In adult walking, ground reaction force parameters are related to time-distance measurements. There is little agreement as to this relationship in the early period of independent walking. The aim of the present research was to examine the relationship between ground reaction force parameters and cadence in independent walking of one-year-old infants. Twenty-four infants, ranging from 10 to 23 months of age, were examined by means of a force plate system and a three-dimensional motion analysis system. Parents of all subjects were told the purpose and contents of this research before measurement. As control subjects, 11 adult males were examined. Maxima of the brake component and the propulsive component in infant walking are smaller than those in adult walking, when differences between subjects in body mass are cancelled by dividing by body weight. The first and second maxima of the vertical component in infants are smaller than those in adults. The minimum of the vertical component and the impulse of the transverse component in infants are larger than in adults. The cadence in infant walking is higher than in adult walking, the cadence decreasing as age increases. Though the result is the same as in previous reports, the present research revealed the new fact that the cadence of infants increases until 17 months of age, peaks at 17 to 20 months, and decreases after 20 months. The minimum of the vertical component and the impulse of the transverse component decrease, and the maxima of the brake and propulsive components increase when the cadence increases. Force parameters of infants differ from those of adults in the same range of cadence. For example, the maximum of the propulsive component of infants is remarkably smaller than that of adults. No differences were observed between infants and adults in the minimum of the vertical component, the maximum of the brake component, or the impulse of the transverse component in the same range of relative cadence (cadence×√<stature>). The maximum of the propulsive component of infants is smaller than that of adults at the same relative cadence. Comparison between infants and adults revealed that the angular displacement of the hip joint is related to the maximum of the propulsive component.
