Although walking is considered a simple straightforward activity, it is actually a complex series of co-ordinated movements involving muscles and joints of the upper and lower body. The manner or style in which a person walks or runs is known as their gait. A gait cycle consists of 2 steps, 1 with the right foot and 1 with the left foot i.e. from right foot initial contact through right limb stance phase and swing phase and ends at right foot initial contact.
The gait cycle can be divided into 2 parts, stance phase and swing phase (fig. 1). Stance phase is the period when the limb is in contact with the ground, this accounts for 60% of the gait cycle. Swing phase is when the limb is not in contact with the ground, this account for 40% of the gait cycle. There are 2 periods of double support, where both limbs are in contact with the ground, both of these last for 10-12% of the gait cycle. The 1st double support starts at initial contact and ends when the opposite foot leaves the ground at toe off. The 2nd double support begins as the opposite limb contacts the ground and ends when the limb in question leaves the ground at toe off.
Stance phase can be divided into 3 parts; 1st rocker which consists of initial contact and load response. During this phase the heel contacts the ground and the ankle plantarflexes until the forefoot is in contact with the ground. When the forefoot has made contact the 2nd rocker begins. This consists of ankle dorsiflexion as the tibia moves from behind the foot, through mid stance to in front of the foot. The 3rd rocker starts as the heel lifts off the floor, causing dorsiflexion at the metatarsalphalageal joints (ball of the foot) and continues through the propulsive phase until the big toe leave the ground at toe off (see fig. 2 below). The big toe leaving the floor marks the end of the stance phase of the gait cycle