Heel strike (HS)During normal walking, the heel of the swing leg strikes the floor first. This instant is termed heel strike. As the weight shifts forward onto the front foot, the foot rolls forward to footflat. The entire foot bears weight while the contralateral limb is in swing phase.
Toe-off (TO)After heel strike of the contralateral leg, double support occurs. During this time, the heel of the back leg lifts off the floor; this is followed by a pushing off from the toes of this foot. This push off is termed toe-off.
Frequency and cadenceFrequency denotes the number of steps taken per second. Cadence refers to the number of steps per minute and is used in older literature to describe gait. Frequency is much higher in young children than in adults. One year-old children walk with a cadence of about 180 steps per minute (freq = about 3 steps/s) while adults walk at closer to 110-120 steps per minute.
Base of supportThis is the distance in the medial-lateral direction between the right and left foot during double support. In one-year olds, the base of support is wide, in part due to increased hip abduction, knee flexion and pelvic tilt during swing phase (compared to mature gait). As children mature and their balance improves, their base of support during gait narrows.
Stride lengthStride length is the distance from the point where one heel strikes the floor to the next spot where the same heel strikes, in the direction of propulsion. (Left HS to left HS or right HS to the adjacent right HS).
Step lengthStep length is the distance from right heel strike to the adjacent left heel strike, in the direction of propulsion.
Other featuresOne-year olds have recently learned to walk. They hold their arms straight out in front of them and keep their hips and knees flexed throughout the gait cycle. Their foot strikes the ground with a plantarflexed ankle such that the heel does not strike the ground prior to the rest of the foot. By 18 months, heel strike is evident along with, in most children, reciprocal arm swing.