, the hip flexes (about 30 degrees), the knee fully extends and the ankle is neutral – all preparing the heel to contact the ground.