Movements of the legs that can be elicited in the human newborn. When held upright, tilted slightly forward, supported under the armpits, and the soles of the feet are brought into contact with a surface, the infant displays an alternating and plantigrade stepping pattern. It is usually observed for 2-3 months postnatally and then can no longer be elicited. Evidence suggests it cannot be elicited due to increases in mass of legs and a lack of muscle power to move their increased weight, rather than through cortical inhibition.
See Cortical inhibition hypothesis, Infantile responses, Plantigrade locomotion, Qualitative and quantitative regressions